Process for preparing silanol-functional organosilicon compounds

Abstract

A process for preparing a silanol-functional organosilicon compound from a silyl hydride and an oxidizing agent is provided. The oxidizing agent comprises peracetic acid.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Serial No. 63 / 461,105, filed April 21, 2023. U.S. Provisional Patent Application Serial No. 63 / 461,105 is hereby incorporated by reference. TECHNICAL FIELD

[0003] A method for preparing a silanol-functional organosilicon compound is provided. BACKGROUND

[0004] Silanol-functional organosilicon compounds can be used to produce a number of siloxane intermediates and formulations, such as room temperature vulcanizable (RTV) formulations. However, silanol-functional organosilicon compounds can be difficult to synthesize in a controlled manner without further condensation of the silanol (Si-OH) moieties into siloxane (Si-O-Si) moieties. Various methods for synthesizing silanol-functional organosilicon compounds have been proposed, however, the use of transition metal compounds as catalysts increases cost and process steps for removing the catalyst from the final reaction product. Silane hydrolysis with oxidizing agents, namely dioxymethylene, meta-chloroperoxybenzoic acid (mCPBA), and perbenzoic acid and potassium permanganate have been proposed, however some of these oxidizing agents can not be commercially available and these oxidizing agents can result in one or more drawbacks such as difficult to remove byproducts and / or unstable silanol-functional organosilicon products.

[0005] There is an industrial need to produce silanol-functional organosilicon compounds that minimize or eliminate one or more drawbacks associated with these oxidizing agents. SUMMARY

[0006] A method for preparing a silanol-functional organosilicon compound is provided. The method includes combining starting materials including a silyl hydride and peroxoacetic acid under conditions for effecting synthesis of Si-OH moieties. DETAILED DESCRIPTION

[0007] The method introduced above can include:

[0008] 1) combining starting materials including:

[0009] A) a silyl hydride,

[0010] optionally B) a solvent,

[0011] C) peroxoacetic acid,

[0012] optionally D) a neutralizing agent;

[0013] thereby forming a reaction mixture comprising a silanol-functional organosilicon compound.

[0014] A) silyl hydride

[0015] The starting material A) in the methods described herein is a silyl hydride. The silyl hydride can be A-1) a hydrosilane or A-2) an organohydrogensiloxane. The starting material A-1) a hydrosilane has the formula HSiR 1 3, wherein each R 1 is an independently selected monovalent organic group.

[0016] In the above formula, each R 1 is an independently selected monovalent organic group. Alternatively, each R 1 may be independently selected from the group consisting of alkyl groups of 1 to 18 carbon atoms, alkenyl groups of 2 to 18 carbon atoms, and aryl groups of 6 to 18 carbon atoms. Suitable alkyl groups include, but are not limited to, straight chain and branched alkyl groups such as methyl, ethyl, propyl (including n-propyl and isopropyl), butyl (including n-butyl, isobutyl, sec-butyl, and t-butyl), pentyl, hexyl, heptyl, octyl, decyl, dodecyl, undecyl, octadecyl (including straight chain and branched alkyl groups of 5 to 18 carbon atoms), and cycloalkyl groups (e.g., cyclopentyl and cyclohexyl). Suitable alkenyl groups include vinyl, allyl, and hexenyl. Suitable aryl groups include, but are not limited to, phenyl, tolyl, xylyl, naphthyl, benzyl, 1-phenylethyl, and 2-phenylethyl.

[0017] Alternatively, R 1 may comprise a halogenated hydrocarbon group or a hydrocarbon substituted with an oxygen atom. Suitable halogenated hydrocarbon groups for R 1 may be any of the monovalent hydrocarbon groups exemplified above in which at least one hydrogen atom bonded to a carbon atom has been formally replaced with a halogen atom such as bromine, chlorine, or fluorine; alternatively chlorine or fluorine, and alternatively chlorine. For example, the halogenated hydrocarbon group can be a fluoroalkyl group such as trifluoromethyl (CF3), fluoromethyl, trifluoroethyl, 2-fluoropropyl, 3,3,3-trifluoropropyl, 4,4,4-trifluorobutyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, 6,6,6,5,5,4,4,3,3-nonafluorohexyl, 8,8,8,7,7-pentafluorooctyl, 2,2-difluorocyclopropyl, 2,3-difluorocyclobutyl, 3,4-difluorocyclohexyl, and 3,4-difluoro-5-methylcycloheptyl; or a chloroalkyl group such as chloromethyl, 3-chloropropyl, 2,2-dichlorocyclopropyl, 2,3-dichlorocyclopentyl. Halogenated alkenyl groups include chloroallyl.

[0018] Alternatively, R 1The hydrocarbon group that is substituted with an oxygen atom can be a (meth)acrylate functional group, such as an (meth)acrylate alkyl group, such as propyl methacrylate, propyl acrylate, butyl methacrylate, or butyl acrylate, or an alkoxy group of the formula -OR, where R is an alkyl group or an aryl group, where R can be as described and exemplified above for R 1 The and exemplified alkyl group or aryl group. Alternatively, the alkoxy group can be, for example, methoxy, ethoxy, propoxy, or butoxy.

[0019] Examples of suitable silyl hydrides for starting material A) are exemplified by trimethylsilane of the formula HSiMe3, triethylsilane of the formula HiEt3, dimethylphenylsilane, diphenylmethylsilane, t-butyl(dimethyl)silane, tri(isopropyl)silane, triethoxysilane, diethylsilane, vinyl dimethylsilane, chloropropyldimethylsilane, and triphenylsilane. Alternatively, the silyl hydride can be selected from the group consisting of triethylsilane, dimethylphenylsilane, and triphenylsilane.

[0020] Alternatively, the silyl hydride compound can comprise A-2) an organohydrogensiloxane comprising two or more siloxane units selected from the group consisting of HR 1 2SiO 1 / 2 , R 1 3SiO 1 / 2 , HR 1 SiO 2 / 2 , R 1 2SiO 2 / 2 , R 1 SiO 3 / 2 , HSiO 3 / 2 , and SiO 4 / 2 units, with the proviso that at least one unit per molecule contains a silicon-bonded hydrogen atom. In the foregoing formula, each R 1 is a monovalent organic group as described and exemplified above. The organohydrogensiloxane can be linear, branched, cyclic, resinous, or a combination thereof. Alternatively, the organohydrogensiloxane can be linear or branched. Alternatively, the organohydrogensiloxane can be linear.

[0021] Starting material A-2) organohydrogensiloxane can have the unit formula (I): (R 1 3SiO 1 / 2 ) a (HR 1 2SiO 1 / 2 ) b (R 1 2SiO 2 / 2 ) c (HR 1 SiO 2 / 2 )d (R 1 SiO 3 / 2 ) e (HSiO 3 / 2 ) f (SiO 4 / 2 ) g (ZO 1 / 2 ) h wherein each R 1 is a monovalent organic group; each Z independently represents H or an alkyl group of 1 to 6 carbon atoms; subscripts a to g represent the average number of each siloxane unit per molecule, subscript h represents the number of hydrolyzable groups per molecule, and subscripts a to h have values such that: a > 0, b > 0, c > 0, d > 0, e > 0, f > 0, g > 0, h > 0, the quantity (b + d + f) > 1, and 2 < (a + b + c + d + e + f + g) < 10,000. In unit formula (I), R 1 is a monovalent organic group as described above for silanes. Alternatively, in unit formula (I), each R 1 may be an alkyl group or an aryl group as described above, independently selected.

[0022] Alternatively, the A-2) organohydrogensiloxane can be substantially straight chain or straight chain, for example when each of subscripts e, f, g, and h is 0. Alternatively, the starting material A-2) can comprise unit formula (II): (R 1 3SiO 1 / 2 ) a (HR 1 2SiO 1 / 2 ) b (R 1 2SiO 2 / 2 ) c (HR 1 SiO 2 / 2 ) d wherein R 1 , a, b, c, and d are as described above, the quantity (a + b) = 2, and the quantity (b + d) > 1. In formula (II), the quantity (c + d) can have a value of 0 to 200, alternatively 0 to 150, alternatively 0 to 100, alternatively 0 to 99, and alternatively 1 to 99. Alternatively, in formula (II), when d = 0, then b is 1 or 2. Alternatively, the quantity (b + d) can be 1 to 10, alternatively 1 to 9, alternatively 1 to 8, and alternatively 1 to 7.

[0023] Alternatively, the A-2) straight chain organohydrogensiloxane can be a (meth)acrylate functional organohydrogensiloxane, and can comprise formula (III): wherein each R 5independently selected from the group consisting of alkyl groups of 1 to 6 carbon atoms and aryl groups of 6 to 10 carbon atoms; each R 2 independently selected from the group consisting of alkyl groups of 1 to 6 carbon atoms and aryl groups of 6 to 10 carbon atoms; R 3 is an alkane-diyl group of 1 to 10 carbon atoms, R 4 is hydrogen or an alkyl group of 1 to 6 carbon atoms, and subscript j is 0 to 20, alternatively 0 or 1. Alternatively, the (meth)acrylate-functional organohydrogensiloxane can be such that each R 5 is a methyl group, each R 2 is a methyl group, R 3 is a methanediyl group, R 4 is a methyl group, and subscript j = 0. Examples include the formula 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate. (Meth)acrylate-functional organohydrogensiloxanes and methods of making the same are disclosed, for example, in EP 3387045 A by Eldred et al.

[0024] Alternatively, A-2) can be branched. For example, starting material A-2) can comprise unit formula (IV) or (V), wherein

[0025] unit formula (IV) is: (R 1 3SiO 1 / 2 ) a (HR 1 2SiO 1 / 2 ) b (R 1 2SiO 2 / 2 ) c (HR 1 SiO 2 / 2 ) d (R 1 SiO 3 / 2 ) e (HSiO 3 / 2 ) f , and

[0026] unit formula (V) is: (R 1 3SiO 1 / 2 ) a (HR 1 2SiO 1 / 2 ) b (R 1 2SiO 2 / 2 ) c (HR 1 SiO 2 / 2 ) d (SiO 4 / 2 ) g ,

[0027] wherein R 1 , a, b, c, d, e, f, and g are as described above.

[0028] Alternatively, in the above formulas (IV) and (V), each R 1 may be an alkyl group or an aryl group as described above for R. Alternatively, R 1 may be an alkyl group as described above for R. Examples of branched organohydrogensiloxanes are known in the art. For example, tris(trimethylsilyloxy)silane (Me3SiO 1 / 2 )3SiH is commercially available from Sigma-Aldrich, St. Louis, Missouri, USA.

[0029] Alternatively, A-2) can be an alkoxy-functional organohydrogensiloxane, which can be linear or branched. For example, the alkoxy-functional organohydrogensiloxane can have formula (VI): wherein each D 1 is an independently selected alkane-diyl group, each R 6 is an independently selected alkyl group, which can be as described above for the alkyl groups of R, subscript y is 1 or 2, and subscript x is 1, 2, or 3. Alternatively, x can be 2 or 3. Alternatively, x can be 3. Alternatively, subscript y can be 1. Alternatively, each R 6 may be a methyl group. The alkane-diyl groups D 1 may have an empirical formula of -C z H 2z - wherein subscript z is 2 to 6. Alternatively, n can be 2 to 4, alternatively 2 to 3. Alternatively, at least 90% of all instances of D 1 may be linear. For example, at least 90% of all instances of D 1 may be -CH2-CH2-.

[0030] Alternatively, in formula (VI), each R 6 may be a methyl group, and each D 1 may have an empirical formula of -C2H4-. Alternatively, formula (VI) can include 1,1,3,3,5,5-hexamethyl-1-(2-(trimethoxysilyl)ethyl)trisiloxane of formula ; formula 1,1,3,3-tetramethyl-1-(2-(trimethoxysilyl)ethyl)disiloxane; or a combination thereof. Alternatively, formula (VI) can include 1,1,3,3-tetramethyl-1-(1- (trimethoxysilyl)ethyl)disiloxane and 1,1,3,3-tetramethyl-1-(2- (trimethoxysilyl)ethyl)disiloxane.

[0031] Alternatively, the alkoxy-functional organohydrogensiloxane can have formula (VII):

[0032] where R 6 , D 1 and subscript x are as described above. Alternatively, formula (VII) can include formula 7-((dimethylsilyl)oxy)-3,3,11,11-tetramethoxy-4,5,5,7,9,9,10- heptamethyl-2,6,8,12-tetraoxa-3,5,7,9,11-pentasilatridecan-14- one, formula 8-((dimethylsilyl)oxy)-3,3,13,13-tetramethoxy-6,6,8,10,10- pentamethyl-2,7,9,14-tetraoxa-3,6,8,10,13-pentasilatridecan-15-one

[0033] or a mixture thereof. Alternatively, formula (VII) can include 8-((dimethylsilyl)oxy)-3,3,13,13-tetramethoxy-6,6,8,10,10-pentamethyl-2,7,9,14- tetraoxa-3,6,8,10,13-pentasilatridecan-15-one. Alkoxy-functional organohydrogensiloxanes are known in the art and can be prepared by known methods, such as those described in U.S. Patent Nos. 10,968,317 to Gohndrone et al.; 11,098,163 to Gohndrone et al.; 11,161,939 to Zhou et al.; 11,168,181 to Zhou et al.; and 11,492,448 to Gohndrone et al.; and JP2007077136 to Uehara et al.

[0034] Alternatively, the polyorganohydrogensiloxane for starting material A-2) is exemplified by:

[0035] a) dimethylhydrogensiloxy-terminated polydimethylsiloxane;

[0036] b) dimethylhydrogensiloxy-terminated poly(dimethyl / methylhydrogen) siloxane;

[0037] c) dimethylhydrogensiloxy-terminated polymethylhydrogen siloxane;

[0038] d) trimethylsiloxy-terminated poly(dimethylsiloxane / methylhydrogenosiloxane);

[0039] e) trimethylsiloxy-terminated polymethylhydrogenosiloxane;

[0040] f) 1,1,3,3,3-pentamethyldisiloxane;

[0041] g) 1,1,3,3-tetramethyldisiloxane;

[0042] h) 1,1,1,3,5,5,5-heptamethyltrisiloxane;

[0043] i) 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate;

[0044] j) 1,1,3,3-tetramethyl-1-(2-(trimethoxysilyl)ethyl)disiloxane;

[0045] k) tris(trimethylsiloxy)silane;

[0046] l) 8-((dimethylsilyl)oxy)-3,3,13,13-tetramethoxy-6,6,10,10-tetramethyl-8- propyl-2,7,9,14-tetraoxa-3,6,8,10,13-pentasilapentadecane;

[0047] m) a resin consisting essentially of H(CH3)2SiO 1 / 2 units and SiO 4 / 2 units; and

[0048] n) combinations of two or more thereof.

[0049] Polyorganohydrogensiloxanes are also commercially available, such as those available from Gelest, Inc., Morrisville, Pennsylvania, USA, for example, HMS-H271, HMS-071, HMS-993; MS-301 and HMS-301R, HMS-031, HMS-991, HMS-992, HMS-993, HMS-082, HMS-151, HMS-013, HMS-053, HAM-301 (octyl functional), HPM-502 (phenyl functional), and HMS-HM271. Other polyorganohydrogensiloxanes include DOWSIL TM 6-3570 Polymer, DOWSIL TM SH1107 Fluid, XIAMETER TM MHX-11007 Fluid, and XIAMETERTM OFS-5057 fluids, all of which are commercially available from Dow. Methods of preparing linear, branched, and cyclic organohydrogensiloxanes, such as the hydrolysis and condensation of organohalosilanes, are well known in the art, see, for example, U.S. Patent Nos. 3,957,713 to Jeram et al. and 4,329,273 to Hardman et al. Methods of preparing organohydrogenpolysiloxane resins suitable for use herein are exemplified, for example, in U.S. Patent Nos. 5,310,843; 4,370,358; and 4,707,531. U.S. Patent No. 2,823,218 to Speier et al. discloses organohydrogensiloxane oligomers and linear polymers, such as 1,1,3,3-tetramethyldisiloxane; 1,1,1,3,3-pentamethyldisiloxane; 1,1,1,3,5,5,5-heptamethyltrisiloxane; bis-trimethylsiloxy terminated polymethylhydrogenosiloxane homopolymer; bis-trimethylsiloxy terminated poly(dimethyl / methylhydrogen)siloxane copolymer; and cyclic polymethylhydrogenosiloxane.

[0050] The amount of starting material A) depends on various factors, including the process conditions selected and the content of silicon-bonded hydrogen atoms. However, the amount of starting material A) and C) used can be sufficient to provide C) peroxyacetic acid in an amount of 1 to 2 molar equivalents relative to the silicon-bonded hydrogen content of A).

[0051] B) solvent

[0052] Starting material B) is an optional solvent that can be used in the process described herein to aid in mixing starting materials A) and C). For example, A) silyl hydride can be dissolved in B) solvent prior to combining A) silyl hydride and C) peroxyacetic acid. Solvents that can be used herein are those that aid in fluidizing starting materials A) and C) but do not substantially react with these starting materials. The solvent can be selected based on the solubility of starting materials A) and C) and the volatility of the solvent. Solubility refers to the solvent being sufficient to dissolve and / or disperse the starting materials. Volatility refers to the vapor pressure of the solvent. For example, if the solvent is not volatile enough (too low vapor pressure), it can be difficult to remove the solvent after step 1).

[0053] Suitable solvents include polyorganosiloxanes having a suitable vapor pressure, such as hexamethyldisiloxane, octamethyltrisiloxane, hexamethylcyclotrisiloxane, and other low molecular weight polyorganosiloxanes, such as DOWSIL TM 200 fluids and DOWSIL TM OS fluids.

[0054] Alternatively, the solvent can include an organic solvent. The organic solvent can be an alcohol such as methanol, ethanol, isopropanol, butanol, or n-propanol; a ketone such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; an aromatic hydrocarbon such as benzene, toluene, ethylbenzene, or xylene; an aliphatic hydrocarbon such as heptane, hexane, or octane; a glycol ether such as propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether, or ethylene glycol n-butyl ether; a halogenated hydrocarbon such as dichloromethane, 1,1,1-trichloroethane, or dichloromethane; chloroform; dimethyl sulfoxide; dimethylformamide, acetonitrile; tetrahydrofuran; petroleum solvent; mineral spirits; naphtha; N-methylpyrrolidone; or a combination thereof.

[0055] The amount of solvent will depend on various factors, including the type of solvent selected and the amount and type of other starting materials selected for use in the process. However, the amount of solvent can range from 1% to 99%, alternatively 2% to 90%, based on the weight of all starting materials used in step 1) of the process described herein. The solvent can be added during the preparation of the reaction mixture, for example, to aid in mixing and delivery. All or a portion of the solvent can optionally be removed after step 1).

[0056] C) peroxyacetic acid

[0057] The starting material C) used in the process described herein comprises peroxyacetic acid, which has the formula: Without wishing to be bound by theory, it is believed that the peroxyacetic acid acts as an oxidizing agent, thereby forming a silanol (Si-OH) moiety from the Si-H moiety of starting material A) in step 1) of the process described herein. Peroxyacetic acid (peracetic acid) is known in the art and is commercially available. For example, a solution of peracetic acid (32% peracetic acid by weight in dilute acetic acid) is commercially available from Sigma-Aldrich. Without wishing to be bound by theory, it is believed that peroxyacetic acid is prepared by condensing hydrogen peroxide with acetic acid in aqueous solution, and thus the peroxyacetic acid useful herein can further comprise residual hydrogen peroxide and / or acetic acid, which has the formula

[0058] D) neutralizing agent

[0059] Starting material D) is an optional neutralizing agent that can be used in the process described herein. Without wishing to be bound by theory, it is believed that peroxyacetic acid contains residual inorganic acid (e.g., in commercially available peroxyacetic acid, pH < 1). A neutralizing agent can be added to prevent or minimize undesirable condensation. For example, a mild basic neutralizing agent can be added in an amount sufficient to provide a pH of 3 to 4 for the C) peroxyacetic acid, where condensation is relatively slow. The starting material D) neutralizing agent can be added with other starting materials in step 1), or the starting material comprising C) peroxyacetic acid can be combined with the D) neutralizing agent prior to being combined with the starting material A) silyl hydride in step 1). Suitable neutralizing agents include sodium carbonate, sodium bicarbonate, calcium carbonate CaO3, and potassium carbonate, all of which are commercially available, e.g., from Sigma-Aldrich.

[0060] Step 1) of the process comprises combining the starting materials described above under conditions to effect synthesis of Si-OH moieties. The starting materials can be combined by any convenient means, such as mixing, in any convenient equipment, such as a batch reactor optionally having a stirrer, and heating and cooling provisions. Step 1) of the process can be conducted at an elevated temperature, e.g., > RT to < 110 °C (boiling point of peroxyacetic acid), alternatively 50 °C to 75 °C.

[0061] The process described herein can also optionally include one or more additional steps. For example, an additional step can include:

[0062] 2) drying the reaction mixture comprising silanol-functional organosilicon compounds, and / or

[0063] 3) isolating the silanol-functional organosilicon compounds. The drying in step 2) can be conducted by any convenient means. For example, a drying agent, such as a commercially available adsorbent, can be combined with the reaction mixture. An example of a suitable adsorbent can be an inorganic particulate. The adsorbent can have a particle size of 10 microns or less, alternatively 5 microns or less. The adsorbent can have an average pore size sufficient to adsorb water and alcohols, e.g., (Angstroms) or less, alternatively or less, and alternatively or less. Examples of adsorbents include zeolites, such as chabazite, mordenite, and offretite; molecular sieves, such as alkali metal aluminosilicates, silica gel, silica-magnesia gel, activated carbon, activated alumina, calcium oxide, and combinations thereof. In step 3), the silanol-functional organosilicon compounds can be isolated by any convenient means, e.g., filtration (e.g., to remove the drying agent from step 2), stripping, and / or distillation, optionally under heating and / or reduced pressure. The resulting product is a silanol-functional organosilicon compound derived from the starting material A) silyl hydride, wherein at least one silicon-bonded hydrogen from the silyl hydride has been converted to a silanol moiety.

[0064] Examples

[0065] These examples are intended to illustrate the application to one of ordinary skill in the art and should not be construed as limiting the application set forth in the claims. The starting materials used herein are described in Table 1.

[0066] Table 1 - Starting materials

[0067]

[0068]

[0069] In this reference example 1, peracetic acid solution (32 wt% in dilute acetic acid) was obtained from Sigma Aldrich and was immediately neutralized to pH ~ 3.5 with 60 mg NaHC03per mL of peracetic acid solution added, unless otherwise noted, prior to use.

[0070] In this working example 1 (IE1): In a 3 neck 250 mL round bottom flask, 35 g of polysiloxane 1 was dissolved in 35 mL of toluene. The solution was heated to 50 °C under a nitrogen purge. Peracetic acid solution was added and the mixture was stirred vigorously for 1 hour. IR was checked and conversion was almost complete, an additional 1 mL of peracetic acid solution was added and stirring was continued for 30 minutes. The reaction was stirred for an additional 30 minutes. -SiH remained unchanged, so the mixture was washed twice with 100 mL of water, once with brine, then dried over sodium sulfate and filtered (all with the aid of an additional 100 mL of toluene). The resulting solution was stripped in a rotary evaporator at up to 50 °C for 90 minutes, then placed under high vacuum for 15 minutes prior to analysis.

[0071] In this working example 2 (IE2): In a 3 neck 250 mL round bottom flask, 35 g of polymer 1 was dissolved in 35 mL of toluene. The solution was heated to 50 °C under a nitrogen purge. Peracetic acid solution was added and the mixture was stirred vigorously for 1 hour. IR was checked and conversion was almost complete, an additional 1 mL of peracetic acid solution was added and stirring was continued for 30 minutes. The reaction was stirred for an additional 30 minutes. SiH remained unchanged, so the mixture was washed twice with 100 mL of water, once with brine, then dried over sodium sulfate and filtered (all with the aid of an additional 100 mL of toluene). The resulting solution was stripped in a rotary evaporator at up to 50 °C for 90 minutes, then placed under high vacuum for 15 minutes prior to analysis.

[0072] In this reference example 2, working examples 3-20 (IE3 to IE20) and comparative examples 1-2 (CE1 to CE2) were prepared as follows: Hydrogensilane and TES were prepared as solutions in toluene with known mass concentrations. The target in Table 2 below was a typical hydrogen silane concentration of about 0.2 M and a TES concentration of about 0.15 M, unless otherwise specified. To calculate conversion by the TES standard, a portion of the solution was analyzed by Si NMR as the 0 minute sample. 1 mL of the solution was transferred to a 2 dram glass vial with a stir bar, then a portion of the neutralized peracetic acid solution prepared as described above in reference example 1 was added by volume. A nitrogen line was inserted through the septum cap, and the solution was placed in an aluminum heating block and stirred vigorously for the specified time at the specified temperature. The reaction was stopped by washing the organic layer with deionized water, then dried over sodium sulfate to obtain a product solution for analysis. 1 H and 29 A portion of this solution was analyzed by Si NMR as the 0 minute sample. 1 mL of the solution was transferred to a 2 dram glass vial with a stir bar, then a portion of the neutralized peracetic acid solution prepared as described above in reference example 1 was added by volume. A nitrogen line was inserted through the septum cap, and the solution was placed in an aluminum heating block and stirred vigorously for the specified time at the specified temperature. The reaction was stopped by washing the organic layer with deionized water, then dried over sodium sulfate to obtain a product solution for analysis.

[0073] In this comparative example 3 (CE3), (35 g of polysiloxane 1 was dissolved in 35 mL of toluene in a 3 neck 250 mL round bottom flask. The solution was heated to 50 °C under a nitrogen purge. 1.25 equivalents of mCPBA were added and the mixture was stirred vigorously for 1.5 hours. The resulting yellow slurry was cooled. A portion of the yellow slurry was filtered through a 0.45 micron PTFE filter, however this resulted in a suspension that was still milky white. The suspension was then washed twice with 100 mL of water, once with brine, then dried over sodium sulfate and filtered (all with the aid of an additional 100 mL of toluene). The resulting solution was stripped with a rotary evaporator at up to 50 °C for 90 minutes, then placed under high vacuum for 15 minutes prior to analysis. Conversion was complete (>95%), however the recovered material was a white slurry that could not be easily filtered. The siloxane oil itself appeared distinctly yellow. According to the NMR analysis, the concentration of chlorobenzoic acid was 4% by weight. 1 H NMR, concentration of chlorobenzoic acid was 4% by weight.

[0074] Table 2: Reaction conditions

[0075]

[0076]

[0077] Table 3 - Silanol functional polyorganosiloxanes formed

[0078]

[0079] Industrial applicability

[0080] It has been discovered that aqueous solutions of peroxoacetic acid are stoichiometric oxidants for the synthesis of silanol (Si-OH) functional organosilicon compounds from silyl hydride (Si-H functional) that have one or more of the following characteristics:

[0081] • high conversion in short reaction times

[0082] • works in non-polar solvents such as toluene

[0083] • commercially available and inexpensive

[0084] • degradable to relatively mild and volatile (strippable) byproducts - hydrogen peroxide and acetic acid

[0085] • can be considered broadly “green” for water treatment and disinfection

[0086] • can be used as a “finishing” agent to remove residual / reactive SiH from materials.

[0087] Without wishing to be bound by theory, it is believed that because peroxoacetic acid is generally considered to be a milder oxidant than other oxidants that produce poorer reaction efficiency (such as tBuOOH and H2O2 described above in Comparative Examples CE1 and CE2), the inventors surprisingly found that peroxoacetic acid is effective for reactions to form Si-OH moieties from Si-H moieties and that peroxoacetic acid is effective to produce a variety of silanol functional organosilicon compounds (e.g., silanes and polyorganosiloxanes with different silicon-bonded organic groups, number and structure of siloxane units per molecule). In addition, peroxoacetic acid provides the additional benefit of avoiding yellowing of the produced silanol functional organosilicon compounds (compared to mCPBA used in Comparative Example CE3).

[0088] Test methods

[0089] In this application, NMR was performed as follows:

[0090] The crude solution was mixed with a 40 mM solution of Cr(acac)3in CDC13 at a 60:40 v / v ratio (solvent to sample). The 1 H and 29 Si were obtained using a standard of D1 = 13 s. 29 Si NMR. Conversion and yield were determined by peak integration normalized to the internal standard of tetraethylsilane (TES) by 29 Si NMR. Conversion (%) was defined by the percent disappearance of hydrosilane and yield (%) was defined by the percent formation of silanol relative to theoretical yield. All peaks were referenced to the TES peak (δ = 7.10 ppm).

[0091] In the present application, GPC was performed as follows:

[0092] GPC samples were prepared as 2 mg / mL samples in toluene and run on an Agilent 1260 GPC with mixed-D columns and a refractive index detector. Samples were run with toluene eluent at a flow rate of 1.00 mL / min at a temperature of 35 °C. MW and MWD were determined by a standard calibration against polystyrene standards.

[0093] Definitions and use of terms

[0094] The amounts of all starting materials in the compositions total 100% by weight. The summary and abstract are incorporated by reference. The articles “a,” “an,” and “the” each refer to one or more items unless otherwise indicated by the context. Plural includes the singular unless otherwise indicated by the context. Each embodiment or alternative presented herein can be combined with any other embodiment or alternative. The terms “comprising,” “having,” and “including” and conjugations thereof are used herein in their broadest sense to mean and encompass the concepts of “including,” “including but not limited to,” and “including at least the following items, with congregations thereof.” The use of “for example,” “e.g.,” “such as,” and “including” to list illustrative examples does not limit to only the listed examples. Thus, “for example” or “such as” means “for example, but not limited to” or “such as, but not limited to” and encompasses other similar or equivalent examples.

[0095] It is to be understood that the appended claims are not limited to specific exemplary and particular compounds, compositions or methods described in the specific embodiments, which can vary in specific embodiments falling within the scope of the appended claims. With respect to any Markush groups recited herein, each member of the group can be used individually and / or in combination with other members of the group to provide specific embodiments falling within the scope of the appended claims. Each member of the Markush group can be used individually and / or in combination with other members of the group and provide sufficient support for specific embodiments falling within the scope of the appended claims.

[0096] Abbreviations used in the present application are defined in Table 4 below.

[0097] Table 4 - Abbreviations

[0098] Abbreviations Definitions acac acetylacetonate ℃ degrees Celsius D diorganosiloxy units of the formula (Me2SiO 2 / 2 ) and bifunctional dimethylsiloxy units of the formula (Me2SiO D' bisfunctional methylhydrogensiloxy units of the formula (HMeSiO 2 / 2 )]]> <![CDATA[D OH ]]> bis-silanol functional siloxy units of the formula [(HO)(Me)SiO 2 / 2 ] of the formula [(HO)(Me)SiO Et ethyl GPC gel permeation chromatography M monofunctional trimethylsiloxy units of the formula (Me3SiO 1 / 2 )]]> M' monofunctional dimethylhydrogensiloxy units of the formula (HMe2SiO 1 / 2 )]]> M OH ]]> monofunctional dimethyl / silanol functional siloxy units of the formula [(HO)(Me)2SiO1 / 2 ] monofunctional dimethyl / silanol functional siloxy units of the formula [(HO)(Me)2SiO1 Me methyl MHz megahertz min minute mL milliliter mM millimole Mn number average molecular weight MW or Mw weight average molecular weight MWD molecular weight distribution, defined as Mw / Mn NMR nuclear magnetic resonance s sec T trifunctional methylsiloxy units of the formula (MeSiO 3 / 2 )]]> T' trifunctional hydrosiloxy units of the formula (HSiO 3 / 2 )]]> [CAT OH ]]> of the formula HOSiO 3 / 2 trifunctional silanol functional units of the formula HOSiO v / v volume / volume

[0099] Embodiments of the invention

[0100] In a first embodiment, a method for preparing a silanol-functional organosilicon compound comprises:

[0101] 1) mixing and heating at temperatures up to 110 °C starting materials comprising:

[0102] A) a silyl hydride,

[0103] B) a solvent,

[0104] C) peroxyacetic acid,

[0105] optionally D) a neutralizing agent;

[0106] to thereby form a reaction mixture comprising a silanol-functional organosilicon compound.

[0107] In a second embodiment, in the method of the first embodiment, the silyl hydride comprises a hydrosilane of the formula HSiR3, wherein each R is independently selected from the group consisting of an alkyl group of 1 to 18 carbon atoms and an aryl group of 6 to 18 carbon atoms.

[0108] In a third embodiment, in the method of the second embodiment, the hydrosilane is selected from the group consisting of triethylsilane, dimethylphenylsilane, and triphenylsilane.

[0109] In a fourth embodiment, in the method of the first embodiment, the silyl hydride comprises an organohydrogensiloxane.

[0110] In a fifth embodiment, in the method of the fourth embodiment, the organohydrogensiloxane is linear and comprises units of the formula (R 1 3SiO 1 / 2 ) a (HR 1 2SiO 1 / 2 ) b (R 1 2SiO 2 / 2 ) c (HR 1 SiO 2 / 2 ) d wherein each R 1 is an independently selected monovalent organic group, a > 0, b > 0, c > 0, d > 0, the amount (a+b) = 2, the amount (b+d) > 1, and 2 < (a+b+c+d) < 10,000.

[0111] In a sixth embodiment, in the method of the fifth embodiment, the organohydrogensiloxane is selected from the group consisting of: bis-trimethylsiloxy terminated poly(dimethyl / methylhydrogen)siloxane; 1,1,3,3,3-pentamethyldisiloxane; 1,1,3,3-tetramethyldisiloxane; 1,1,1,3,5,5,5-heptamethyltrisiloxane; 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate; and 1,1,3,3-tetramethyl-1-(2-(trimethoxysilyl)ethyl)disiloxane.

[0112] In a seventh embodiment, in the method of the fourth embodiment, the organohydrogensiloxane is branched.

[0113] In an eighth embodiment, in the method of the seventh embodiment, the branched organohydrogensiloxane is selected from the group consisting of: tris(trimethylsiloxy)silane and 8-((dimethylsilyl)oxy)-3,3,13,13-tetramethoxy-6,6,10,10-tetramethyl-8-propyl-2,7,9,14-tetraoxa-3,6,8,10,13-pentasilapentadecane.

[0114] In a ninth embodiment, in the method of any one of the first through eighth embodiments, B) the solvent comprises toluene.

[0115] In a tenth embodiment, in the method of the ninth embodiment, prior to mixing and heating in step 1), A) the silyl hydride is dissolved in B) the solvent.

[0116] In an eleventh embodiment, in the method of any one of the first through tenth embodiments, wherein D) the neutralizing agent is present.

[0117] In a twelfth embodiment, in the method of the eleventh embodiment, wherein C) the peroxoacetic acid is combined with D) the neutralizing agent to form a solution having a pH of 3 to 4 prior to mixing and heating in step 1).

[0118] In a thirteenth embodiment, in the method of the twelfth embodiment, D) the neutralizing agent is selected from the group consisting of: sodium carbonate, sodium bicarbonate, calcium carbonate CaO3, and potassium carbonate.

[0119] In a fourteenth embodiment, in the method of any one of the first through thirteenth embodiments, C) the peroxoacetic acid is used in an amount of 1 to 2 molar equivalents of peroxoacetic acid based on the silicon-bonded hydrogen content of A) the silyl hydride.

Claims

1. A method for preparing a silanol functional organosilicon compound, wherein the method comprises: 1) combining starting materials comprising: A) a silyl hydride, optionally B) a solvent, C) peroxoacetic acid, optionally D) a neutralizing agent; under conditions to effect synthesis of Si-OH moieties; 2. The method of claim 1, wherein the silyl hydride comprises a hydrosilane of the formula HSiR 1 3, wherein each R 1 is an independently selected monovalent organic group.

3. The method of claim 2, wherein each R 1 is independently selected from the group consisting of an alkyl group of 1 to 18 carbon atoms and an aryl group of 6 to 18 carbon atoms. thereby forming a reaction mixture comprising the silanol functional organosilicon compound.

5. The method of claim 1, wherein the silyl hydride comprises an organohydrogensiloxane of the following unit formula: (R 1 3SiO 1 / 2 ) a (HR 1 2SiO 1 / 2 ) b (R 1 2SiO 2 / 2 ) c (HR 1 SiO 2 / 2 ) d (R 1 SiO 3 / 2 ) e (HSiO 3 / 2 ) f (SiO 4 / 2 ) g (ZO 1 / 2 ) h where each R 1 is a monovalent organic group; each Z independently represents H or an alkyl group of 1 to 6 carbon atoms; subscripts a to g represent the average number of each siloxane unit per molecule, subscript h represents the number of hydrolyzable groups per molecule, and subscripts a to h have values such that: a > 0, b > 0, c > 0, d > 0, e > 0, f > 0, g > 0, h > 0, the quantity (b + d + f) > 1, and 2 < (a + b + c + d + e + f + g) < 10,000.

6. The method of claim 5, wherein the organohydrogensiloxane is linear or substantially linear and comprises the unit formula (R 1 3SiO 1 / 2 ) a (HR 1 2SiO 1 / 2 ) b (R 1 2SiO 2 / 2 ) c (HR 1 SiO 2 / 2 ) d wherein R 1 , a, b, c, and d are as described above, the amount (a+b) = 2, and the amount (b+d) > 1.

4. The method of claim 3, wherein the hydrosilane is selected from the group consisting of triethylsilane, dimethylphenylsilane, and triphenylsilane.

7. The method of claim 6, wherein the organohydrogensiloxane is selected from the group consisting of bis-trimethylsiloxy terminated poly(dimethyl / methylhydrogen)siloxane; 1,1,3,3,3-pentamethyldisiloxane; 1,1,3,3-tetramethyldisiloxane; 1,1,1,3,5,5,5-heptamethyltrisiloxane; 3-(1,1,3,3-tetramethyldisiloxanyl)propyl methacrylate; and 1,1,3,3-tetramethyl-1-(2-(trimethoxysilyl)ethyl)disiloxane.

8. The method of claim 5, wherein the organohydrogensiloxane is branched.

9. The method of claim 8, wherein the branched organohydrogensiloxane is selected from the group consisting of tris(trimethylsiloxy)silane and 8-((dimethylsilyl)oxy)-3,3,13,13-tetramethoxy-6,6,10,10-tetramethyl-8-propyl-2,7,9,14-tetraoxa-3,6,8,10,13-pentasilapentadecane.

10. The method of any one of claims 1 to 9, wherein the solvent B) is present.

11. The method of claim 10, wherein the silyl hydride A) is dissolved in the solvent B) prior to combining the peroxoacetic acid C) with the silyl hydride A).

12. The method of any one of claims 1 to 11, wherein the method further comprises heating the reaction mixture at a temperature of 50 °C to 75 °C.

13. The method of any one of claims 1 to 12, further comprising one or more additional steps, wherein the additional steps comprise: 2) drying the reaction mixture comprising the silanol functional organosilicon compound, and 3) isolating the silanol functional organosilicon compound.

14. The method of any one of claims 1 to 13, wherein the neutralizing agent D) is present.

15. The method of any one of claims 1 to 14, wherein the peroxoacetic acid C) is used in an amount of 1 to 2 molar equivalents of peroxoacetic acid, based on the silicon-bonded hydrogen content of the silyl hydride A).

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