Synergistic antifouling composition and method of use thereof

Abstract

A polymerization inhibitor composition is provided. The polymerization inhibitor composition includes at least a first inhibitor compound having a stable nitroxide radical and a second inhibitor compound having a hydroxylamine. Methods of inhibiting polymerization of a monomer using the disclosed composition are also provided. The method of inhibiting polymerization of a monomer includes adding the disclosed composition to the monomer. In some cases, the monomer is an ethylenically unsaturated monomer. Such ethylenically unsaturated monomers include, but are not limited to, vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof. Methods of preparing the disclosed polymerization inhibitors and compositions are also provided.

Description

[Technical field]

[0001] The present disclosure generally relates to compositions comprising a blend of polymerization inhibitors and methods of use thereof. More specifically, the present disclosure relates to compositions comprising at least one compound having a stable nitroxide radical and at least one compound having a hydroxylamine, which are useful for inhibiting the polymerization of ethylenically unsaturated monomers. The present disclosure further relates to a method for preparing the compound having a stable nitroxide radical and a method for preparing the compound having a hydroxylamine. [Background technology]

[0002] The production of ethylenically unsaturated monomers typically involves three stages: reaction, recovery, and purification. Distillation operations at high temperatures are often included in the recovery and purification stages. Ethylenically unsaturated monomers such as vinyl acetate, acrylate, and methacrylate monomers can be present in process streams or in refined products made by various chemical industrial processes. However, these monomer types can polymerize undesirably by radical polymerization, especially at high temperatures and in the presence of polymerization initiators. As a result, solid deposits of polymer can form on the surfaces of process equipment during industrial production, processing, handling, or storage. The resulting polymers can be problematic and result in equipment "fouling" and product contamination. This may therefore require the equipment to be treated to remove the polymer or may require processing steps to remove the polymer from the composition stream or stored composition. These undesirable polymerization reactions consume valuable reagents and result in loss of production efficiency, as additional steps may be required to clean equipment and / or to remove the undesired polymer.

[0003] The premature polymerization of these monomers is generally controlled by administering a polymerization inhibitor that can reduce the premature polymerization of the monomers. Conventional polymerization inhibitors contain stable free radicals that can effectively capture carbon-centered radicals. Conventional polymerization inhibitors such as 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (HTEMPO) and 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxyl (OTEMPO) generally decompose in an acidic environment and lose their efficacy as polymerization inhibitors. Therefore, there is a need to develop novel polymerization inhibitors, especially inhibitors that are stable under acidic conditions. Summary of the Invention

[0004] Disclosed herein is a composition for inhibiting the polymerization of monomers. The composition comprises a first inhibitor compound having a stable nitroxide radical and a second inhibitor compound having a hydroxylamine. In some embodiments, the composition is useful for inhibiting the polymerization of ethylenically unsaturated monomers, including vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof.

[0005] In some embodiments, compositions of the present disclosure demonstrate synergy with respect to their ability to inhibit polymerization of monomers, for example, in some embodiments, compositions of the present disclosure control the dosage of active components to demonstrate greater inhibition of polymerization than the individual components present within the composition.

[0006] In some embodiments, the compositions of the present disclosure are active even under acidic conditions, unlike conventional polymerization inhibitors known in the art, hi some embodiments, the compositions of the present disclosure also include one or more acids.

[0007] Also disclosed herein is a method of inhibiting polymerization of a monomer. The method of inhibiting polymerization of a monomer includes adding a composition of the present disclosure to the monomer. Adding the polymerization inhibitor composition of the present disclosure to the monomer inhibits polymerization of the monomer.

[0008] Processes for preparing the polymerization inhibitors and compositions of the present disclosure are also disclosed herein. The process for preparing the polymerization inhibitor comprises treating a compound of formula (IIIa) with a compound of formula (IIIb) in solution to obtain a polymerization inhibitor compound.

[0009] The foregoing has outlined rather broadly the features and technical advantages of the present disclosure so that the detailed description of the embodiments that follow may be better understood. Additional features and advantages of the present disclosure will be described hereinafter which form the subject of the claims of this application. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present disclosure. It should also be appreciated by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the present disclosure as set forth in the appended claims. [Brief description of the drawings]

[0010] A detailed description of the invention is set forth herein below with specific reference to the following drawings:

[0011] [Figure 1] Gelling test results for acrylic acid treated with 3.2 ppm to 3.3 ppm dosages of Formulation 2 or Formulation 4 are shown. Results are compared to gelling test results for acrylic acid treated with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (HTEMPO) or 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (OTEMPO).

[0012] [Diagram 2]Figure 1 shows gelation test results for vinyl acetate in the presence of acetic acid treated with about 50 ppm dosage of Formulation 1 or Formulation 4. Results are compared to gelation test results for acrylic acid treated with HTEMPO or OTEMPO. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Various embodiments of the present disclosure are described below. The relationship and function of the various elements of the embodiments can be better understood by referring to the detailed description below. However, it should be understood that the embodiments are not limited to those explicitly described herein, and in certain cases, details that are not necessary for understanding the embodiments disclosed herein, such as conventional synthesis and / or compounding, may be omitted.

[0014] The present disclosure relates to compositions comprising a blend of polymerization inhibitors for inhibiting the polymerization of ethylenically unsaturated monomers, and methods of using the same. The polymerization inhibitor composition of the present disclosure comprises at least one compound having a stable nitroxide radical and at least one compound having a hydroxylamine. The polymerization inhibitor composition can be a blend of multiple components including components in addition to the aforementioned compounds having a stable nitroxide radical and a hydroxylamine.

[0015] The present disclosure further relates to methods for preparing compounds having stable nitroxide radicals, and methods for preparing compounds having hydroxylamines. All of the polymerization inhibitor compositions of the present disclosure are effective in scavenging free radicals that would otherwise cause the initiation and propagation of polymerization reactions involving ethylenically unsaturated monomers.

[0016] In the presence of polymerizable monomers, a "polymerization inhibitor" inhibits the formation of polymer from those monomers during an induction period. After the induction period has elapsed, formation of polymer occurs at substantially the same rate as it would form in the absence of the polymerization inhibitor.

[0017] Polymerization inhibitors and retarders can generally be considered "polymerization inhibitors," that is compounds capable of inhibiting or reducing the formation of polymer from one or more radically polymerizable compounds.

[0018] The term "fouling" refers to the formation of polymers, prepolymers, oligomers, and / or other materials that become insoluble in a stream and / or precipitate from the stream and deposit on the equipment under the conditions under which the equipment is operated. Similarly, the inhibitors, retarders, and amine stabilizer components and compositions of the present disclosure inhibit or reduce such formation and therefore can be referred to as "antifouling."

[0019] Compositions of the Disclosure The present disclosure relates to a composition for inhibiting monomer polymerization, comprising a first inhibitor compound having a stable nitroxide radical and a second inhibitor compound having a hydroxylamine. In some embodiments, the composition is for inhibiting monomer polymerization, and the monomer is an ethylenically unsaturated monomer. For example, the composition of the present disclosure is useful for inhibiting the polymerization of ethylenically unsaturated monomers, including, but not limited to, vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof.

[0020] In some embodiments, the first inhibitor compound having a stable nitroxide radical has formula (I): [ka] wherein R1 is H, C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 Alkynyl, C1-C 22 Cycloalkyl, aryl, -C1~C 22 Alkylene aryl, -C(O)(C1-C 22 Alkyl), -C(O)(C1-C 22 alkenyl), -C(O)(C1-C22 alkynyl), -C(O)(C1-C 22 -C(O)(cycloalkyl), -C(O)(aryl), and -C(O)(C1-C 22 cycloalkyl and aryl are optionally selected from C1 to C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 It is substituted with one or more of alkynyl, or aryl.

[0021] In certain embodiments, R1 is -C(O)(C1-C 22 Alkyl), -C(O)(C1-C 22 alkenyl), -C(O)(C1-C 22 alkynyl), -C(O)(C1-C 22 -C(O)(cycloalkyl), -C(O)(aryl), and -C(O)(C1-C 22 cycloalkyl and aryl are optionally selected from C1 to C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 It is substituted with one or more of alkynyl and aryl.

[0022] In some embodiments, R1 is H. In some embodiments, R1 is C1-C 22 In some embodiments, R is C1-C 22 In some embodiments, R1 is C1-C 22 In some embodiments, R is C1-C 22 Cycloalkyl, cycloalkyl is optionally C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R is aryl, and aryl is optionally substituted with one or more of C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22In some embodiments, R1 is substituted with one or more of -C1 to -C2. 22 alkylenearyl, aryl optionally being C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R1 is substituted with one or more of -C(O)(C1-C 22 In some embodiments, R1 is -C(O)(C1-C 12 In some embodiments, R1 is -C(O)(C1-C6 alkyl). In some embodiments, R1 is -C(O)(methyl). In some embodiments, R1 is -C(O)(ethyl). In some embodiments, R1 is -C(O)(propyl). In some embodiments, R1 is -C(O)(butyl). In some embodiments, R1 is -C(O)(C1-C6 alkyl ... 22 alkenyl). In some embodiments, R1 is -C(O)(C1~C 22 In some embodiments, R1 is -C(O)(C1-C 22 cycloalkyl), where cycloalkyl is optionally C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R1 is -C(O)(aryl), and aryl is optionally substituted with one or more of C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R1 is substituted with one or more of -C(O)(C1-C 22 alkylenearyl), wherein aryl is optionally C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 It is substituted with one or more of alkynyl, or aryl.

[0023] In some embodiments, the second inhibitor compound having a hydroxylamine has the formula (II): [ka] wherein R2 is H, C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 Alkynyl, C1-C 22 Cycloalkyl, aryl, -C1~C 22 Alkylene aryl, -C(O)(C1-C 22 Alkyl), -C(O)(C1-C 22 alkenyl), -C(O)(C1-C 22 alkynyl), -C(O)(C1-C 22 -C(O)(cycloalkyl), -C(O)(aryl), and -C(O)(C1-C 22 cycloalkyl and aryl are optionally selected from C1 to C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 It is substituted with one or more of alkynyl, or aryl.

[0024] In certain embodiments, R2 is -C(O)(C1-C 22 Alkyl), -C(O)(C1-C 22 alkenyl), -C(O)(C1-C 22 alkynyl), -C(O)(C1-C 22 -C(O)(cycloalkyl), -C(O)(aryl), and -C(O)(C1-C 22 cycloalkyl and aryl are optionally C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 It is substituted with one or more of alkynyl, or aryl.

[0025] In some embodiments, R2 is H. In some embodiments, R2 is C1-C 22In some embodiments, R2 is C1-C 22 In some embodiments, R2 is C1-C 22 In some embodiments, R2 is C1-C 22 Cycloalkyl, cycloalkyl optionally having C1 to C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R2 is aryl, and aryl is optionally substituted with one or more of C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R2 is substituted with one or more of -C1-C 22 alkylenearyl, aryl optionally being C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R2 is substituted with one or more of -C(O)(C1-C 22 In some embodiments, R2 is -C(O)(C1-C 12 In some embodiments, R2 is -C(O)(C1-C6 alkyl). In some embodiments, R2 is -C(O)(methyl). In some embodiments, R2 is -C(O)(ethyl). In some embodiments, R2 is -C(O)(propyl). In some embodiments, R2 is -C(O)(butyl). In some embodiments, R2 is -C(O)(C1-C6 alkyl ... 22 In some embodiments, R2 is -C(O)(C1-C alkenyl). 22 In some embodiments, R2 is -C(O)(C1-C 22 cycloalkyl), where cycloalkyl is optionally C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22In some embodiments, R2 is -C(O)(aryl), and aryl is optionally substituted with one or more of C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 In some embodiments, R2 is substituted with one or more of -C(O)(C1-C 22 alkylenearyl), wherein aryl is optionally C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 It is substituted with one or more of alkynyl, or aryl.

[0026] In certain embodiments, the compositions of the present disclosure include first and second inhibitor compounds of formula (I) and (II), respectively, where R1 and R2 are the same. For example, in some embodiments, the compositions of the present disclosure include first and second inhibitor compounds of formula (I) and (II), respectively, where R1 and R2 are each independently -C(O)(C1-C2 22 In certain embodiments, the compositions of the present disclosure include first and second inhibitor compounds of formula (I) and (II), respectively, where R1 and R2 are different.

[0027] In some embodiments, the first inhibitor compound having a stable nitroxide radical is [ka] The compound is selected from the group consisting of: In certain embodiments, the first inhibitor compound having a stable nitroxide radical is [ka] The compound is selected from the group consisting of: In some embodiments, the first inhibitor compound having a stable nitroxide radical is [ka] 4-Acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl. In some embodiments, the first inhibitor compound having a stable nitroxide radical is [ka] 4-Propionoxy-2,2,6,6-tetramethylpiperidine-1-oxyl. In some embodiments, the first inhibitor compound having a stable nitroxide radical is [ka] 4-Butyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl. In some embodiments, the first inhibitor compound having a stable nitroxide radical is [ka] 4-valeroxy-2,2,6,6-tetramethylpiperidine-1-oxyl.

[0028] In some embodiments, the second inhibitor compound having a hydroxylamine is [ka] is selected from. In some embodiments, the second inhibitor compound having a hydroxylamine is [ka] 4-Acetoxy-2,2,6,6-tetramethylpiperidin-1-ol. In some embodiments, the second inhibitor compound having a hydroxylamine is [ka] 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-ol. In some embodiments, the second inhibitor compound having a hydroxylamine is [ka] 4-Butyloxy-2,2,6,6-tetramethylpiperidin-1-ol. In some embodiments, the second inhibitor compound having a hydroxylamine is [ka] 4-valeroxy-2,2,6,6-tetramethylpiperidin-1-ol.

[0029] The second inhibitor compounds of the present disclosure having hydroxylamines have advantages over the corresponding nitroxides, such as the ability to provide additional polymerization inhibition, as described more fully below. A common synthetic route to produce hydroxylamines of nitroxides is the reduction of the corresponding nitroxide with a reducing agent, such as: [ka]

[0030] The hydroxylamines of nitroxides have the potential to provide additional polymerization inhibition in the presence of carbon- and oxygen-centered radical initiators, as compared to the corresponding nitroxides, as described below. [ka]

[0031] Nitroxide hydroxylamines are excellent hydrogen donors and therefore efficient antioxidants due to the weak NO-H bond in the compounds. As antioxidants, nitroxide hydroxylamines react readily with oxygen-centered radicals, such as peroxide radicals, while being converted to their corresponding nitroxides. Nitroxides are generally known as the most effective inhibitors due to their excellent inhibition ability by scavenging carbon-centered free radicals at a rate that is mostly diffusion-controlled. This rate is several orders of magnitude faster than phenolic compounds. However, their kinetic advantage is not always favorable. For example, they may lose their advantage when oxygen-centered radicals are present as the predominant free radicals. Another problem associated with nitroxides is their consumption due to non-inhibition and undesirable reactions with process stream components or other inhibitor additives. As a result, high nitroxide inhibitor dosages are often required for a given inhibition potency, thereby making their use economically unattractive or even infeasible.

[0032] In essence, each hydroxylamine of a nitroxide represents one hydrogen donor plus one nitroxide polymerization inhibitor when both oxygen- and carbon-centered radicals are present, which is an attractive incentive offered by the hydroxylamine of a nitroxide: one hydroxylamine of a nitroxide can scavenge one oxygen-centered radical and one carbon-centered radical, whereas the nitroxide can only scavenge carbon-centered radicals.

[0033] In some embodiments, the compositions exhibit unexpected synergy, where the combination of the first and second inhibitor compounds results in a greater degree of polymerization inhibition than would be expected for the combination. This unexpected synergy is demonstrated in the examples presented herein, as well as in Figures 1 and 2.

[0034] In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 80% by weight. In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 70% by weight. In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 60% by weight. In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 50% by weight. In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 40% by weight. In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 30% by weight. In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 20% by weight. In some embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01% to about 10% by weight.

[0035] For example, in certain embodiments, the first inhibitor compound having a stable nitroxide radical is present in the composition at a concentration of about 0.01%, about 0.1%, about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, or about 80% by weight.

[0036] In some embodiments, the second inhibitor compound having a hydroxylamine is present in the composition at a concentration of about 0.01% to about 50% by weight. In some embodiments, the second inhibitor compound having a hydroxylamine is present in the composition at a concentration of about 0.01% to about 40% by weight. In some embodiments, the second inhibitor compound having a hydroxylamine is present in the composition at a concentration of about 0.01% to about 30% by weight. In some embodiments, the second inhibitor compound having a hydroxylamine is present in the composition at a concentration of about 0.01% to about 20% by weight. In some embodiments, the second inhibitor compound having a hydroxylamine is present in the composition at a concentration of about 0.01% to about 10% by weight.

[0037] For example, in certain embodiments, the second inhibitor compound having a hydroxylamine is present in the composition at a concentration of about 0.01%, about 0.1%, about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or about 50% by weight.

[0038] In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 100:1 to about 1:100. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 90:1 to about 1:90. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 80:1 to about 1:80. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 70:1 to about 1:70. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 60:1 to about 1:60. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 50:1 to about 1:50. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 40:1 to about 1:40. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 30:1 to about 1:30. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 20:1 to about 1:20. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 10:1 to about 1:10. In some embodiments, the molar ratio of the first inhibitor compound having a stable nitroxide radical to the second inhibitor compound having a hydroxylamine is about 1:1.

[0039] In some embodiments, the composition also comprises 2,2,6,6-tetramethylpiperidine-1-oxyl, 2,2,6,6-tetramethylpiperidin-1-ol, 4-hydroxyl-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-ol, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidin-1-ol, 4-acetate. The composition also includes one or more additional compounds selected from the group consisting of 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-ol, 4-propionoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-ol, and bis((2,2,6,6-tetramethylpiperidine-1-oxyl)-4-yl)oxalate. In some embodiments, the composition also includes 2,2,6,6-tetramethylpiperidine-1-oxyl. In some embodiments, the composition also includes 2,2,6,6-tetramethylpiperidin-1-ol. In some embodiments, the composition also includes 4-hydroxy-2,2,6,6-tetramethylpiperidyl-1-oxyl. In some embodiments, the composition also includes 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-ol. In some embodiments, the composition also includes 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxyl. In some embodiments, the composition also includes 4-oxo-2,2,6,6-tetramethylpiperidin-1-ol. In some embodiments, the composition also includes 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-oxyl. In some embodiments, the composition also includes 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-ol. In some embodiments, the composition also includes 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-oxyl. In some embodiments, the composition also includes 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-ol.In some embodiments, the composition also includes bis((2,2,6,6-tetramethylpiperidine-1-oxyl)-4-yl)oxalate.

[0040] The composition may also optionally include one or more organic solvents. Those skilled in the art will understand that there are many organic solvents that are compatible with the compositions of the present disclosure. For example, in some embodiments, the one or more organic solvents are selected from vinyl acetate, dimethyl phthalate, dimethylformamide, toluene, xylene, highly aromatic naphtha, acetonitrile, ethyl acetate, acetone, dichloromethane, tetrahydrofuran, hexane, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and combinations thereof. In certain embodiments, the composition also includes vinyl acetate. In certain embodiments, the composition also includes dimethyl phthalate. In certain embodiments, the composition also includes dimethylformamide. In certain embodiments, the composition also includes toluene. In certain embodiments, the composition also includes xylene. In certain embodiments, the composition also includes highly aromatic naphtha. In certain embodiments, the composition also includes acetonitrile.

[0041] In some embodiments, the composition also includes one or more ethylenically unsaturated monomers. Those skilled in the art will understand that there are many ethylenically unsaturated monomers that are compatible with the compositions of the present disclosure. For example, in some embodiments, the one or more ethylenically unsaturated monomers are selected from vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof. In certain embodiments, the composition also includes vinyl acetate. In certain embodiments, the composition also includes acrylonitrile. In certain embodiments, the composition also includes an acrylate. In certain embodiments, the composition also includes a methacrylate. In certain embodiments, the composition also includes 1,3-butadiene. In certain embodiments, the composition also includes styrene. In certain embodiments, the composition also includes isoprene. In certain embodiments, the composition also includes (meth)acrylic acid.

[0042] The compositions of the present disclosure are stable and remain useful polymerization inhibitors even under acidic conditions.Therefore, the compositions of the present disclosure are useful for inhibiting premature polymerization of monomers during manufacturing processes, especially during processes carried out under acidic conditions.For example, the compositions of the present disclosure are useful for preventing polymerization of acrylates, which may include, but are not limited to, acrylonitrile, acrylic acid, methyl methacrylic acid and its esters, and vinyl acetate.

[0043] In certain embodiments, the compositions of the present disclosure are generally stable under acidic conditions, which is a significant improvement over conventional polymerization inhibitors known in the art. Thus, in some embodiments, the compositions also include one or more acids. For example, in some embodiments, the compositions also include one or more acids selected from the group consisting of mineral acids and carboxylic acids. Mineral acids include, but are not limited to, hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, perchloric acid, and the like. Carboxylic acids include, but are not limited to, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, ethanoic acid, caprylic acid, undecylic acid, lauric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and the like. In some embodiments, the compositions of the present disclosure also include hydrochloric acid. In some embodiments, the compositions of the present disclosure also include nitric acid. In some embodiments, the compositions of the present disclosure also include phosphoric acid. In some embodiments, the compositions of the present disclosure also include sulfuric acid. In some embodiments, the compositions of the present disclosure also include acetic acid. In some embodiments, the compositions of the present disclosure also include propionic acid. In some embodiments, the compositions of the present disclosure also include butyric acid. In some embodiments, the compositions of the present disclosure also include valeric acid.

[0044] In some embodiments, the composition also includes acetaldehyde.

[0045] The compositions of the present disclosure have a balanced partition coefficient between the polar organic phase and the polar phase, and therefore are also useful in butadiene extraction processes.

[0046] Methods of Using the Disclosed Compositions The present disclosure also relates to a method of inhibiting polymerization of a monomer comprising adding a composition of the present disclosure to the monomer, hi some aspects, an effective amount of a composition of the present disclosure is added to the monomer, where an effective amount is any amount sufficient to inhibit polymerization of the monomer.

[0047] In some aspects, the monomer is an ethylenically unsaturated monomer. In some aspects, the monomer is an ethylenically unsaturated monomer selected from vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of vinyl acetate. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of acrylonitrile. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of acrylates. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of methacrylates. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of 1,3-butadiene. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of styrene. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of isoprene. In some aspects, the methods disclosed herein are useful for inhibiting the polymerization of (meth)acrylic acid.

[0048] The composition of the present disclosure can be added to the fluid manually or automatically. The composition can also be added continuously and / or intermittently. Automatic addition can be achieved by using a chemical injection pump. The chemical injection pump can be programmed to add a specific amount of the polymerization inhibitor composition or any of its components to the fluid at a certain time interval. In another aspect, the chemical injection pump can be manually controlled to add a specific amount of the polymerization inhibitor composition or any of its components to the fluid. Adding the polymerization inhibitor composition of the present disclosure to a monomer inhibits the polymerization of the monomer.

[0049] In some aspects, the monomers are provided as a neat solution, while in other aspects, the monomers are provided in a solution, hereinafter referred to as a "monomer solution."

[0050] In some embodiments, the monomer solution also includes one or more additional components selected from an acid, an organic solvent, water, and combinations thereof. For example, in some embodiments, the monomer solution includes one or more organic solvents selected from vinyl acetate, dimethyl phthalate, dimethylformamide, toluene, xylene, highly aromatic naphtha, acetonitrile, ethyl acetate, acetone, dichloromethane, tetrahydrofuran, hexane, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and combinations thereof. In some embodiments, the monomer solution includes one or more acids selected from hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, perchloric acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, ethanoic acid, caprylic acid, undecylic acid, lauric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid. In some embodiments, the monomer solution includes water.

[0051] In some embodiments, the monomer solution has a pH value of about 1 to about 7. In some embodiments, the monomer solution has a pH value of about 1 to about 6. In some embodiments, the monomer solution has a pH value of about 2 to about 6. In some embodiments, the monomer solution has a pH value of about 3 to about 6. In some embodiments, the monomer solution has a pH value of about 4 to about 6. In some embodiments, the monomer solution has a pH value of about 5 to about 6.

[0052] In some embodiments, the composition is added to the monomer such that the concentration of the first inhibitor compound is about 0.1 ppm to about 10,000 ppm. In some embodiments, the composition is added to the monomer such that the concentration of the first inhibitor compound is about 0.1 ppm to about 5,000 ppm. In some embodiments, the composition is added to the monomer such that the concentration of the first inhibitor compound is about 0.1 ppm to about 1,000 ppm. In some embodiments, the composition is added to the monomer such that the concentration of the first inhibitor compound is about 0.1 ppm to about 500 ppm.

[0053] In some embodiments, the composition is added to the monomer such that the concentration of the second inhibitor compound is about 0.1 ppm to about 10,000 ppm. In some embodiments, the composition is added to the monomer such that the concentration of the second inhibitor compound is about 0.1 ppm to about 5,000 ppm. In some embodiments, the composition is added to the monomer such that the concentration of the second inhibitor compound is about 0.1 ppm to about 1,000 ppm. In some embodiments, the composition is added to the monomer such that the concentration of the second inhibitor compound is about 0.1 ppm to about 500 ppm.

[0054] The disclosed method is useful for inhibiting premature polymerization of monomers during manufacturing processes, particularly during processes conducted under acidic conditions. For example, the disclosed method is useful for preventing polymerization of acrylates, which may include, but are not limited to, acrylonitrile, acrylic acid, methyl methacrylic acid and its esters, and vinyl acetate.

[0055] The methods of the present disclosure are also useful in preventing the premature polymerization of styrene during the manufacturing and purification processes.

[0056] The disclosed method is also useful in butadiene extraction processes. This utility stems from the balanced partition coefficient between the polar organic phase and the organic phase.

[0057] Process for preparing the polymerization inhibitors of the present disclosure The present disclosure also provides a compound of formula (III): [ka] The present invention also relates to a process for preparing the compound of During the ceremony, R3 is -O· or -OH; R4 is C1~C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 Alkynyl, C1-C 22 Cycloalkyl, aryl, and C1-C 22alkylenearyl, where cycloalkyl and aryl are optionally C1-C 22 Alkyl, C1-C 22 Alkenyl, C1-C 22 It is substituted with one or more of alkynyl, or aryl.

[0058] In some embodiments, the process for preparing a compound of formula (III) comprises reacting in solution a compound of formula (IIIa): [ka] With the compound of formula (IIIb): [ka] (Wherein, R5 is C1 to C 22 Alkyl or C1-C 22 alkenyl) to obtain a compound of formula (III).

[0059] In some embodiments, R3 is -O. In some embodiments, R3 is -OH.

[0060] In some embodiments, R4 is C1-C 22 In some embodiments, R4 is C1-C 12 In some embodiments, R4 is alkyl. In some embodiments, R4 is C1-C6 alkyl. In some embodiments, R4 is ethyl. In some embodiments, R4 is methyl.

[0061] In one embodiment, R3 is -O· and R4 is methyl. In some embodiments, R3 is -O· and R4 is ethyl. In some embodiments, R3 is -OH and R4 is methyl. In some embodiments, R3 is -OH and R4 is ethyl.

[0062] In some embodiments, R5 is C1-C 22 In some embodiments, R5 is C1-C 12In some embodiments, R5 is C1-C6 alkyl.

[0063] In some embodiments, R5 is C1-C 22 In some embodiments, R5 is C1-C 12 In some embodiments, R5 is C1-C6 alkenyl. In some embodiments, R5 is C2 alkenyl.

[0064] In some embodiments, the process for preparing a compound of formula (III) comprises reacting in solution a compound of formula (IIIa): [ka] With the compound of formula (IIIc): [ka] to obtain a compound of formula (III).

[0065] In some embodiments, the compound of formula (IIIa) is treated with a compound of formula (IIIb) in the presence of a catalyst and heat. In some embodiments, the compound of formula (IIIa) is treated with a compound of formula (IIIc) in the presence of a catalyst and heat. One skilled in the art will appreciate that there are many suitable catalysts that can be used to form a compound of formula (III) by treating a compound of formula (IIIa) with a compound of formula (IIIb) or (IIIc). For example, in some embodiments, the catalyst is an amine-containing compound. In certain embodiments, the catalyst is 4-dimethylaminopyridine, also known as DMAP. In some embodiments, the solution of the compounds of formula (IIIa) and (IIIb) or (IIIc) is heated to a temperature of about 50°C to about 100°C. In some embodiments, the solution is heated to a temperature of about 50°C to about 85°C.

[0066] In some embodiments, the process for preparing a compound of formula (III) also includes purging the solution with a nitrogen stream. In some embodiments, the step of purging the solution with a nitrogen stream is performed simultaneously with the step of treating the compound of formula (IIIa) with a compound of formula (IIIb) to obtain a compound of formula (III). In some embodiments, the step of purging the solution with a nitrogen stream is performed simultaneously with the step of treating the compound of formula (IIIa) with a compound of formula (IIIc) to obtain a compound of formula (III). In some embodiments, the step of purging the solution with a nitrogen stream is performed after the step of treating the compound of formula (IIIa) with a compound of formula (IIIb) to obtain a compound of formula (III). In some embodiments, the step of purging the solution with a nitrogen stream is performed after the step of treating the compound of formula (IIIa) with a compound of formula (IIIc) to obtain a compound of formula (III). Without wishing to be bound by theory, purging the solution with a stream of nitrogen may be useful in removing certain reaction by-products that drive the reaction equilibrium towards the formation of the compound of formula (III). EXAMPLES

[0067] Example 1 - Preparation of Formulation 1 A composition of the present disclosure, hereafter referred to as Formulation 1, was prepared using the following procedure.

[0068] A reaction vessel was charged with 206 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (HTEMPO) and 290 g of vinyl acetate. The resulting solution was then stirred until all of the HTEMPO was dissolved and the resulting mixture was heated to 65° C. This was followed by the addition of 1.5 g of 4-dimethylaminopyridine (DMAP). The reaction temperature was maintained at 65° C. and the mixture was agitated for 30 minutes. The reaction temperature was then increased to 75° C. and the solution was agitated for an additional 30 minutes. 2.4 g of DMAP was then slowly added to the reaction mixture which was then agitated for an additional hour while maintaining the reaction temperature at 75° C. The reaction mixture was then heated to a temperature of 80° C.-85° C. and agitated for an additional 2 hours. The reaction mixture was then adjusted to a temperature of 75° C. and purged with a nitrogen stream for 150 minutes. The reaction mixture was then cooled to room temperature and an additional 762 g of vinyl acetate was added. The final product solution was transferred to a storage container.

[0069] The final product of Formulation 1 is a solution having the following components: [Table 1]

[0070] Example 2 - Preparation of Formulation 2 A composition of the present disclosure, hereafter referred to as Formulation 2, was prepared using the following procedure.

[0071] A reaction vessel was charged with 206 g of HTEMPO, 114 g of vinyl acetate, 6.18 g of DMAP, and 50 g of dimethyl phthalate. The resulting solution was heated to 65° C. and stirred until all of the HTEMPO was dissolved. The reaction mixture was then stirred at a temperature of 50° C. for 30 minutes. The reaction mixture was then heated to 83° C. and stirred for 1 hour. The reaction mixture was then maintained at a temperature of 75° C. and purged with a nitrogen stream for 150 minutes. The reaction mixture was then cooled to room temperature and 635 g of dimethyl phthalate was added. The final product solution was transferred to a storage vessel.

[0072] The final product of Formulation 2 is a solution having the following components: [Table 2]

[0073] Example 3 - Preparation of Formulation 3 A composition of the present disclosure, hereafter referred to as Formulation 3, was prepared using the following procedure.

[0074] A reaction vessel was charged with 206 g of HTEMPO, 114 g of vinyl acetate, 6.18 g of DMAP, and 50 g of DMF. The resulting solution was heated to 65° C. to dissolve the HTEMPO, after which the reaction temperature was maintained at 50° C. for 30 minutes. The reaction solution was kept stirred for 60 minutes while the temperature was increased to 83° C. The resulting solution was heated to 65° C. and stirred until all of the HTEMPO was dissolved. The reaction mixture was then stirred at a temperature of 50° C. for 30 minutes. The reaction mixture was then heated to 83° C. and stirred for 1 hour. The reaction mixture was then maintained at a temperature of 75° C. and purged with a stream of nitrogen for 150 minutes to remove the acetaldehyde by-product. The reaction mixture was then cooled to room temperature and 635 g of dimethylformamide was added. The final product solution was transferred to a storage vessel.

[0075] The final product of Formulation 3 is a solution having the following components: [Table 3]

[0076] Example 4 - Preparation of Formulation 4 A composition of the present disclosure, hereafter referred to as Formulation 4, was prepared using the following procedure.

[0077] A reaction vessel was charged with 206 g of HTEMPO, 132 g of vinyl propionate, 6.18 g of DMAP, and 50 g of dimethyl phthalate. The resulting solution was heated to 65° C. and stirred until all of the HTEMPO was dissolved. The reaction mixture was then stirred at a temperature of 50° C. for 30 minutes. The reaction mixture was then heated to 83° C. and stirred for 1 hour. The reaction mixture was then maintained at a temperature of 75° C. and purged with a nitrogen stream for 150 minutes to remove reaction by-products. The reaction mixture was then cooled to room temperature and 635 g of dimethyl phthalate was added. The final product solution was transferred to a storage vessel.

[0078] The final product of Formulation 4 is a solution having the following components: [Table 4]

[0079] Example 5 - Inhibition of Polymerization of Acrylic Acid The ability of the compositions of the present disclosure to inhibit the polymerization of acrylic acid was evaluated by the following protocol.

[0080] 250 mL round bottom flasks were charged with 30 g of freshly distilled acrylic acid, and the polymerization inhibitors to be tested were added to each flask individually. In particular, the polymerization inhibition provided by 3.2 ppm HTEMPO, 3.2 ppm OTEMPO, 6.4 ppm Formulation 1 (50% active component), and 6.4 ppm Formulation 4 (50% active component) were evaluated. The samples were heated to 110° C. and stirred on a carousel. The time from when the solution reached 110° C. until the solution became cloudy was then recorded as the assay endpoint.

[0081] The samples tested and the results of the assay are summarized below in Table 1. The results are also presented in Figure 1.

[0082] Formulations 2 and 4 are 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-acetoxyTEMPO), 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-ol (4-acetoxyTEMPOH), 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-proprionateTEMPO), 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-ol (4-p It unexpectedly exhibits higher polymerization inhibitor activity than 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-ol (TEMPOH), 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (HTEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-ol (HTEMPOH), and 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxyl (OTEMPO) alone. Furthermore, formulations 2 and 4 demonstrate synergy in that the combination of a polymerization inhibitor having a stable nitroxide radical with a polymerization inhibitor having a hydroxylamine provided greater polymerization inhibition than either component alone, while controlling for the total dosage of the active components.

[0083] [Table 5]

[0084] Example 6 - Inhibition of the polymerization of vinyl acetate in acetic acid The ability of compositions of the present disclosure to inhibit the polymerization of vinyl acetate in the presence of acetic acid was evaluated by the following protocol.

[0085] Eight ounce jars were filled with 0.0125g HTEMPO, OTEMPO, 0.0250g Formulation 2 (50% active components), or 0.0250g Formulation 4 (50% active components). 0.125g benzoyl peroxide was added to each jar, followed by a 40% by weight acetic acid in free vinyl acetate solution to a final mass of 250g. A batch of 12 pressure tubes was filled with 10g of the above solution using a stir bar. The pressure tubes were purged with nitrogen for 2 minutes, and then each tube was immediately sealed to maintain a nitrogen headspace. The tubes were loaded into a heating block preheated to 75°C. After 20 minutes, and every 30 minutes thereafter, two tubes were removed from the block and cooled in an ice bath to quench the polymerization reaction. The cooled polymer solution was immediately diluted with tetrahydrofuran, as necessary. Each dilution was then assessed for polymer content. The time required to reach a soluble polymer content greater than 2% was used as the end point to determine gelation of the sample.

[0086] The samples tested and the results of the assay are summarized below in Table 2. The results are also presented in Figure 2.

[0087] Formulations 2 and 4 unexpectedly exhibit greater polymerization inhibitor activity than 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-acetoxyTEMPO), 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-ol (4-acetoxyTEMPOH), 4-propionoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-proprionateTEMPO), 4-propionoxy-2,2,6,6-tetramethylpiperidin-1-ol (4-proprionateTEMPOH), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (HTEMPO), and 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (OTEMPO) alone. Furthermore, Formulations 1 and 4 demonstrate synergy in that the combination of a polymerization inhibitor having a stable nitroxide radical with a polymerization inhibitor having a hydroxylamine provided greater polymerization inhibition than either component alone, while controlling for the total dosage of the active components.

[0088] [Table 6]

[0089] All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. The present invention can be embodied in many different forms, and certain preferred embodiments of the present invention are described in detail herein. The present disclosure is an exemplification of the principles of the present invention, and is not intended to limit the invention to the specific embodiments illustrated. In addition, unless expressly stated otherwise, use of the term "a" is intended to include "at least one" or "one or more." For example, "a compound" is intended to include "at least one compound" or "one or more compounds."

[0090] Any ranges expressed in either absolute or approximate terms are intended to encompass both, and any definitions used herein are intended to be illustrative, not limiting. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein should be understood to encompass any and all subranges subsumed therein, including all fractional and whole values.

[0091] Any composition disclosed herein can comprise, consist of, or consist essentially of any element, component, and / or ingredient disclosed herein, or any combination of two or more of the elements, components, or ingredients disclosed herein.

[0092] Any method disclosed herein may comprise, consist of, or consist essentially of any method steps disclosed herein, or any combination of two or more of the method steps disclosed herein.

[0093] The transitional phrase "comprising," which is synonymous with "including," "containing," or "characterized by," is inclusive or open-ended and does not exclude additional, unrecited elements, components, ingredients, and / or method steps.

[0094] The transitional phrase "consisting of" excludes any element, component, ingredient, and / or method step not specified in the claim.

[0095] The transitional phrase "consisting essentially of" limits the scope of the claim to certain elements, components, ingredients, and / or steps, and those that do not materially affect the basic and novel characteristics of the claimed invention.

[0096] Unless otherwise specified, all molecular weights referred to herein are weight average molecular weights and all viscosities were measured at 25° C. using neat (undiluted) polymer.

[0097] As used herein, the term "about" refers to a cited value that is within error resulting from the standard deviation found in their respective testing measurements; where such error cannot be determined, "about" may refer, for example, to within 5% of the cited value.

[0098] Moreover, the present invention encompasses all possible combinations of any or all of the various embodiments described herein. It should also be understood that various changes and modifications to the preferred embodiments of the invention described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. Accordingly, such changes and modifications are intended to be covered by the appended claims.

Claims

1. A composition for inhibiting monomer polymerization, A first inhibitor compound containing a stable nitroxide radical, A composition comprising a second inhibitor compound containing hydroxylamine.

2. The first inhibitor compound is defined by formula (I): 【Chemistry 1】 which is, in the formula, R １ is H, C １ to C ２２ alkyl, C １ to C ２２ alkenyl, C １ to C ２２ alkynyl, C １ to C ２２ cycloalkyl, aryl, -C １ ~C ２２ Alkylenearyl, -C(O)(C １ ~C ２２ Alkyl), -C(O)(C １ ~C ２２ Alkenyl), -C(O)(C １ ~C ２２ Alkinyl) -C(O)(C １ ~C ２２ Cycloalkyl), -C(O)(aryl), and -C(O)(C １ ~C ２２ Selected from alkylenearyl, wherein the cycloalkyl and the aryl are C １ ~C ２２ Alkyl, C １ ~C ２２ Alkenil, C １ ~C ２２ The composition according to claim 1, wherein it is optionally substituted with one or more alkynyls or aryls.

3. R １ However, -C(O)(C １ ~C ２２ Alkyl), -C(O)(C １ ~C ２２ Alkenyl), -C(O)(C １ ~C ２２ Alkinyl), -C(O)(C １ ~C ２２ Cycloalkyl), -C(O)(aryl), and -C(O)(C １ ~C ２２ Selected from alkylenearyl, the cycloalkyl and optionally the aryl are C １ ~C ２２ Alkyl, C １ ~C ２２ Alkenil, C １ ~C ２２ The composition according to claim 1 or 2, wherein it is optionally substituted with one or more alkynyls or aryls.

4. The second inhibitor compound is given by formula (II): 【Chemistry 2】 It is such that, in the formula, R ２ However, H, C １ ~C ２２ Alkyl, C １ ~C ２２ Alkenil, C １ ~C ２２ Alkinyl, C １ ~C ２２ Cycloalkyl, aryl, -C １ ~C ２２ Alkylenearyl, -C(O)(C １ ~C ２２ Alkyl), -C(O)(C １ ~C ２２ Alkenyl), -C(O)(C １ ~C ２２ Alkinyl), -C(O)(C １ ~C ２２ Cycloalkyl), -C(O)(aryl), and -C(O)(C １ ~C ２２ Selected from alkylenearyl, wherein the cycloalkyl and the aryl are C １ ~C ２２ Alkyl, C １ ~C ２２ Alkenil, C １ ~C ２２ The composition according to claim 1 or 2, wherein it is optionally substituted with one or more alkynyls or aryls.

5. R ２ However, -C(O)(C １ ~C ２２ Alkyl), -C(O)(C １ ~C ２２ Alkenyl), -C(O)(C １ ~C ２２ Alkinyl), -C(O)(C １ ~C ２２ Cycloalkyl), -C(O)(aryl), and -C(O)(C １ ~C ２２ Selected from alkylenearyl, wherein the cycloalkyl and the aryl are C １ ~C ２２ Alkyl, C １ ~C ２２ Alkenil, C １ ~C ２２ The composition according to claim 1 or 2, wherein it is optionally substituted with one or more alkynyls or aryls.

6. The first inhibitor compound is 【Transformation 3】 A composition according to claim 1 or 2, selected from the group consisting of the following.

7. The second inhibitor compound is 【Chemistry 4】 A composition according to claim 1 or 2, selected from the group consisting of the following.

8. The composition according to claim 1 or 2, wherein the first inhibitor compound is present in the composition at a concentration of about 0.01% by weight to about 80% by weight.

9. The composition according to claim 1 or 2, wherein the second inhibitor compound is present in the composition at a concentration of about 0.01% to about 50% by weight.

10. The composition according to claim 1 or 2, wherein the molar ratio of the first inhibitor compound to the second inhibitor compound is about 100:1 to about 1:

100.

11. The composition is 2,2,6,6-tetramethylpiperidine-1-oxyl, 2,2,6,6-tetramethylpiperidine-1-ol, 4-hydroxyl-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-ol, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-1-ol, 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-ol, 4-propionoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, The composition according to claim 1 or 2, further comprising one or more additional compounds selected from the group consisting of 4-propionoxy-2,2,6,6-tetramethylpiperidine-1-ol and bis((2,2,6,6-tetramethylpiperidine-1-oxyl)-4-yl) oxalate.

12. The composition according to claim 1 or 2, wherein the composition further comprises an organic solvent.

13. The composition according to claim 1 or 2, wherein the composition further comprises an ethylenically unsaturated monomer.

14. The composition according to claim 13, wherein the ethylenically unsaturated monomer is selected from the group consisting of vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, styrene, isoprene, acrylic acid, methacrylic acid, and any combination thereof.

15. The composition according to claim 1 or 2, wherein the composition further comprises an acid.

16. The composition according to claim 1 or 2, wherein the composition further comprises acetaldehyde.

17. A method for inhibiting monomer polymerization, A method comprising adding the composition according to claim 1 to the monomer.

18. The method according to claim 17, wherein the monomer is provided in a solution.

19. The method according to claim 18, wherein the solution further comprises one or more additional components selected from an acid, an organic solvent, and water.

20. The method according to any one of claims 17 to 19, wherein the monomer is an ethylenically unsaturated monomer.

21. The method according to any one of claims 17 to 19, wherein the composition is added to the monomer such that the concentration of the first inhibitor compound is about 0.1 ppm to about 10,000 ppm.

22. The method according to any one of claims 17 to 19, wherein the composition is added to the monomer such that the concentration of the second inhibitor compound is about 0.1 ppm to about 10,000 ppm.

23. The method according to any one of claims 17 to 19, wherein the monomer is selected from the group consisting of vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, styrene, isoprene, acrylic acid, methacrylic acid, and any combination thereof.

24. Formula (III): 【Transformation 5】 A process for preparing the compound, During the ceremony, R ３ However, it is -O• or -OH, R ４ is C １ -C ２２ alkyl, C １ -C ２２ alkenyl, C １ -C ２２ alkynyl, C １ -C ２２ cycloalkyl, aryl, and C １ -C ２２ alkylene aryl, and the cycloalkyl and aryl are optionally substituted with one or more of C １ -C ２２ alkyl, C １ -C ２２ alkenyl, C １ -C ２２ alkynyl, or aryl, In solution, formula (IIIa): 【Transformation 6】 The compound of formula (IIIb): 【Transformation 7】 (In the formula, R ５ However, C １ ~C ２２ Alkyl or C １ ~C ２２ (It is Alkenil) A process comprising treating with a compound to obtain the compound of formula (III).

25. The process according to claim 24, wherein the compound of formula (IIIa) is treated with the compound of formula (IIIb) in the presence of a catalyst and heat.

26. The process according to claim 24 or 25, further comprising purging the solution with a stream of nitrogen.

27. The process according to claim 26, wherein the step of purging the solution with a nitrogen stream is performed simultaneously with the step of treating the compound of formula (IIIa) with the compound of formula (IIIb) to obtain the compound of formula (III).

28. The process according to claim 26, wherein the step of purging the solution with a nitrogen stream is performed after the step of treating the compound of formula (IIIa) with the compound of formula (IIIb) to obtain the compound of formula (III).

29. R ３ However, it is -O•, R ４ However, -C １ The process according to claim 24 or 25, wherein the alkyl group is involved.

30. R ３ However, it is -O•, R ４ However, -C ２ The process according to claim 24 or 25, wherein the alkyl group is involved.

31. R ３ However, it is -OH, R ４ However, -C １ The process according to claim 24 or 25, wherein the alkyl group is involved.

32. R ３ However, it is -OH, R ４ However, -C ２ The process according to claim 24 or 25, wherein the alkyl group is involved.

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