Method for manufacture of alkoxysilyl-containing thiocarboxylic acid esters

Abstract

To provide a composition containing alkoxysilyl-containing thiocarboxylic acid esters obtained by a method for the manufacture which avoids the use of phosgene or thionyl chloride reagents and minimizes non-recyclable and environmentally harmful byproducts.SOLUTION: There is provided herein a method for the manufacture of alkoxysilyl-containing thiocarboxylic acid ester which comprises reacting a thioester with a mercapto-functional alkoxysilane and / or an alkali metal salt, an alkaline earth metal salt or a trisubstituted ammonium salt of an alkoxysilyl-functional thiolate. The method uses economical and readily available reagents, avoids the use of phosgene or thionyl chloride reagents, and produces recyclable byproducts.SELECTED DRAWING: None

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Application Serial No. 62 / 840,752, filed April 30, 2019, the entire contents of which are incorporated herein by reference.

[0002] The present invention provides a method for producing alkoxysilyl-containing thiocarboxylic acid esters and alkoxysilyl-containing thiocarboxylic acid ester compositions containing the thioesters that avoids the use of phosgene or thionyl chloride reagents and minimizes non-recyclable and environmentally harmful by-products. [Background technology]

[0003] Alkoxysilyl-containing thiocarboxylic acid esters are derivatives of mercapto-functional alkoxysilanes in which the mercapto hydrogen atom has been replaced with an acyl group (hereinafter referred to as a "blocking group"). These alkoxysilyl-containing thiocarboxylic acid esters are often referred to as blocked mercaptosilanes. These alkoxysilyl-containing thiocarboxylic acid esters can be used as dispersing agents to improve the dispersion of inorganic fillers in polymers, especially rubbers, and as coupling agents between polymers and inorganic fillers after being deblocked using a deblocking agent during compounding to form reactive mercapto functional groups. These silane-coupled mineral-filled polymers can be used in the manufacture of a variety of products, especially tires when the polymer is rubber.

[0004] Alkoxysilyl-containing thiocarboxylic acid esters have been produced by a variety of conventional methods. However, these methods generally rely on acyl chloride intermediates, also known as carboxylic acid halide intermediates, which require the use of toxic phosgene or thionyl chloride for preparation from carboxylic acids and generate chloride compounds, such as alkali metal chloride salts. These alkali metal salts are waste products contaminated with organic compounds that require proper disposal.

[0005] For example, alkoxysilyl-containing thiocarboxylic acid esters have been prepared by reacting a carboxylic acid halide with aqueous alkali metal sulfide to produce an aqueous solution of the alkali metal salt of the thiocarboxylic acid, which is subsequently reacted with a halo-functional alkoxysilane. This method produces two equivalents of alkali metal halide dissolved in water, which must be properly disposed of as waste, and a second, non-aqueous phase containing the product. The non-aqueous product phase must be separated from the aqueous phase containing the alkali metal salt and may contain a phase transfer catalyst to promote the two-phase reaction. Another method involves reacting a carboxylic acid halide with an alkali metal salt of an alkoxysilyl-functional mercaptide. The resulting by-product, the alkali metal halide, precipitates from the reaction mixture. Separating the alkali metal halide from the alkoxysilyl-containing thiocarboxylic acid ester product requires filtration, centrifugation, or decantation, which results in product loss and the need for proper disposal of the alkali metal halide salt.

[0006] As a result of the problems associated with conventional methods for producing alkoxysilyl-containing thiocarboxylic acid esters, a method is needed that uses readily available reagents to provide cost-effective alkoxysilyl-containing thiocarboxylic acid ester products, while avoiding the use of toxic phosgene or thionyl halide to produce acyl halide intermediates and minimizing the formation of non-recyclable alkali halide waste. Summary of the Invention

[0007] Surprisingly, the present inventors have discovered a method for preparing an alkoxysilyl-containing thiocarboxylic acid ester that avoids the aforementioned problems. Specifically, the alkoxysilyl-containing thiocarboxylic acid ester herein is prepared by a method comprising reacting a thioester that does not contain an alkoxysilyl group with an alkali metal salt, alkaline metal salt, or trisubstituted ammonium salt of an alkoxysilyl-functional mercaptide or alkoxysilyl-functional mercaptan. The trisubstituted ammonium salt is preferably based on a trialkylamine to prevent reaction with the thioester to form an amide. The method described herein avoids the formation of alkali metal halides, alkaline metal halides, or trisubstituted ammonium halides. The method herein produces an alkali metal salt, alkaline metal salt, or trisubstituted ammonium salt of a mercaptide that does not contain an alkoxysilyl functionality, which can be reused to regenerate the thioester reagent.

[0008] The thioester reagents do not contain reactive alkoxysilyl groups. These thioester reagents can be prepared by recycling alkali metal, alkaline metal, or trisubstituted ammonium salts of alkoxysilyl-free mercaptides. These salts can be protonated using Bronsted-Lowry acid, preferably a mercapto-functional alkoxysilane. The mercapto-functional silane is reacted (deprotonated) with an alkali metal, alkaline metal, or trisubstituted ammonium salt of the mercaptide to form an alkali metal, alkaline metal, or trisubstituted ammonium salt of the alkoxysilyl-functional mercaptide and an alkoxysilyl-free mercaptan. The alkoxysilyl-free mercaptan can be isolated from the alkali metal, alkaline metal, or trisubstituted ammonium salt of the alkoxysilyl-functional mercaptide using distillation, membrane separation, or extraction, more specifically, distillation. The thioester reagents are prepared by reacting an alkoxysilyl-free mercaptan with a carboxylic acid. This reaction produces water, a non-toxic and environmentally friendly by-product. Additionally, the present invention can use the carboxylic acids described herein, which are much cheaper than the carboxylic acid chlorides or thioacids of previous methods that require the handling of phosgene or thionyl halides.

[0009] More specifically, provided herein is a process for preparing an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I): R 1 -[C(=O)-SR 2 -SiR 3 a (OR 4 ) 3-a ] z (I) where R 1is a monovalent radical selected from a straight chain alkyl containing 1 to 18 carbon atoms, a branched chain alkyl containing 3 to 18 carbon atoms, a cycloalkyl containing 5 to 18 carbon atoms, an alkenyl containing 2 to 18 carbon atoms, an aryl group containing 6 to 18 carbon atoms, an aralkyl containing 7 to 18 carbon atoms or hydrogen, or is a divalent radical selected from an alkyl containing 1 to 10 carbon atoms, a cycloalkyl containing 5 to 10 carbon atoms or phenyl; Each R 2 are divalent radicals independently selected from a straight chain alkyl containing 1 to 10 carbon atoms, a branched chain alkyl containing 3 to 10 carbon atoms, a cycloalkyl containing 5 to 10 carbon atoms, an alkenyl containing 2 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms, or an aralkyl containing 7 to 10 carbon atoms; Each R 3 are monovalent groups independently selected from a straight chain alkyl containing 1 to 6 carbon atoms, a branched chain alkyl containing 3 to 6 carbon atoms, a cycloalkyl containing 5 or 6 carbon atoms, an alkenyl containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, or an aralkyl containing 7 to 10 carbon atoms; R 4 are independently a linear alkyl containing 1 to 6 carbon atoms, a branched alkyl containing 3 to 6 carbon atoms, a cycloalkyl containing 5 or 6 carbon atoms, an alkenyl containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, an aralkyl containing 7 to 10 carbon atoms, a linear alkyl containing 2 to 6 carbon atoms and a hydroxyl group, or a branched alkyl containing 3 to 6 carbon atoms and a hydroxyl group, a group having the structure -R 2 -(OCH2CH2) m (OCH2CH(CH3)) n OR 1 or two covalently bonded R 4 a divalent group formed from groups, provided that (i) two R 4provided that when the groups are joined together, a is 0 or 1, and (ii) the sum of m+n is 1 to 20; a, m, n, and z are integers, where a is 0, 1, or 2, m is 0 to 10, n is 0 to 10, and z is 1 or 2, and wherein the method comprises: The thioester of general formula (II) R 1 [C(=O)SR 5 ] z (II) where Each R 5 are monovalent groups independently selected from linear alkyl groups containing 1 to 18 carbon atoms, branched alkyl groups containing 3 to 18 carbon atoms, cycloalkyl groups containing 5 to 18 carbon atoms, alkenyl groups containing 2 to 18 carbon atoms, aryl groups containing 6 to 18 carbon atoms, and aralkyl groups containing 7 to 18 carbon atoms; and where R 1 and z is as defined above, a mercapto-functional alkoxysilane of formula (V), HS-R 2 -SiR 3 a (OR 4 ) 3-a (V), and / or Alkali metal salts, alkaline earth metal salts, trisubstituted ammonium salts of alkoxysilyl-functional thiolates of general formula (III), M +- SR 2 -SiR 3 a (OR 4 ) 3-a (III) Here, M + is an alkali metal ion, alkaline earth metal ion, or trisubstituted ammonium ion, and R 2 , R 3 , R 4 , and a is as defined above, Detailed Description of the Invention

[0010] In the specification and claims herein, the following terms and phrases should be understood as indicated.

[0011] The singular forms "a," "an," and "the" include the plural, and references to particular values ​​include at least that particular value unless the context clearly dictates otherwise.

[0012] All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. Any and all examples provided herein, or the use of exemplary language (e.g., "etc.") are intended merely to better illuminate the invention and do not limit the scope of the invention unless otherwise claimed.

[0013] No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0014] The terms "comprising," "including," "containing," "characterized by," and their grammatical equivalents are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps, but are also understood to include the more restrictive terms "consisting of" and "consisting essentially of."

[0015] Any numerical range recited herein will be understood to include all sub-ranges within that range, and any combination of the various endpoints of such range or sub-range.

[0016] Any compound, material, or substance explicitly or implicitly disclosed and / or claimed in the specification as belonging to a group of structurally, compositionally, and / or functionally related compounds, materials, or substances will be further understood to include each individual representative of the group and all combinations thereof.

[0017] The term "alkyl" means any monovalent or divalent saturated straight-chain or branched hydrocarbon group; the term "cycloalkyl" means any monovalent or divalent cyclic saturated hydrocarbon group; and the term "alkenyl" means any monovalent or divalent straight-chain or branched hydrocarbon group containing one or more carbon-carbon double bonds, where the point of attachment of the group may be either through the carbon-carbon double bond or elsewhere.

[0018] Examples of alkyl include methyl, ethyl, propyl, isopropyl, butyl, and isobutyl. Examples of alkenyl include vinyl, propenyl, allyl, and methallyl. Examples of cycloalkenyl include ethylidenylnorbornane, ethylidenenorbornyl, ethylidenylnorbornene, and ethylidenenorbornenyl.

[0019] The terms "cycloalkyl" and "cycloalkenyl" include bicyclic, tricyclic and higher cyclic structures, as well as the aforementioned cyclic structures further substituted with alkyl and / or alkenyl groups. Representative examples include norbornyl, norbornenyl, ethylnorbornyl, ethylnorbornenyl, cyclohexyl, ethylcyclohexyl, ethylcyclohexenyl, cyclohexylcyclohexyl, and cyclododecatrienyl.

[0020] The term "aryl" means any monovalent or divalent aromatic hydrocarbon group; and the term "aralkyl" means any monovalent or divalent alkyl group, as defined herein, in which one or more hydrogen atoms are replaced with an equal number of similar and / or different aryl (as defined herein) groups. Examples of aryl include phenyl and naphthalenyl. Examples of aralkyl include benzyl and phenethyl.

[0021] In describing the chain lengths of various groups herein, it is understood that the term "maximum" can include the lowest possible value for any chain length described herein, and where such lower limits on chain length may exist, for example, the endpoints of these lower range limits can include 1 carbon atom alkyl, i.e., methyl, 2 carbon atom alkenyl, 6 carbon atom aryl, 7 carbon atom aralkyl, etc.

[0022] In the method for producing an alkoxysilyl-containing thiocarboxylic acid ester described herein, Reaction Scheme A for producing an alkoxysilyl-containing thiocarboxylic acid ester can be represented by an equilibrium chemical equation: [ka] where R 1 , R 2 , R 3 , R 4 , R 5 , M + , a, and z are as defined herein. The value of capital "Z" herein is understood to be the relative molar amount and is defined to have the same value as the subscript z herein, i.e., when subscript z is 1, Z=1, and when subscript z is 2, Z=2.

[0023] In the methods for producing an alkoxysilyl-containing thiocarboxylic acid ester described herein, Reaction Scheme B for producing an alkoxysilyl-containing thiocarboxylic acid ester can be represented by the balanced chemical equation: [ka] where R 1 , R 2 , R 3 , R 4 , R 5 , a, and z are as defined herein. The value of capital "Z" herein is understood to be the relative molar amount and is defined to have the same value as the subscript z herein, i.e., when subscript z is 1, Z=1, and when subscript z is 2, Z=2.

[0024] In the process for preparing an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I) described herein, R 1 R may be a monovalent radical selected from a straight chain alkyl containing from 5 to 15 carbon atoms, even more specifically from 5 to 9 carbon atoms, and even more specifically from 7 carbon atoms, a branched chain alkyl containing from 5 to 15 carbon atoms, a straight chain alkenyl containing from 5 to 15 carbon atoms, a branched chain alkenyl containing from 5 to 15 carbon atoms, or a divalent radical selected from an alkyl of from 2 to 10 carbon atoms, preferably from 2 to 8 carbon atoms. 1 Representative, non-limiting examples are monovalent pentyl, hexyl, heptyl, octyl, nonyl, decyl, 2-ethylhexyl or divalent ethyl, butyl or hexyl.

[0025] R as described herein 2 R may more specifically be a divalent straight chain alkyl containing 1 to 8 carbon atoms, even more specifically 1 to 3 carbon atoms, and even more specifically 3 carbon atoms, or a branched chain alkyl containing 3 to 6 carbon atoms, and even more specifically 4 carbon atoms. 2 Representative, non-limiting examples of are divalent methyl, ethyl, propyl, or 2-methylpropyl.

[0026] R as described herein 3R may more specifically be a straight chain alkyl group containing 1 to 6 carbon atoms, a branched chain alkyl group containing 3 to 6 carbon atoms or phenyl, or even more specifically monovalent methyl. 3 Representative non-limiting examples are monovalent methyl, ethyl, and phenyl.

[0027] R as described herein 4 R may more specifically be a straight chain alkyl group containing 1 to 6 carbon atoms, a branched chain alkyl group containing 3 to 6 carbon atoms, a straight chain alkyl group containing 1 to 6 carbon atoms and at least one hydroxyl group, or a branched chain alkyl group containing 3 to 6 carbon atoms and at least one hydroxyl group. 4 Representative, non-limiting examples of R are monovalent methyl, ethyl, propyl, butyl, isopropyl, isobutyl, pentyl, hexyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxy-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, or 3-hydroxy-1,3-dimethylbutyl, more specifically ethyl, 3-hydroxy-2-methylpropyl, or 3-hydroxybutyl. 4 When the groups are joined together, more specifically, a divalent group having 2 to 12 carbon atoms is formed. 4 A representative example of a divalent group formed from combining groups together can be a divalent -CH2CH2-, -CH2CH2CH2-, -CH2CH(CH3)CH2-, or -CH2CH2CH(CH3)-.

[0028] R as described herein 5 may more specifically be a monovalent straight chain alkyl group containing from 1 to 10 carbon atoms, a monovalent branched chain alkyl group containing from 3 to 10 carbon atoms, a monovalent cycloalkyl group containing from 5 to 10 carbon atoms, and even more specifically a monovalent straight chain alkyl group containing from 3 to 8 carbon atoms or a branched chain alkyl group containing from 3 to 8 carbon atoms.

[0029] M +may more preferably be an alkali metal cation ion, such as, by way of non-limiting example, sodium or potassium, preferably sodium, or a tri-substituted ammonium ion, such as triethylammonium, tripropylammonium, triisopropylammonium, piperidinium, pyridinium, or protonated 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane.

[0030] As used herein, the subscripts a and z may be integers, where a is more particularly 0 or 1, preferably 0, and z is 1 or 2, more preferably 1.

[0031] In one embodiment, R 1 is a monovalent linear alkyl group containing from 5 to 11 carbon atoms, a monovalent branched alkyl group containing from 5 to 11 carbon atoms, or a divalent linear alkyl group of from 1 to 8 carbon atoms; R 2 is a divalent alkyl group containing 1 to 6 carbon atoms or a branched alkyl group containing 3 to 6 carbon atoms; R 3 is methyl and R 4 is monovalent ethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxy-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, or 3-hydroxy-1,3-dimethylbutyl, or two R 4 are joined together to form a divalent group -R having the structure -CH2CH2CH2-, -CH2CH(CH3)CH2-, or -CH2CH2CH(CH3)- 4 -R 4 -forms R 5 is a monovalent linear alkyl group of 4 to 8 carbon atoms, a monovalent branched alkyl group of 4 to 8 carbon atoms, or a monovalent cycloalkyl group of 5 to 8 carbon atoms; M + is a sodium ion, a is 0 or 1, preferably 0, and z is 1 or 2, preferably 1.

[0032] The alkoxysilyl-containing thiocarboxylic acid esters of general formula (I) described herein include 2-triethoxysilyl-1-ethylthioacetate; 2-trimethoxysilyl-1-ethylthioacetate; 2-(methyldimethoxysilyl)-1-ethylthioacetate; 3-trimethoxysilyl-1-propylthioacetate; triethoxysilylmethylthioacetate; trimethoxysilylmethylthioacetate; triisopropoxysilylmethylthioacetate; methyldiethoxysilylmethylthioacetate; methyldimethoxysilylmethylthioacetate ;Methyldiisopropoxysilylmethylthioacetate;Dimethylethoxysilylmethylthioacetate;Dimethylmethoxysilylmethylthioacetate;Dimethylisopropoxysilylmethylthioacetate;2-Triisopropoxysilyl-1-ethylthioacetate;2-(Methyldiethoxysilyl)-1-ethylthioacetate;2-(Methyldiisopropoxysilyl)-1-ethylthioacetate;2-(Dimethylethoxysilyl)-1-ethylthioacetate;2-(Dimethylmethoxysilyl)-1-ethylthioacetate 3-Triethoxysilyl-1-propylthioacetate;3-Triisopropoxysilyl-1-propylthioacetate;3-Triisopropoxysilyl-1-propylthioacetate;3-Methyldiethoxysilyl-1-propylthioacetate;3-Methyldimethoxysilyl-1-propylthioacetate;3-Methyldiisopropoxysilyl-1-propylthioacetate;1-(2-Triethoxysilyl-1-ethyl)-4-thioacetylcyclohexane;1-(2-Triethoxysilyl-1-ethyl)-3-thioacetylcyclohexane;2-Triethoxy Silyl-5-thioacetylnorbornene;2-Triethoxysilyl-4-thioacetylnorbornene;2-(2-Triethoxysilyl-1-ethyl)-5-thioacetylnorbornene;2-(2-Triethoxysilyl-1-ethyl)-4-thioacetylnorbornene;6-Triethoxysilyl-1-hexylthioacetate;1-Triethoxysilyl-5-hexylthioacetate;8-Triethoxysilyl-1-octylthioacetate;1-Triethoxysilyl-7-octylthioacetate;6-Triethoxysilyl-1-hexylthioacetate1-Triethoxysilyl-5-octylthioacetate;8-Trimethoxysilyl-1-octylthioacetate;1-Trimethoxysilyl-7-octylthioacetate;10-Triethoxysilyl-1-decylthioacetate;1-Triethoxysilyl-9-decylthioacetate;1-Triethoxysilyl-2-butylthioacetate;1-Triethoxysilyl-3-butylthioacetate;1-Triethoxysilyl-3-methyl-2-butylthioacetate 3-Butylthioacetate;3-Trimethoxysilyl-1-propylthiooctanoate;3-Triethoxysilyl-1-propylthiopalmitate;3-Triethoxysilyl-1-propylthiooctanoate;3-Triethoxysilyl-1-propylthiobenzoate;3-Triethoxysilyl-1-propylthio-2-ethylhexanoate;3-Methyldiacetoxysilyl-1-propylthioacetate;3-Triacetoxysilyl-1-propylthioacetate;2-Methyldiacetoxysilyl- 1-Ethylthioacetate;2-Triacetoxysilyl-1-ethylthioacetate;1-Methyldiacetoxysilyl-1-ethylthioacetate;1-Triacetoxysilyl-1-ethylthioacetate;Bis-(3-triethoxysilyl-1-propyl)dithiophthalate;Bis-(3-triethoxysilyl-1-propyl)dithio-isophthalate;Bis-(3-triethoxysilyl-1-propyl)dithioterephthalate;Bis-(3-triethoxysilyl-1-propyl)dithiosuccinate , Bis-(3-triethoxysilyl-1-propyl)dithiooxalate;Bis-(3-triethoxysilyl-1-propyl)dithiosebacate, Bis-(3-triethoxysilyl-1-propyl)dithioadipate;Thioacetic acid S-(2-methyl-[1,3,2]dioxasilinan-2-ylmethyl) ester;Thioacetic acid S-(2-ethoxy-[1,3,2]dioxasilinan-2-ylmethyl) ester;Thioacetic acid S-(2,5-dimethyl-[1,3,2]dioxasilinan-2-ylmethyl) ester;Thioacetic acid S-(2-ethoxy-5-methyl-[1,3,2]dioxasilinan-2-ylmethyl) ester;Thioacetic acid S-[2-(3-hydroxypropoxy)-[1,3,2]dioxasilinan-2-ylmethyl] ester;Thioacetic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylmethyl] ester;Thioacetic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylmethyl] ester;Thioacetic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylmethyl] ester Acid S-[2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1,3,2]dioxasilinan-2-ylmethyl] ester;Thioacetic acid S-(2-methyl-[1,3,2]dioxasilinan-2-ylpropyl) ester;Thioacetic acid S-(2-ethoxy-[1,3,2]dioxasilinan-2-ylpropyl) ester;Thioacetic acid S-(2,5-dimethyl-[1,3,2]dioxasilinan-2-ylpropyl) ester;Thioacetic acid S-(2-ethoxy-5-methyl-[1,3,2]dioxasilinan-2-yl) propyl) ester, thioacetic acid S-[2-(3-hydroxypropoxy)-[1,3,2]dioxasilinan-2-ylpropyl] ester;thioacetic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester;thioacetic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester;thioacetic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester;thioacetic acid S-[2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1, 3,2]dioxasilinan-2-ylpropyl] ester;Thiopropionic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester;Thiopentanoic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester;Thiohexanoic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester;2-Ethyl-thiohexanoic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester;Thiooctanoic acid S-(2-methyl-[1,3,2]dioxasilinan-2-ylpropyl) ester;Thiooctanoic acid S-(2-ethoxy-[1,3,2]dioxasilinan-2-ylpropyl) ester;Thiooctanoic acid S-(2,5-dimethyl-[1,3,2]dioxasilinan-2-ylpropyl) ester;Thiooctanoic acid S-(2-ethoxy-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl) ester;Thiooctanoic acid S-[2-(3-hydroxypropoxy)-[1,3,2]dioxasilinan-2-ylpropyl] ester;Thiooctanoic acid S-[2-(3-hydroxy-2-methylpropoxy)-[1,3,2]dioxasilinan-2-ylpropyl] ester Thiooctanoic acid S-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester; thiooctanoic acid S-[2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1,3,2]dioxasilinan-2-ylpropyl] ester; thioacetic acid S-(2,4-dimethyl-[1,3,2]dioxasilolan-2-ylmethyl) ester; thioacetic acid S-(2,4-dimethyl-[1,3,2]dioxasilolan-2-ylpropyl) ester; thiooctanoic acid S-(2,4-dimethyl-[1,3,2]dioxasilolan-2-ylpropyl) ester, and combinations thereof.

[0033] The thioester of general formula (II) described herein can be selected from the group consisting of methyl thioacetate, ethyl thioacetate, allyl thioacetate, propyl thioacetate, butyl thioacetate, pentathioacetate, hexyl thioacetate, cyclohexyl thioacetate, phenyl thioacetate, benzyl thioacetate, methyl thiooctanoate, ethyl thiooctanoate, allyl thiooctanoate, propyl thiooctanoate, butyl thiooctanoate, pentathiooctanoate, hexyl thiooctanoate, cyclohexyl thiooctanoate, phenyl thiooctanoate, benzyl thiooctanoate, hexyl thioadipate, cyclohexyl thioadipate, phenyl thioadipate, benzyl thioadipate, and combinations thereof.

[0034] Mercapto-functional alkoxysilanes include (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, (3-mercaptopropyl)dimethoxymethylsilane, (3-mercaptopropyl)diethoxymethylsilane, (3-mercaptopropyl)dimethyl(methoxy)silane, (3-mercaptopropyl)dimethyl(ethoxy)silane, (2-mercaptoethyl)trimethoxysilane, (2-mercaptoethyl)triethoxysilane, (2-mercaptoethyl)dimethoxymethylsilane, (2-mercaptoethyl) Diethoxymethylsilane, (2-mercaptoethyl)dimethyl(methoxy)silane, (2-mercaptoethyl)dimethyl(ethoxy)silane, 2-methyl-[1,3,2]dioxasilinan-2-ylmethyl mercaptan, 2-ethoxy-[1,3,2]dioxasilinan-2-ylmethyl mercaptan, 2,5-dimethyl-[1,3,2]dioxasilinan-2-ylmethyl mercaptan, 2-ethoxy-5-methyl-[1,3,2]dioxasilinan-2-ylmethyl mercaptan, 2-(3-hydroxypropoxy)-[1,3,2]dioxasilinan-2-ylmethyl mercaptan Linan-2-ylmethyl mercaptan, 2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylmethyl mercaptan, 2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylmethyl mercaptan, 2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1,3,2]dioxasilinan-2-ylmethyl mercaptan, 2-methyl-[1,3,2]dioxasilinan-2-ylpropyl mercaptan, 2-ethoxy-[1,3,2]dioxasilinan-2-ylpropyl mercaptan Dioxasilinan-2-ylpropyl mercaptan, 2,5-dimethyl-[1,3,2]dioxasilinan-2-ylpropyl mercaptan, 2-ethoxy-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl mercaptan, 2-(3-hydroxypropoxy)-[1,3,2]dioxasilinan-2-ylpropyl mercaptan, 2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl mercaptan, 2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-ylpropyl mercaptan, 2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1,3,2]dioxasilinan-2-ylpropyl mercaptan, and combinations thereof.

[0035] Alkali metal, alkaline earth metal, and trisubstituted ammonium salts of alkoxysilyl functional thiolates of formula (III) include sodium 3-trimethoxysilylpropanethiolate, sodium 3-triethoxysilylpropanethiolate, sodium 3-diethoxymethylsilylpropanethiolate, sodium trimethoxysilylmethanethiolate, sodium 3-[2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1,3,2]dioxasilinan-2-yl]propanethiolate, sodium 3-[2-(3-hydroxy-2 ... 3-(2,4-dimethyl-[1,3,2]dioxasilolan-2-yl)propanethiolate sodium, 3-(2,4-dimethyl-[1,3,2]dioxasilolan-2-yl)propanethiolate sodium, 3-trimethoxysilylpropanethiolate potassium, 3-triethoxysilylpropanethiolate potassium, 3-diethoxymethylsilylpropanethiolate potassium, trimethoxysilylmethanethiolate potassium Sodium, 3-[2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1,3,2]dioxasilinan-2-yl]propanethiolate potassium, 3-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2]dioxasilinan-2-yl]propanethiolate potassium, 3-[2-ethoxy-5-methyl-[1,3,2]dioxasilinan-2-yl]propanethiolate potassium, 3-(2,4-dimethyl-[1,3,2]dioxasilolan-2-yl)propanethiolate sodium, trimethylammonium ammonium 3-trimethoxysilylpropanethiolate, triethylammonium 3-triethoxysilylpropanethiolate, triisopropylammonium 3-diethoxymethylsilylpropanethiolate, trimethylammonium trimethoxysilylmethanethiolate, triethylammonium 3-[2-(3-hydroxy-3-methylpropoxy)-4-methyl-[1,3,2]dioxasilinan-2-yl]propanethiolate, triisopropylammonium 3-[2-(3-hydroxy-2-methylpropoxy)-5-methyl-[1,3,2-dioxasilinan-2-yl]propanethiolate, triisopropylammonium 3-[2-ethoxy-5-methyl-[1,3,2]dioxasilinan-2-yl]propanethiolate, trimethylammonium 3-(2,4-dimethyl-[1,3,2]dioxasilolan-2-yl)propanethiolate, and combinations thereof.

[0036] M + The alkali metal, alkaline earth metal, and trisubstituted ammonium salts of alkoxy-functional thiolates of general formula (III), where is an alkali metal ion, alkaline earth metal ion, or trisubstituted ammonium ion, can be obtained by deprotonation of mercaptosilanes or other methods known to those skilled in the art, such as those described in U.S. Pat. No. 6,777,569, the entire contents of which are incorporated herein by reference.

[0037] It is understood herein that the mercapto-functional alkoxysilane of formula (V) or alkoxysilyl-functional thiolate of formula (III) described herein can also include one or more mercapto-functional alkoxysilanes of formula (V), one or more mercapto-functional thiolates of formula (III), or one or more mercapto-functional alkoxysilanes of formula (V) and one or more alkoxysilyl-functional thiolates of formula (III).

[0038] In one embodiment herein, there is provided a process for preparing an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I), comprising: R 1 -[C(=O)-SR 2 -SiR 3 a (OR 4 ) 3-a ] z (I) where R 1is a monovalent radical selected from a straight chain alkyl containing 1 to 18 carbon atoms, a branched chain alkyl containing 3 to 18 carbon atoms, a cycloalkyl containing 5 to 18 carbon atoms, an alkenyl containing 2 to 18 carbon atoms, an aryl group containing 6 to 18 carbon atoms, an aralkyl containing 7 to 18 carbon atoms, or hydrogen, or is a divalent radical selected from an alkyl containing 1 to 10 carbon atoms, a cycloalkyl containing 5 to 10 carbon atoms, or phenyl; Each R 2 are divalent radicals independently selected from a straight chain alkyl containing 1 to 10 carbon atoms, a branched chain alkyl containing 3 to 10 carbon atoms, a cycloalkyl containing 5 to 10 carbon atoms, an alkenyl containing 2 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms, or an aralkyl containing 7 to 10 carbon atoms; Each R 3 are monovalent radicals independently selected from a straight chain alkyl containing 1 to 6 carbon atoms, a branched chain alkyl containing 3 to 6 carbon atoms, a cycloalkyl containing 5 or 6 carbon atoms, an alkenyl containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, or an aralkyl containing 7 to 10 carbon atoms; R 4 are independently a straight chain alkyl containing 1 to 6 carbon atoms, a branched chain alkyl containing 3 to 6 carbon atoms, a cycloalkyl containing 5 or 6 carbon atoms, an alkenyl containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, an aralkyl containing 7 to 10 carbon atoms, a straight chain alkyl containing 2 to 6 carbon atoms and a hydroxyl group, or a branched chain alkyl containing 3 to 6 carbon atoms and a hydroxyl group, and a group having the structure -R 2 -(OCH2CH2) m (OCH2CH(CH3)) n OR 1 or two R 4 a divalent group formed from groups, provided that (i) two R 4provided that if the group is attached, a is 0 or 1, and (ii) the sum of m+n is 1 to 20; a, m, n, and z are integers, where a is 0, 1, or 2, m is 0 to 10, n is 0 to 10, and z is 1 or 2; (a) reacting a thioester of general formula (II) with R 1 [C(=O)SR 5 ] z (II) where Each R 5 are monovalent radicals independently selected from linear alkyl containing 1 to 18 carbon atoms, branched alkyl containing 3 to 18 carbon atoms, cycloalkyl containing 5 to 18 carbon atoms, alkenyl containing 2 to 18 carbon atoms, aryl containing 6 to 18 carbon atoms, and aralkyl containing 7 to 18 carbon atoms; and where R 1 and z is as defined above. Mercapto-functional alkoxysilanes of formula (V) HS-R 2 -SiR 3 a (OR 4 ) 3-a (V), and / or Alkali metal salts, alkaline earth metal salts, and trisubstituted ammonium salts of alkoxysilyl-functional thiolates of general formula (III) M +- SR 2 -SiR 3 a (OR 4 ) 3-a (III) Here, M + is an alkali metal ion, alkaline earth metal ion, or trisubstituted ammonium ion, and R 2 , R 3 , R 4 and a is as defined above; contacting with (b) reacting the thioester with an alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt of the mercapto-functional alkoxysilane and / or alkoxysilyl-functional thiolate of step (a) to produce an alkoxysilyl-containing thiocarboxylic acid ester having formula (I) and a by-product HSR of formula (VI) 5 and / or M of formula (IV) +- SR 5 producing a mixture of; (c) Removal of the by-product HSR from the mixture of step (b). 5 and / or M +- SR 5 Taking out; (d) optionally further treating the mixture of step (c) containing the alkoxysilyl-containing thiocarboxylic acid ester to provide the alkoxysilyl-containing thiocarboxylic acid ester; and (a) optionally, the by-product HSR of step (c); 5 and / or M +- SR 5 thioester R of general formula (II) used in step (a) 1 [C(=O)SR 5 ] z To prepare A method comprising:

[0039] In one embodiment herein, step (a) does not include a mercapto-functional alkoxysilane in the reaction mixture. The reaction of a thioester of formula (II) with an alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt of an alkoxysilyl-functional thiolate of formula (III) provides an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I) and, as a by-product, an alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt of a thiolate having formula (IV), as illustrated in chemical reaction equation (A).

[0040] The alkoxysilyl-functional thiolate of formula (III) can be formed by reacting a mercapto-functional alkoxysilane with a base selected from the group consisting of alkali metals, alkaline earth metals, alkali metal hydrides, alkaline earth metal hydrides, or metal hydroxides, metal alkoxides, metal amides, metal thiolates, and amines, examples of which are known to those skilled in the art. Useful alkali metals for deprotonating the mercapto-functional alkoxysilanes are sodium and potassium. Some specific examples of alkali metal hydroxides or alkali metal alkoxides can be found, for example, in U.S. Patent Nos. 3,829,505, 3,941,849, 4,242,490, 4,335,188, 4,687,851, 4,985,491, 5,096,993, 5,100,997, 5,106,874, 5,116,931, 5,136,010, 5,185,420, and 5,266,681, the contents of all of which are incorporated herein by reference in their entirety.

[0041] Some non-limiting examples of alkali metals, alkali metal hydrides and alkali metal alkoxides or hydroxides include sodium, potassium, sodium hydride, potassium hydride, cesium hydroxide, rubidium hydroxide, potassium hydroxide, potassium methoxide, potassium ethoxide, potassium tert-butoxide, sodium hydroxide, sodium methoxide, sodium ethoxide and sodium tert-butoxide.

[0042] In one embodiment, the alkali metal, alkaline earth metal, or tri-substituted ammonium salt of the alkoxysilyl-functional thiolate of Formula (III) is soluble in the reaction mixture, while the alkali metal, alkaline earth metal, or tri-substituted ammonium salt of the thiolate having Formula (IV) is insoluble in the reaction mixture. The insoluble alkali metal, alkaline earth metal, or tri-substituted ammonium salt of the thiolate precipitates from the reaction mixture, thereby completing the equilibrium reaction of Formula (A). The precipitate of the insoluble alkali metal, alkaline earth metal, or tri-substituted ammonium salt of the thiolate can be removed from the reaction mixture using decantation, filtration, centrifugation, or washing methods.

[0043] The alkoxysilyl group attached to the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of the alkoxysilyl-functional thiolate enhances its solubility in the reaction mixture. The solubility of the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of the alkoxysilyl-functional thiolate is specifically determined by the R 4 is greater than one carbon atom, more specifically, R 4 is a straight chain alkyl containing 2 to 6 carbon atoms, or a branched chain alkyl containing 3 to 6 carbon atoms, even more specifically ethyl; 4 is affected by.

[0044] R is the alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt of the by-product thiolate. 5 Motoi and M + The R of the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of the by-product thiolate can affect its solubility in the reaction mixture. 5 is a straight chain alkyl group of 1 to 10 carbon atoms, more specifically 1 to 6 carbon atoms. M + When R is an alkali metal ion, specifically sodium or potassium, more specifically sodium, its solubility in the reaction mixture may be reduced. 5 is a straight chain alkyl group of 1 to 6 carbon atoms, and M +is sodium or potassium.

[0045] An organic solvent can be used to reduce the solubility of the by-product thiolate alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt in the reaction mixture. An aprotic solvent can be used to reduce the solubility of the by-product thiolate alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt in the reaction mixture. Specifically, the solvent can be a hydrocarbon, ester, ketone, or ether, more specifically a hydrocarbon. Representative, non-limiting solvents include alkanes, cycloalkanes, and aromatic compounds, such as hexane, heptane, octane, decane, 2-methylpentane, 2-methylnonane, cyclopentane, cyclohexane, cyclooctane, benzene, toluene, xylene, and mixtures thereof.

[0046] The amount of solvent in the reaction mixture can be from 1 to 50 weight percent, more specifically from 2 to 20 weight percent, and even more specifically from 5 to 15 weight percent, based on the weight of the alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt of the alkali silyl-functional thiolate and the initial weight of the thioacid ester reagent.

[0047] The by-product thiolate, an alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt, can also be removed from the reaction mixture by adding a Brønsted-Lowry acid to protonate the thiolate anion and then removing the thiol by distillation or stripping. Representative Brønsted-Lowry acids include strong acids such as hydrogen chloride, sulfuric acid, paratoluenesulfonic acid, trifluoromethylsulfonic acid, carboxylic acids, and mercapto-functional alkoxysilanes. The Brønsted-Lowry acid can be added to the reaction mixture containing the thiolate by-product or to the thiolate by-product after separation from the reaction mixture. The thiol formed from the neutralization of the thiolate by-product can be separated from the Brønsted-Lowry acid salt and used to prepare thiocarboxylic acid ester reagents.

[0048] A particularly useful Bronsted-Lowry acid is a mercapto-functional alkoxysilane of formula (V). Neutralized mercapto-functional alkoxysilanes are alkali metal, alkaline earth metal, or trisubstituted ammonium salts of alkoxysilyl-functional thiolates of formula (III), which can be used to prepare alkoxysilyl-functional thiocarboxylic acid esters of formula (I). The thiol formed from the neutralization reaction can be separated from the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolates of formula (III) by stripping or distillation. Distillation is facilitated when the boiling point of the thiol is lower than that of the mercapto-functional alkoxysilane and / or thioester, specifically, when the boiling point is less than 5°C at 1.013 bar atmospheric pressure, more specifically, less than 50°C at 1.013 bar, and even more specifically, less than 100°C at 1.013 bar.

[0049] The by-product alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt of the thiolate can also be removed from the reaction mixture by washing the reaction mixture with an aqueous solution. The aqueous solution may be buffered or contain salts to reduce the solubility of the reaction product in the aqueous phase, thereby forming a two-phase mixture. The two-phase mixture can be separated from each other by centrifugation or decantation. Representative, non-limiting aqueous solutions include sodium carbonate solution and brine solution.

[0050] Once separated from the reaction product, the aqueous phase containing the by-product alkali metal, alkaline earth metal, or trisubstituted ammonium salt of thiolate can be neutralized with acid to form the thiol compound, which can form a two-phase mixture. The thiol can be removed from the aqueous phase by stripping, distillation, or decantation using centrifugation.

[0051] The amount of alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate used in the reaction can be less than, equal to, or more than the stoichiometric amount relative to the thioester of Formula (II). Specifically, the amount of alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate of Formula (III) is about 0.5 to about 1.5 equivalents based on the thioester of Formula (II), more specifically about 0.9 to about 1.2 equivalents based on the thioester, and even more specifically about 0.95 to 1.05 equivalents based on the thioester.

[0052] The reaction of the thioester with the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of an alkoxysilyl-functional thiolate can be carried out at a temperature of from about 15° C. to about 200° C., more specifically from about 25° C. to about 150° C., even more specifically from about 40° C. to about 100° C., and a pressure of from about 0.001 bar to about 2 bar, more specifically from about 0.1 bar to about 1.2 bar, and even more specifically from about 0.75 bar to about 1.1 bar.

[0053] In another embodiment, step (a) does not include an alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt of an alkoxysilyl-functional thiolate in the reaction mixture. The reaction of a thioester of formula (II) with a mercapto-functional alkoxysilane of formula (V) provides an alkoxysilyl-containing thiocarboxylic acid ester of formula (I) and a by-product thiol of formula (VI), as described in the equilibrium reaction of chemical reaction equation (B). The reaction is preferably carried out in the presence of a catalyst.

[0054] The catalyst that can be used can be an acid. The acid can be a Bronsted-Lowry acid or a Lewis acid. Since this reaction can be described as a transesterification reaction, a Bronsted-Lowry acid or a Lewis acid functions as the transesterification catalyst. A suitable Bronsted-Lowry acid catalyst is a protonic acid, preferably one that has a pKa of less than 5.0 in aqueous solution. The pKa values ​​of Bronsted-Lowry acid catalysts can be found in the CRC Handbook of Chemistry and Physics, 72 nd edition, DR Lide (ed), CRC Press, Boston (1991), pp. 8-39 to 8-41. If the pKa of an acid is not reported, the value can be determined using potentiometric titration, Albert, A. & Sergeant, E. P., Ionization Constants of Acids and Bases, Wiley, Inc., New York, 1962.

[0055] Representative, non-limiting examples of Bronsted-Lowry acid catalysts include sulfuric acid, phosphoric acid, trifluoromethanesulfonic acid, toluenesulfonic acid, trifluoroacetic acid, acetic acid, and hydrochloric acid.

[0056] Lewis acids, such as metal salts or metal complexes, can be used as catalysts. The metal salts or metal complexes can be derived from tin, titanium, zirconium, bismuth, iron, nickel, cobalt, and aluminum. Representative, non-limiting examples of Lewis acid catalysts include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin oxide, tetraethyl titanate, tetraethyl zirconate, zirconium tetrafluoride, zirconium tetrachloride, zirconium acetoacetonate, zirconium acetate, aluminum chloride, and bismuth acetate.

[0057] In one embodiment, the amount of Bronsted-Lowry or Lewis acid catalyst is from about 0.001 to about 10 weight percent, more specifically, from about 0.1 to about 2 weight percent, based on the initial weight of the mercapto-functional alkoxysilane.

[0058] The catalyst used in the reaction of Equation (B) can be removed to improve the hydrolytic stability of the alkoxysilyl-functional thiocarboxylic acid ester product of Formula (I). The acid catalyst can be neutralized with a base or simply washed away. Water, brine, aqueous sodium carbonate, and aqueous sodium phosphate monobasic solution can be used as wash media, with the preferred wash media being aqueous sodium phosphate monobasic solution.

[0059] In yet another embodiment, the by-product thiol of formula (VI) is removed from the reaction mixture, thereby completing the equilibrium reaction of chemical reaction (B). The thiol can be removed from the reaction mixture by stripping or distillation. Distillation is facilitated when the boiling point of the thiol is lower than the boiling point of the mercapto-functional alkoxysilane. Specifically, the boiling point of the thiol is less than about 5° C. at atmospheric pressure of about 1.013 bar, more specifically, less than about 50° C. at about 1.013 bar, and even more specifically, less than about 100° C. at about 1.013 bar, than the boiling point of the mercapto-functional alkoxysilane.

[0060] The amount of mercapto-functional alkoxysilane of formula (V) used in the reaction can be less than, equal to, or greater than the stoichiometric amount relative to the thiol ester of formula (II). Specifically, the amount of mercapto-functional alkoxysilane of formula (V) is about 0.5 to about 1.5 equivalents based on the thioester of formula (II), more specifically about 0.9 to about 1.2 equivalents based on the thioester, and even more specifically about 0.95 to about 1.05 equivalents based on the thioester.

[0061] The reaction of the thioester with the mercapto-functional alkoxysilane can be carried out at a temperature of from about 15° C. to about 200° C., more specifically from about 25° C. to about 150° C., even more specifically from about 40° C. to about 100° C., and at a pressure of from about 0.001 bar to about 2 bar, more specifically from about 0.1 bar to about 1.2 bar, and even more specifically from about 0.75 bar to about 1.1 bar.

[0062] The reaction of the thioester with the mercapto-functional alkoxysilane can be carried out in the presence of an organic solvent. Solvents are particularly useful if they form a low-boiling azeotrope with the thiol, thereby facilitating their removal from the reaction mixture by distillation or stripping.

[0063] In yet another embodiment, step (a) includes both a mercapto-functional alkoxysilane of formula (V) and an alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt of an alkoxysilyl-functional thiolate of formula (III) in the reaction mixture. The reaction between the thioester of formula (II) and the alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt of an alkoxysilyl-functional thiolate of formula (III) can be faster than the reaction between the thioester and the mercapto-functional alkoxysilane. The alkoxysilyl-containing thiocarboxylic acid ester of general formula (I) and the by-product alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt of a thiolate having formula (IV) are formed primarily by the reaction described by chemical reaction equation (A).

[0064] In one embodiment herein, the process for preparing an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I) comprises: (a) reacting a thioester of general formula (II) with R 1 [C(=O)SR 5 ]2(II) where Each R 5are monovalent groups independently selected from linear alkyl groups containing 1 to 18 carbon atoms, branched alkyl groups containing 3 to 18 carbon atoms, cycloalkyl groups containing 5 to 18 carbon atoms, alkenyl groups containing 2 to 18 carbon atoms, aryl groups containing 6 to 18 carbon atoms, and aralkyl groups containing 7 to 18 carbon atoms; and where R 1 and z is as defined above. a mercapto-functional alkoxysilane of formula (V), HS-R 2 -SiR 3 a (OR4) 3-a (V), and Alkali metal salts, alkaline earth metal salts, trisubstituted ammonium salts of alkoxysilyl-functional thiolates of general formula (III), M + - SR 2 -SiR 3 a (OR4) 3-a (III) Here, M + is an alkali metal ion, alkaline earth metal ion, or trisubstituted ammonium ion, and R 2 , R 3 , R 4 , and a is as defined above, to come into contact with; (b) reacting the thioester with an alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt of the alkoxysilyl-functional thiolate of step (a) to produce an alkoxysilyl-containing thiocarboxylic acid ester having formula (I) and a by-product, M, of formula (IV) +- SR 5 producing a mixture of; (b1) M, a by-product of step (b) +- SR 5 with a mercapto-functional alkoxysilane of formula (V) to give an alkali metal, alkaline earth metal, or trisubstituted ammonium salt of an alkoxysilyl-functional thiolate of general formula (III), M +- SR 2 -SiR3 a (OR 4 ) 3-a and the by-product HSR of formula (VI) 5 To form; (c) Removal of the by-product HSR from the mixture of step (b1). 5 Taking out; (d) optionally further treating the mixture of step (c) containing the alkoxysilyl-containing thiocarboxylic acid ester to provide the alkoxysilyl-containing thiocarboxylic acid ester; and (e) optionally, the by-product HSR of step (c); 5 thioester R of general formula (II) used in step (a) 1 [C(=O)SR 5 ] z preparing; Includes.

[0065] In one embodiment, the process for preparing the alkoxysilyl-containing thiocarboxylic acid esters of general formula (I) can be a batch process, a semi-batch process, or a continuous process.

[0066] The amount of alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate used in the reaction can be less than the stoichiometric amount relative to the thioester of Formula (II) because the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate is constantly being produced from the reaction of the mercapto-functional alkoxysilane with the by-product alkali metal, alkaline earth metal, or trisubstituted ammonium salt of thiolate. Specifically, the amount of alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate of Formula (III) is about 0.001 to about 0.9 equivalents based on the thioester of Formula (II), more specifically, 0.01 to about 0.5 equivalents based on the thioester, and even more specifically, about 0.01 to about 0.3 equivalents based on the thioester.

[0067] In another embodiment, the molar ratio of the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of the alkoxysilyl-functional thiolate of Formula (III) to the mercapto-functional alkoxysilane of Formula (V) used in the reaction is from about 0.00065 to about 1.5, more specifically from about 0.0065 to about 0.5, and even more specifically from about 0.0065 to about 0.25.

[0068] The reaction of the thioester with the alkali metal, alkaline earth metal or trisubstituted ammonium salt of the alkoxysilyl-functional thiolate, when carried out in the presence of the mercapto-functional alkoxysilane (V), can be carried out at a temperature of from about 15° C. to about 200° C., more specifically from about 25° C. to about 150° C., even more specifically from about 40° C. to about 100° C., and at a pressure of from about 0.001 bar to about 2 bar, more specifically from about 0.1 bar to about 1.2 bar, and even more specifically from about 0.75 bar to about 1.1 bar.

[0069] In yet another embodiment, the by-product thiol of formula (VI) is removed from the reaction mixture, thereby completing the equilibrium reaction of chemical reaction (A). The thiol can be removed from the reaction mixture by stripping or distillation. Distillation is facilitated when the boiling point of the thiol is lower than the boiling points of the mercapto-functional alkoxysilane and the thiol ester. Specifically, the boiling point of the thiol is less than about 5° C. at atmospheric pressure of about 1.013 bar, more specifically less than about 50° C. at about 1.013 bar, and even more specifically less than about 100° C. at about 1.013 bar, than the boiling points of the mercapto-functional alkoxysilane and the thiol ester.

[0070] The reaction of the thioester with the mercapto-functional alkoxysilane can be carried out at a temperature of from about 15° C. to about 200° C., more specifically from about 25° C. to about 150° C., even more specifically from about 40° C. to about 100° C., and at a pressure of from about 0.001 bar to about 2 bar, more specifically from about 0.1 bar to about 1.2 bar, and even more specifically from about 0.75 bar to about 1.1 bar.

[0071] The reaction of the thioester with the mercapto-functional alkoxysilane can be carried out in the presence of an organic solvent. Solvents are particularly useful if they form a low-boiling azeotrope with the thiol, thereby facilitating their removal from the reaction mixture by distillation or stripping.

[0072] In another embodiment, the process for preparing an alkoxysilyl-containing thiocarboxylic acid ester is a continuous process. The continuous process for preparing an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I) comprises: (a) sequentially contacting a thioester of general formula (II) with a mercapto-functional alkoxysilane of formula (V) and an alkali metal, alkaline earth metal, tri-substituted ammonium salt of an alkoxysilyl-functional thiolate of general formula (III) by sequentially adding the thioester of general formula (II), the mercapto-functional alkoxysilane of formula (V), and the alkali metal, alkaline earth metal, tri-substituted ammonium salt of an alkoxysilyl-functional thiolate of general formula (III) to a first reaction vessel; (b) sequentially reacting in a first reaction vessel the thioester with an alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt of the alkoxysilyl-functional thiolate of step (a) to produce an alkoxysilyl-containing thiocarboxylic acid ester of formula (I) and a by-product alkali metal salt, alkaline earth metal salt, or tri-substituted ammonium salt of the thiolate of formula (IV); (b1) sequentially reacting the alkali metal, alkaline earth metal, or tri-substituted ammonium salt of a thiolate of Formula (IV) formed in step (b) with a mercapto-functional alkoxysilane of Formula (V) to form in a first reaction vessel an alkali metal, alkaline earth metal, or tri-substituted ammonium salt of an alkoxysilyl-functional thiolate of Formula (III) and a by-product thiol of Formula (VI), wherein the reaction of steps (b) and (b1) forms a reaction mixture comprising a product alkoxysilyl-containing thiocarboxylic acid ester having Formula (I), reactants a thioester of general Formula (II), an alkali metal, alkaline earth metal, or tri-substituted ammonium salt of an alkoxysilyl-functional thiolate of general Formula (III), and a mercapto-functional alkoxysilane of Formula (V), and a by-product an alkali metal, alkaline earth metal, or tri-substituted ammonium salt of a thiolate of Formula (IV) and a thiol of Formula (VI); (c) continuously removing the reaction mixture of step (b1) from the first reaction vessel and transferring the reaction mixture to a distillation apparatus; (c1) continuously separating the thiol of formula (VI) from other components in the reaction mixture of step (b1) by passing the reaction mixture through a distillation apparatus to form a mixture of separated thiol and other components; (c2) continuously removing a portion of the mixture of other components of step (c1); (c3) continuously transferring a portion of the mixture of other components of step (c1) to the first reaction vessel; (d) continuously transferring the mixture of other components of step (c1) to a second reactor for further processing to form the product alkoxysilyl-containing thiocarboxylic acid ester having formula (I); (d1) continuously transferring the reaction product of step (d) to a storage vessel; (e) optionally, the separate HSR of step (c1); 5 with a carboxylic acid to prepare a thioester of general formula (II) and transferring the thioester to the first reaction vessel of step (a); may include:

[0073] The amount of alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate used in the reaction can be less than the stoichiometric amount relative to the thioester of Formula (II) because the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate is constantly being generated from the reaction of the mercapto-functional alkoxysilane with the by-product alkali metal, alkaline earth metal, or trisubstituted ammonium salt of thiolate. Specifically, the amount of alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate of Formula (III) is from about 0.001 to about 0.9 equivalents based on the thioester of Formula (II), more specifically, from 0.01 to about 0.5 equivalents based on the thioester, and even more specifically, from about 0.01 to about 0.3 equivalents based on the thioester.

[0074] In another embodiment, the molar ratio of alkali metal, alkaline earth metal, or trisubstituted ammonium salt of alkoxysilyl-functional thiolate of Formula (III) to mercapto-functional alkoxysilane of Formula (V) used in the reaction is from about 0.00065 to about 1.5, more specifically from about 0.0065 to about 0.5, and even more specifically from about 0.0065 to about 0.25.

[0075] The reaction of the thioester with the alkali metal, alkaline earth metal, or trisubstituted ammonium salt of the alkoxysilyl-functional thiolate, when carried out in the presence of the mercapto-functional alkoxysilane (V), can be carried out at a temperature of from about 15° C. to about 200° C., more specifically from about 25° C. to about 150° C., even more specifically from about 40° C. to about 100° C., and at a pressure of from about 0.001 bar to about 2 bar, more specifically from about 0.1 bar to about 1.2 bar, and even more specifically from about 0.75 bar to about 1.1 bar.

[0076] In yet another embodiment, the by-product thiol of formula (VI) is removed from the reaction mixture, thereby completing the equilibrium reaction of chemical reaction (A). The thiol can be removed from the reaction mixture by stripping or distillation. Distillation is facilitated when the boiling point of the thiol is lower than the boiling points of the mercapto-functional alkoxysilane and the thiol ester. Specifically, the boiling point of the thiol is less than about 5° C. at atmospheric pressure of about 1.013 bar, more specifically, less than about 50° C. at about 1.013 bar, and even more specifically, less than about 100° C. at about 1.013 bar, than the boiling points of the mercapto-functional alkoxysilane and the thiol ester.

[0077] The reaction of the thioester with the mercapto-functional alkoxysilane can be carried out at a temperature of from about 15° C. to about 200° C., more specifically from about 25° C. to about 150° C., even more specifically from about 40° C. to about 100° C., and at a pressure of from about 0.001 bar to about 2 bar, more specifically from about 0.1 bar to about 1.2 bar, and even more specifically from about 0.75 bar to about 1.1 bar.

[0078] The reaction of the thioester with the mercapto-functional alkoxysilane can be carried out in the presence of an organic solvent. Solvents are particularly useful if they form a low-boiling azeotrope with the thiol, thereby facilitating their removal from the reaction mixture by distillation or stripping.

[0079] In yet another embodiment, R 1 is a monovalent linear or branched alkyl group having 5 to 11 carbon atoms, and R 2 is a divalent linear alkyl group of 1 to 3 carbon atoms, and R 3 is methyl and R 4 is a monovalent linear or branched alkyl group of 2 to 4 carbon atoms, or two R 4 The groups are linked to form a divalent -R 4 -R 4 - group, a is an integer of 0 or 1, and z is 1.

[0080] The first reactor may be a continuously stirred reactor, a tube reactor with static mixing, a tube reactor with dynamic stirring, more specifically a continuously stirred reactor. The second reactor may be a continuously stirred reactor, a tube reactor with static mixing, a tube reactor with dynamic stirring, a decanter, or a centrifuge, more specifically a continuously stirred reactor equipped with a decanter, a filter, or a stripper.

[0081] The distillation apparatus may be a kettle equipped with a fractionating column, a wiped film evaporator or a thin film evaporator.

[0082] The further processing in step (c2) can be neutralization of the alkali metal, alkaline earth metal, tri-substituted ammonium salts of alkoxysilyl-functional thiolates of general formula (III) and alkali metal, alkaline earth metal, tri-substituted ammonium salts of thiolates of formula (IV) with Bronsted-Lowry acid, optionally followed by a filtration step and a stripping step, or a washing step with water, a brine solution, or an aqueous buffer solution, to extract the alkali metal, alkaline earth metal, tri-substituted ammonium salts of alkoxysilyl-functional thiolates of general formula (III) and alkali metal, alkaline earth metal, tri-substituted ammonium salts of thiolates of formula (IV) from the mixture.

[0083] In one embodiment, a thiol of general formula (VI) can be reacted with a carboxylic acid of general formula (VII): R 1 (COOH) z (VII) where R 1and z are as defined herein, and wherein such reaction can regenerate a thioester of general formula (II) as defined in the methods described herein. It will be understood that while the thiol of formula (VI) can be reacted directly with the carboxylic acid component (VII) herein, the alkali metal salt, alkaline earth metal salt, or trisubstituted ammonium salt of the thiolate of formula (IV) can first be acidified, for example, by reaction with a strong acid such as HCl, sulfuric acid, or other known strong acid, to form a thiol of formula (VI), which can then be reacted with a carboxylic acid as described above and in the following general chemical formula (C). [ka] where R 1 , R 5 , M, and z are as defined herein.

[0084] Some non-limiting examples of suitable carboxylic acids of general formula (VII) are those selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, pivalic acid, neopentanoic acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, 2-ethylhexanoic acid, Versatic™ acids, particularly neononanoic and neodecanoic acids (e.g., VeoVa™ vinyl esters of Versatic acids), capric acid, neoundecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, succinic acid, arachidic acid, and combinations thereof.

[0085] The reaction can be carried out in the presence of an acid catalyst, a dehydrating agent or a moisture scavenger.

[0086] The catalyst that can be used can be an acid. The acid can be a Bronsted-Lowry acid or a Lewis acid. Since this reaction can be described as a transesterification reaction, a Bronsted-Lowry acid or a Lewis acid functions as the transesterification catalyst. A suitable Bronsted-Lowry acid catalyst is a protonic acid, preferably one that has a pKa of less than 5.0 in aqueous solution. The pKa values ​​of Bronsted-Lowry acid catalysts can be found in the CRC Handbook of Chemistry and Physics, 72 nd edition, DR Lide (ed), CRC Press, Boston (1991), pp. 8-39 to 8-41. If the pKa of an acid is not reported, the value can be determined using potentiometric titration, Albert, A. & Sergeant, E. P., Ionization Constants of Acids and Bases, Wiley, Inc., New York, 1962.

[0087] Representative, non-limiting examples of Bronsted-Lowry acid catalysts include sulfuric acid, phosphoric acid, trifluoromethanesulfonic acid, toluenesulfonic acid, trifluoroacetic acid, acetic acid, and hydrochloric acid.

[0088] Lewis acids, such as metal salts or metal complexes, can be used as catalysts. The metal salts or metal complexes can be derived from tin, titanium, zirconium, bismuth, iron, nickel, cobalt, and aluminum. Representative, non-limiting examples of Lewis acid catalysts include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin oxide, tetraethyl titanate, tetraethyl zirconate, zirconium tetrafluoride, zirconium tetrachloride, zirconium acetoacetonate, zirconium acetate, aluminum chloride, and bismuth acetate.

[0089] In one embodiment, the amount of Bronsted-Lowry or Lewis acid catalyst is from about 0.001 to about 10 weight percent, more specifically, from about 0.1 to about 2 weight percent, based on the initial weight of the mercapto-functional alkoxysilane.

[0090] Strong dehydrating agents include anhydrides of phosphoric acid, such as phosphorus pentoxide, and chlorosilanes, such as silicon tetrachloride and methyltrichlorosilane. The strong dehydrating agent is used in an amount less than, equal to, or greater than the stoichiometric amount relative to the carboxylic acid of formula (VII), more specifically, from about 0.5 to about 1.5 equivalents of the dehydrating agent.

[0091] The reaction can be carried out at a temperature of from about 15° C. to about 200° C., more specifically from about 25° C. to about 100° C., and at subatmospheric, atmospheric, or superatmospheric pressure, specifically from about 1.03 mbar to about 2 bar, more specifically from about 15 mbar to about 1.3 bar, and even more specifically from about 100 mbar to about 1.1 bar.

[0092] The reaction depicted in Scheme C can also be carried out in the presence of a solvent, such as, for example, an aliphatic or aromatic solvent.

[0093] The reaction can also be driven to completion by removing the water that is formed. Water can be removed using a dehydrating agent, distillation, or stripping. Organic solvents that form azeotropes with water, such as toluene, can help drive the reaction to completion.

[0094] In one embodiment, (i) an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I) R 1 -[C(=O)-SR 2 -SiR 3 a (OR 4 ) 3-a ] z (I) where R 1is a monovalent radical selected from a straight chain alkyl containing 1 to 18 carbon atoms, a branched chain alkyl containing 3 to 18 carbon atoms, a cycloalkyl containing 5 to 18 carbon atoms, an alkenyl containing 2 to 18 carbon atoms, an aryl group containing 6 to 18 carbon atoms, an aralkyl containing 7 to 18 carbon atoms, or hydrogen, or is a divalent radical selected from an alkyl containing 1 to 10 carbon atoms, a cycloalkyl containing 5 to 10 carbon atoms, or phenyl; Each R 2 are divalent radicals independently selected from a straight chain alkyl containing 1 to 10 carbon atoms, a branched chain alkyl containing 3 to 10 carbon atoms, a cycloalkyl containing 5 to 10 carbon atoms, an alkenyl containing 2 to 10 carbon atoms, an aryl group containing 6 to 10 carbon atoms, or an aralkyl containing 7 to 10 carbon atoms; Each R 3 are monovalent groups independently selected from a straight chain alkyl containing 1 to 6 carbon atoms, a branched chain alkyl containing 3 to 6 carbon atoms, a cycloalkyl containing 5 or 6 carbon atoms, an alkenyl containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, or an aralkyl containing 7 to 10 carbon atoms; R 4 are independently a straight chain alkyl containing 1 to 6 carbon atoms, a branched chain alkyl containing 3 to 6 carbon atoms, a cycloalkyl containing 5 or 6 carbon atoms, an alkenyl containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, an aralkyl containing 7 to 10 carbon atoms, a straight chain alkyl containing 2 to 6 carbon atoms and a hydroxyl group, or a branched chain alkyl containing 3 to 6 carbon atoms and a hydroxyl group, the structure -R 2 -(OCH2CH2) m (OCH2CH(CH3)) n OR 1 or two covalently bonded R 4 a divalent group formed from groups, provided that (i) two R 4provided that if the group is attached, a is 0 or 1, and (ii) the sum of m+n is 1 to 20; a, m, n, and z are integers, where a is 0, 1, or 2, m is 0 to 10, n is 0 to 10, and z is 1 or 2; and (ii) a thioester of general formula (II) R 1 [C(=O)SR 5 ] z (II) where R 1 is a monovalent radical selected from a straight chain alkyl containing 1 to 18 carbon atoms, a branched chain alkyl containing 3 to 18 carbon atoms, a cycloalkyl containing 5 to 18 carbon atoms, an alkenyl containing 2 to 18 carbon atoms, an aryl group containing 6 to 18 carbon atoms, an aralkyl containing 7 to 18 carbon atoms or hydrogen, or is a divalent radical selected from an alkyl containing 1 to 10 carbon atoms, a cycloalkyl containing 5 to 10 carbon atoms, or phenyl; Each R 5 are monovalent groups independently selected from linear alkyl groups containing 1 to 18 carbon atoms, branched alkyl groups containing 3 to 18 carbon atoms, cycloalkyl groups containing 5 to 18 carbon atoms, alkenyl groups containing 2 to 18 carbon atoms, aryl groups containing 6 to 18 carbon atoms, and aralkyl groups containing 7 to 18 carbon atoms; and z is an integer, where z is 1 or 2; An alkoxysilyl-containing thiocarboxylic acid ester composition is provided, comprising:

[0095] In another embodiment, the alkoxysilyl-containing thiocarboxylic acid ester composition comprises from about 70 to about 99.9 weight percent of the alkoxysilyl-containing thiocarboxylic acid ester (i) and from about 0.1 to about 30 weight percent of the thioester (ii), more specifically, from about 85 to about 95.5 weight percent of the alkoxysilyl-containing thiocarboxylic acid ester (i) and from about 0.5 to about 15 percent of the thioester, wherein said weight percents are based on the total weight of the alkoxysilyl-containing thiocarboxylic acid ester (i) and the thioester (ii).

[0096] In another embodiment, the alkoxysilyl-containing thiocarboxylic acid ester composition further comprises a mercapto-functional alkoxysilane in an amount of from about 0.1 to about 50 weight percent, based on the total weight of the alkoxysilyl-containing thiocarboxylic acid (i) and the thioester (ii).

[0097] In yet another embodiment, a rubber composition comprises an alkoxysilyl-containing thiocarboxylic acid ester (i) and a thioester (ii), wherein the amount of the alkoxysilyl-containing thiocarboxylic acid ester in the rubber composition is from about 1 to about 14 weight percent, and the weight of the thioester is from about 0.001 to about 6 weight percent, said weight percents being based on the weight of the rubber component.

[0098] The rubber composition may further comprise a mercapto-functional alkoxysilane, wherein the amount of alkoxysilyl-containing thiocarboxylic acid ester (i) in the rubber composition is from about 1 to about 14 weight percent, the amount of thioester (ii) is from about 0.001 to about 6 weight percent, and the amount of mercapto-functional alkoxysilane is from about 0.001 to about 10 weight percent, said weight percents being based on the weight of the rubber component. [Example]

[0099] The following examples are illustrative of the methods of the present invention.

[0100] All manipulations were performed under a nitrogen atmosphere. Octanoic acid (>98%), cyclohexanethiol (97%), adipic acid (99%), trifluoromethanesulfonic acid (99%), phosphorus pentoxide (99%), monobasic sodium phosphate (99%), sodium carbonate decahydrate (99%), potassium tert-butoxide (98%), and sodium (cubes, with mineral oil, 99.9%) were all obtained from Sigma-Aldrich and used without further purification. Toluene and cyclohexane were obtained from Fisher Chemical. 3-Mercaptopropyltriethoxysilane was obtained from Momentive Performance Materials, Inc. Bis(triethoxysilylpropyl) disulfide (>90%) was obtained from Gelest.

[0101] Example 1 Synthesis of 3-(octanoylthio)-1-propyltriethoxysilane from a mixture of sodium 3-triethoxysilylpropylthiol and 3-mercaptopropyltriethoxysilane

[0102] In a three-necked, 2-L round-bottom flask, octanoic acid (352.40 grams, 2.44 moles), cyclohexanethiol (284.01 grams, 2.44 moles), and trifluoromethanesulfonic acid (5.50 grams, 0.04 moles) were mixed with 112.5 grams of toluene solvent. The reaction mixture was stirred, and water was removed using an azeotropic reflux apparatus at 1 bar pressure for 12 hours. The water formed a low-boiling azeotrope with toluene. The reaction mixture was cooled to room temperature. Unreacted octanoic acid was neutralized with 10% aqueous sodium carbonate until no octanoic acid was detected by gas chromatography. The aqueous and organic layers were separated using a separatory funnel. Unreacted cyclohexanethiol in the organic layer was removed under vacuum at 100°C and 5 mmHg pressure for 1.5 hours. The amount of cyclohexanethiooctanoate produced was 426.0 grams, or a 72.0% yield.

[0103] In a three-necked, 250 mL round-bottom flask equipped with a distillation head, a mixture of cyclohexanethiooctanoate (94.60 grams, 0.39 moles) and 3-mercaptopropyltriethoxysilane (95.02 grams, 0.40 moles) was treated with 2.24 grams (0.009 moles) of potassium tert-butoxide. The reaction mixture was magnetically stirred under a vacuum of 14 to 20 mmHg with a nitrogen purge. The reaction mixture was heated at 80°C for 1 hour, then increased to 100°C for an additional hour, and finally increased to 120°C for an additional 4 hours. The cyclohexanethiol by-product was distilled and collected during the reaction. Upon completion of the reaction, the mixture was cooled to room temperature. The reaction mixture was washed with 14.0 grams of 10% aqueous monobasic sodium phosphate, and the organic layer was separated from the aqueous layer. Volatiles from the organic layer were removed under vacuum at 90°C and 15 mmHg pressure for 90 minutes to give 126 grams of 3-(octanoylthio)-1-propyltriethoxysilane, a yield of 88.7%. The structure of the product was confirmed using GC / MS spectroscopy.

[0104] Example 2 Synthesis of 3-(octanoylthio)-1-propyltriethoxysilane from sodium 3-trimethoxysilylpropylthiolate

[0105] At ambient temperature, 4.78 grams (0.208 moles) of sodium was added to toluene and warmed to approximately 110°C at atmospheric pressure. To the molten sodium-toluene suspension, 45.51 grams (0.096 moles) of bis(triethoxysilylpropyl) disulfide was added over 35 minutes. The reaction mixture was stirred at 105°C for approximately 1 hour and cooled to approximately 40°C. Cyclohexanethiooctanoate (45.10 grams, 0.186 moles) was added to the reaction mixture over 20 minutes to give a viscous salt suspension. The reaction was stirred for an additional 2 hours. The reaction mixture was treated with 72 grams of 12.5% ​​brine solution, dissolving the salt and leaving clear, yellow-orange toluene and water layers. GC of the organic layer showed 77% GC area percent of 3-(octanoylthio)-1-propyltriethoxysilane and 8% GC area percent of cyclohexanethiooctanoate in the mixture, where the area percent excluded the toluene peak.

[0106] Example 3 Synthesis of bis-(3-triethoxysilyl-1-propyl)dithioadipate using a mixture of sodium triethoxysilylpropyl thiolate and 3-mercaptopropyltriethoxysilane

[0107] In a three-neck, 1 L round-bottom flask, adipic acid (94.53 grams, 0.65 moles), cyclohexanethiol (151.50 grams, 1.30 moles), and phosphorus pentoxide (22.75 grams, 0.16 moles) were mixed with 165 grams of cyclohexane solvent. The reaction mixture was stirred and heated at 80°C and atmospheric pressure for 16 hours. Over the course of the reaction, additional phosphorus pentoxide was added every 4 hours (22.75 grams, 0.16 moles each time, for a total of 91.00 grams, 0.64 moles). Two layers formed during the reaction: a colorless upper organic layer and a thick, black lower layer. The reaction was cooled to approximately 65°C, and the upper layer was decanted into a separate flask. A white, crystalline solid precipitated as the temperature cooled to room temperature. The solid was washed with 10% aqueous sodium carbonate and recrystallized again using toluene / cyclohexane to give 177.01 grams of bis-cyclohexanethioadipate, a yield of 80.1%.

[0108] A three-necked, 250 mL round-bottom flask equipped with a distillation head was charged with a mixture of bis-cyclohexanethioadipate (107.38 grams, 0.31 moles) and 3-mercaptopropyltriethoxysilane (142.15 grams, 0.60 moles), followed by 2.02 grams of potassium tert-butoxide (0.018 moles). The reaction mixture was stirred using a magnetic stirrer under a nitrogen atmosphere at a reduced pressure of 14 to 20 mmHg. The reaction mixture was heated at 80°C for 1 hour, then at 100°C for an additional hour, and finally at 120°C for an additional 6 hours. The cyclohexanethiol by-product was distilled and collected during heating of the reaction mixture. Upon completion of the reaction, the mixture was cooled to room temperature and washed with 22.70 grams of 10% aqueous monobasic sodium phosphate to form two layers, and the organic layer was separated from the aqueous layer. Volatiles from the organic layer are removed under vacuum at a temperature of 90° C. and a pressure of 15 mm Hg for 90 minutes to produce 150.0 grams of bis-(3-triethoxysilyl-1-propyl)dithioadipate in 81.5% yield.

[0109] Example 4 Synthesis of 3-(octanoylthio)-1-propyltriethoxysilane from a mixture of sodium 3-triethoxysilylpropylthiol and 3-mercaptopropyltriethoxysilane

[0110] A four-necked, 2000 mL round-bottom flask was charged with octanoic acid (372.2 grams, 2.58 moles), hexanethiol (534 grams, 4.51 moles), and 197 grams of cyclohexane solvent. The reaction mixture was magnetically stirred and heated to a pot temperature of 126-132°C at atmospheric pressure. Trifluoromethanesulfonic acid (2.9 grams, 0.02 moles) was added at reflux. The reaction mixture was refluxed under azeotropic distillation conditions for approximately 10 hours and then cooled to room temperature. After 7 hours, GC analysis indicated 8.2 area percent unreacted octanoic acid, and after 10 hours, GC analysis indicated 2.6 area percent unreacted octanoic acid in the reaction mixture. Water (42.6 grams) and 64.7 grams of cyclohexane were collected in a Dean-Stark collector. The reddish mixture was treated with 273.7 grams of 10% aqueous sodium carbonate to remove octanoic acid, and the two phases were separated. The organic layer was stripped at 50°C and 5 mmHg pressure for 2 hours, then at 85°C and 5 mmHg pressure for approximately 6 hours. A total of 338 grams of liquid was collected in the cold trap. The hexylthiooctanoate intermediate, a clear, slightly yellow liquid (609.9 grams), was collected for a 96.8% yield based on octanoic acid.

[0111] A 500 mL round-bottom reaction flask equipped with a nitrogen bubbler, vacuum, and short distillation head was charged with mercaptopropyltriethoxysilane (163.72 grams, 0.687 moles) and a 2.0 mole percent solution of sodium ethoxide in ethanol (4.5 grams). The mixture was allowed to cool to room temperature and all ethanol was removed. Hexylthiooctanoate (163.28 grams, 0.669 moles) was added to the reaction, and the flask was placed under a vacuum of 140 mmHg and heated to 80°C. The reactor was set up for distillation, and the hexanethiol distillate was collected. The reaction mixture was then heated at 80°C and 140 mmHg pressure for 20 minutes, 120 mmHg pressure for 20 minutes, and 30 mmHg pressure for 20 minutes. The reaction temperature was increased to 100°C for 20 minutes at 120 mmHg pressure, 20 minutes at 50 mmHg pressure, and 20 minutes at 30 mmHg pressure. The reaction mixture was further heated at 120°C, 20 minutes at 50 mmHg pressure, 20 minutes at 40 mmHg pressure, and 20 minutes at 30 mmHg pressure. Hexanethiol (68.8 grams) was collected, indicating that the reaction was approximately 80% complete. The reaction mixture was heated at 120°C and 30 mmHg pressure for an additional 5 hours, collecting an additional 13.1 grams of distillate. The reaction mixture was then cooled to room temperature and placed under a nitrogen atmosphere. An aqueous solution of 10% monobasic sodium phosphate (12.6 grams) was added to neutralize the base catalyst. The neutralized mixture was then stripped to remove traces of water and residual hexanethiol at 55°C and 30 mmHg pressure for 1 hour and 100°C and 30 mmHg pressure for 3 hours. The stripped mixture was filtered using 1 micron media to provide 228.5 grams, a 93.8% yield, of 3-triethoxysilylpropylthiooctanoate as a clear liquid. GC analysis of the liquid indicated the product was 91% pure.

[0112] Example 5 Synthesis of hexylthiooctanoate using tetrachlorosilane moisture scavenger

[0113] Octanoic acid (213.7 grams, 1.48 moles), hexanethiol (175.2 grams, 1.48 moles), tetrachlorosilane (150.8 grams, 0.89 moles), and triflic acid (0.44 grams) were added to a reaction flask under a nitrogen blanket. The reaction mixture was stirred and heated between 90 and 105°C for approximately 4 hours. The mixture was cooled to room temperature. 10% aqueous sodium carbonate solution was added to neutralize unreacted octanoic acid and triflic acid catalyst. After standing for approximately 30 minutes, a solid precipitated at the bottom of the reaction flask. The organic and aqueous liquids were decanted into a separatory funnel and separated. The organic layer containing the product was vacuum stripped to remove all unreacted hexanethiol and traces of water. Hexylthiooctanoate (305.5 grams) was collected for an 84.6% yield.

[0114] Example 6 Synthesis of 3-triethoxysilylpropylthiooctanoate using a tubular reactor

[0115] The reactor was a vertical column packed with glass beads. At the top of the column was an addition funnel and a joint containing a short-path column equipped with a distillation head and an upper receiving flask. At the bottom of the column was a lower receiving flask. A mixture of 3-mercaptopropyltriethoxysilane, sodium 3-triethoxysilylpropylthiolate, and hexylthiooctanoate was added to the addition funnel. The mixture was prepared by mixing 3-mercaptopropyltriethoxysilane (118.2 grams, 0.496 moles) and sodium ethoxide (3.0 grams, 0.009 moles) in ethanol. The ethanol was removed under vacuum. Hexylthiooctanoate (118.1 grams, 0.484 moles) was added.

[0116] The packed column was heated and maintained at a temperature between 110°C and 125°C under approximately 70 mmHg pressure. The mixture in the addition funnel was slowly added to the heated packed column, allowing it to pass through the heated packed column, and the liquid was collected in the bottom receiving flask. All low-boiling components passed through the short column and were collected in the top receiving flask. After adding all of the mixture in the addition funnel to the packed column, the reaction mixture in the bottom receiving flask was transferred to the addition funnel, and the addition process was repeated. After two passes were completed, 40.0 grams of low-boiling liquid was collected in the top receiving flask. The low-boiling liquid was analyzed by gas chromatography. Analysis showed it to be 95% hexanethiol. Gas chromatography analysis of the liquid in the bottom flask revealed it to be a mixture of 64.5% 3-triethoxysilylpropylthiooctanoate, 12% 3-mercaptopropyltriethoxysilane, and 14% hexylthiooctanoate. The contents of the bottom receiving flask were transferred to an addition funnel and passed through the heated packed column three more times. After five passes through the heated packed column, the liquid in the bottom receiving flask was analyzed. The liquid was a mixture of 75.1% 3-triethoxysilylpropylthiooctanoate, 6.8% 3-mercaptopropyltriethoxysilane, and 8.9% hexylthiooctanoate.

[0117] The process of Example 6 can be converted to a continuous process by continuously adding fresh reagents to the addition funnel and removing a portion of the reaction mixture from the bottom receiving flask.

[0118] While the present disclosure has been described with reference to preferred embodiments, those skilled in the art will recognize that various changes can be made and equivalents substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the disclosure without departing from its essential scope. Therefore, it is not intended that the disclosure be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the disclosure, but rather that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims

1. (i) an alkoxysilyl-containing thiocarboxylic acid ester of general formula (I): R １ -[C(=O)-S-R ２ -SiR ３ ａ (OR ４ ) ３－ａ ] ｚ (I) Here, R １ is a monovalent radical selected from a linear alkyl group containing 1 to 18 carbon atoms, a branched alkyl group containing 3 to 18 carbon atoms, a cycloalkyl group containing 5 to 18 carbon atoms, an alkenyl group containing 2 to 18 carbon atoms, an aryl group containing 6 to 18 carbon atoms, an aralkyl group containing 7 to 18 carbon atoms, or hydrogen when z is 1, or is a divalent radical selected from an alkylene group containing 1 to 10 carbon atoms, a cycloalkylene group containing 5 to 10 carbon atoms, or phenylene when z is 2; Each R ２ are independently a divalent radical selected from a linear alkylene group containing 1 to 10 carbon atoms, a branched alkylene group containing 3 to 10 carbon atoms, a cycloalkylene group containing 5 to 10 carbon atoms, an alkenylene group containing 2 to 10 carbon atoms, an arylene group containing 6 to 10 carbon atoms, or an aralkylene group containing 7 to 10 carbon atoms; Each R ３ are independently a straight chain alkyl group containing 1 to 6 carbon atoms, a branched chain alkyl group containing 3 to 6 carbon atoms, a cycloalkyl group containing 5 or 6 carbon atoms, an alkenyl group containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, or an aralkyl group containing 7 to 10 carbon atoms; R ４ are independently a straight chain alkyl group containing 1 to 6 carbon atoms, a branched chain alkyl group containing 3 to 6 carbon atoms, a cycloalkyl group containing 5 or 6 carbon atoms, an alkenyl group containing 2 to 6 carbon atoms, an aryl group containing 6 carbon atoms, an aralkyl group containing 7 to 10 carbon atoms, a straight chain alkyl group containing 2 to 6 carbon atoms and a hydroxyl group, a group having the structure -R ２ -(OCH ２ CH ２ ) ｍ (OCH ２ CH (CH ３ )) ｎ OR １ or two R ４ A divalent group formed from two R ４ provided that, when the group is attached, a is 0 or 1, and (2) the sum of m+n is 1 to 20; a, m, n, and z are integers, where a is 0, 1, or 2, m is 0 to 10, n is 0 to 10, and z is 1 or 2; (ii) a thioester of general formula (II), R １ [C(]SR] ５ ] ｚ (II) where R １ is a monovalent radical selected from a linear alkyl group containing 1 to 18 carbon atoms, a branched alkyl group containing 3 to 18 carbon atoms, a cycloalkyl group containing 5 to 18 carbon atoms, an alkenyl group containing 2 to 18 carbon atoms, an aryl group containing 6 to 18 carbon atoms, an aralkyl group containing 7 to 18 carbon atoms, or hydrogen when z is 1, or is a divalent radical selected from an alkylene group containing 1 to 10 carbon atoms, a cycloalkylene group containing 5 to 10 carbon atoms, or phenylene when z is 2; Each R ５ are independently monovalent groups selected from linear alkyl groups containing 1 to 18 carbon atoms, branched alkyl groups containing 3 to 18 carbon atoms, cycloalkyl groups containing 5 to 18 carbon atoms, alkenyl groups containing 2 to 18 carbon atoms, aryl groups containing 6 to 18 carbon atoms, and aralkyl groups containing 7 to 18 carbon atoms, and wherein R １ and z is an integer, where z is 1 or 2, and (iii) mercapto-functional alkoxysilanes; 1. An alkoxysilyl-containing thiocarboxylic acid ester composition comprising:

2. 2. The alkoxysilyl-containing thiocarboxylic acid ester composition of claim 1, wherein the composition comprises 70 to 99.9 weight percent of the alkoxysilyl-containing thiocarboxylic acid ester (i) and 0.1 to 30 weight percent of the thioester (ii), based on the total weight of the alkoxysilyl-containing thiocarboxylic acid (i) and the thioester (ii).

3. 2. The alkoxysilyl-containing thiocarboxylic acid ester composition of claim 1, wherein the mercapto-functional alkoxysilane (iii) is 0.1 to 50 weight percent, based on the total weight of the alkoxysilyl-containing thiocarboxylic acid (i) and the thioester (ii).

4. A rubber composition comprising the alkoxysilyl-containing thiocarboxylic acid ester composition according to any one of claims 1 to 3.

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