Storage and transport stabilizers for polymerizable compounds

Abstract

The present invention relates to a mixture comprising (meth)acrylic acid and / or a (meth)acrylate having an alkyl group of C 1 to C 8 and one or more compounds of general formula (II) as a quality retention and storage stabilizer.

Description

[0001] Compounds containing one or more ethylenically unsaturated groups have a distinct tendency to radical polymerization. Therefore, such compounds are also referred to as polymerizable compounds. The tendency of these compounds to radical polymerization means that they are used as monomers for the preparation of polymers, for example by intentional radical polymerization. However, the distinct tendency of these compounds to radical polymerization is also a disadvantage, because during storage and transport and during chemical and physical processing, such as by distillation or rectification, in particular under the action of energy (such as heat and / or light), unwanted spontaneous radical polymerization may occur. This uncontrolled polymerization leads to the gradual formation of polymer deposits, for example on heated surfaces, which requires the removal of the polymer deposits and thus often results in a reduction of the operating time or may even lead to an explosion.

[0002] Therefore, during the storage and transport and during chemical and / or physical processing of ethylenically unsaturated compounds having a tendency to radical polymerization or mixtures containing such compounds, substances are generally added which prevent or retard unwanted spontaneous radical polymerization. Such substances are generally and hereinafter referred to as polymerization inhibitors or polymerization stabilizers.

[0003] The polymerization stabilizer can be used in the form of a single compound or a mixture of compounds. Depending on its field of use, the polymerization stabilizer may have specific requirements. For example, for a polymerization stabilizer suitable as a stabilizer for the transport and storage of ethylenically unsaturated compounds, it is important that the efficiency of the polymerization stabilizer can be adjusted, i.e., the degree of stabilization or inhibition of polymerization. Under the storage and / or transport conditions of the ethylenically unsaturated compound, the polymerization stabilizer should be sufficient to prevent or delay unwanted spontaneous free-radical polymerization, while under appropriate polymerization conditions, the desired free-radical polymerization of the ethylenically unsaturated compound should be possible without first separating the polymerization stabilizer used during storage and / or transport. If the stabilizer used during storage and / or transport is not separated during the desired polymerization, it is important that no adverse effects are produced or that it does not inadvertently act as a chain transfer agent during the desired polymerization (for polymerization chain transfer agents, see, for example, Ullmann's Encyclopedia of Industrial Chemistry, Polymerization Processes, 1. Fundamentals, 6 Free-Radical Polymerization, DOI 10.1002 / 14356007.21_305.pub3 or Ullmann's Encyclopedia of Industrial Chemistry, Polyacrylates, 4.1.1 Starting Materials, DOI 10.1002 / 14356007.a21_157.pub2).

[0004] In terms of global production, acrylic acid is undoubtedly one of the most important ethylenically unsaturated compounds. Based on the amount of acrylic acid during storage and / or transportation, as a standard, acrylic acid is stabilized with 180 to 220 weight ppm of methyl hydroquinone (MEHQ) to prevent unwanted spontaneous free radical polymerization. In order to fully stabilize acrylic acid with MEHQ to prevent the occurrence of unwanted spontaneous free radical polymerization, a sufficient amount of oxygen must be dissolved in acrylic acid. When acrylic acid is stored and / or transported in an atmosphere containing 5 to 21% by volume of oxygen, usually a sufficient amount of oxygen is dissolved in acrylic acid. The stabilization of acrylic acid with MEHQ during transportation and / or storage is described, for example, in Acrylic Acid, A Summary of Safety and Handling, 4th Edition, 2013, 6.1 Instability and Reactivity - Polymerisation, and 7.1. Bulk Storage Facilities and Accessories - General Considerations. In the desired polymerization of acrylic acid, for example in the production of polyacrylates, the content of dissolved oxygen in acrylic acid is reduced, which reduces the efficiency of MEHQ as a polymerization stabilizer, thereby enabling acrylic acid to polymerize in the presence of MEHQ.

[0005] In addition to being used as a polymerization stabilizer during the storage and / or transportation of acrylic acid, MEHQ is also used as a polymerization stabilizer during the storage and / or transportation of methacrylic acid, acrylates, methacrylates, or mixtures containing one or more of the said compounds. Acrylic acid or methacrylic acid is hereinafter referred to as (meth)acrylic acid, and its esters are hereinafter referred to as (meth)acrylates.

[0006] Due to its wide range of uses, MEHQ is one of the most important storage and / or transportation stabilizers for usually polymerizable compounds, especially (meth)acrylic acid and (meth)acrylates.

[0007] The polymerizable compound is stored in a suitable, permanently installed container, such as a storage tank or other suitable storage container (see, for example, Acrylic Acid, A Summary of Safety and Handling, 4th Edition, 2013, 7Bulk Storage Facilities and Accessories). The storage of the polymerizable compound in each container is preferably for more than 1 minute, more preferably for more than 10 minutes, and particularly preferably for more than 60 minutes. Although the storage time under appropriate conditions is theoretically unlimited, for economic reasons, the storage time is usually reduced to a minimum. The storage of the polymerizable compound in each container is preferably not more than 180 days, more preferably not more than 90 days, and particularly preferably not more than 30 days. The particularly preferred range comes from the free combination of the above lower and upper limit ranges.

[0008] The transportation of the polymerizable compound by ship, rail, and / or truck usually uses suitable transportable containers, such as tanks or other suitable containers (see, for example, Acrylic Acid, A Summary of Safety and Handling, 4th Edition, 2013, 9Safe Transport of Acrylic Acid). The transportable containers can of course also be permanently installed, such as tanks on ships or rail tank cars. Of course, the containers can also be stored at a specific location for a period of time before transporting them elsewhere. The transportation of the polymerizable compound can also be carried out in pipelines or hoses, such as during the transportation of the polymerizable compound to the storage tank after purification, during the loading from the storage tank to the transportable container, and / or during the loading from one transportable container to another. The transportation of the polymerizable compound in each container is preferably for more than 10 seconds, more preferably for more than 1 minute, more preferably for more than 10 minutes, and particularly preferably for more than 60 minutes. Although the time under appropriate conditions is theoretically unlimited, for economic and safety reasons, the time is usually reduced to a minimum. The transportation of the polymerizable compound in each container is preferably not more than 180 days, more preferably not more than 90 days, and particularly preferably not more than 30 days. The particularly preferred range comes from the free combination of the above lower and upper limit ranges.

[0009] To reduce the dependence on MEHQ, it is an object of the present invention to provide a mixture comprising (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters and one or more storage and / or transport stabilizers. The storage and / or transport stabilizer should ensure that (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8The alkyl esters are sufficiently stable to prevent unwanted free radical polymerization. Additionally, it is also advantageous if, in the desired free radical polymerization, it is not necessary to separate the storage and / or transport stabilizer from the mixture prior to polymerization. Thus, the storage and / or transport stabilizer should not act as a chain transfer agent and / or inhibitor in the desired free radical polymerization.

[0010] In the context of the present invention, a compound is suitable as a storage and / or transport stabilizer for (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters and does not act as a chain transfer agent and / or inhibitor in the desired free radical polymerization, wherein, under comparable conditions, the compound

[0011] a) Based on the efficiency meter of equimolar amounts of MEHQ, inhibits the spontaneous free radical polymerization of liquid acrylic acid stored in an atmosphere containing 5 to 30% by volume of oxygen with an efficiency of 75% or higher,

[0012] and

[0013] b) Based on the efficiency meter of equimolar amounts of MEHQ, inhibits the free radical polymerization of liquid acrylic acid stored in an atmosphere containing 96 to 100% by volume of nitrogen and added with 1000 to 15000 ppm by weight of a polymerization initiator with an efficiency of 130% or lower, and obtains comparable or similar polymers after polymerization. The nitrogen content in the atmosphere is preferably 99 to 100% by volume.

[0014] In a) and b), the amount of MEHQ used is 10 to 250 ppm by weight, preferably 35 to 45 ppm by weight. The values in ppm by weight are based on the amount of the liquid acrylic acid used.

[0015] Comparable or similar polymers are obtained when the polymers have substantially the same weight average (measured according to the same GPC method). Substantially the same weight average exists when the weight averages differ by 20% or less.

[0016] Suitable as the polymerization initiator are the polymerization initiators commonly used for (meth)acrylic acid polymerization known to those skilled in the art (see, for example, The Chemistry of Radical Polymerisation, 2nd Edition, 2005, pages 49 to 166).

[0017] This object is achieved by a mixture comprising one or more compounds of general formula (I)

[0018]

[0019] wherein

[0020] R 6 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl includes a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group; an alkanoyl group having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl includes a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl includes a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl,

[0021] R 7 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl includes a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group; phenyl; a carboxylic acid ester having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl includes a straight-chain or branched C 1 to C 8Alkyl group or cyclic C 3 to C 8 alkyl group; alkanoyl having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl contains a straight-chain or branched C 1 to C 8 alkyl group or cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl)phenyl, sulfamoylphenyl or 4-isopropoxyphenyl, and

[0022] R 8 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or cyclic C 3 to C 20 alkyl group; phenyl; carboxylic acid ester having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl contains a straight-chain or branched C 1 to C 8 alkyl group or cyclic C 3 to C 8 alkyl group; alkanoyl having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl contains a straight-chain or branched C1 to C 8 alkyl group or cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl,

[0023] and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl ester.

[0024] C 1 to C 8 alkyl contains a straight-chain or branched C 1 to C 8 alkyl group or cyclic C 3 to C 8 alkyl group. C 1 to C 8 Examples of C to C alkyls are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, 2-methylbutyl, 3-methylbutyl, cyclopentyl, n-hexyl, cyclohexyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 3,3-dimethylbutyl, 2-ethylbutyl, n-heptyl, 2-methylhexyl, 2-ethylpentyl, 4-methylcyclohexyl, n-octyl, isooctyl or 2-ethylhexyl.

[0025] The present invention further provides the use of one or more compounds of general formula (II) as storage and / or transport stabilizers for (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl ester.

[0026] The present invention also provides a method for stabilizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters during transportation and / or storage by using one or more compounds of formula (II).

[0027] The present invention also provides a method for polymerizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters in the presence of one or more compounds of formula (II).

[0028] The mixture of the present invention is a liquid under standard conditions.

[0029] Description:

[0030] In the compound of formula (I),

[0031]

[0032] R 1 is H; C 1 to C 20 alkyl, wherein the C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, preferably the alkyl is C 1 to C 8 alkyl and more preferably the alkyl group is C 1 to C 6 alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein the C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C1 to C 6 alkanoyl of an alkyl group, wherein C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0033] R 2 is H, C 1 to C 20 alkyl group, wherein C 1 to C 20 alkyl group contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl group is C 1 to C 8 alkyl group and the more preferred alkyl group is C 1 to C 6 alkyl group; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl group, wherein C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C 1 to C 8 alkyl group of a carboxylic acid ester such as -COOMe; having C 1 to C 6 alkanoyl of an alkyl group, wherein C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6an alkyl group; or 4-isopropoxyphenyl, and

[0034] R 3 is H; C 2 to C 20 alkyl, wherein C 2 to C 20 alkyl includes a straight-chain or branched C 2 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl is C 2 to C 8 alkyl and the more preferred alkyl group is C 2 to C 6 alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, (carboxymethyl)phenyl, wherein the carboxyl can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl includes a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl, a carboxylic acid ester having C 1 to C 8 alkyl such as -COOMe; an alkanoyl group having C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl includes a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl.

[0035] In the preferred compounds of general formula (I),

[0036] R 1 is H; C 1 to C 6 alkyl, wherein C 1to C 6 The alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with a C 1 to C 6 alkyl group, where C 1 to C 6 The alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 6 alkanoyl group of an alkyl group, where C 1 to C 6 The alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl;

[0037] R 2 is H or C 1 to C 6 alkyl group, where C 1 to C 6 The alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; and

[0038] R 3 is H.

[0039] Particularly preferably,

[0040] R 1 is H; C 1 to C 6 alkyl group, where C 1 to C6 The alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with a C 1 to C 6 alkyl group, where the C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 6 alkanoyl group with an alkyl group, where the C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0041] R 2 is H or methyl, and

[0042] R 3 is H.

[0043] The compound of general formula (I) is in equilibrium with its keto form.

[0044]

[0045] In its enol form, the compound of general formula (I) can undergo an addition reaction with (meth)acrylic acid and / or a C 1 to C 8 alkyl (meth)acrylate. Thus, in a mixture of the compound of general formula (I) with (meth)acrylic acid and / or a C 1 to C 8 alkyl (meth)acrylate, the corresponding addition product may be present. When R3 When it is H, in addition to single addition, double addition may also occur.

[0046] The addition of (meth)acrylic acid and 5-methyl-2-phenyl-4H-pyrazol-3-one is exemplified to illustrate the addition of (meth)acrylic acid and the compound of general formula (I).

[0047]

[0048] According to the addition of (meth)acrylic acid and 5-methyl-2-phenyl-4H-pyrazol-3-one, (meth)acrylate can also undergo an addition reaction with the compound of general formula (I). In addition to single addition, double addition can also occur.

[0049] It is also disclosed a mixture comprising one or more compounds of general formula (I) and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters.

[0050] In the compound of general formula (II),

[0051]

[0052] R 6 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6 alkyl; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1to C 6 alkyl group or cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoylamino)phenyl, sulfamoylphenyl or 4-isopropoxyphenyl,

[0053] R 7 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains straight-chain or branched C 1 to C 20 alkyl group or cyclic C 3 to C 20 alkyl group, preferred alkyl is C 1 to C 8 alkyl and more preferred alkyl group is C 1 to C 6 alkyl; alkanoyl having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl contains straight-chain or branched C 1 to C 8 alkyl group or cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains straight-chain or branched C 1 to C 6 alkyl group or cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoylamino)phenyl, sulfamoylphenyl or 4-isopropoxyphenyl, and

[0054] R 8 is H; C 1 to C 20 alkyl, wherein C 1 to C 20The alkyl group contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl group is C 1 to C 8 alkyl, and the more preferred alkyl group is C 1 to C 6 alkyl; an alkanoyl group having C 1 to C 8 alkyl, wherein the C 1 to C 8 alkyl group contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with a C 1 to C 6 alkyl group, wherein the C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl.

[0055] In the more preferred compounds of formula (II),

[0056] R 6 is H or C 1 to C 6 alkyl, wherein the C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group;

[0057] R 7 is H; C 1 to C 6Alkyl, wherein C 1 to C 6 alkyl comprises a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; an alkanoyl group having a C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl comprises a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; and

[0058] R 8 is H or C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl comprises a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group.

[0059] Also disclosed is a mixture comprising one or more compounds of general formula (II) and (meth)acrylic acid and / or a C 1 to C 8 alkyl (meth)acrylate.

[0060] In the compound of general formula (III),

[0061]

[0062] R 9 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl comprises a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, preferably the alkyl is C 1 to C 8 alkyl and more preferably the alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 6 alkanoyl group of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0063] R 10 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein said carboxyl may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 8 alkyl carboxylate such as -COOMe; having a C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl, and

[0064] R 11 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with a C 1 to C 6 alkyl group, wherein C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl, having a C 1 to C 8 alkyl group carboxylic acid ester such as -COOMe; having a C 1 to C 6 alkyl group alkanoyl group, wherein C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl.

[0065] Also disclosed is a mixture comprising one or more compounds of general formula (III) and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl ester.

[0066] In the compound of general formula (IV),

[0067]

[0068] R 12 is H; C 1 to C 20 alkyl group, wherein C 1 to C 20 alkyl group contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl group is C 1 to C 8Alkyl and more preferably alkyl groups are C 1 to C 6 alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains straight-chain or branched C 1 to C 6 alkyl groups or cyclic C 3 to C 6 alkyl groups; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains straight-chain or branched C 1 to C 6 alkyl groups or cyclic C 3 to C 6 alkyl groups; or 4-isopropoxyphenyl,

[0069] R 13 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains straight-chain or branched C 1 to C 20 alkyl groups or cyclic C 3 to C 20 alkyl, and more preferably alkyl groups are C 1 to C 8 alkyl and more preferably alkyl groups are C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl, having a C 1 to C 8 alkyl carboxylate such as -COOMe; having a C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0070] R 14 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl, having a C 1 to C 8 alkyl carboxylate such as -COOMe; having a C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl, and

[0071] R 15 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl, having a C 1 to C 8 alkyl carboxylate such as -COOMe; having a C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; 4-isopropoxyphenyl, NH 2 ; NH(CO)R 16 wherein R 16 is H, C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; phenyl, tolyl such as m-tolyl or p-tolyl, 4-methoxyphenyl or dimethylphenyl such as 3,4-dimethylphenyl.

[0072] Also disclosed is a mixture comprising one or more compounds of general formula (IV) and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl ester.

[0073] (Meth)acrylic acid C 1 to C 8The alkyl ester is preferably methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylate esters.

[0074] The preparation of the compounds of general formula (I), (II), (III) or (IV) is known to those skilled in the art or can be set by them based on their common general knowledge.

[0075] The total amount of the compounds of general formula (I), (II), (III) or (IV) in the mixture is preferably from 0.1 to 1000 weight ppm, based on the total weight of the (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture. The total amount of the compounds of general formula (I), (II), (III) or (IV) in the mixture is particularly preferably from 1 to 900 weight ppm, very particularly preferably from 10 to 800 weight ppm, especially from 10 to 500 weight ppm, in each case based on the total weight of the (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture.

[0076] If, in addition to the (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters and one or more compounds of general formula (I), (II), (III) or (IV), the mixture further comprises other components, then the total amount of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters in the mixture according to the invention is preferably at least 5% by weight, based on the total weight of the mixture, more preferably at least 20% by weight, more preferably at least 30% by weight, more preferably at least 40% by weight, more preferably at least 50% by weight, more preferably at least 60% by weight, more preferably at least 70% by weight, more preferably at least 80% by weight, more preferably at least 90% by weight, particularly preferably at least 95% by weight.

[0077] Examples of other components are solvents such as organic solvents, water or solvent mixtures, dissolved gases such as air, minor components, co-stabilizers or any desired mixture of several of these components.

[0078] Examples of minor components are by-products formed during the production and / or purification of the (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters and which are not completely removed during their purification. Minor components can also be in the (meth)acrylic acid and / or (meth)acrylic acid C1 to C 8 Various contaminants introduced during the production, purification and / or storage of the alkyl esters. Minor components can be introduced into the mixture in the same manner via compounds of the general formula (I), (II), (III) or (IV).

[0079] Depending on the production and purification, (meth)acrylic acid may contain one or more minor components. Examples of minor components that may be present are water, di(meth)acrylic acid, acetic acid, propionic acid, one or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, protoanemonin, maleic acid, maleic anhydride, allyl acrylate or any desired mixture of two or more of said minor components. The content of the minor components is generally in the range from the determinable detection limit to 20,000 ppm by weight, based on the amount of (meth)acrylic acid.

[0080] Depending on the production and purification, (meth)acrylic acid C 1 to C 8 alkyl esters may contain one or more minor components. Examples of minor components that may be present are water, (meth)acrylic acid, the alcohol of the corresponding (meth)acrylate, the propionate of the alcohol of the corresponding (meth)acrylate, the acetate of the alcohol of the corresponding (meth)acrylate, the ether of the alcohol of the corresponding (meth)acrylate or any desired mixture of two or more of said minor components. The content of the minor components is generally in the range from the determinable detection limit to 20,000 ppm by weight, based on the amount of (meth)acrylate.

[0081] The mixtures according to the invention are preferably stored and / or transported in an oxygen-containing atmosphere. The oxygen-containing atmosphere preferably has an oxygen content of 5 to 30% by volume, in particular 5 to 21% by volume.

[0082] In order to achieve the oxygen saturation of the mixtures according to the invention as quickly as possible and / or to ensure continuous oxygen saturation, it is preferred to introduce an oxygen-containing gas into the mixture. The oxygen-containing gas can be introduced into the mixture, for example, through one or more nozzles which are positioned such that their openings extend into the mixture.

[0083] The oxygen-containing gas is, for example, air, a nitrogen-air mixture or an oxygen-nitrogen mixture other than air having an oxygen content of 5 to 30% by volume. In addition to oxygen and nitrogen, the oxygen-nitrogen mixture can also contain other gases, such as carbon dioxide, carbon monoxide, hydrogen, methane, one or more noble gases or a mixture of two or more of said gases.

[0084] The mixture can be prepared by mixing one or more compounds of the general formula (I), (II), (III) or (IV) with (meth)acrylic acid and / or (meth)acrylic acid C 1 to C8 Prepared from an alkyl ester mixture. Conveniently, the compounds of general formula (I), (II), (III) or (IV) are prepared in a concentrate of (meth)acrylic acid, (meth)acrylic acid C 1 to C 8 alkyl esters and / or a suitable solvent, and the concentrate thus obtained is then diluted with (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters. When selecting a suitable solvent (which can also be a solvent mixture), those skilled in the art are guided by conventional advantageous reasons such as solubility, miscibility and possible potential side effects. (Meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters can be added to the concentrate, or the concentrate can be added to (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters.

[0085] The mixture preferably contains a co-stabilizer. The co-stabilizer can be present in the mixture of the present invention as a single compound or as a mixture of compounds. The co-stabilizer helps to prevent or delay the free radical polymerization of (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters. In preventing or delaying the free radical polymerization of (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters, the co-stabilizer can act synergistically with the compounds of general formula (I), (II), (III) or (IV). The co-stabilizer can be added to the mixture before and / or during storage and / or transportation. The co-stabilizer can be added to (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters together with or separately from the compounds of general formula (I), (II), (III) or (IV). However, a co-stabilizer may have been added during the preparation and / or purification of (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters, in which case the compounds of general formula (I), (II), (III) or (IV) are subsequently added to the mixture of the present invention.

[0086] Based on (meth)acrylic acid and (meth)acrylic acid C in the mixture 1 to C 8Based on the total amount of the alkyl esters, the total amount of the co-stabilizer in the mixture of the present invention is preferably from 0.1 to 5000 ppm by weight. The total amount of the co-stabilizer is more preferably from 1 to 4000 ppm by weight, particularly from 5 to 2500 ppm by weight, and very particularly preferably from 50 to 750 ppm by weight, in each case based on the total amount of (meth)acrylic acid and C 1 to C 8 alkyl esters in the mixture.

[0087] The amount of the co-stabilizer can be adjusted by addition or removal. Methods for removing the co-stabilizer are known to those skilled in the art (see, for example, US 6 046 357). Examples of suitable methods include distillation, crystallization, ion exchange, extraction, reverse osmosis and / or membrane processes. When selecting a suitable method or combination of methods, those skilled in the art are guided by their general knowledge in the art. If the compounds of the general formula (I), (II), (III) or (IV) are removed together with them, these compounds can optionally be replenished. If the content of the co-stabilizer in the mixture is reduced or eliminated, it may also be necessary to increase the content of the compounds of the general formula (I), (II), (III) or (IV) to achieve the desired polymerization stability.

[0088] Examples of co-stabilizers are metal salts selected from copper, manganese and cerium salts, phenothiazine, phenolic compounds, N-oxyls, phenylenediamines, nitroso compounds, ureas, thioureas or mixtures of two or more of these classes of substances. The co-stabilizer is preferably phenothiazine, a phenolic compound, an N-oxyl or a mixture of two or more of these classes of substances.

[0089] The copper salts are preferably copper(I) and / or copper(II) salts which have sufficient solubility in the polymerizable compounds and in the mixtures of the present invention. Examples of suitable copper salts are copper(II) phenolate, copper(II) acetylacetonate, copper(II) gluconate, copper(II) tartrate, copper(II) acetate, copper(II) formate, copper(II) nitrate, copper(II) hydroxide, copper(II) sulfate, copper(II) carbonate, copper(II) naphthenate, copper(II) acrylate, copper(II) halides such as copper(II) chloride, copper(II) salicylate, copper(II) sulfonate, copper(II) propionate, copper(II) octanoate, copper(I) chloride, copper(I) iodide, copper(I) bromide, copper(I) cyanide, copper(I) acetate, copper(I) oxide, copper(I) sulfate, complex copper salts such as Cu(NH 3 ) 4 + copper complexes stabilized with suitable counterions and ligands such as those disclosed in DE 10 2012 223 695 A1, or any desired mixture of two or more of said copper salts. The relevant copper salts can also be used in the form of their hydrates.

[0090] The manganese salt is preferably a manganese(II) salt having sufficient solubility in the polymerizable compound and in the mixtures of the present invention. Examples of suitable manganese salts are manganese(II) phenolate, manganese(II) acetylacetonate, manganese(II) gluconate, manganese(II) tartrate, manganese(II) acetate, manganese(II) formate, manganese(II) nitrate, manganese(II) hydroxide, manganese(II) sulfate, manganese(II) carbonate, manganese(II) naphthenate, manganese(II) acrylate, manganese(II) halides such as manganese(II) chloride, manganese(II) salicylate, manganese(II) sulfonate, manganese(II) propionate, manganese(II) octanoate, ligand-stabilized manganese complexes such as those disclosed in DE 10 2012 223 695 A1, or any desired mixture of two or more of the said manganese salts. The relevant manganese salts can also be used in the form of their hydrates.

[0091] The cerium salt is preferably a cerium(III) salt having sufficient solubility in the polymerizable compound and in the mixtures of the present invention. Examples of suitable cerium salts are cerium(III) phenolate, cerium(III) acetylacetonate, cerium(III) gluconate, cerium(III) tartrate, cerium(III) acetate, cerium(III) formate, cerium(III) nitrate, cerium(III) hydroxide, cerium(III) sulfate, cerium(III) carbonate, cerium(III) naphthenate, cerium(III) acrylate, cerium(III) halides such as cerium(III) chloride, cerium(III) salicylate, cerium(III) sulfonate, cerium(III) propionate, cerium(III) octanoate, ligand-stabilized cerium complexes such as those disclosed in DE 10 2012 223 695 A1, or any desired mixture of two or more of the said cerium salts. The relevant cerium salts can also be used in the form of their hydrates.

[0092] Examples of phenothiazine are bis(α-methylbenzyl)phenothiazine, 3,7-dioctylphenothiazine, bis(α-dimethylbenzyl)phenothiazine or any desired mixture of two or more of the said compounds.

[0093] Examples of phenolic compounds are hydroquinone, hydroquinone monomethyl ether such as p-methoxyphenol (MEHQ), pyrogallol, catechol, resorcinol, phenol, cresol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-p-cresol or any desired mixture of two or more of the said compounds.

[0094] Examples of N-oxides are di-tert-butyl nitroxide, 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl, 2,2,6,6-tetramethylpiperidin-1-oxyl, 2,2,6,6-tetramethylpiperidyloxy, 4-hydroxy-2,2,6,6-tetramethylpiperidyloxy, 4,4',4''-tris-1-(2,2,6,6-tetramethylpiperidyloxy) phosphite or any desired mixture of two or more of said compounds.

[0095] The present application further provides the use of one or more compounds of general formula (I), (II), (III) or (IV) as storage and / or transport stabilizers for (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters. All refer to the preferred embodiments already described. Thus, particularly preferred, very particularly preferred or embodiments characterized as preferred by similar formulations are also covered.

[0096] The present application further provides a method for stabilizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters during transport and / or storage by using one or more compounds of general formula (I), (II), (III) or (IV). All refer to the preferred embodiments already described. Thus, particularly preferred, very particularly preferred or embodiments characterized as preferred by similar formulations are also covered.

[0097] The method of the invention comprises providing a mixture comprising one or more compounds of general formula (I), (II), (III) or (IV) and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters, which mixture is oxygen-saturated to 50 to 100%, preferably 90 to 100%, more preferably 95 to 100%. The degree of oxygen saturation refers to the degree of oxygen saturation reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably an oxygen content of 5 to 21% by volume.

[0098] The invention also provides a method for polymerizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters in the presence of one or more compounds of general formula (I), (II), (III) or (IV), wherein the reaction mixture is oxygen-saturated to 0 to 50%, preferably 0 to 10%, more preferably 0 to 5%, particularly preferably 0 to 1%, most preferably 0 to 0.1%. The degree of oxygen saturation refers to the degree of oxygen saturation reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume and preferably an oxygen content of 5 to 21% by volume.

[0099] If the oxygen saturation of the reaction mixture is too high, the oxygen saturation can be reduced, for example, by introducing nitrogen into the reaction mixture and / or the atmosphere above the reaction mixture. The introduced nitrogen should be substantially oxygen-free, for example, with an oxygen content of less than 1% by volume, preferably less than 0.1% by volume.

[0100] In addition to (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters, the reaction mixture may also contain other polymerizable compounds.

[0101] All refer to the preferred embodiments already described. Thus, particularly preferred, very particularly preferred or embodiments characterized as preferred by similar formulations are also covered.

[0102] The polymerization is preferably carried out at a temperature of 50 to 150 °C, more preferably at a temperature of 70 to 120 °C.

[0103] Preferably, the polymerization is carried out under a nitrogen atmosphere. The nitrogen content of the nitrogen atmosphere is 85 to 100% by volume, preferably 90 to 100% by volume, more preferably 99 to 100%. The oxygen content in the nitrogen atmosphere is less than 5% by volume.

[0104] Preferably, the polymerization is carried out in the presence of a polymerization initiator. Suitable polymerization initiators are those known to those skilled in the art, such as those described in The Chemistry of Radical Polymerisation, 2nd Edition, 2005, pages 49 - 166. The polymerization initiator is used in an effective amount.

[0105] By the process according to the invention, (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters stabilized for storage and / or transport with one or more compounds of general formula (I), (II), (III) or (IV) can be polymerized without first separating the compounds of general formula (I), (II), (III) or (IV) from the reaction mixture to be polymerized. Thus, the reaction mixture can first be charged into a reactor for polymerization in a stable form. By reducing the oxygen saturation in the reaction mixture, preferably by introducing nitrogen into the space above the reaction mixture in the reactor and / or by introducing nitrogen into the reaction mixture, the stabilizing effect of the compounds of general formula (I), (II), (III) or (IV) can be reduced to an extent sufficient for the reaction mixture to polymerize. The polymerization initiator can be added before, during or after the reduction of oxygen saturation. For safety reasons, it is preferably added before the reduction of oxygen saturation.

[0106] In particular, the present invention encompasses the following embodiments.

[0107] 1. A mixture comprising one or more compounds of formula (II)

[0108]

[0109] wherein

[0110] R 6 is H; C 1 to C 20 alkyl, wherein the C 1 to C 20 alkyl comprises a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group; an alkanoyl group having C 1 to C 8 alkyl, wherein the C 1 to C 8 alkyl comprises a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein the C 1 to C 6 alkyl comprises a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl,

[0111] R 7 is H; C 1 to C 20 alkyl, wherein the C 1 to C 20 alkyl comprises a straight-chain or branched C 1 to C 20an alkyl group or a cyclic C 3 to C 20 alkyl group; phenyl; a carboxylic acid ester having a C 1 to C 8 alkyl group, wherein the C 1 to C 8 alkyl group contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; an alkanoyl group having a C 1 to C 8 alkyl group, wherein the C 1 to C 8 alkyl group contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with a C 1 to C 6 alkyl group, wherein the C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamino phenyl or 4-isopropoxyphenyl, and

[0112] R 8 is H; C 1 to C 20 alkyl group, wherein the C 1 to C 20 alkyl group contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group; phenyl, a carboxylic acid ester having a C 1 to C 8 alkyl group, wherein the C 1 to C 8The alkyl group includes a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; an alkanoyl group having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl group includes a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl group includes a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl,

[0113] and (meth)acrylic acid and / or C 1 to C 8 (meth)acrylate.

[0114] 2. The mixture according to embodiment 1, wherein

[0115] R 6 is H; C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl group includes a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; an alkanoyl group having C 1 to C 8 alkyl, wherein C 1 to C 8The alkyl group contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with a C 1 to C 6 alkyl group, where the C 1 to C 6 alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl,

[0116] R 7 is H; C 1 to C 8 alkyl group, where the C 1 to C 8 alkyl group contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; phenyl, a carboxylic acid ester having a C 1 to C 8 alkyl group, where the C 1 to C 8 alkyl group contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; an alkanoyl group having a C 1 to C 8 alkyl group, where the C 1 to C 8 alkyl group contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8Alkyl groups; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl, and

[0117] R 8 is H; C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; phenyl, a carboxylic acid ester having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8 alkyl group; an alkanoyl group having C 1 to C 8 alkyl, wherein C 1 to C 8 alkyl contains a straight-chain or branched C 1 to C 8 alkyl group or a cyclic C 3 to C 8Alkyl groups; cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl or 4-isopropoxyphenyl.

[0118] 3. The mixture according to embodiment 1, wherein

[0119] R 6 is H or C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group;

[0120] R 7 is H; C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or an alkanoyl group having C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; and

[0121] R 8is H or C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group.

[0122] 4. A mixture according to any one of embodiments 1 to 3, wherein the C 1 to C 8 alkyl (meth)acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0123] 5. A mixture according to any one of embodiments 1 to 4, wherein the total amount of the compound of general formula (II) in the mixture is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and especially 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylate present in the mixture.

[0124] 6. A mixture according to any one of embodiments 1 to 5, wherein the total amount of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylate in the mixture is at least 5% by weight, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, particularly preferably at least 95% by weight, in each case based on the total weight of the mixture.

[0125] 7. A mixture according to any one of embodiments 1 to 3 or 5 to 6, wherein the mixture contains (meth)acrylic acid and wherein the mixture contains one or more of the following components:

[0126] a. water, 20 to 15000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0127] b. di(meth)acrylic acid, 100 to 20000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0128] c. Acetic acid, 100 to 2000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture

[0129] d. Propionic acid, 100 to 2000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture

[0130] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, each in an amount of 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture

[0131] f. Protoanemonin, 0 to 2 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture

[0132] g. Maleic acid, 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture

[0133] h. Maleic anhydride, 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture

[0134] i. Allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture

[0135] 8. A mixture according to any one of embodiments 4 to 6, wherein the mixture comprises one or more (meth)acrylates of embodiment 4, and wherein the mixture comprises one or more of the following components:

[0136] a. Water, 1 to 2000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 4 present in the mixture

[0137] b. (Meth)acrylic acid, 1 to 2000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 4 present in the mixture

[0138] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 4 present in the mixture

[0139] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 4 present in the mixture

[0140] e. Acetates of the alcohols corresponding to the respective (meth)acrylates, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the total weight of the (meth)acrylates of embodiment 4 present in the mixture.

[0141] f. Ethers of the corresponding (meth)acrylate alcohols, 0 to 2000 ppm by weight, in each case based on the total weight of the (meth)acrylates of embodiment 4 present in the mixture.

[0142] 9. A mixture according to any one of embodiments 1 to 8, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere.

[0143] 10. A mixture according to embodiment 9, wherein the oxygen content of the oxygen-containing atmosphere is 5 to 30% by volume of oxygen, preferably the oxygen content is 5 to 21% by volume.

[0144] 11. A mixture according to embodiment 9 or 10, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere for 10 seconds or longer, preferably 1 minute or longer, more preferably 10 minutes or longer, particularly preferably 60 minutes or longer.

[0145] 12. A mixture according to any one of embodiments 1 to 11, wherein the mixture contains a co-stabilizer.

[0146] 13. A mixture according to embodiment 12, wherein the total amount of the co-stabilizer present in the mixture is 0.1 to 5000 ppm by weight, preferably 1 to 4000 ppm by weight, particularly 5 to 2500 ppm by weight, more preferably 50 to 750 ppm by weight, based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture.

[0147] 14. A mixture according to any one of embodiments 12 or 13, wherein the co-stabilizer is a metal salt selected from copper, manganese and cerium salts, phenothiazine, phenolic compounds, N-oxides, phenylenediamines, nitroso compounds, ureas, thioureas or a mixture of two or more of these types of substances.

[0148] 15. Use of one or more compounds of general formula (II) as defined in any one of embodiments 1 to 3 for stabilizing the storage and / or transport of (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters.

[0149] 16. Use according to embodiment 15, wherein the (meth)acrylic acid C 1 to C 8The alkyl ester is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0150] 17. Use according to any one of embodiments 15 or 16, wherein the total amount of the compound of general formula (II) used is from 0.1 to 1000 ppm by weight, preferably from 1 to 900 ppm by weight, more preferably from 10 to 800 ppm by weight, in particular from 10 to 500 ppm by weight, based on the total weight of the (meth)acrylic acid and the (meth)acrylic acid C 1 to C 8 alkyl esters to be stabilized.

[0151] 18. Use according to any one of embodiments 15 or 17, wherein the (meth)acrylic acid is stabilized and wherein the (meth)acrylic acid to be stabilized comprises one or more of the following components:

[0152] a. water, from 20 to 15 000 ppm by weight, based on the amount of (meth)acrylic acid,

[0153] b. di(meth)acrylic acid, from 100 to 20 000 ppm by weight, based on the amount of (meth)acrylic acid,

[0154] c. acetic acid, from 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0155] d. propionic acid, from 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0156] e. one or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being from 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0157] f. protoanemonin, from 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0158] g. maleic acid, from 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0159] H. maleic anhydride, from 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0160] i. allyl acrylate, from 0 to 30 ppm by weight, preferably from 0 to 1 ppm by weight, in each case based on the amount of (meth)acrylic acid.

[0161] 19. Use according to any one of embodiments 16 or 17, wherein one or more of the (meth)acrylates of embodiment 16 are stabilized and wherein the (meth)acrylate to be stabilized comprises one or more of the following components:

[0162] a. Water, 1 to 2000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 16.

[0163] b. (Meth)acrylic acid, 1 to 2000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 16.

[0164] c. Alcohol of the corresponding (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 16.

[0165] d. Propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 16.

[0166] e. Acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 16.

[0167] f. Ether of the corresponding (meth)acrylate alcohol, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 16.

[0168] 20. A process for polymerizing (meth)acrylic acid and / or C 1 to C 8 alkyl (meth)acrylates in the presence of one or more compounds of general formula (II) as defined in any one of embodiments 1 to 3, wherein the reaction mixture is saturated with oxygen to 0 to 50%, preferably 0 to 10%, more preferably 0 to 5%, particularly preferably 0 to 1%, most preferably 0 to 0.1%, and the degree of oxygen saturation means the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably an oxygen content of 5 to 21% by volume, and reaches equilibrium.

[0169] 21. A method according to embodiment 20, wherein the total amount of the compound of general formula (II) in the reaction mixture is from 0.1 to 1000 ppm by weight, preferably from 1 to 900 ppm by weight, more preferably from 10 to 800 ppm by weight, and in particular from 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the reaction mixture.

[0170] 22. A method according to any one of embodiments 20 or 21, wherein the polymerization is carried out at a temperature of from 50 to 150 °C, preferably from 70 to 120 °C.

[0171] 23. A method according to any one of embodiments 20 to 22, wherein the polymerization is carried out under a nitrogen atmosphere having a nitrogen content of from 85 to 100% by volume and an oxygen content of less than 5% by volume, preferably a nitrogen content of from 90 to 100% by volume, more preferably a nitrogen content of from 99 to 100% by volume.

[0172] 24. A method according to any one of embodiments 20 to 23, wherein the (meth)acrylic acid C 1 to C 8 alkyl esters are methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0173] 25. A method according to any one of embodiments 20 or 23, wherein the (meth)acrylic acid to be polymerized comprises one or more of the following components:

[0174] a. Water, from 20 to 15 000 ppm by weight, based on the amount of (meth)acrylic acid,

[0175] b. Di(meth)acrylic acid, from 100 to 20 000 ppm by weight, based on the amount of (meth)acrylic acid,

[0176] c. Acetic acid, from 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0177] d. Propionic acid, from 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0178] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being from 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0179] f. Protoanemonin, from 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0180] g. Maleic acid, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0181] h. Maleic anhydride, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0182] i. Allyl acrylate, 0 to 30 weight ppm, preferably 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0183] 26. The method according to embodiment 24, wherein the (meth)acrylate to be polymerized comprises one or more of the following components:

[0184] a. Water, 1 to 2000 weight ppm, preferably 1 to 500 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 24

[0185] b. (Meth)acrylic acid, 1 to 2000 weight ppm, preferably 1 to 100 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 24

[0186] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 weight ppm, preferably 0.1 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 24

[0187] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 weight ppm, preferably 10 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 24

[0188] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 weight ppm, preferably 5 to 2000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 24

[0189] f. The ether of the corresponding (meth)acrylate alcohol, 0 to 2000 weight ppm, based on the amount of the (meth)acrylate of embodiment 24

[0190] 27. A method for stabilizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters by using one or more compounds of general formula (II) as defined in any one of embodiments 1 to 3

[0191] 28. The method according to embodiment 27, wherein the (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8The alkyl ester is stabilized during storage and / or transportation.

[0192] 29. The method according to any one of embodiments 27 or 28, wherein the C 1 to C 8 alkyl (meth)acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0193] 30. The method according to any one of embodiments 27 or 28, wherein the (meth)acrylic acid comprises one or more of the following components:

[0194] a. water, 20 to 15,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0195] b. di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0196] c. acetic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0197] d. propionic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0198] e. one or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, each aldehyde in an amount of 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0199] f. protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0200] g. maleic acid, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0201] h. maleic anhydride, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0202] i. allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid.

[0203] 31. The method according to embodiment 29, wherein the (meth)acrylate comprises one or more of the following components:

[0204] a. water, 1 to 2,000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 29,

[0205] b. (Meth)acrylic acid, 1 to 2000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 29,

[0206] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 29,

[0207] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 29,

[0208] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 29,

[0209] f. The ether of the corresponding (meth)acrylate alcohol, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 29.

[0210] 32. A method according to any one of embodiments 27 to 31, wherein the method comprises providing a mixture comprising one or more compounds of formula (II) and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters, the mixture being oxygen-saturated to 50 to 100%, preferably 90 to 100%, more preferably 95 to 100%, the degree of oxygen saturation meaning the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably an oxygen content of 5 to 21% by volume, and reaches equilibrium.

[0211] 33. A method according to embodiment 32, wherein the total amount of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters in the mixture is at least 5% by weight, based on the total weight of the mixture, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, particularly preferably at least 95% by weight.

[0212] 34. A method according to any one of embodiments 27 to 33, wherein the total amount of the compound of general formula (II) used is from 0.1 to 1000 ppm by weight, preferably from 1 to 900 ppm by weight, more preferably from 10 to 800 ppm by weight, and especially from 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture.

[0213] 35. A mixture comprising one or more compounds of general formula (I)

[0214]

[0215] wherein

[0216] R 1 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, preferred alkyls are C 1 to C 8 alkyl and more preferred alkyl groups are C 1 to C 6 alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl)phenyl, sulfamoylphenyl; an alkanoyl group having C 1 to C 6 alkyl, wherein C 1 to C6 The alkyl group includes a linear or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0217] R 2 is H; C 1 to C 20 alkyl, wherein the C 1 to C 20 alkyl group includes a linear or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl group is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6 alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein the C 1 to C 6 alkyl group includes a linear or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 8 alkyl carboxylate such as -COOMe; having a C 1 to C 6 alkanoyl of alkyl, wherein the C 1 to C 6 alkyl group includes a linear or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl, and

[0218] R 3 is H; C2 to C 20 alkyl, wherein C 2 to C 20 alkyl comprises a straight-chain or branched C 2 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl is C 2 to C 8 alkyl and the more preferred alkyl group is C 2 to C 6 alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein said carboxyl may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl comprises a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C 1 to C 8 alkyl carboxylate such as -COOMe; having C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl comprises a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl, and

[0219] and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl ester.

[0220] 36. The mixture according to embodiment 35, wherein

[0221] R 1 is H; C 1 to C 6an alkyl group, where C 1 to C 6 the alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, where the carboxyl group may also be esterified with a C 1 to C 6 alkyl group, where C 1 to C 6 the alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; an alkanoyl group having a C 1 to C 6 alkyl group, where C 1 to C 6 the alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0222] R 2 is -H or a C 1 to C 6 alkyl group, and

[0223] R 3 is H.

[0224] 37. The mixture according to embodiment 35, wherein

[0225] R 1 is H; a C 1 to C 6 alkyl group, where C 1 to C 6 the alkyl group contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6Alkyl groups; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0226] R 2 is H or methyl, and

[0227] R 3 is H.

[0228] 38. A mixture according to any one of embodiments 35 to 37, wherein the C 1 to C 8 alkyl (meth)acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0229] 39. A mixture according to any one of embodiments 35 to 38, wherein the total amount of the compound of general formula (I) in the mixture is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and in particular 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylate present in the mixture.

[0230] 40. A mixture according to any one of embodiments 35 to 39, wherein the total amount of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylates in the mixture is at least 5% by weight, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, particularly preferably at least 95% by weight, in each case based on the total weight of the mixture.

[0231] 41. A mixture according to any one of embodiments 35 to 37 or 39 to 40, wherein the mixture comprises (meth)acrylic acid and wherein the mixture comprises one or more of the following components:

[0232] a. Water, 20 to 15 000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0233] b. Di(meth)acrylic acid, 100 to 20 000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0234] c. Acetic acid, 100 to 2000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0235] d. Propionic acid, 100 to 2000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0236] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0237] f. Protoanemonin, 0 to 2 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0238] g. Maleic acid, 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0239] h. Maleic anhydride, 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0240] i. Allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture.

[0241] 42. A mixture according to embodiment 38, wherein the mixture comprises one or more (meth)acrylates of embodiment 38 and wherein the mixture comprises one or more of the following components:

[0242] a. Water, 1 to 2000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 38 present in the mixture,

[0243] b. (Meth)acrylic acid, 1 to 2000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 38 present in the mixture,

[0244] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 38 present in the mixture,

[0245] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 38 present in the mixture,

[0246] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 38 present in the mixture,

[0247] f. The ether of the corresponding (meth)acrylate alcohol, 0 to 2000 ppm by weight, in each case based on the total weight of the (meth)acrylate of embodiment 38 present in the mixture.

[0248] 43. A mixture according to any one of embodiments 35 to 42, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere.

[0249] 44. A mixture according to embodiment 43, wherein the oxygen-containing atmosphere has an oxygen content of 5 to 30% by volume of oxygen, and preferably an oxygen content of 5 to 21% by volume.

[0250] 45. A mixture according to embodiment 43 or 44, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere for 10 seconds or longer, preferably 1 minute or longer, more preferably 10 minutes or longer, and particularly preferably 60 minutes or longer.

[0251] 46. A mixture according to any one of embodiments 35 to 45, wherein the mixture comprises a co-stabilizer.

[0252] 47. A mixture according to embodiment 46, wherein the total amount of co-stabilizer present in the mixture is from 0.1 to 5000 ppm by weight, preferably from 1 to 4000 ppm by weight, in particular from 5 to 2500 ppm by weight, more preferably from 50 to 750 ppm by weight, based on the total weight of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylates present in the mixture.

[0253] 48. A mixture according to any one of embodiments 46 or 47, wherein the co-stabilizer is a metal salt selected from copper, manganese and cerium salts, phenothiazine, phenolic compounds, N-oxides, phenylenediamines, nitroso compounds, urea, thiourea or a mixture of two or more of said classes of substances.

[0254] 49. Use of one or more compounds of general formula (I) as defined in any one of embodiments 35 to 37 for stabilizing the storage and / or transport of (meth)acrylic acid and / or C 1 to C 8 alkyl (meth)acrylates.

[0255] 50. Use according to embodiment 49, wherein the C 1 to C 8 alkyl (meth)acrylates are methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0256] 51. Use according to any one of embodiments 49 or 50, wherein the total amount of the compound of general formula (I) used is from 0.1 to 1000 ppm by weight, preferably from 1 to 900 ppm by weight, more preferably from 10 to 800 ppm by weight, and in particular from 10 to 500 ppm by weight, based on the total weight of the (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylates to be stabilized.

[0257] 52. Use according to any one of embodiments 49 or 51, wherein (meth)acrylic acid is stabilized and wherein the (meth)acrylic acid to be stabilized comprises one or more of the following components:

[0258] a. water, from 20 to 15 000 ppm by weight, based on the amount of (meth)acrylic acid,

[0259] b. di(meth)acrylic acid, from 100 to 20 000 ppm by weight, based on the amount of (meth)acrylic acid,

[0260] c. Acetic acid, 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0261] d. Propionic acid, 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0262] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0263] f. Protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0264] g. Maleic acid, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0265] h. Maleic anhydride, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0266] i. Allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, in each case based on the amount of (meth)acrylic acid.

[0267] 53. Use according to embodiment 50 or 51, wherein one or more of the (meth)acrylates of embodiment 50 are stabilized and the (meth)acrylate to be stabilized comprises one or more of the following components:

[0268] a. Water, 1 to 2000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 50,

[0269] b. (Meth)acrylic acid, 1 to 2000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 50,

[0270] c. Alcohol of the corresponding (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 50,

[0271] d. Propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 50,

[0272] e. Acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 50,

[0273] f. Ether of the corresponding (meth)acrylate alcohol, 0 to 2000 ppm by weight, based on the amount of (meth)acrylate of embodiment 50.

[0274] 54. A method for polymerizing (meth)acrylic acid and / or C 1 to C 8 alkyl (meth)acrylate in the presence of a compound of general formula (I) according to any one of one or more of embodiments 35 to 37, wherein the reaction mixture is saturated with oxygen to 0 to 50%, preferably 0 to 10%, more preferably 0 to 5%, particularly preferably 0 to 1%, and most preferably 0 to 0.1%. The degree of oxygen saturation means the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably 5 to 21% by volume.

[0275] 55. The method according to embodiment 54, wherein the total amount of the compound of general formula (I) in the reaction mixture is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and particularly 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylate present in the reaction mixture.

[0276] 56. The method according to any one of embodiments 54 or 55, wherein the polymerization is carried out at a temperature of 50 to 150 °C and preferably 70 to 120 °C.

[0277] 57. The method according to any one of embodiments 54 to 56, wherein the polymerization is carried out in a nitrogen atmosphere having a nitrogen content of 85 to 100% by volume and an oxygen content of less than 5% by volume, preferably a nitrogen content of 90 to 100% by volume, more preferably a nitrogen content of 99 to 100%.

[0278] 58. The method according to any one of embodiments 54 to 58, wherein the C 1 to C 8 alkyl (meth)acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0279] 59. The method according to any one of embodiments 54 or 57, wherein the (meth)acrylic acid to be polymerized comprises one or more of the following components:

[0280] a. Water, 20 to 15000 ppm by weight, based on the amount of (meth)acrylic acid.

[0281] b. Di(meth)acrylic acid, 100 to 20,000 weight ppm, based on the amount of (meth)acrylic acid

[0282] c. Acetic acid, 100 to 2000 weight ppm, based on the amount of (meth)acrylic acid

[0283] d. Propionic acid, 100 to 2000 weight ppm, based on the amount of (meth)acrylic acid

[0284] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0285] f. Protoanemonin, 0 to 2 weight ppm, based on the amount of (meth)acrylic acid

[0286] g. Maleic acid, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0287] h. Maleic anhydride, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0288] i. Allyl acrylate, 0 to 30 weight ppm, preferably 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0289] 60. The method according to embodiment 58, wherein the (meth)acrylate to be polymerized comprises one or more of the following components:

[0290] a. Water, 1 to 2000 weight ppm, preferably 1 to 500 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 58

[0291] b. (Meth)acrylic acid, 1 to 2000 weight ppm, preferably 1 to 100 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 58

[0292] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 weight ppm, preferably 0.1 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 58

[0293] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 weight ppm, preferably 10 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 58

[0294] e. Acetates of the alcohols of the corresponding (meth)acrylates, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 58,

[0295] f. Ethers of the corresponding (meth)acrylate alcohols, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 58.

[0296] 61. A method for stabilizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters by using a compound of general formula (I) as defined in any one of embodiments 35 to 37.

[0297] 62. The method according to embodiment 61, wherein the (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters are stabilized during storage and / or transportation.

[0298] 63. The method according to any one of embodiments 61 or 62, wherein the (meth)acrylic acid C 1 to C 8 alkyl esters are methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0299] 64. The method according to any one of embodiments 61 or 62, wherein the (meth)acrylic acid comprises one or more of the following components:

[0300] a. Water, 20 to 15,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0301] b. Di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0302] c. Acetic acid, 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0303] d. Propionic acid, 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid,

[0304] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0305] f. Protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0306] g. Maleic acid, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0307] h. Maleic anhydride, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0308] i. Allyl acrylate, 0 to 30 weight ppm, preferably 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0309] 65. The method according to embodiment 63, wherein the (meth)acrylate comprises one or more of the following components:

[0310] a. Water, 1 to 2000 weight ppm, preferably 1 to 500 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 63

[0311] b. (Meth)acrylic acid, 1 to 2000 weight ppm, preferably 1 to 100 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 63

[0312] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 weight ppm, preferably 0.1 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 63

[0313] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 weight ppm, preferably 10 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 63

[0314] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 weight ppm, preferably 5 to 2000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 63

[0315] f. The ether of the corresponding (meth)acrylate alcohol, 0 to 2000 weight ppm, based on the (meth)acrylate of embodiment 63

[0316] 66. The method according to any one of embodiments 61 to 65, wherein the method comprises providing a composition comprising one or more compounds of general formula (I) and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8Mixture of alkyl esters, the mixture being oxygen-saturated to 50 to 100%, preferably 90 to 100%, more preferably 95 to 100%, the degree of oxygen saturation meaning the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably an oxygen content of 5 to 21% by volume.

[0317] 67. The method according to embodiment 66, wherein the total amount of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters in the mixture is at least 5% by weight, based on the total weight of the mixture, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, and particularly preferably at least 95% by weight.

[0318] 68. The method according to any one of embodiments 61 to 67, wherein the total amount of the compound of general formula (I) used is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and in particular 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture.

[0319] 69. A mixture comprising one or more compounds of general formula (III)

[0320]

[0321] wherein

[0322] R 9 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl being C 1 to C 8 alkyl and the more preferred alkyl group being C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0323] R 10 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl, having a C 1 to C 8 alkyl carboxylate ester such as -COOMe, having a C 1 to C 6 alkyl alkanoyl group, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or is 4-isopropoxyphenyl, and

[0324] R 11 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 8 alkyl carboxylate such as -COOMe; having a C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or is 4-isopropoxyphenyl,

[0325] and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl ester.

[0326] 70. The mixture according to embodiment 69, wherein the (meth)acrylic acid C 1 to C 8 alkyl ester is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylate esters.

[0327] 71. The mixture according to any one of embodiments 69 or 70, wherein the total amount of the compound of general formula (III) in the mixture is 0.1 to 1000 weight ppm, preferably 1 to 900 weight ppm, more preferably 10 to 800 weight ppm, and especially 10 to 500 weight ppm, in each case based on the (meth)acrylic acid and (meth)acrylic acid C 1 to C8 based on the total weight of the alkyl esters.

[0328] 72. A mixture according to any one of embodiments 69 to 71, wherein the total amount of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylates in the mixture is at least 5% by weight, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, particularly preferably at least 95% by weight, in each case based on the total weight of the mixture.

[0329] 73. A mixture according to any one of embodiments 69, 71 or 72, wherein the mixture comprises (meth)acrylic acid and wherein the mixture comprises one or more of the following components:

[0330] a. Water, 20 to 15,000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0331] b. Di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0332] c. Acetic acid, 100 to 2,000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0333] d. Propionic acid, 100 to 2,000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0334] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0335] f. Protoanemonin, 0 to 2 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0336] g. Maleic acid, 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0337] h. Maleic anhydride, 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0338] i. Allyl acrylate, 0 to 30 weight ppm, preferably 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture.

[0339] 74. A mixture according to any one of embodiments 70 to 72, wherein the mixture comprises one or more (meth)acrylates of embodiment 70 and wherein the mixture comprises one or more of the following components:

[0340] a. Water, 1 to 2000 weight ppm, preferably 1 to 500 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 70 present in the mixture,

[0341] b. (Meth)acrylic acid, 1 to 2000 weight ppm, preferably 1 to 100 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 70 present in the mixture,

[0342] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 weight ppm, preferably 0.1 to 1000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 70 present in the mixture,

[0343] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 weight ppm, preferably 10 to 1000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 70 present in the mixture,

[0344] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 weight ppm, preferably 5 to 2000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 70 present in the mixture,

[0345] f. The ether of the corresponding (meth)acrylate alcohol, 0 to 2000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 70 present in the mixture.

[0346] 75. A mixture according to any one of embodiments 69 to 74, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere.

[0347] 76. A mixture according to embodiment 75, wherein the oxygen-containing atmosphere has an oxygen content of 5 to 30 volume % oxygen and preferably an oxygen content of 5 to 21 volume %.

[0348] 77. A mixture according to embodiment 75 or 76, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere for 10 seconds or longer, preferably 1 minute or longer, more preferably 10 minutes or longer, and particularly preferably 60 minutes or longer.

[0349] 78. A mixture according to any one of embodiments 69 to 77, wherein the mixture comprises a co-stabilizer.

[0350] 79. A mixture according to embodiment 78, wherein the total amount of co-stabilizer present in the mixture is from 0.1 to 5000 ppm by weight, preferably from 1 to 4000 ppm by weight, in particular from 5 to 2500 ppm by weight, more preferably from 50 to 750 ppm by weight, based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture.

[0351] 80. A mixture according to any one of embodiments 78 or 79, wherein the co-stabilizer is a metal salt selected from copper, manganese and cerium salts, phenothiazine, phenolic compounds, N-oxides, phenylenediamines, nitroso compounds, ureas, thioureas or a mixture of two or more of said species of substances.

[0352] 81. Use of one or more compounds of general formula (III) as defined in embodiment 69 for stabilizing the storage and / or transport of (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters.

[0353] 82. Use according to embodiment 81, wherein the (meth)acrylic acid C 1 to C 8 alkyl esters are methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylic esters.

[0354] 83. Use according to any one of embodiments 81 or 82, wherein the total amount of the compound of general formula (III) used is from 0.1 to 1000 ppm by weight, preferably from 1 to 900 ppm by weight, more preferably from 10 to 800 ppm by weight, and in particular from 10 to 500 ppm by weight, based on the total weight of the (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters to be stabilized.

[0355] 84. Use according to any one of embodiments 81 or 83, wherein (meth)acrylic acid is stabilized and wherein the (meth)acrylic acid to be stabilized comprises one or more of the following components:

[0356] a. Water, 20 to 15,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0357] b. Di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0358] c. Acetic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0359] d. Propionic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0360] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0361] f. Protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0362] g. Maleic acid, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0363] h. Maleic anhydride, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0364] i. Allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, in each case based on the amount of (meth)acrylic acid.

[0365] 85. Use according to any one of embodiments 82 or 83, wherein one or more (meth)acrylates of embodiment 82 are stabilized and wherein the (meth)acrylate to be stabilized comprises one or more of the following components:

[0366] a. Water, 1 to 2,000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 82,

[0367] b. (Meth)acrylic acid, 1 to 2,000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 82,

[0368] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2,000 ppm by weight, preferably 0.1 to 1,000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 82,

[0369] d. Propionate of the alcohol corresponding to the respective (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 82.

[0370] e. Acetate of the alcohol corresponding to the respective (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 82.

[0371] f. Ether of the corresponding (meth)acrylate alcohol, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 82.

[0372] 86. A method for polymerizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters in the presence of a compound of general formula (III) as defined in one or more of embodiments 69, wherein the reaction mixture is saturated with oxygen to 0 to 50%, preferably 0 to 10%, more preferably 0 to 5%, particularly preferably 0 to 1%, most preferably 0 to 0.1%. The degree of oxygen saturation means the degree of oxygen saturation that is achieved when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably 5 to 21% by volume.

[0373] 87. The method according to embodiment 86, wherein the total amount of the compound of general formula (III) in the reaction mixture is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and in particular 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the reaction mixture.

[0374] 88. The method according to any one of embodiments 86 or 87, wherein the polymerization is carried out at a temperature of 50 to 150 °C and preferably 70 to 120 °C.

[0375] 89. The method according to any one of embodiments 86 to 88, wherein the polymerization is carried out in a nitrogen atmosphere having a nitrogen content of 85 to 100% by volume and an oxygen content of less than 5% by volume, preferably a nitrogen content of 90 to 100% by volume, more preferably a nitrogen content of 99 to 100%.

[0376] 90. The method according to any one of embodiments 86 to 89, wherein (meth)acrylic acid C 1 to C 8The alkyl ester is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or a mixture of two or more of said (meth)acrylates.

[0377] 91. The method according to any one of embodiments 86 or 89, wherein the (meth)acrylic acid to be polymerized comprises one or more of the following components:

[0378] a. Water, 20 to 15,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0379] b. Di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0380] c. Acetic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0381] d. Propionic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0382] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran, or benzaldehyde, each aldehyde in an amount of 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0383] f. Protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0384] g. Maleic acid, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0385] h. Maleic anhydride, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0386] i. Allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid.

[0387] 92. The method according to embodiment 90, wherein the (meth)acrylate to be polymerized comprises one or more of the following components:

[0388] a. Water, 1 to 2,000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 90,

[0389] b. (Meth)acrylic acid, 1 to 2,000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 90,

[0390] c. The alcohol corresponding to the (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 90.

[0391] d. The propionate of the alcohol corresponding to the (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 90.

[0392] e. The acetate of the alcohol corresponding to the (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 90.

[0393] f. The ether of the (meth)acrylate alcohol, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 90.

[0394] 93. A method for stabilizing (meth)acrylic acid and / or C 1 to C 8 alkyl esters of (meth)acrylic acid by using one or more compounds of general formula (III) defined in embodiment 69.

[0395] 94. The method according to embodiment 93, wherein the (meth)acrylic acid and / or C 1 to C 8 alkyl esters of (meth)acrylic acid are stabilized during storage and / or transportation.

[0396] 95. The method according to any one of embodiments 93 or 94, wherein the C 1 to C 8 alkyl esters of (meth)acrylic acid are methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0397] 96. The method according to any one of embodiments 93 or 94, wherein the (meth)acrylic acid comprises one or more of the following components:

[0398] a. Water, 20 to 15,000 ppm by weight, based on the amount of (meth)acrylic acid.

[0399] b. Di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the amount of (meth)acrylic acid.

[0400] c. Acetic acid, 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid.

[0401] d. Propionic acid, 100 to 2000 ppm by weight, based on the amount of (meth)acrylic acid

[0402] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furaldehyde, 3-furaldehyde, benzofuran or benzaldehyde, each aldehyde in an amount of 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid

[0403] f. Protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid

[0404] g. Maleic acid, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid

[0405] h. Maleic anhydride, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid

[0406] i. Allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid

[0407] 97. The method according to embodiment 95, wherein the (meth)acrylate comprises one or more of the following components:

[0408] a. Water, 1 to 2000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 95

[0409] b. (Meth)acrylic acid, 1 to 2000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 95

[0410] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 95

[0411] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 95

[0412] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 95

[0413] f. The ether of the alcohol of the corresponding (meth)acrylate, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 95

[0414] 98. A method according to any one of embodiments 93 to 97, wherein the method comprises providing a mixture comprising one or more compounds of general formula (III) and (meth)acrylic acid and / or a C 1 to C 8 alkyl (meth)acrylate, the mixture being oxygen-saturated to 50 to 100%, preferably 90 to 100%, more preferably 95 to 100%, the degree of oxygen saturation meaning the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere having an oxygen content of 5 to 30% by volume, preferably an oxygen content of 5 to 21% by volume, and reaches equilibrium.

[0415] 99. A method according to embodiment 98, wherein the total amount of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylate in the mixture is at least 5% by weight, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, particularly preferably at least 95% by weight, based on the total weight of the mixture.

[0416] 100. A method according to any one of embodiments 93 to 99, wherein the total amount of the compound of general formula (III) used is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and in particular 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and C 1 to C 8 alkyl (meth)acrylate present in the mixture.

[0417] 101. A mixture comprising one or more compounds of general formula (IV)

[0418]

[0419] wherein

[0420] R 12 is H; C 1 to C 20 alkyl, wherein the C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, and the preferred alkyl is C 1 to C 8Alkyl and more preferably alkyl groups are C 1 to C 6 alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group can also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0421] R 13 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl, and more preferably the alkyl group is C 1 to C 8 alkyl and more preferably the alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein the carboxyl group may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having a C 1 to C 8 alkyl carboxylate such as -COOMe; having a C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl,

[0422] R 14 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl group, the preferred alkyl is C 1 to C 8 alkyl and the more preferred alkyl group is C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein said carboxyl may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C 1 to C 8 alkyl carboxylate such as -COOMe; having C 1 to C 6 alkanoyl of alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; or 4-isopropoxyphenyl, and

[0423] R 15 is H; C 1 to C 20 alkyl, wherein C 1 to C 20 alkyl contains a straight-chain or branched C 1 to C 20 alkyl group or a cyclic C 3 to C 20 alkyl, the preferred alkyl being C 1 to C 8 alkyl and the more preferred alkyl group being C 1 to C 6Alkyl; phenyl, cyanophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, dimethylphenyl such as 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 4-isopropylphenyl, benzyl, 2-pyridyl, 3-pyridyl, 4-pyridyl; (carboxymethyl)phenyl, wherein said carboxyl may also be esterified with C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; (N,N-dimethylsulfamoyl) phenyl, sulfamoylphenyl; having C 1 to C 8 alkyl carboxylic acid esters such as -COOMe; having C 1 to C 6 alkyl alkanoyl, wherein C 1 to C 6 alkyl contains a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; 4-isopropoxyphenyl, NH 2 ; NH(CO)R 16 wherein R 16 is H, C 1 to C 6 alkyl, phenyl, tolyl such as m-tolyl or p-tolyl, 4-methoxyphenyl or dimethylphenyl such as 3,4-dimethylphenyl;

[0424] and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters.

[0425] 102. The mixture according to embodiment 101, wherein the (meth)acrylic acid C 1 to C 8 alkyl esters are (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid 2-ethylhexyl ester or a mixture of two or more of said (meth)acrylic acid esters.

[0426] 103. A mixture according to any one of embodiments 101 or 102, wherein the total amount of the compound of general formula (IV) in the mixture is from 0.1 to 1000 ppm by weight, preferably from 1 to 900 ppm by weight, more preferably from 10 to 800 ppm by weight, and in particular from 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and C 1 to C 8 alkyl esters present in the mixture.

[0427] 104. A mixture according to any one of embodiments 101 to 103, wherein the total amount of (meth)acrylic acid and C 1 to C 8 alkyl esters in the mixture is at least 5% by weight, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, particularly preferably at least 95% by weight, in each case based on the total weight of the mixture.

[0428] 105. A mixture according to any one of embodiments 101, 103 or 104, wherein the mixture comprises (meth)acrylic acid and wherein the mixture comprises one or more of the following components:

[0429] a. Water, from 20 to 15 000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0430] b. Di(meth)acrylic acid, from 100 to 20 000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0431] c. Acetic acid, from 100 to 2000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0432] d. Propionic acid, from 100 to 2000 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0433] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being from 0 to 1 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0434] f. Protoanemonin, from 0 to 2 ppm by weight, based on the total weight of (meth)acrylic acid present in the mixture,

[0435] g. Maleic acid, 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture.

[0436] h. Maleic anhydride, 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture.

[0437] i. Allyl acrylate, 0 to 30 weight ppm, preferably 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture.

[0438] 106. A mixture according to any one of embodiments 102 to 104, wherein the mixture comprises one or more (meth)acrylates of embodiment 102 and wherein the mixture comprises one or more of the following components:

[0439] a. Water, 1 to 2000 weight ppm, preferably 1 to 500 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 102 present in the mixture.

[0440] b. (Meth)acrylic acid, 1 to 2000 weight ppm, preferably 1 to 100 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 102 present in the mixture.

[0441] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 weight ppm, preferably 0.1 to 1000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 102 present in the mixture.

[0442] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 weight ppm, preferably 10 to 1000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 102 present in the mixture.

[0443] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 weight ppm, preferably 5 to 2000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 102 present in the mixture.

[0444] f. The ether of the corresponding (meth)acrylate alcohol, 0 to 2000 weight ppm, in each case based on the total weight of the (meth)acrylate of embodiment 102 present in the mixture.

[0445] 107. A mixture according to any one of embodiments 101 to 106, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere.

[0446] 108. The mixture according to embodiment 107, wherein the oxygen-containing atmosphere has an oxygen content of 5 to 30% by volume of oxygen and preferably an oxygen content of 5 to 21% by volume.

[0447] 109. The mixture according to embodiment 107 or 108, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere for 10 seconds or longer, preferably 1 minute or longer, more preferably 10 minutes or longer, and particularly preferably 60 minutes or longer.

[0448] 110. The mixture 101 to 109 according to any one of the embodiments, wherein the mixture comprises a co-stabilizer.

[0449] 111. The mixture according to embodiment 110, wherein the total amount of the co-stabilizer present in the mixture is 0.1 to 5000 ppm by weight, preferably 1 to 4000 ppm by weight, particularly 5 to 2500 ppm by weight, and more preferably 50 to 750 ppm by weight, based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture.

[0450] 112. The mixture according to any one of embodiments 110 or 111, wherein the co-stabilizer is a metal salt selected from copper, manganese and cerium salts, phenothiazine, phenolic compounds, N-oxyls, phenylenediamines, nitroso compounds, ureas, thioureas or a mixture of two or more of said species of substances.

[0451] 113. Use of one or more compounds of the general formula (IV) as defined in embodiment 101 for stabilizing the storage and / or transport of (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters.

[0452] 114. The use according to embodiment 113, wherein the (meth)acrylic acid C 1 to C 8 alkyl esters are methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylic esters.

[0453] 115. The use according to any one of embodiments 113 or 114, wherein the total amount of the compound of the general formula (IV) used is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and particularly 10 to 500 ppm by weight, based on the total weight of the (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters to be stabilized.

[0454] Use according to any one of embodiments 113 or 115, wherein the (meth)acrylic acid is stabilized and wherein the (meth)acrylic acid to be stabilized comprises one or more of the following components:

[0455] a. Water, 20 to 15,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0456] b. Di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0457] c. Acetic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0458] d. Propionic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0459] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, each aldehyde in an amount of 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0460] f. Protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0461] g. Maleic acid, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0462] h. Maleic anhydride, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0463] i. Allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, in each case based on the amount of (meth)acrylic acid.

[0464] 117. Use according to any one of embodiments 114 or 115, wherein one or more of the (meth)acrylates of embodiment 114 are stabilized and wherein the (meth)acrylate to be stabilized comprises one or more of the following components:

[0465] a. Water, 1 to 2,000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 114,

[0466] b. (Meth)acrylic acid, 1 to 2,000 ppm by weight, preferably 1 to 100 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 114,

[0467] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 ppm by weight, preferably 0.1 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 114.

[0468] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 ppm by weight, preferably 10 to 1000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 114.

[0469] e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 114.

[0470] f. The ether of the corresponding (meth)acrylate alcohol, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 114.

[0471] 118. A method for polymerizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters in the presence of one or more compounds of general formula (IV) of embodiment 101, wherein the reaction mixture is saturated with oxygen to 0 to 50%, preferably 0 to 10%, more preferably 0 to 5%, particularly preferably 0 to 1%, most preferably 0 to 0.1%. The degree of oxygen saturation means the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably 5 to 21% by volume.

[0472] 119. The method according to embodiment 118, wherein the total amount of the compound of general formula (IV) in the reaction mixture is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, especially 10 to 500 ppm by weight, in each case based on the total weight of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the reaction mixture.

[0473] 120. The method according to any one of embodiments 118 or 119, wherein the polymerization is carried out at a temperature of 50 to 150 °C and preferably 70 to 120 °C.

[0474] 121. The method according to any one of embodiments 118 to 120, wherein the polymerization is carried out in a nitrogen atmosphere having a nitrogen content of 85 to 100% by volume and an oxygen content of less than 5% by volume, preferably a nitrogen content of 90 to 100% by volume, more preferably a nitrogen content of 99 to 100%.

[0475] 122. A method according to any one of embodiments 118 to 121, wherein the C 1 to C 8 alkyl (meth)acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0476] 123. A method according to any one of embodiments 118 to 121, wherein the (meth)acrylic acid to be polymerized comprises one or more of the following components:

[0477] a. water, 20 to 15,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0478] b. di(meth)acrylic acid, 100 to 20,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0479] c. acetic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0480] d. propionic acid, 100 to 2,000 ppm by weight, based on the amount of (meth)acrylic acid,

[0481] e. one or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0482] f. protoanemonin, 0 to 2 ppm by weight, based on the amount of (meth)acrylic acid,

[0483] g. maleic acid, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0484] h. maleic anhydride, 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid,

[0485] i. allyl acrylate, 0 to 30 ppm by weight, preferably 0 to 1 ppm by weight, based on the amount of (meth)acrylic acid.

[0486] 124. A method according to embodiment 122, wherein the (meth)acrylate to be polymerized comprises one or more of the following components:

[0487] a. water, 1 to 2,000 ppm by weight, preferably 1 to 500 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 122,

[0488] b. (Meth)acrylic acid, 1 to 2000 weight ppm, preferably 1 to 100 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 122,

[0489] c. Alcohol of the corresponding (meth)acrylate, 0.01 to 2000 weight ppm, preferably 0.1 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 122,

[0490] d. Propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 weight ppm, preferably 10 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 122,

[0491] e. Acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2000 weight ppm, preferably 5 to 2000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 122,

[0492] f. Ether of the corresponding (meth)acrylate alcohol, 0 to 2000 weight ppm, based on the amount of the (meth)acrylate of embodiment 122.

[0493] 125. A method for stabilizing (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters by using one or more compounds of general formula (IV) defined in embodiment 101.

[0494] 126. The method according to embodiment 125, wherein the (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters are stabilized during storage and / or transportation.

[0495] 127. The method according to any one of embodiments 125 or 126, wherein the (meth)acrylic acid C 1 to C 8 alkyl esters are methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

[0496] 128. The method according to any one of embodiments 125 or 126, wherein the (meth)acrylic acid comprises one or more of the following components:

[0497] a. Water, 20 to 15000 weight ppm, based on the amount of (meth)acrylic acid,

[0498] b. Di(meth)acrylic acid, 100 to 20,000 weight ppm, based on the amount of (meth)acrylic acid

[0499] c. Acetic acid, 100 to 2000 weight ppm, based on the amount of (meth)acrylic acid

[0500] d. Propionic acid, 100 to 2000 weight ppm, based on the amount of (meth)acrylic acid

[0501] e. One or more aldehydes such as acetaldehyde, acrolein, propionaldehyde, 2-furfural, 3-furfural, benzofuran or benzaldehyde, the amount of each aldehyde being 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0502] f. Protoanemonin, 0 to 2 weight ppm, based on the amount of (meth)acrylic acid

[0503] g. Maleic acid, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0504] h. Maleic anhydride, 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0505] i. Allyl acrylate, 0 to 30 weight ppm, preferably 0 to 1 weight ppm, based on the amount of (meth)acrylic acid

[0506] 129. The method according to embodiment 127, wherein the (meth)acrylate comprises one or more of the following components:

[0507] a. Water, 1 to 2000 weight ppm, preferably 1 to 500 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 127

[0508] b. (Meth)acrylic acid, 1 to 2000 weight ppm, preferably 1 to 100 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 127

[0509] c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2000 weight ppm, preferably 0.1 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 127

[0510] d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2000 weight ppm, preferably 10 to 1000 weight ppm, in each case based on the amount of the (meth)acrylate of embodiment 127

[0511] e. Acetates of the alcohols corresponding to the (meth)acrylates, 1 to 2000 ppm by weight, preferably 5 to 2000 ppm by weight, in each case based on the amount of the (meth)acrylate of embodiment 127.

[0512] f. Ethers of the corresponding (meth)acrylate alcohols, 0 to 2000 ppm by weight, based on the amount of the (meth)acrylate of embodiment 127.

[0513] 130. A method according to any one of embodiments 125 to 129, wherein the method comprises providing a mixture comprising one or more compounds of formula (IV) and (meth)acrylic acid and / or (meth)acrylic acid C 1 to C 8 alkyl esters, the mixture being saturated with oxygen to 50 to 100%, preferably 90 to 100%, more preferably 95 to 100%, the degree of oxygen saturation meaning the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere with an oxygen content of 5 to 30% by volume, preferably an oxygen content of 5 to 21% by volume, until equilibrium is reached.

[0514] 131. A method according to embodiment 130, wherein the total amount of (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters in the mixture is at least 5% by weight, based on the total weight of the mixture, further preferably at least 20% by weight, further preferably at least 30% by weight, further preferably at least 40% by weight, further preferably at least 50% by weight, further preferably at least 60% by weight, further preferably at least 70% by weight, further preferably at least 80% by weight, further preferably at least 90% by weight, particularly preferably at least 95% by weight.

[0515] 132. A method according to any one of embodiments 125 to 131, wherein the total amount of the compound of formula (IV) used is 0.1 to 1000 ppm by weight, preferably 1 to 900 ppm by weight, more preferably 10 to 800 ppm by weight, and in particular 10 to 500 ppm by weight, in each case based on the total weight of the (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters present in the mixture. Examples:

[0516] The following examples do not limit the inventive subject matter of the invention.

[0517]

[0518] First, the acrylic acid used in the experiment was distilled to remove the stabilizer contained therein. The purity of the distilled acrylic acid was greater than 99.5% by weight. The minor components present in the distilled acrylic acid were acetic acid (0.0726% by weight), diacrylic acid (0.0497% by weight), and propionic acid (0.0184% by weight).

[0519] The weights reported in the experimental description, such as weight percentages (% by weight) or weight ppm values based on acrylic acid, are based on the mass of the acrylic acid used in each case, including the minor components contained therein.

[0520] Experiment for examining polymerization inhibition under air or nitrogen:

[0521] For the comparative experiment, an acrylic acid solution containing 40 weight ppm of 4-methoxyphenol (MEHQ) was prepared. The weight ppm value was based on the mass of the acrylic acid used.

[0522] For a further comparative experiment, a mixture of acrylic acid and a compound different from the compounds of general formula (I), (II), (III), or (IV) was prepared, and the molar amount of the compound used corresponded to the molar amount of MEHQ in the comparative experiment.

[0523] For the experiment of the present invention, a mixture of acrylic acid and a compound of general formula (I), (II), (III), and / or (IV) was prepared, and the molar amount of the compound of general formula (I), (II), (III), and / or (IV) in the mixture corresponded to the molar amount of MEHQ in the comparative experiment.

[0524] Exemplary dilution series:

[0525] 2.5 g of an acrylic acid solution having an MEHQ content of 1000 weight ppm based on the mass of the acrylic acid used was diluted with acrylic acid to an MEHQ content of 500 weight ppm based on the mass of the acrylic acid used.

[0526] 2.5 g of the acrylic acid solution thus obtained was diluted with acrylic acid to an MEHQ content of 250 weight ppm based on the mass of the acrylic acid used.

[0527] 2.5 g of the acrylic acid solution thus obtained was diluted with acrylic acid to an MEHQ content of 125 weight ppm based on the mass of the acrylic acid used.

[0528] 2.5 g of the acrylic acid solution thus obtained was diluted with acrylic acid to an MEHQ content of 80 weight ppm based on the mass of the acrylic acid used.

[0529] 2.5 g of the acrylic acid solution thus obtained was diluted with acrylic acid to an MEHQ content of 40 weight ppm based on the mass of the acrylic acid used.

[0530] The initiator solution used is a freshly prepared toluene solution of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). The content of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) in the initiator solution is 6420 weight ppm, based on the mass of toluene in the initiator solution.

[0531] Inhibitory test for polymerization under air:

[0532] Under air, first, 2.2 g of an acrylic acid solution containing 0.000715 mmol of the corresponding polymerization stabilizer was added. 0.22 g of the initiator solution was added to the first-added acrylic acid solution and the mixture was homogenized. The 1.9 ml of the resulting mixture was transferred to a 4.5 ml reaction vessel in air. The reaction vessel was sealed and equipped with a temperature sensor. The temperature sensor extended into the mixture in the reaction vessel.

[0533] Then, the reaction vessel containing the mixture was placed in a heating block heated to 40 °C.

[0534] Once the mixture reached a temperature of 40 °C, the temperature profile over time was measured. The time period from reaching 40 °C to reaching the maximum temperature was used as a reference value for the inhibitory ability of each polymerization inhibitor.

[0535] For the mixture with MEHQ as the polymerization stabilizer, it was measured that the temperature increased from 145 °C to the maximum temperature of 185 °C, and the increase lasted for 42 seconds. The mixture reached the maximum temperature 9188 seconds after thermal equilibrium at 40 °C. When calculating the efficiency of the polymerization stabilizer relative to MEHQ, the value of 9188 seconds corresponds to 100% efficiency.

[0536] For the mixture with 5-methyl-2-phenyl-4H-pyrazol-3-one as the polymerization stabilizer, it was observed that the temperature increased from 125 °C to the maximum temperature of 165 °C, and the increase lasted for 48 seconds. The mixture reached the maximum temperature 7874 seconds after thermal equilibrium at 40 °C.

[0537] Therefore, the efficiency of 5-methyl-2-phenyl-4H-pyrazol-3-one as a polymerization stabilizer relative to MEHQ is 86%.

[0538] Polymerization inhibition test under nitrogen:

[0539] First, 2.2 g of an acrylic acid solution containing 0.000715 mmol of the corresponding polymerization stabilizer was added to the air. 0.22 g of an initiator solution was added to the initially added acrylic acid solution and the mixture was homogenized. The 1.9 ml of the resulting mixture was transferred to a 4.5 ml reaction vessel in the air. The reaction vessel was sealed and equipped with a temperature sensor. The temperature sensor extended into the mixture in the reaction vessel. Under pressure equilibrium, nitrogen was introduced above the initially added mixture in the reaction vessel. The nitrogen flow rate was 3 to 4 l / h. The inflow time was 20 seconds. The purity of the nitrogen was greater than 99.9%.

[0540] The reaction vessel containing the mixture was placed in a heating block. Then the mixture was heated to 40 °C in the heating block within 4 minutes.

[0541] Once the mixture reached a temperature of 40 °C, the temperature curve over time was measured. The time period from reaching 40 °C to reaching the maximum temperature was used as a reference value for the inhibitory capacity of each polymerization inhibitor.

[0542] For the mixture with MEHQ as the polymerization stabilizer, it was measured that the temperature increased from 133 °C to the maximum temperature of 173 °C, and the increase lasted for 54 seconds. The maximum temperature was reached 3978 seconds after the mixture was in thermal equilibrium at 40 °C. When calculating the efficiency of the polymerization stabilizer relative to MEHQ, the value of 3978 seconds corresponded to 100% efficiency.

[0543] For the mixture with 5-methyl-2-phenyl-4H-pyrazol-3-one as the polymerization stabilizer, it was observed that the temperature increased from 119 °C to the maximum temperature of 159 °C, and the increase lasted for 66 seconds. The maximum temperature was reached 1056 seconds after the mixture was in thermal equilibrium at 40 °C.

[0544] Therefore, the efficiency of 5-methyl-2-phenyl-4H-pyrazol-3-one as a polymerization stabilizer relative to MEHQ was 27%.

[0545] Test results using non-compounds of the present invention in acrylic acid:

[0546]

[0547]

[0548] Test results using compounds of the present invention in acrylic acid:

[0549]

[0550]

[0551]

[0552]

[0553]

[0554]

[0555]

[0556] Polymerization experiment:

[0557] Under a nitrogen atmosphere, 450 g of deionized water was added to the reaction vessel. The initially added reaction mixture was heated to 95 °C with stirring. Once the temperature of 95 °C was reached, while maintaining this temperature, three feeds were introduced.

[0558] Feed stream 1: 500 g of acrylic acid, fed for 5 hours

[0559] Feed stream 2: 15 g of sodium hypophosphite in 35 g of deionized water, fed for 4.75 hours

[0560] Feed stream 3: 5 g of sodium persulfate in 66.4 g of deionized water, fed for 5.25 hours

[0561] After adding the three feeds, the reaction mixture was stirred at 95 °C for an additional 1 hour. Then the reaction mixture was cooled to room temperature and 80 g of deionized water was added.

[0562] In the experiments of the present invention, the acrylic acid from feed stream 1 was stabilized with edaravone (5-methyl-2-phenyl-4H-pyrazol-3-one) at 280 weight ppm based on the mass of acrylic acid. In the comparative experiment, the acrylic acid from feed stream 1 was stabilized with MEHQ at 200 weight ppm based on the mass of acrylic acid.

[0563] The resulting polymer was analyzed by GPC (calibrated with Na-PAA standards, eluent 0.01 mol / l phosphate buffer pH 7.4, in distilled water containing 0.01 M NaN 3 ).

[0564] Mw (g / mol) Polymer (edaravone) 9560 Polymer (MEHQ) 9400

[0565] Test in acrylate:

[0566] Experiment for testing the inhibition of polymerization in air or nitrogen:

[0567] The experiment for detecting polymerization inhibition under air or nitrogen was carried out using ethyl acrylate from which the stabilizer had been removed. The ethyl acrylate used for this contained 10 to 20 weight ppm of MEHQ based on the amount of ethyl acrylate and was filtered through type 90 activated neutral alumina without applying pressure. For every 100 ml of stabilized ethyl acrylate, 20 g of type 90 activated neutral alumina was used. After filtration, MEHQ was no longer detected by HPLC analysis in the ethyl acrylate.

[0568] For the comparative experiment, an ethyl acrylate solution containing 13 weight ppm of MEHQ was prepared. The ppm weight value was based on the mass of ethyl acrylate present in the solution.

[0569] For a further comparative experiment, a mixture of ethyl acrylate and a compound different from the compounds of general formula (I), (II), (III) or (IV) was prepared, and the molar amount of the compound used corresponded to the molar amount of MEHQ in the comparative experiment.

[0570] For the experiment of the present invention, a mixture of ethyl acrylate and a compound of general formula (I), (II), (III) or (IV) was prepared, and the molar amount of the compound of general formula (I), (II), (III) or (IV) in the mixture corresponded to the molar amount of MEHQ in the comparative experiment.

[0571] Exemplary dilution series:

[0572] 1.0 g of an ethyl acrylate solution containing 500 weight ppm of MEHQ content based on the mass of ethyl acrylate present in the solution was diluted with ethyl acrylate to a MEHQ content of 240 weight ppm based on the mass of ethyl acrylate in the solution.

[0573] 1.5 g of the ethyl acrylate solution thus obtained was diluted with ethyl acrylate to a MEHQ content of 80 weight ppm based on the mass of ethyl acrylate in the solution.

[0574] 1.5 g of the ethyl acrylate solution thus obtained was diluted with ethyl acrylate to a MEHQ content of 30 weight ppm based on the mass of ethyl acrylate in the solution.

[0575] 2.0 g of the ethyl acrylate solution thus obtained was diluted with ethyl acrylate to a MEHQ content of 13 weight ppm based on the mass of ethyl acrylate in the solution.

[0576] The initiator solution used was a freshly prepared toluene solution of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). Based on the mass of toluene in the initiator solution, the content of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) in the initiator solution was 6420 weight ppm.

[0577] Experiment for the inhibition of polymerization in air:

[0578] First, 2.0 g of an ethyl acrylate solution containing 0.00021 mmol of the corresponding polymerization stabilizer was added in air. 0.17 g of an initiator solution was added to the initially added ethyl acrylate solution and the mixture was homogenized. The 1.9 ml of the mixture thus obtained was transferred in air to a 4.5 ml reaction vessel. The reaction vessel was closed and equipped with a temperature sensor. The temperature sensor extended into the mixture in the reaction vessel.

[0579] The reaction vessel containing the mixture was placed in a heating block heated to 40 °C.

[0580] Once the mixture reached a temperature of 40 °C, the temperature profile over time was measured. The time period from reaching 40 °C to reaching the maximum temperature was used as a reference value for the inhibitory capacity of each polymerization inhibitor.

[0581] For the mixture with MEHQ as the polymerization stabilizer, it was measured that the temperature increased from 8 °C to a maximum temperature of 48 °C, and the increase lasted for 1200 seconds. The maximum temperature was reached 29084 seconds after the mixture was in thermal equilibrium at 40 °C. When calculating the efficiency of the polymerization stabilizer relative to MEHQ, the value of 29084 seconds corresponded to 100% efficiency.

[0582] For the inventive mixture with 5-methyl-2-phenyl-4H-pyrazol-3-one as the polymerization stabilizer, it was observed that the temperature increased from 6 °C to a maximum temperature of 46 °C, and the increase lasted for 1200 seconds. The maximum temperature was reached 28470 seconds after the mixture was in thermal equilibrium at 40 °C.

[0583] Therefore, the efficiency of 5-methyl-2-phenyl-4H-pyrazol-3-one as a polymerization stabilizer was 98% relative to MEHQ.

[0584] Experiment for the inhibition of polymerization in nitrogen:

[0585] First, 2.0 g of an ethyl acrylate solution containing 000021 mmol of the corresponding polymerization stabilizer was added in air. 0.17 g of an initiator solution was added to the initially added ethyl acrylate solution and the mixture was homogenized. The 1.9 ml of the mixture thus obtained was transferred in air to a 4.5 ml reaction vessel. The reaction vessel was closed and equipped with a temperature sensor. The temperature sensor extended into the mixture in the reaction vessel. Under pressure equilibrium, nitrogen was introduced above the initially added mixture in the reaction vessel. The nitrogen flow rate was 3 to 4 l / h. The inflow time was 20 seconds. The purity of the nitrogen was greater than 99.9%.

[0586] Place the reaction vessel containing the mixture in a heating block. Then heat the mixture in the heating block to 40 °C within 4 minutes.

[0587] Once the mixture reaches a temperature of 40 °C, measure the temperature profile over time. The time period from reaching 40 °C to reaching the maximum temperature is used as a reference value for the inhibitory capacity of each polymerization inhibitor.

[0588] For the mixture with MEHQ as the polymerization stabilizer, the temperature was measured to increase from 73 °C to a maximum temperature of 113 °C, and this increase continued for 240 seconds. The maximum temperature was reached 460 seconds after the mixture reached thermal equilibrium at 40 °C. When calculating the efficiency of the polymerization stabilizer relative to MEHQ, the value of 460 seconds corresponds to 100% efficiency.

[0589] For the inventive mixture with 5-methyl-2-phenyl-4H-pyrazol-3-one as the polymerization stabilizer, the temperature was observed to increase from 80 °C to a maximum temperature of 120 °C, and this increase continued for 240 seconds. The maximum temperature was reached 426 seconds after the mixture reached thermal equilibrium at 40 °C.

[0590] Therefore, the efficiency of 5-methyl-2-phenyl-4H-pyrazol-3-one as a polymerization stabilizer is 93% relative to MEHQ.

[0591] Test results using the compounds of the present invention in ethyl acrylate:

[0592]

[0593]

[0594]

[0595] Polymerization experiment with acrylates:

[0596] Homopolymerization of n-butyl acrylate:

[0597] Comparative experiment:

[0598] Under a nitrogen atmosphere, add 210 g of n-butyl acetate, 14.7 g of n-butyl acrylate (stabilized with 15 weight ppm of MEHQ based on the amount of n-butyl acrylate), and 0.08 g of azobisisobutyronitrile (AIBN) to the reaction vessel. Heat the initially added reaction mixture to 80 °C with stirring. After reaching a temperature of 80 °C for 15 minutes, add two feed streams while maintaining the temperature.

[0599] Feed stream 1: 195.3 g of n-butyl acrylate (stabilized with 15 ppm weight of MEHQ based on the amount of n-butyl acrylate) and 100.5 g of n-butyl acetate, and the feeding continues for 2 hours

[0600] Feed stream 2: 0.98 g of AIBN and 74.1 g of n-butyl acetate, fed for 3 hours

[0601] After adding the said feed streams, the reaction mixture was stirred at 80 °C for 2 hours and then cooled to 25 °C.

[0602] The present invention:

[0603] Under a nitrogen atmosphere, 210 g of n-butyl acetate, 14.7 g of n-butyl acrylate (stabilized with 21 weight ppm of 5-methyl-2-phenyl-4H-pyrazol-3-one based on the amount of n-butyl acrylate) and 0.08 g of AIBN were added to a reaction vessel. The initially added reaction mixture was heated to 80 °C with stirring. 15 minutes after reaching the temperature of 80 °C, two feed streams were added while maintaining this temperature.

[0604] Feed stream 1: 195.3 g of n-butyl acrylate (stabilized with 21 weight ppm of 5-methyl-2-phenyl-4H-pyrazol-3-one based on the amount of n-butyl acrylate) and 100.5 g of n-butyl acetate, fed for 2 hours

[0605] Feed stream 2: 0.98 g of AIBN and 74.1 g of n-butyl acetate, fed for 3 hours

[0606] After adding the said feed streams, the reaction mixture was stirred at 80 °C for 2 hours and then cooled to room temperature.

[0607] The resulting polymer was analyzed by GPC (calibrated with polystyrene standards, eluent: THF + 0.1 vol% trifluoroacetic acid).

[0608] Mw (g / mol) Polymer (the present invention) 164 000 Polymer (MEHQ) 163 000

[0609] Emulsion polymerization of n-butyl acrylate, styrene and methacrylic acid:

[0610] Comparative experiment:

[0611] Under a nitrogen atmosphere, 250 g of softened water and 4 g of potassium persulfate were added to a reaction vessel. The initially added reaction mixture was heated to 60 °C with stirring. At 60 °C, 8 g of Feed 1 was added to the reaction mixture while stirring. After 5 minutes of addition, the remaining Feed 1 and Feed 2 were added to the reaction mixture at 60 °C while stirring. The remaining Feed 1 was added to the reaction mixture within 160 minutes and Feed 2 was added within 150 minutes.

[0612] Feed 1: 4 g of sodium bisulfite, 100 g of softened water

[0613] Feed 2: 400 g of styrene (stabilized with 20 ppm by weight of MEHQ based on the amount of styrene), 400 g of n-butyl acrylate (stabilized with 15 ppm by weight of MEHQ based on the amount of n-butyl acrylate), 15 g of methacrylic acid (stabilized with 200 ppm by weight of MEHQ based on the amount of methacrylic acid), 20 g of Disponil FES 147, and 450 g of softened water.

[0614] At the end of the addition of Feed 1, the temperature of the reaction mixture was raised to 65 °C and the reaction mixture was maintained at this temperature for 1 hour. The resulting dispersion was cooled to ambient temperature, adjusted to pH 7 with an aqueous ammonia solution (25 wt%), and filtered through a sieve.

[0615] The present invention:

[0616] Under a nitrogen atmosphere, 250 g of softened water and 4 g of potassium persulfate were added to a reaction vessel. The initially added reaction mixture was heated to 60 °C with stirring. At 60 °C, while stirring, 8 g of Feed 1 was added to the reaction mixture. Five minutes after the addition, the remaining Feed 1 and Feed 2 were added to the reaction mixture at 60 °C with stirring. The remaining Feed 1 was added to the reaction mixture within 160 minutes, and Feed 2 was added within 150 minutes.

[0617] Feed 1: 4 g of sodium bisulfite, 100 g of softened water

[0618] Feed 2: 400 g of styrene (stabilized with 28 ppm by weight of edaravone based on the amount of styrene), 400 g of n-butyl acrylate (stabilized with 21 ppm by weight of edaravone based on the amount of n-butyl acrylate), 15 g of methacrylic acid (stabilized with 280 ppm by weight of edaravone based on the amount of methacrylic acid), 20 g of Disponil FES 147, and 450 g of softened water.

[0619] At the end of the addition of Feed 1, the temperature of the reaction mixture was raised to 65 °C and the reaction mixture was maintained at this temperature for 1 hour. The resulting dispersion was cooled to ambient temperature, adjusted to pH 7 with an aqueous ammonia solution (25 wt%), and filtered through a sieve.

[0620]

[0621] The average particle size (z-average) was determined as follows:

[0622] Samples were analyzed using a Malvern Zetasizer Nano analyzer. They were diluted to a measurement concentration of 0.0005% with Millipore water (pH 4), and then measured with a 5 μm filter. The measurements were carried out at 25 °C.

[0623] The glass transition temperature was determined as follows:

[0624] The polymer dispersion was dried at 80 °C under reduced pressure. The glass transition temperature was determined by DSC. Before measurement, the sample was rapidly cooled from 140 °C and then measured from -50 °C to 140 °C at 20 K / min.

[0625] The molar mass was determined by GPC (calibrated with polystyrene standards, eluent: THF + 0.1 vol% trifluoroacetic acid).

[0626] The residual monomer content was determined by headspace GC.

[0627] The amount of the weighed coagulum (aggregated polymer colloid in the apparatus and in the filtration residue) was measured.

Claims

1. A mixture comprising one or more compounds of general formula (II) wherein R 6 is H or C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl includes a straight-chain or branched C 1 to C 6 alkyl group or a cyclic C 3 to C 6 alkyl group; R 7 is H; C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain C 1 to C 6 alkyl group; or an alkanoyl group having C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain C 1 to C 6 alkyl group; and R 8 is H or C 1 to C 6 alkyl, wherein C 1 to C 6 alkyl contains a straight-chain C 1 to C 6 alkyl group; and (Meth)acrylic acid, (meth)acrylic acid C 1 to C 8 alkyl esters, or (meth)acrylic acid and (meth)acrylic acid C 1 to C 8 alkyl esters; wherein the total amount of the compound of the general formula (II) in the mixture is from 0.1 to 1000 weight ppm, based on the total weight of the (meth)acrylic acid and the C 1 to C 8 alkyl esters present in the mixture.

2. The mixture according to claim 1, wherein the C 1 to C 8 alkyl (meth)acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or a mixture of two or more of said (meth)acrylates.

3. The mixture according to claim 1 or 2, wherein the total amount of (meth)acrylic acid and C 1 to C 8 alkyl esters in the mixture is at least 5% by weight, based on the total weight of the mixture.

4. The mixture according to claim 1, wherein the mixture comprises (meth)acrylic acid and wherein the mixture comprises one or more of the following components: a. Water, 20 to 15,000 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, b. Di(meth)acrylic acid, 100 to 20,000 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, c. Acetic acid, 100 to 2,000 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, d. Propionic acid, 100 to 2,000 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, e. One or more aldehydes, each in an amount of 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, f. Protoanemonin, 0 to 2 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, g. Maleic acid, 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, h. Maleic anhydride, 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture, i. Allyl acrylate, 0 to 30 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture.

5. The mixture according to claim 4, wherein the aldehydes are selected from acetaldehyde, acrolein, propionaldehyde, 2-furaldehyde, 3-furaldehyde, benzofuran or benzaldehyde.

6. The mixture according to claim 4, wherein the amount of allyl acrylate is 0 to 1 weight ppm, based on the total weight of (meth)acrylic acid present in the mixture.

7. The mixture according to claim 2, wherein the mixture comprises one or more (meth)acrylates of claim 2 and wherein the mixture comprises one or more of the following components: a. Water, 1 to 2,000 weight ppm, in each case based on the total weight of the (meth)acrylate of claim 2 present in the mixture, b. (Meth)acrylic acid, 1 to 2,000 weight ppm, in each case based on the total weight of the (meth)acrylate of claim 2 present in the mixture, c. The alcohol of the corresponding (meth)acrylate, 0.01 to 2,000 weight ppm, in each case based on the total weight of the (meth)acrylate of claim 2 present in the mixture, d. The propionate of the alcohol of the corresponding (meth)acrylate, 0.1 to 2,000 weight ppm, in each case based on the total weight of the (meth)acrylate of claim 2 present in the mixture, e. The acetate of the alcohol of the corresponding (meth)acrylate, 1 to 2,000 weight ppm, in each case based on the total weight of the (meth)acrylate of claim 2 present in the mixture, f. Ethers of the corresponding (meth)acrylate alcohols, 0 to 2000 weight ppm, in each case based on the total weight of the (meth)acrylates according to claim 2 present in the mixture.

8. The mixture according to claim 7, wherein the amount of water is 1 to 500 weight ppm, in each case based on the total weight of the (meth)acrylates according to claim 2 present in the mixture.

9. The mixture according to claim 7, wherein the amount of (meth)acrylic acid is 1 to 100 weight ppm, in each case based on the total weight of the (meth)acrylates according to claim 2 present in the mixture.

10. The mixture according to claim 7, wherein the amount of the alcohol of the corresponding (meth)acrylate is 0.1 to 1000 weight ppm, in each case based on the total weight of the (meth)acrylates according to claim 2 present in the mixture.

11. The mixture according to claim 7, wherein the amount of the propionate of the alcohol of the corresponding (meth)acrylate is 10 to 1000 weight ppm, in each case based on the total weight of the (meth)acrylates according to claim 2 present in the mixture.

12. The mixture according to claim 7, wherein the amount of the acetate of the alcohol of the corresponding (meth)acrylate is 5 to 2000 weight ppm, in each case based on the total weight of the (meth)acrylates according to claim 2 present in the mixture.

13. The mixture according to claim 1 or 2, wherein the mixture is stored and / or transported in an oxygen-containing atmosphere.

14. The mixture according to claim 1 or 2, wherein the mixture contains a co-stabilizer.

15. Use of one or more compounds of general formula (II) as defined in claim 1 for stabilizing (meth)acrylic acid, C 1 to C 8 alkyl esters of (meth)acrylic acid, or storage and / or transportation of (meth)acrylic acid and C 1 to C 8 alkyl esters of (meth)acrylic acid.

16. Polymerization of (meth)acrylic acid, C 1 to C 8 alkyl esters of (meth)acrylic acid, or (meth)acrylic acid and C 1 to C 8 alkyl esters of (meth)acrylic acid in the presence of one or more compounds of general formula (II) as defined in claim 1, the reaction mixture being saturated with oxygen to 0 to 50%, the degree of oxygen saturation meaning the degree of oxygen saturation that is reached when the mixture is stored and / or transported under standard conditions in an oxygen-containing atmosphere having an oxygen content of 5 to 30% by volume and reaches equilibrium.

17. A method for stabilizing (meth)acrylic acid, a C 1 to C 8 alkyl ester of (meth)acrylic acid, or a mixture of (meth)acrylic acid and a C 1 to C 8 alkyl ester of (meth)acrylic acid by using one or more compounds of general formula (II) as defined in claim 1.

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