Method for producing acyloxysilanes

Abstract

To provide a method for efficiently producing an acyloxysilane.SOLUTION: A method for producing an acyloxysilane includes a reaction step for reacting an alkoxysilane with a carboxylic acid anhydride in the presence of a catalyst and an additive, the catalyst being a solid acid catalyst and the additive being carboxylic acid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an efficient method for producing acyloxysilanes and the like. [Background technology]

[0002] Acyloxysilanes are functional chemicals that are used as reagents for the precision synthesis of pharmaceuticals, agricultural chemicals, electronic materials, etc., as well as synthetic intermediates for these materials. They are also used as raw materials for surface modifiers, sol-gel materials, nanomaterials, and organic-inorganic hybrid materials. Known methods for producing acyloxysilanes using carboxylic acid anhydrides include, for example, (A) a method of reacting a chlorosilane with a carboxylic acid anhydride (Patent Document 1), (B) a method of reacting a silanol with a carboxylic acid anhydride (Non-Patent Document 1), (C) a method of reacting an alkoxysilane with a carboxylic acid anhydride (Non-Patent Document 2), and (D) a method of reacting an alkoxysilane with a carboxylic acid anhydride in the presence of an acid catalyst such as a solid acid or a Lewis acid (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] German Patent No. 882401 [Patent Document 2] International Publication No. 2016 / 143835 [Non-patent literature]

[0004] [Non-Patent Document 1] J. Am. Chem. Soc. 1946, 68, 11, 2282-2284 [Non-patent document 2] J. Org. Chem. 1940, 05, 4, 443-448 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the methods using chlorosilanes have the following problems: (1) the raw material is difficult to handle because chlorosilanes generate corrosive hydrogen chloride upon hydrolysis (Method A), and (2) the reaction with carboxylic anhydrides produces by-product acyl chlorides that are easily hydrolyzed and generate corrosive hydrogen chloride (Method A).Furthermore, the method using silanols (Method B) has the problem that silicon compounds are not necessarily easy to obtain or are expensive. On the other hand, the method using alkoxysilanes (Method C) has problems such as the need to heat the mixture of raw materials at a high reflux temperature for a long time. Furthermore, the method of reacting alkoxysilanes with carboxylic acid anhydrides in the presence of an acid catalyst (Method D) has problems such as a tendency for activity to decrease due to catalyst deterioration when a solid acid catalyst is used as the acid catalyst. Therefore, an industrially more advantageous method is desired.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for more efficiently producing acyloxysilanes. [Means for solving the problem]

[0007] As a result of extensive research aimed at solving the above problems, the present inventors discovered that the use of a carboxylic acid as an additive in the reaction of alkoxysilanes with a carboxylic acid anhydride in the presence of a solid acid catalyst suppresses catalyst deterioration and efficiently produces acyloxysilanes, leading to the completion of the present invention. The manufacturing method of the present invention has the following features. (1) Raw materials, catalysts, and additives are readily available, easy to handle, and highly safe. (2) Because the reaction system uses a solid catalyst, the catalyst can be easily separated and recovered. (3) Since acyl chloride is not produced as a by-product, corrosion of the reaction vessel, etc. can be suppressed. The manufacturing method of the present invention enables low-cost and highly efficient manufacturing processes, and is believed to have significant advantages over conventional techniques in terms of economy, environmental impact, etc.

[0008] That is, this application provides the following inventions. <1> The method includes a reaction step of reacting an alkoxysilane with a carboxylic acid anhydride in the presence of a catalyst and an additive, A method for producing acyloxysilanes, wherein the catalyst is a solid acid catalyst and the additive is a carboxylic acid. <2> The alkoxysilane is represented by the following general formula (I), the carboxylic acid anhydride is represented by the following general formula (II), and the acyloxysilane is represented by the following general formula (III): <1> 1. A method for producing acyloxysilanes according to claim 1. R 1 p R 2 q R 3 r Si(OR 4 ) 4-(p+q+r) (I) (In the formula, p, q, and r are each independently an integer of 0 to 3; p+q+r is an integer of 0 to 3; R 1 , R 2 , and R 3 are each independently a hydrocarbon group having 1 to 24 carbon atoms or a hydrogen atom, and some or all of the hydrogen atoms bonded to carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction; R 4 are each independently an alkyl group having 1 to 6 carbon atoms. (R 5 CO)2O (II) (In the formula, R 5 is a hydrocarbon group having 1 to 24 carbon atoms, and some or all of the hydrogen atoms bonded to carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction. R 1 p R 2 q R 3 r Si(OR 4 ) 4-(p+q+r+s) (OCOR 5 ) s (III) (In the formula, p, q, r, R 1 , R 2 , R 3 , R 4 , and R 5 are as defined above; and s is an integer of 1 or more and 4-(p+q+r) or less. <3> The carboxylic acid is represented by general formula (IV): <1> or <2> 1. A method for producing acyloxysilanes according to claim 1. R 6 CO2H(IV) (In the formula, R 6 is a hydrocarbon group having 1 to 3 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction. <4> the solid acid catalyst is an organic solid acid and / or an inorganic solid acid; <1> ~ <3> 10. A method for producing an acyloxysilane according to any one of the above. <5> the organic solid acid is a solid acid having a sulfo group and / or a carboxy group; <4> 1. A method for producing acyloxysilanes according to claim 1. <6> The inorganic solid acid is an inorganic solid acid having regular pores and / or a layered structure. <4> 1. A method for producing acyloxysilanes according to claim 1. <7> The inorganic solid acid is zeolite and / or montmorillonite. <4> 1. A method for producing acyloxysilanes according to claim 1. <8> The reaction step is carried out using a flow reaction system. <1> ~ <7> 10. A method for producing an acyloxysilane according to any one of the above. [Effects of the Invention]

[0009] According to the present invention, acyloxysilanes can be produced more efficiently than by conventional methods. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. Unless otherwise specified, when a symbol in a formula in this specification is used in other formulas, the same symbol has the same meaning. A method for producing acyloxysilanes according to one embodiment of the present invention includes a reaction step of reacting alkoxysilanes with a carboxylic acid anhydride in the presence of a catalyst and an additive, wherein the catalyst is a solid acid catalyst and the additive is a carboxylic acid. Note that, in this specification, the term "additive" refers to a substance intentionally added to the reaction system in the reaction step, and does not refer to a by-product of the reaction (e.g., a carboxylic acid produced as a by-product in Scheme 6).

[0011] In this embodiment, the alkoxysilanes used as raw materials are represented by the following general formula (I), for example. R 1 p R 2 q R 3 r Si(OR 4 ) 4-(p+q+r) (I) In general formula (I), p, q, and r are each independently an integer of 0 to 3; p+q+r is an integer of 0 to 3. 1 , R 2 , and R 3 R are each independently a hydrocarbon group having 1 to 24 carbon atoms or a hydrogen atom, and some or all of the hydrogen atoms bonded to carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction. 4 are each independently an alkyl group having 1 to 6 carbon atoms. In this specification, "not involved in the reaction" means that it does not directly participate in the target reaction as a reactant and does not inhibit the reaction.

[0012] R 1 , R 2 , and R 3 Examples of the hydrocarbon group represented by the formula include an alkyl group, an aryl group, an aralkyl group, and an alkenyl group. When the hydrocarbon group is an alkyl group, the number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 18, even more preferably 1 to 10, and particularly preferably 1 to 4. Some or all of the hydrogen atoms bonded to the carbon atoms of the alkyl group may be substituted with groups that do not participate in the reaction.

[0013] Examples of groups that do not participate in the reaction include alkoxy groups having 1 to 6 carbon atoms, alkoxycarbonyl groups having 1 to 6 carbon atoms, dialkylamino groups having 1 to 6 carbon atoms, cyano groups, nitro groups, halogen atoms, etc. More specifically, alkoxy groups, alkoxycarbonyl groups, dialkylamino groups, and halogen atoms include methoxy, ethoxy, and hexoxy groups as specific examples of alkoxy groups having 1 to 6 carbon atoms; methoxycarbonyl and propoxycarbonyl groups as specific examples of dialkylamino groups having 1 to 6 carbon atoms; dimethylamino and diethylamino groups as specific examples of halogen atoms; and fluorine, chlorine, and bromine atoms.

[0014] Specific examples of the alkyl group which may be substituted with a group which does not participate in the reaction include a methyl group, an ethyl group, a propyl group, a butyl group, a sec-butyl group, a pentyl group, a hexyl group, a cyclohexyl group, an octyl group, a decyl group, a 2-methoxyethyl group, a 3-ethoxypropyl group, a 2-methoxycarbonylethyl group, a 2-dimethylaminoethyl group, a 2-cyanoethyl group, a trifluoromethyl group, and a 3-chloropropyl group.

[0015] When the hydrocarbon group is an aryl group, a monovalent aromatic organic group of a hydrocarbon ring system or a heterocyclic ring system can be used as the aryl group. When the aryl group is a monovalent aromatic organic group of a hydrocarbon ring system, the number of carbon atoms is preferably 6 to 22, more preferably 6 to 14, and even more preferably 6 to 10. Specific examples of monovalent aromatic organic groups of a hydrocarbon ring system include phenanthroline, ... Examples of the aryl group include an aryl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a perylenyl group, and a pentacenyl group. When the aryl group is a heterocyclic monovalent aromatic organic group, the heteroatom in the heterocycle is a sulfur atom, an oxygen atom, or the like. The number of carbon atoms in the heterocyclic monovalent aromatic organic group is preferably 4 to 12, and more preferably 4 to 8. Specific examples of the heterocyclic monovalent aromatic organic group include a thienyl group, a benzothienyl group, a dibenzothienyl group, a furyl group, a benzofuryl group, and a dibenzofuryl group. Some or all of the hydrogen atoms bonded to the carbon atoms of the aryl group may be substituted with groups that do not participate in the reaction. Examples of groups that do not participate in the reaction include those listed above as groups that may be substituted on the alkyl group. Other groups that do not participate in the reaction include oxyethylene groups and oxyethyleneoxy groups, which are divalent groups that bond two carbon atoms on a ring.

[0016] Specific examples of the aryl group which may be substituted with a group which does not participate in the reaction include a methylphenyl group, an ethylphenyl group, a hexylphenyl group, a methoxyphenyl group, an ethoxyphenyl group, a butoxyphenyl group, an octoxyphenyl group, a methyl(methoxy)phenyl group, a fluoro(methyl)phenyl group, a chloro(methoxy)phenyl group, a bromo(methoxy)phenyl group, a 2,3-dihydrobenzofuranyl group, and a 1,4-benzodioxanyl group.

[0017] Furthermore, when the hydrocarbon group is an aralkyl group, the number of carbon atoms in the aralkyl group is preferably 7 to 23, more preferably 7 to 16. In addition, some or all of the hydrogen atoms bonded to the carbon atoms of the aralkyl group may be substituted with groups that do not participate in the reaction. Examples of the group that does not participate in the reaction include those groups that may be substituted on the alkyl group and do not participate in the reaction.

[0018] Specific examples of the aralkyl group which may be substituted with a group which does not participate in the reaction include a benzyl group, a phenethyl group, a 2-naphthylmethyl group, a 9-anthrylmethyl group, a (4-chlorophenyl)methyl group, and a 1-(4-methoxyphenyl)ethyl group.

[0019] When the hydrocarbon group is an alkenyl group, the number of carbon atoms in the alkenyl group is preferably 2 to 23, more preferably 2 to 20, and even more preferably 2 to 10. Some or all of the hydrogen atoms on the carbon bonded to the carbon atom of the alkenyl group may be substituted with groups that do not participate in the reaction. Examples of the group that does not participate in the reaction include the above-mentioned groups that may be substituted on the alkyl group and that do not participate in the reaction, as well as the above-mentioned aryl groups.

[0020] Specific examples of the alkenyl group which may be substituted with a group which does not participate in the reaction include a vinyl group, a 2-propenyl group, a 3-butenyl group, a 5-hexenyl group, a 9-decenyl group, a 2-phenylethenyl group, a 2-(methoxyphenyl)ethenyl group, a 2-naphthylethenyl group, and a 2-anthrylethenyl group.

[0021] R 4 The alkyl group having 1 to 6 carbon atoms represented by the formula (I) preferably has 1 to 4 carbon atoms, and more preferably has 1 to 3 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a sec-butyl group, a pentyl group, a hexyl group, and a cyclohexyl group.

[0022] p+q+r is preferably an integer of 0 or more and 2 or less, and more preferably 0 or 1.

[0023] Specific examples of the alkoxysilanes represented by the general formula (I) include trimethyl(methoxy)silanes. )silane (Me3Si(OMe)), trimethyl(ethoxy)silane (Me3Si(OEt)), methylphenyldi(methoxy)silane (MePhSi(OMe)2), dimethyldi(methoxy)silane (Me2Si(OMe)2), dimethyldi(ethoxy)silane (Me2Si(OEt)2), di(ethoxy)(phenyl)vinylsilane (PhViSi(OEt)2), methyltri(methoxy)silane (MeSi(OMe)3), methyltri(ethoxy)silane (MeSi(OEt)3), phenyltri(methoxy)silane (PhSi Examples include phenyltri(ethoxy)silane (PhSi(OEt)), vinyltri(methoxy)silane (ViSi(OMe)), vinyltri(ethoxy)silane (ViSi(OEt)), tri(methoxy)silane (HSi(OMe)), tri(ethoxy)silane (HSi(OEt)), tetra(methoxy)silane (Si(OMe)), tetra(ethoxy)silane (Si(OEt)), tetra(propoxy)silane (Si(OPr)), and tetra(butoxy)silane (Si(OBu)).

[0024] On the other hand, the carboxylic acid anhydride to be reacted with the alkoxysilane is represented by, for example, the following general formula (II). (R 5 CO)2O (II)

[0025] In general formula (II), R 5 is a hydrocarbon group having 1 to 24 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction. R 5 Examples of the hydrocarbon group represented by R include an alkyl group, an aryl group, an aralkyl group, and an alkenyl group. 1 , R 2 , and R 3 The groups that do not participate in the reaction are defined in the same manner as the alkyl group, aryl group, aralkyl group, alkenyl group, etc., as described above. 1 , R 2 , and R 3Examples of the groups that do not participate in the reaction include those shown in the explanation of the above. Regarding the number of carbon atoms in the hydrocarbon group, when the hydrocarbon group is an alkyl group, it is preferably 1 to 20, more preferably 1 to 18, even more preferably 1 to 12, and particularly preferably 1 to 6; when the hydrocarbon group is an aryl group, it is preferably 4 to 20, more preferably 4 to 18; when the hydrocarbon group is an aralkyl group, it is preferably 5 to 21, more preferably 5 to 19; and when the hydrocarbon group is an alkenyl group, it is preferably 2 to 20, more preferably 2 to 18. Specific examples of these hydrocarbon groups include R 1 , R 2 , and R 3 Examples of the hydrocarbon groups include those described in the above.

[0026] Specific examples of the carboxylic acid anhydride represented by general formula (II) include acetic anhydride (Ac2O), propionic anhydride ((EtCO2O), butyric anhydride (PrCO2O), isobutyric anhydride (( i Pr2CO)2O), valeric anhydride ((BuCO)2O), isovaleric anhydride (( i PrCH2CO)2O), pivalic anhydride (( t BuCO)2O), hexanoic anhydride ((PentCO)2O), heptanoic anhydride ((HexCO)2O), cyclohexanecarboxylic anhydride ((cyc-HexCO)2O), octanoic anhydride ((HeptCO)2O), nonanoic anhydride ((OctCO)2O), decanoic anhydride ([Me(CH2)8CO]2O), lauric anhydride ([Me(CH2)9CO]2O), myristic anhydride ([Me(CH2) 12 CO]2O), palmitic anhydride ([Me(CH2) 14 CO]2O), stearic anhydride ([Me(CH2) 16CO]2O), difluoroacetic anhydride ((CHF2CO)2O), trifluoroacetic anhydride ((CF3CO)2O), trichloroacetic anhydride ((CCl3CO)2O), chlorodifluoroacetic anhydride ((CF2ClCO)2O), benzoic anhydride ((PhCO)2O), toluic anhydride ((MeC6H4CO)2O), naphthoic anhydride ((C 10 Examples of the anhydride include phenylacetic anhydride ((PhCHCO)O), crotonic anhydride ((MeCH=CHCO)O), oleic anhydride ([OctCH=CH(CH)CO]O), and the like, and preferred are acetic anhydride (AcO) and trifluoroacetic anhydride ((CFCO)O).

[0027] The ratio of carboxylic acid anhydride to alkoxysilanes can be selected arbitrarily, but considering the yield of acyloxysilanes based on alkoxysilanes, the molar ratio or weight ratio is usually 0.4 or more and 300 or less, more preferably 0.5 or more and 200 or less, even more preferably 0.5 or more and 150 or less, and particularly preferably 0.5 or more and 10 or less.

[0028] In this embodiment, an acyloxysilane represented by the following general formula (III) can be produced by reacting an alkoxysilane represented by the above general formula (I) with a carboxylic acid anhydride represented by the above general formula (II). R 1 p R 2 q R 3 r Si(OR 4 ) 4-(p+q+r+s) (OCOR 5 ) s (III)

[0029] p, q, r, and R in general formula (III) 1 , R 2 , R 3 , R 4 , and R 5are the same as defined above, and specific examples thereof include those shown in the general formulas (I) and (II) above. s is an integer of 1 or more and 4-(p+q+r) or less, and is preferably 1 or 2.

[0030] In the reaction step, the carboxylic acid added to the reaction system as an additive is represented by, for example, the following general formula (IV). R 6 CO2H(IV)

[0031] In general formula (IV), R 6 is a hydrocarbon group having 1 to 3 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction. The hydrocarbon group may be an alkyl group, and the alkyl group may be R 1 , R 2 , and R 3 The groups that do not participate in the reaction are defined in the same manner as the alkyl groups described in the explanation of the general formula (I). 1 , R 2 , and R 3 Examples of the groups that do not participate in the reaction include those shown in the explanation of the above. The number of carbon atoms in the hydrocarbon group is preferably 1 to 2 when the hydrocarbon group is an alkyl group. Specific examples of these hydrocarbon groups include a methyl group, an ethyl group, and a trifluoromethyl group.

[0032] Specific examples of the carboxylic acid represented by the general formula (IV) include acetic acid, propionic acid, trifluoroacetic acid, etc., and preferred are acetic acid and trifluoroacetic acid.

[0033] The ratio of carboxylic acid to alkoxysilanes can be selected arbitrarily, but in terms of molar ratio or weight, it is usually 0.001 or more and 10 or less, more preferably 0.005 or more and 2 or less, even more preferably 0.01 or more and 1 or less, and particularly preferably 0.01 or more and 0.5 or less.

[0034] The reaction step in this embodiment involves a nucleophilic substitution reaction of alkoxysilanes, which are raw materials having an alkoxy group, with a carboxylic acid anhydride. Therefore, when the alkoxysilanes represented by the general formula (I) are reacted with the carboxylic acid anhydrides represented by the general formula (II), the elimination of the carboxylic acid ester occurs. In this case, the reaction is thought to proceed as shown in the following schemes 1 to 4. Schemes 1 to 4 show that the alkoxysilanes are converted into monoalkoxysilanes, dialkoxysilanes, and This is a scheme for the cases of alkoxysilanes, trialkoxysilanes, and tetraalkoxysilanes.

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] That is, the acyloxysilanes obtained by the production method according to this embodiment are of one type when monoalkoxysilanes are used as raw materials, but are not limited to one type when dialkoxysilanes, trialkoxysilanes, or tetraalkoxysilanes are used as raw materials. For example, when dialkoxysilanes are used as raw materials, the obtained acyloxysilanes may be acyloxysilanes substituted with one alkoxy group, acyloxysilanes substituted with two alkoxy groups, or a mixture thereof. Furthermore, when trialkoxysilanes are used as raw materials, the obtained acyloxysilanes may be acyloxysilanes substituted with one alkoxy group, acyloxysilanes substituted with two alkoxy groups, acyloxysilanes substituted with three alkoxy groups, or a mixture thereof. In addition, when tetraalkoxysilanes are used as raw materials, the resulting acyloxysilanes may be acyloxysilanes substituted with one alkoxy group, acyloxysilanes substituted with two alkoxy groups, acyloxysilanes substituted with three alkoxy groups, acyloxysilanes substituted with four alkoxy groups, or mixtures thereof.

[0040] The solid acid catalyst used in the reaction step is thought to promote the production of acyloxysilanes from alkoxysilanes, for example, in a reaction format such as that shown in Scheme 5 below.

[0041] [ka]

[0042] In other words, in Scheme 5, the catalytic reaction is thought to proceed by cycling through the following pathways: (a) protonation of the carbonyl oxygen of acetic anhydride by the solid acid catalyst, (b) nucleophilic attack of the alkoxysilane on the carbonyl carbon, and (c) production of acyloxysilanes and carboxylic acid esters via a six-membered cyclic transition state and regeneration of the solid acid catalyst.

[0043] On the other hand, the acidic sites (e.g., sulfo groups) of the solid acid catalyst may be converted to silyl esters by reaction with the acyloxylanes produced in this reaction system, with the release of carboxylic acids, as shown in Scheme 6 below.

[0044] [ka]

[0045] As this silyl esterification reaction proceeds, the acidic sites of the solid acid catalyst decrease, causing a decrease in catalytic activity (deactivation). Since this silyl esterification produces a carboxylic acid, adding a carboxylic acid to the reaction system may be able to suppress the silyl esterification. The addition of a carboxylic acid to the reaction process is thought to have the effect of suppressing the silyl esterification reaction and suppressing the decrease in catalytic activity.

[0046] As the catalyst used in the reaction step, various conventionally known organic solid acid catalysts and inorganic solid acid catalysts can be used. The organic solid acid catalyst is a polymer having an acidic functional group, such as a sulfo group, a carboxy group, or a phosphoryl group, and the polymer may be a Teflon (registered trademark) backbone polymer having a perfluoro side chain, or a styrene-divinylbenzene copolymer. Specific examples of organic solid acid catalysts include sulfo-containing catalysts such as Nafion (NAFION®, available from DuPont), Dowex (DOWEX®, available from Dow Chemical Company), Amberlite (AMBERLITE®, available from Rohm & Hass), Amberlyst (AMBERLYST®, available from Dow Chemical Company), and Purolite (Purolite®, available from Purolite). More specific examples include Nafion NR50, Dowex 50WX2, Dowex 50WX4, Dowex 50WX8, Amberlite IR120, Amberlite IRP-64, Amberlyst 15, and Amberlyst 36. Furthermore, a catalyst in which an organic solid acid such as Nafion is supported on an inorganic material such as silica (for example, Nafion SAC-13) can also be used.

[0047] On the other hand, examples of inorganic solid acid catalysts include solid inorganic substances such as metal salts and metal oxides, etc. More specifically, these include zeolites, mesoporous silica, montmorillonite, etc., which have protic hydrogen atoms or metal cations (cations of aluminum, titanium, gallium, iron, cerium, scandium, etc.), as well as inorganic solid acids supported by silica gel, heteropolyacids, carbon-based materials, etc. Among these, in terms of catalytic activity and product selectivity, solid acids selected from zeolites, mesoporous silica, and montmorillonite, which are inorganic solid acids having regular pores and / or a layered structure, are preferred, with solid acids selected from zeolites and montmorillonite being more preferred. There are no particular limitations on the type of regular pores and / or layered structure of the inorganic solid acid, but considering the ease of diffusion of reacting molecules and product molecules, solid acid catalysts having a pore structure typically have pore diameters in the range of 0.2 to 20 nm, preferably 0.3 to 15 nm, and more preferably 0.3 to 10 nm. Furthermore, solid acid catalysts having a layered structure typically have interlayer distances in the range of 0.2 to 20 nm, preferably 0.3 to 15 nm, and more preferably 0.3 to 10 nm.

[0048] When a zeolite is used as an inorganic solid acid catalyst having a regular pore structure, various types of zeolites having a basic skeleton such as Y-type, beta-type, ZSM-5-type, mordenite-type, SAPO-type, etc. can be used. In addition, USY-type (Ultrastable Y) zeolites, known as SUSY-type (Super Ultrastable Y), VUSY-type (Very Ultrastable Y), SDUSY-type (Super Dealuminated Ultrastable Y), etc., which are obtained by secondary treatment of Y-type zeolite (Na-Y), can also be preferably used (for details of USY-type, see, for example, "Molecular Sieves," Advances in Chemistry, Volume 121, American Chemical Society, 1973, Chapter 9, etc.).

[0049] In terms of reaction rate, among these zeolites, USY type, beta type, Y type, ZSM- Zeolites of the type 5 and mordenite are preferred, of which the USY, beta, and Y types are more preferred, and the USY and beta types are even more preferred. Furthermore, the USY and beta types are also preferred as zeolites for selectively converting a part or all of the alkoxy groups into acyloxy groups. Various types of zeolites can be used, including Bronsted acid zeolites having protic hydrogen atoms and Lewis acid zeolites having metal cations. Among these, proton zeolites having protic hydrogen atoms are represented by HY, H-SDUSY, H-SUSY, H-beta, H-mordenite, H-ZSM-5, etc. In addition, ammonium zeolites such as NH4-Y, NH4-VUSY, NH4-beta, NH4-mordenite, and NH4-ZSM-5 can also be used after calcination to convert them to proton types.

[0050] Furthermore, the silica / alumina ratio (ratio of substances) of the zeolite can be selected from various ratios depending on the reaction conditions, but is usually 3-1000, preferably 3-800, more preferably 5-600, and even more preferably 5-400.

[0051] Various zeolites, including commercially available products, can be used. Specific examples of commercially available products include USY zeolites such as CBV760, CBV780, CBV720, CBV712, and CBV600, commercially available from Zeolyst Co., Ltd.; Y zeolites such as HSZ-360HOA and HSZ-320HOA, commercially available from Tosoh Corporation; and beta zeolites such as CP811C, CP814N, CP7119, CP814E, CP7105, CP814CN, CP811TL, CP814T, CP814Q, CP811Q, CP811E-75, CP811E, and CP811C-300, commercially available from Zeolyst Co., Ltd.; HSZ-930HOA and HSZ-940HOA, commercially available from Tosoh Corporation; and UOP-Beta, commercially available from UOP Co., Ltd. Further, examples of mordenite-type zeolites include CBV21A, CBV90A, etc., commercially available from Zeolyst Co., Ltd.; and HSZ-660HOA, HSZ-620HOA, HSZ-690HOA, etc., commercially available from Tosoh Corporation. Examples of ZSM-5-type zeolites include CBV5524G, CBV8020, CBV8014N, etc., commercially available from Zeolyst Co., Ltd. The organic solid acid catalyst and the inorganic solid acid catalyst can be used alone, but a plurality of solid acid catalysts can also be used in any ratio and combination.

[0052] The amount of catalyst relative to the raw material can be determined arbitrarily, but is usually about 0.0001 to 10, preferably about 0.001 to 8, and more preferably about 0.001 to 6 in weight ratio.

[0053] The reaction in the reaction step can be carried out in a liquid phase or a gas phase depending on the reaction temperature, reaction pressure, etc. The reaction temperature is usually -20°C or higher, preferably -10 to 300°C, more preferably -10 to 200°C, and even more preferably 0 to 150°C. When the reaction is carried out at room temperature to control the reactivity of the alcohol, the temperature range of room temperature is usually 0 to 40°C, preferably 5 to 40°C, and more preferably 10 to 35°C. Furthermore, the reaction pressure is usually 0.1 to 100 atmospheres, preferably 0.1 to 50 atmospheres, and more preferably 0.1 to 10 atmospheres. The reaction time depends on the amount of raw materials, the amount of catalyst, the reaction temperature, the shape of the reaction apparatus, etc., but in consideration of productivity and efficiency, it is usually about 0.1 to 1200 minutes, preferably about 0.1 to 600 minutes, and more preferably about 0.1 to 300 minutes.

[0054] When the reaction is carried out in a liquid phase system, it can be carried out with or without a solvent. In this case, various solvents that do not react with the raw materials can be used, such as hydrocarbons such as decalin (decahydronaphthalene) and decane; halogenated hydrocarbons such as chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2-trichlorobenzene, 1,3-trichlorobenzene, and 1,2,4-trichlorobenzene; and ethers such as tert-butyl methyl ether and dibutyl ether. Two or more solvents can also be mixed in any combination and ratio. When the reaction is carried out in the gas phase, the reaction can also be carried out by mixing an inert gas such as nitrogen.

[0055] The reaction step can also be carried out under microwave irradiation. In this reaction system, the carboxylic acid anhydride, catalyst, etc. have relatively large dielectric loss coefficients and efficiently absorb microwaves, so that the carboxylic acid anhydride, catalyst, etc. are activated under microwave irradiation, allowing the reaction to be carried out more efficiently.

[0056] In microwave irradiation reactions, various commercially available devices equipped with contact or non-contact temperature sensors can be used. The microwave irradiation output, cavity type (multimode or single mode), irradiation mode (continuous or intermittent), and other parameters can be determined as desired depending on the scale of the reaction, the types of raw materials, catalysts, and additives. The microwave frequency is typically 0.3 to 30 GHz. Among these, the IMS frequency band allocated for use in industrial, scientific, and medical fields is preferred, with the 2.45 GHz and 5.8 GHz bands being even more preferred.

[0057] In microwave irradiation reactions, a heating material (susceptor) that absorbs microwaves and generates heat can be added to the reaction system to heat the reaction system more efficiently. Various types of heating material can be used, including activated carbon, graphite, silicon carbide, and titanium carbide. A molded catalyst can also be used, which is prepared by mixing the catalyst powder with a heating material and calcining it using an appropriate binder such as sepiolite or holmite.

[0058] The reaction step in this embodiment can proceed in a closed-system reaction apparatus. However, the reaction can also proceed more efficiently by using an open-system reaction apparatus and continuously removing the reaction product from the reaction system.

[0059] The reactor may be of any of the conventional types, such as a batch type or a flow type. The flow reaction system is an effective production method for scaling up the reaction. However, when the solid acid catalyst is deactivated due to silylation of the acidic site as shown in Scheme 6, the produced carboxylic acid flows out of the reaction system, and therefore the catalyst is more likely to be deactivated more quickly than in a batch reaction system in which the produced carboxylic acid remains within the reaction system. Therefore, it is believed that the production method according to this embodiment, in which a carboxylic acid is added to the reaction system to carry out the reaction, can be carried out particularly effectively in a flow reaction system. In a flow reaction system, various types of conventionally known pumps such as a peristaltic pump, a plunger pump, etc. can be used as the liquid-transfer pump. Among these pumps, a peristaltic pump is advantageous in cases where the raw materials, products, etc. are highly reactive and prone to contamination due to their decomposition, in that the flow paths, piping, etc. within the pump can be easily cleaned and replaced. Furthermore, in a flow reaction system, it is possible to effectively use not only a method in which the raw material mixture is passed through a column packed with a catalyst only once, but also a method in which the effluent from the column is returned to the raw material mixture and the reaction is carried out while circulating.

[0060] In the production method according to this embodiment, a solid acid catalyst is used, so that even in a batch reaction system, separation and recovery of the catalyst after the reaction can be easily carried out by methods such as filtration and centrifugation. Cut. Furthermore, the resulting acyloxysilanes can be easily purified by means commonly used in organic chemistry, such as distillation, recrystallization, and column chromatography. [Example]

[0061] Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples. The main analytical devices used in the following examples are as follows: Nuclear magnetic resonance spectroscopy (hereinafter sometimes referred to as NMR): Bruker AVANCE III HD 600MHz (with cryoprobe) Gas chromatograph analysis (hereinafter sometimes referred to as GC): Shimadzu GC-2014 Gas chromatograph mass spectrometry (hereinafter sometimes referred to as GC-MS): Shimadzu GCMS-QP2010Plus

[0062] The reaction of the present invention can be carried out in either a closed batch reaction system or an open flow reaction system. First, an example of a batch reaction system will be described below.

[0063] Example 1 A mixture of 2.0 mmol of tetra(ethoxy)silane (Si(OEt)), 1.8 mmol of acetic anhydride ((MeCO)O), 0.4 mmol of acetic acid (AcOH), and 4 mg of Amberlyst 15 (Dow Chemical Company) was stirred in a sealed reaction vessel at approximately 25 °C (room temperature) for 30 min. The product was analyzed by GC, GC-MS, and NMR. The product yields were calculated by NMR. The results indicated that (acetoxy)tri(ethoxy)silane (Si(OEt)(OAc), the monosubstituted product) and di(acetoxy)di(ethoxy)silane (Si(OEt)(OAc), the disubstituted product) were produced in 41% and 5% yields, respectively (46% total yield) (see Tables 1-1 and 2).

[0064] (Examples 2 to 36) The reaction and analysis were carried out in the same manner as in Example 1, except that the reaction conditions (raw materials, catalyst, time, etc.) were changed as shown in Tables 1-1 to 1-4, and the yield of the product was calculated by NMR. The results are shown in Tables 1-1 to 1-4. The NMR and GC-MS measurement results of the product are shown in Table 2.

[0065] (Comparative Examples 1 to 36) The reaction was carried out under the same conditions as in Examples 1 to 36, except that no additives were used. The reaction and analysis were carried out, and the yield of the product was calculated by NMR. The results are shown in Tables 1-5 to 1-8. Comparative Examples 6, 7, 16, 17, and 18 are the same experimental examples as Comparative Examples 4, 5, 13, 14, and 15, respectively.

[0066] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5] [Table 1-6] [Table 1-7] [Table 1-8]

[0067] The notes in Tables 1-1 to 1-8 are as follows: 1) The reaction was carried out at room temperature (about 25°C) in a sealed vessel. 2) Si(OEt)4: Tetra(ethoxy)silane Si(OMe)4: tetra(methoxy)silane MeSi(OEt)3: Methyltri(ethoxy)silane PhSi(OEt)3: Phenyltri(ethoxy)silane ViSi(OEt)3: vinyltri(ethoxy)silane 3) Ac2O: Acetic anhydride (CF3CO)2O: Trifluoroacetic anhydride 4) Amberlyst 15: Sulfo group-containing polymer Amberlyst 15 (manufactured by The Dow Chemical Company) Purolite CT175: Sulfo group-containing polymer Purolite CT175 (manufactured by Purolite Co., Ltd.) CBV780: H-SDUSY type zeolite CBV780 (manufactured by Zeolyst, used after calcination at 500°C) 5) AcOH: Acetic acid CF3CO2H: Trifluoroacetic acid 6) The numbers in parentheses indicate the ratio of the alkoxy groups to the acyloxy groups in the products. Si(OEt)3(OAc): (acetoxy)tri(ethoxy)silane Si(OEt)2(OAc)2: Di(acetoxy)di(ethoxy)silane Si(OMe)3(OAc): (acetoxy)tri(methoxy)silane Si(OMe)2(OAc)2: Di(acetoxy)di(methoxy)silane Si(OEt)3(OCOCF3): Tri(ethoxy)(trifluoroacetoxy)silane Si(OEt)2(OCOCF3)2: Di(ethoxy)bis(trifluoroacetoxy)silane Si(OMe)3(OCOCF3): Tri(methoxy)(trifluoroacetoxy)silane Si(OMe)2(OCOCF3)2: Di(methoxy)bis(trifluoroacetoxy)silane MeSi(OEt)2(OAc): (acetoxy)di(ethoxy)methylsilane MeSi(OEt)(OAc)2: Di(acetoxy)(ethoxy)methylsilane PhSi(OEt)2(OAc): (acetoxy)di(ethoxy)phenylsilane PhSi(OEt)(OAc)2: Di(acetoxy)(ethoxy)phenylsilane ViSi(OEt)2(OAc): (acetoxy)di(ethoxy)vinylsilane ViSi(OEt)(OAc)2: Di(acetoxy)(ethoxy)vinylsilane 7) The yield of acyloxysilane is 1 H or 29 The yield was calculated from the integral ratio of the product in Si NMR. When multiple acyloxysilanes are produced, the total yield is shown. When the molar ratio of carboxylic acid anhydride to alkoxysilane is less than 1, the yield relative to the raw material alkoxysilane is corrected by the carboxylic acid anhydride charge ratio. 8) The yield ratio, the yield ratio of the mono-substituted product, and the yield ratio of the di-substituted product are values ​​obtained by dividing the yield, the yield of the mono-substituted product, and the yield of the di-substituted product when the reaction is carried out with the addition of a carboxylic acid by the respective yields when the reaction is carried out without the addition of a carboxylic acid. If these values ​​are greater than 1, it indicates that the addition of a carboxylic acid increases these yields.

[0068] [Table 2]

[0069] The notes in Table 2 are as follows: 1) For the names of acyloxysilanes, see Tables 1-1 to 1-8 and Note 6. 2) Measurements in deuterated chloroform. 3) GC-MS (EI, 70 eV).

[0070] From Table 1-1, it was found that in Example 1, in which acetic acid was added, the total yield was 1.5 times, the yield of the mono-substituted product was 1.4 times, and the yield of the di-substituted product was 1.7 times, compared to Comparative Example 1, in which acetic acid was not added.

[0071] The results of Tables 1-1 to 1-8 show that in reaction systems using raw materials having multiple alkoxy groups, the total yield of mono- and di-substituted products and the mono-substitution yield increase by up to about 2.5 times, and the di-substitution yield increases by up to about 3 times, in reaction systems to which a carboxylic acid is added, compared to reaction systems to which a carboxylic acid is not added. Furthermore, when comparing the effects on the production of mono- and di-substituted compounds, the effect of adding carboxylic acid is thought to be particularly large in the production of di-substituted compounds.

[0072] Next, an example of a flow reaction system will be described below. Example 37 A mixture of 40 mmol of tetra(ethoxy)silane (Si(OEt)), 44 mmol of acetic anhydride ((MeCO)O), and 2 mmol of acetic acid (AcOH) was passed through a glass column packed with 0.31 g of Amberlyst 15 (Dow Chemical Company) at a flow rate of approximately 0.55 mL / min using a peristaltic pump. Fractions of up to 10%, 10-20%, and 20-35% of the reaction mixture were analyzed by NMR to calculate the product yield. As a result, the yields of (acetoxy)tri(ethoxy)silane (Si(OEt)3(OAc), monosubstituted product) and di(acetoxy)di(ethoxy)silane (Si(OEt)2(OAc)2, disubstituted product) were calculated to be 49% and 20% (total 69%) for components with fractions up to 10%, 49% and 17% (total 66%) for components with fractions between 10 and 20%, and 47% and 12% (total 59%) for components with fractions between 20 and 35%.

[0073] (Comparative Example 37) The reaction was carried out under the same conditions as in Example 37, except that acetic acid was not added. As a result, the yields of (acetoxy)tri(ethoxy)silane and di(acetoxy)di(ethoxy)silane were calculated to be 45% and 17% (total 62%) for components with fractions up to 10%, 39% and 9% (total 48%) for components with fractions from 10 to 20%, and 30% and 6% (total 36%) for components with fractions from 20 to 35%.

[0074] It was found from Example 37 and Comparative Example 37 that when acetic acid was added, the total yield increased by 1.1 times, 1.4 times, and 1.6 times, respectively, for the fractionated samples up to 10%, 10 to 20%, and 20 to 30%, compared to when acetic acid was not added. The increase in total yield in the flow reaction carried out with the addition of acetic acid is thought to be due to the fact that the addition of acetic acid was able to suppress the decrease in catalytic activity.

[0075] Further, examples in which reactions were carried out in a similar flow reaction system by changing the amount of carboxylic acid added, the amount of carboxylic acid anhydride charged, etc. are shown below.

[0076] Example 38 A mixture of 40 mmol of tetra(ethoxy)silane (Si(OEt)4), 44 mmol of acetic anhydride ((MeCO)2O), and 6 mmol of acetic acid (AcOH) was peristaltically The reaction mixture was passed through a glass column packed with 0.31 g of Amberlyst 15 (Dow Chemical Co.) at a flow rate of approximately 0.55 mL / min using a pump. Fractions of the reaction mixture were analyzed by NMR for up to 10%, 10-20%, and 20-35% fractions, and the product yield was calculated. As a result, the yields of (acetoxy)tri(ethoxy)silane (Si(OEt)3(OAc), monosubstituted product) and di(acetoxy)di(ethoxy)silane (Si(OEt)2(OAc)2, disubstituted product) were calculated to be 51% and 21% (total 72%) for components with fractions up to 10%, 49% and 19% (total 68%) for components with fractions between 10 and 20%, and 47% and 16% (total 63%) for components with fractions between 20 and 35%.

[0077] Example 39 A mixture of 80 mmol of tetra(ethoxy)silane (Si(OEt)), 72 mmol of acetic anhydride ((MeCO)O), and 8 mmol of acetic acid (AcOH) was passed through a glass column packed with 0.33 g of Amberlyst 15 (Dow Chemical Company) at a flow rate of approximately 0.55 mL / min using a peristaltic pump. Fractions of up to 10%, 10-20%, and 20-35% of the reaction mixture were analyzed by NMR to calculate the product yield. As a result, the yields of (acetoxy)tri(ethoxy)silane (Si(OEt)3(OAc), monosubstituted product) and di(acetoxy)di(ethoxy)silane (Si(OEt)2(OAc)2, disubstituted product) were calculated to be 52% and 15% (total 67%) for components with fractions up to 10%, 48% and 15% (total 63%) for components with fractions between 10 and 20%, and 46% and 14% (total 60%) for components with fractions between 20 and 35%.

[0078] Example 40 A mixture of 80 mmol of tetra(ethoxy)silane (Si(OEt)), 72 mmol of acetic anhydride ((MeCO)O), and 8 mmol of acetic acid (AcOH) was passed through a glass column packed with 0.33 g of Amberlyst 15 (Dow Chemical Co.) at a flow rate of approximately 0.35 mL / min using a peristaltic pump. Fractions of up to 10%, 10-20%, and 20-35% of the fraction were analyzed by NMR to calculate the product yield. As a result, the yields of (acetoxy)tri(ethoxy)silane (Si(OEt)3(OAc), monosubstituted product) and di(acetoxy)di(ethoxy)silane (Si(OEt)2(OAc)2, disubstituted product) were calculated to be 54% and 19% (total 73%) for components with fractions up to 10%, 50% and 18% (total 68%) for components with fractions between 10 and 20%, and 48% and 15% (total 63%) for components with fractions between 20 and 35%.

[0079] Furthermore, an example will be given below in which a reaction was carried out in a flow reaction system in which the effluent from the catalyst column was returned to the container for the raw material mixture, thereby circulating the reaction liquid.

[0080] Example 41 A mixture of 80 mmol of tetra(ethoxy)silane (Si(OEt)), 72 mmol of acetic anhydride ((MeCO)O), and 8 mmol of acetic acid (AcOH) was pumped through a glass column packed with 0.56 g of Amberlyst 15 (Dow Chemical Co.) at a flow rate of approximately 1.1 mL / min using a peristaltic pump. The reaction mixture was then recycled back into the starting mixture. Aliquots of the effluent from the catalyst column were collected after 0.5, 1, 1.5, and 2 hours. The components of the effluent were analyzed by NMR to calculate the product yield. As a result, the yields of (acetoxy)tri(ethoxy)silane (Si(OEt)3(OAc), the monosubstituted product) and di(acetoxy)di(ethoxy)silane (Si(OEt)2(OAc)2, the disubstituted product) were 39% and 7% (46% in total) in the effluent after 0.5 hours. The conversion rates of acetic anhydride were calculated to be 51% and 10% (61% in total) in the effluent after 1 hour, 58% and 12% (70% in total) in the effluent after 1.5 hours, and 60% and 13% (73% in total) in the effluent after 2 hours. The conversion rates of acetic anhydride were calculated to be 59% in the effluent after 0.5 hours, 79% in the effluent after 1 hour, 91% in the effluent after 1.5 hours, and 96% in the effluent after 2 hours. Therefore, under the conditions of this example, it was found that the reaction could be nearly completed (acetic anhydride conversion rate ≥ 95%) by carrying out the reaction for approximately 2 hours using the circulation method. [Industrial Applicability]

[0081] The production method of the present invention makes it possible to more efficiently and safely produce acyloxysilanes, which are useful as functional chemicals, and therefore the present invention is highly useful and has great industrial significance.

Claims

1. The method includes a reaction step of reacting an alkoxysilane with a carboxylic acid anhydride in the presence of a solid acid catalyst and an additive, a method for producing acyloxysilanes, wherein the fixed acid catalyst is a polymer and / or zeolite having an acidic functional group, the additive is a carboxylic acid represented by general formula (IV), and the molar ratio of the carboxylic acid to the alkoxysilanes is 0.01 or more and 10 or less. R 6 CO 2 H (IV) (In the formula, R 6 is a hydrocarbon group having 1 to 3 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction.)

2. 2. The method for producing acyloxysilanes according to claim 1, wherein the alkoxysilanes are represented by the following general formula (I), the carboxylic acid anhydride is represented by the following general formula (II), and the acyloxysilanes are represented by the following general formula (III): R １ ｐ R ２ ｑ R ３ ｒ Si(OR ４ ) ４－（ｐ＋ｑ＋ｒ） (I) (In the formula, p, q, and r are each independently an integer of 0 to 3; p + q + r is an integer of 0 to 3; R １ , R ２ , and R ３ are each independently a hydrocarbon group having 1 to 24 carbon atoms or a hydrogen atom, and some or all of the hydrogen atoms bonded to carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction; R ４ are each independently an alkyl group having 1 to 6 carbon atoms. (R ５ (CO) ２ O (-I) (In the formula, R ５ is a hydrocarbon group having 1 to 24 carbon atoms, and some or all of the hydrogen atoms bonded to carbon atoms of the hydrocarbon group may be substituted with groups that do not participate in the reaction. R １ ｐ R ２ ｑ R ３ ｒ Si(OR ４ ) ４－（ｐ＋ｑ＋ｒ＋ｓ） (OCOR ５ ) ｓ (III) (In the formula, p, q, r, R １ , R ２ , R ３ , R ４ , and R ５ are the same as defined above; and s is an integer of 1 or more and 4-(p+q+r) or less.

3. 3. The method for producing acyloxysilanes according to claim 1, wherein the polymer having an acidic functional group is a polymer having a sulfo group and / or a carboxy group.

4. 4. The method for producing acyloxysilanes according to claim 1, wherein the reaction step is carried out using a flow reaction system.

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