JP7497014B2 - Method for producing acyloxysilane - Google Patents

Description

The present invention relates to an efficient method for producing acyloxysilane.

Acyloxysilanes are functional chemicals that are used as reagents or synthetic intermediates for precision synthesis of medicines, agricultural chemicals, electronic materials, etc., as well as raw materials for surface modifiers, sol-gel materials, nanomaterials, organic-inorganic hybrid materials, etc.
Methods using chlorosilanes as a raw material are known as methods for producing acyloxysilanes.Specifically, methods that have been investigated include (A) a method in which chlorosilane is reacted with a carboxylic acid directly or in the presence of a base (Patent Documents 1 and 2), (B) a method in which chlorosilane is reacted with a metal salt of a carboxylic acid (Patent Document 3), and (C) a method in which chlorosilane is reacted with a carboxylic anhydride (Patent Document 4).
On the other hand, as a method using silanol as a raw material, a reaction example (D) has been reported in which triethylsilanol and acetic anhydride are reacted on a steam bath for 12 hours in the absence of a catalyst, followed by fractional distillation to obtain acetoxytriethylsilane (Non-Patent Document 1).

However, the methods using chlorosilane as a raw material have problems such as: (1) handling of the raw material is difficult because chlorosilane, which generates corrosive hydrogen chloride upon hydrolysis, is used (Methods A and B); (2) when a base is not used in the reaction with a carboxylic acid, corrosive hydrogen chloride is by-produced (Method A); (3) when a base is used in the reaction with a carboxylic acid, a large amount of salt is by-produced (Method A); (4) a large amount of salt is also by-produced in the reaction with a metal carboxylate (Method B); and (5) when a reaction with a carboxylic anhydride is performed, acyl chlorides that are easily hydrolyzed and tend to generate corrosive hydrogen chloride are by-produced (Method C).
On the other hand, the method using silanol as a raw material does not have the problem of generating corrosive hydrogen chloride, but has the problem of low reaction efficiency (Method D), such as the need to carry out the reaction at high temperatures for a long period of time.

Japanese Patent Application Laid-Open No. 54-103500 European Patent Application No. 0837067 U.S. Pat. No. 4,379,766 German Patent No. 882401

J. Am. Chem. Soc., 1946, 68, 11, 2282-2284

The present invention was made in consideration of the above circumstances, and aims to provide a method for efficiently producing acyloxysilane from silanol.

As a result of intensive research aimed at solving the above problems, the inventors discovered that the reaction between silanol and carboxylic acid anhydride proceeds smoothly in the presence of a specific catalyst, and that acyloxysilane can be efficiently obtained even in a short reaction time at around room temperature, thus completing the present invention.

That is, this application provides the following inventions.
＜1＞
A method for producing an acyloxysilane having a Si-OCO bond (OCO represents an oxycarbonyl group, O-C(=O)), comprising a reaction step of reacting a silanol having a Si-OH bond with a carboxylic acid anhydride in the presence of a catalyst,
The method for producing acyloxysilane, wherein the catalyst is an acidic catalyst selected from the following (1) and (2):
(1) A perchlorate, trifluoromethanesulfonate, bis(trifluoromethanesulfonylimide) salt, hexafluorophosphate, chloride, or bromide of an element selected from the elements of Groups 3 to 15 of the periodic table; an inorganic acid; or an organic acid.
(2) Inorganic or organic solid acid compounds.
＜2＞
The method according to <1>, wherein the acid catalyst (1) is a compound containing a Group 8 element. <3>
The method according to <2>, wherein the Group 8 element is an element selected from iron and ruthenium.
＜4＞
The method according to <1>, wherein the acid catalyst (2) is a compound selected from the group consisting of zeolite, montmorillonite, and sulfo group-containing polymers.
＜5＞
The method according to any one of <1> to <4>, wherein the silanol having a Si—OH bond is a silanol represented by the following general formula (I):
R ¹ _a R ² _b R ³ _c Si(OH) _4-(a+b+c) (I)
(In the formula, a, b, and c each independently represent an integer of 0 to 3; a+b+c represents an integer of 0 to 3; R ¹ , R ² , and R ³ each independently represent 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 having 1 to 24 carbon atoms may be substituted with a group that does not participate in the reaction.)
＜6＞
The method according to any one of <1> to <5>, wherein the carboxylic acid anhydride is a carboxylic acid anhydride represented by the following general formula (II):
( ^R4CO ) _2O (II)
(In the formula, R ⁴ 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.)
＜７＞
The method according to any one of <1> to <4>, wherein the silanol having a Si—OH bond is a silane monool represented by the following general formula (I′), the carboxylic acid anhydride is a carboxylic acid anhydride represented by the following general formula (II), and the acyloxysilane produced is an acyloxysilane represented by the following general formula (IIIA):
R ¹ R ² R ³ Si(OH) (I')
(In the formula, 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.)
( ^R4CO ) _2O (II)
(In the formula, R ⁴ 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.)
^R1R2R3Si ( ^{OCOR4 )} ( ^IIIA )
(In the formula, R ¹ , R ² , R ³ , and R ⁴ are defined as above.)
＜8＞
The method according to any one of <1> to <4>, wherein the silanol having a Si—OH bond is a silanediol represented by the following general formula (I″), the carboxylic acid anhydride is a carboxylic acid anhydride represented by the following general formula (II), and the generated acyloxysilane is an acyloxysilane represented by the following general formula (IIIB):
^R1R2Si ( ^OH ) ₂ (I'')
(In the formula, R ¹ and R ² each independently represent 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 having 1 to 24 carbon atoms may be substituted with a group that does not participate in the reaction.)
( ^R4CO ) _2O (II)
(In the formula, R ⁴ 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.)
( ^R4CO )O( ^{SiR1R2O )} _m ( ^COR4 ) (IIIB)
(In the formula, R ¹ , R ² , and R ⁴ are defined as above; and m is an integer of 1 to 20.)
＜9＞
<10> The method according to any one of <1> to <8>, wherein the reaction is carried out under microwave irradiation.
A method for producing an alkoxysilane, comprising: an acyloxysilane production step of producing an acyloxysilane by the production method according to any one of <1> to <9>; and a modification step of reacting the acyloxysilane with an alcohol represented by the following general formula (IV) to convert an acyloxy group of the acyloxysilane into an alkoxy group:
R ⁵ OH (IV)
(In the formula, ^R5 is an alkyl group having 1 to 6 carbon atoms.)

The manufacturing method of the present invention has the effect of making it possible to produce acyloxysilane from silanol more efficiently than conventional methods.

In detail, the manufacturing method of the present invention has the following features.
(1) The raw materials and catalysts are easy to obtain, easy to handle, and highly safe.
(2) Corrosive hydrogen chloride is not produced as a by-product.
(3) The reaction is completed in a short time under mild reaction conditions.
(4) In a reaction system using a solid acid catalyst, the catalyst can be easily separated and recovered.
(5) The reaction can be accelerated by microwave irradiation.
The manufacturing method of the present invention enables a low-cost and highly efficient manufacturing process, and is believed to have significant advantages over conventional techniques in terms of economy, environmental load, etc.

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 an acyloxysilane according to one embodiment of the present invention is characterized by comprising a reaction step of reacting a silanol with a carboxylic acid anhydride in the presence of a catalyst.

In this embodiment, the silanol used as the raw material is, for example, a silanol represented by the following general formula (I):
R ¹ _a R ² _b R ³ _c Si(OH) _4-(a+b+c) (I)
It is expressed as:

In general formula (I), a, b, and c each independently represent an integer of 0 to 3, and a+b+c represents an integer of 0 to 3. Furthermore, R ¹ , R ² , and R ³ each independently represent 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 having 1 to 24 carbon atoms may be substituted with a group that does not participate in the reaction.
Specific examples of the hydrocarbon group include an alkyl group, an aryl group, an aralkyl group, and an alkenyl group.

When the hydrocarbon group is an alkyl group, it preferably has 1 to 20 carbon atoms, more preferably 1 to 18, even more preferably 1 to 12, and particularly preferably 1 to 6 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the alkyl group may be substituted with groups that are not involved in the reaction.

Specific examples of the group that is not involved in the reaction include an alkoxy group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, a dialkylamino group having 1 to 6 carbon atoms, a cyano group, a nitro group, a halogen atom, etc. More specific examples of the alkoxy group, the alkoxycarbonyl group, the dialkylamino group, and the halogen atom include alkoxy groups such as a methoxy group, an ethoxy group, and a hexoxy group; alkoxycarbonyl groups such as a methoxycarbonyl group and a propoxycarbonyl group; dialkylamino groups such as a dimethylamino group and a diethylamino group; and halogen atoms such as a fluorine atom, a chlorine atom, and a bromine atom.
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, a 3-chloropropyl group, a 3,3,3-trifluoropropyl group, a 1H,1H,2H,2H-tridecafluorooctyl group, and a 1H,1H,2H,2H-heptadecafluorodecyl group.

In addition, 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. In the case where the aryl group is a hydrocarbon ring system, the number of carbon atoms of the hydrocarbon ring system is preferably 6 to 22, more preferably 6 to 14, and even more preferably 6 to 10. Specific examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a perylenyl group, and a pentacenyl group. In the case where the aryl group is a heterocyclic ring system, the heteroatom in the heterocyclic ring is a sulfur atom, an oxygen atom, or the like. In addition, the number of carbon atoms of the aryl group is preferably 4 to 12, and more preferably 4 to 8. Specific examples of the aryl group include a thienyl group, a benzothienyl group, a dibenzothienyl group, a furyl group, a benzofuryl group, and a dibenzofuryl group.
A part or all of the hydrogen atoms bonded to the carbon atoms of the aryl group may be substituted with a group that does not participate in the reaction. Specific examples of the group that does not participate in the reaction include those shown in the case of the alkyl group above. Other groups that do not participate in the reaction include an oxyethylene group, an oxyethyleneoxy group, etc., which are divalent groups that bond two carbon atoms on a ring. Specific examples of the aryl group having such groups 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.

Furthermore, when the hydrocarbon group is an aralkyl group, the number of carbon atoms in the aralkyl group is preferably from 7 to 23, more preferably from 7 to 16. A part 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.
Specific examples of the group that does not participate in the reaction include those given above for the alkyl group.
Specific examples of the aralkyl group which may be substituted by 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.

When the hydrocarbon group is an alkenyl group, the number of carbon atoms in the alkenyl group is preferably from 2 to 23, more preferably from 2 to 20. A part or all of the hydrogen atoms bonded to the carbon atoms of the alkenyl group may be substituted with groups that are not involved in the reaction.
Specific examples of the group that does not participate in the reaction include those given above in relation to the alkyl group, as well as the aryl group given above.
Specific examples of the alkenyl group which may be substituted by 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.

Consequently, specific examples of raw silanols having these hydrocarbon groups include trimethylsilanol, triethylsilanol, dimethylphenyldisilanol, methyldiphenylsilanol, triphenylsilanol, benzyldimethylsilanol, dimethylsilanediol, diphenylsilanediol, phenylvinylsilanediol, methylsilanetriol, ethylsilanetriol, phenylsilanetriol, vinylsilanetriol, and silanetetraol.

On the other hand, the carboxylic acid anhydride to be reacted with the alkoxysilane is represented, for example, by the following general formula (II).
( ^R4CO ) _2O (II)

In general formula (II), ^R4 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.
Specific examples of the hydrocarbon group include an alkyl group, an aryl group, an aralkyl group, an alkenyl group, etc. Specific examples of the group that does not participate in the reaction include those described above for R ¹ , R ² , or R ³ in the general formula (I).
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, and even more preferably 4 to 10; 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, and more preferably 2 to 18.
Specific examples of these groups include those given in the explanation of R ¹ , R ² , and R ³ in the above general formula (I).

Therefore, specific examples of the carboxylic acid anhydride (II) having such a hydrocarbon group include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, isovaleric anhydride, pivalic anhydride, hexanoic anhydride, heptanoic anhydride, cyclohexanecarboxylic anhydride, octanoic anhydride, nonanoic anhydride, decanoic anhydride, lauric anhydride, myristic anhydride, palmitic anhydride, stearic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, trichloroacetic anhydride, chlorodifluoroacetic anhydride, benzoic anhydride, toluic anhydride, naphthoic anhydride, phenylacetic anhydride, crotonic anhydride, isocrotonic anhydride, tiglic anhydride, and oleic anhydride.

The molar ratio of carboxylic acid anhydride to silanol in the raw material can be selected arbitrarily, but taking into consideration the yield of acyloxysilane relative to silanol, it is usually 0.4 to 100, more preferably 0.5 to 50, and even more preferably 0.5 to 20.

In this embodiment, when the silanol is a silane monol represented by the following general formula (I'), an acyloxysilane represented by the following general formula (IIIA) can be produced.
R ¹ R ² R ³ Si(OH) (I')
^R1R2R3Si ( ^{OCOR4 )} ( ^IIIA )
In general formula (I'), ^R1 , ^R2 , and ^R3 have the same meanings as ^R1 , ^R2 , and ^R3 in general formula (I). That is, the silane monol represented by general formula (I') is a silanol represented by general formula (I) in which a=b=c=1.
In formula (IIIA), R ¹ , R ² , R ³ and R ⁴ are as defined above.

Therefore, specific examples of acyloxysilanes of general formula (IIIA) having these groups include acetoxytrimethylsilane (Me ₃ SiOAc), acetoxytriethylsilane (Et ₃ SiOAc), acetoxydimethylphenylsilane (Me ₂ PhSiOAc), acetoxymethyldiphenylsilane (MePh ₂ SiOAc), trimethyl(propionyloxy)silane (Me ₃ SiOCOEt), trimethyl(butanoyloxy)silane (Me ₃ SiOCOPr), trimethyl(butanoyloxy)silane (Me ₃ SiOCOPr), (benzoyloxy)trimethylsilane (Me ₃ SiOCOPh), and the like.

In addition, in this embodiment, when the silanol is a silanediol represented by the following general formula (I″), an acyloxysilane represented by the following general formula (IIIB) can be produced.
^R1R2Si ( ^OH ) ₂ (I'')
( ^R4CO )O( ^{SiR1R2O )} _m ( ^COR4 ) (IIIB)
In general formula (I″), ^R1 and ^R2 have the same meanings as ^R1 and ^R2 in general formula (I). That is, the silanediol represented by general formula (I″) is a silanol represented by general formula (I) in which a=b=1 and c=0.
In formula (IIIB), R ¹ , R ² and R ⁴ are as defined above.
Furthermore, m is an integer of 1 to 20, preferably 1 to 18, more preferably 1 to 16, still more preferably 1 to 12, and particularly preferably 1 to 6.

Therefore, specific examples of acyloxysilanes of general formula (IIIB) having these groups or the like include diacetoxydimethylsilane (AcO(SiMe ₂ O) _m Ac(m=1)), 1,3-diacetoxy-1,1,3,3-tetramethyldisiloxane (AcO(SiMe 2 O) _m Ac(m=2)), 1,5-diacetoxy-1,1,3,3,5,5-hexamethyltrisiloxane (AcO(SiMe ₂ O) _m Ac(m=3)), 1,7-diacetoxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane (AcO(SiMe ₂ O) m Ac(m=4)), diacetoxydiphenylsilane (AcO(SiPh ₂ O) _m Ac(m=5)), _and the like _. Examples of the siloxane include 1,3-diacetoxy-1,1,3,3-tetraphenyldisiloxane (AcO(SiPh ₂ O) _m Ac(m=2)), 1,5-diacetoxy-1,1,3,3,5,5-hexaphenyltrisiloxane (AcO(SiPh ₂ O) _m Ac(m=3)), and 1,7-diacetoxy-1,1,3,3,5,5,7,7-octaphenyltetrasiloxane (AcO(SiPh ₂ O) _m Ac(m=4)).

The reaction step in this embodiment is formally considered to be a reaction step involving a nucleophilic substitution reaction of a silanol group of a raw material having a hydroxyl group with a carboxylic acid anhydride.
Therefore, when the carboxylic anhydride of the general formula (II) is used, the reaction in this embodiment is a reaction accompanied by elimination of a carboxylic acid, and the reaction process thereof, for example, in the case where the silanol represented by the general formula (I) is a silane monool represented by the general formula (I'), an acyloxysilane of the general formula (IIIA) is produced accompanied by elimination of a carboxylic acid, as shown in the following scheme 1.

On the other hand, in the case where the silanol represented by the general formula (I) is a silanediol represented by the general formula (I''), not only the acyloxylation of the hydroxyl groups but also the condensation reaction between the hydroxyl groups proceeds, so that in the reaction with the carboxylic anhydride represented by the general formula (II), an oligomer of silanediol having acyloxy groups at both ends represented by the general formula (IIIB) is produced (Scheme 2).

The distribution of oligomers in Scheme 2 varies depending on the reactivity of the silanediol and carboxylic anhydride and their feed ratio, but generally, the higher the feed ratio of carboxylic anhydride to silanediol, the higher the proportion of monomer (m=1) in the distribution.

In the reaction step for producing acyloxysilane, an acidic catalyst selected from either (1) or (2) below is used to promote the reaction.
(1) A perchlorate, trifluoromethanesulfonate, bis(trifluoromethanesulfonylimide) salt, hexafluorophosphate, chloride, or bromide of an element selected from the elements of Groups 3 to 15 of the periodic table; an inorganic acid; or an organic acid.
(2) Inorganic or organic solid acid compounds

As the catalyst (1) above, various known acidic compounds which are compounds of elements in Groups 3 to 15 of the periodic table can be used.
Specific examples of Group 3 to Group 15 elements include scandium, yttrium, cerium, titanium, zirconium, vanadium, chromium, manganese, iron, ruthenium, osmium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, gold, zinc, boron, aluminum, gallium, indium, silicon, tin, phosphorus, antimony, and bismuth.
Among these elements, from the viewpoint of catalytic activity and the like, elements of Group 3, Group 8, or Group 12 to Group 14 are preferred, elements of Group 8, Group 13, or Group 14 are more preferred, and elements of Group 8 are even more preferred.
Among the Group 8 elements, iron or ruthenium is preferred.

In the reaction step of this embodiment, perchlorates, trifluoromethanesulfonates, bis(trifluoromethanesulfonylimide) salts, hexafluorophosphates, chlorides, bromides, etc. of these elements can be used as effective catalysts.
Specific examples of such catalysts include iron(III) perchlorate, aluminum(III) perchlorate, scandium(III) trifluoromethanesulfonate, iron(III) trifluoromethanesulfonate, aluminum(III) trifluoromethanesulfonate, gallium(III) trifluoromethanesulfonate, indium(III) trifluoromethanesulfonate, tin(II) trifluoromethanesulfonate, bismuth(III) trifluoromethanesulfonate, bis(trifluoromethanesulfonylimide)scandium(III), bis(trifluoromethanesulfonyl imide), (III) dithiocarbamate, bis(trifluoromethanesulfonylimido)indium(III), scandium(III) chloride, yttrium(III) chloride, titanium(III or IV) chloride, iron(III) hexafluorophosphate, aluminum(III) hexafluorophosphate, iron(III) chloride, iron(III) bromide, ruthenium(III) chloride, zinc(II) chloride, boron(III) fluoride, boron(III) chloride, aluminum(III) chloride, aluminum(III) bromide, gallium(III) chloride, indium(III) chloride, tin(IV) chloride, bismuth(III) chloride
etc. These compounds may be used in the form of a hydrate.
Among these salts, from the viewpoint of catalytic activity and the like, perchlorates, trifluoromethanesulfonates, bis(trifluoromethanesulfonylimide) salts, chlorides, or bromides are preferred, and perchlorates, trifluoromethanesulfonates, bis(trifluoromethanesulfonylimide) salts, or chlorides are more preferred.
It is also a preferred method to add silver perchlorate or the like to the chloride or bromide to convert the chloride or bromide to a perchlorate or the like before use.

Furthermore, various conventionally known inorganic or organic acids can also be used.
Specific examples of inorganic acids include nitric acid, hydrochloric acid, and sulfuric acid.
On the other hand, specific examples of organic acids include compounds having a protic hydrogen atom, such as sulfonic acid, sulfonylimide, and carboxylic acid, etc. Specific examples of these include trifluoromethanesulfonic acid, nonafluorobutanesulfonic acid, methanesulfonic acid, bis(trifluoromethanesulfonyl)imide, trifluoroacetic acid, and acetic acid.
As the organic acid, a Lewis acid compound such as tri(pentafluorophenyl)borane can also be used.
A combination of inorganic and organic acids may also be used.

On the other hand, as the catalyst (2), various known inorganic or organic solid acid catalysts which are easy to separate, recover, etc. can be used.
Specific examples of inorganic solid acid catalysts include solid inorganic substances such as insoluble metal salts and metal oxides. More specific examples include zeolites, mesoporous silica, montmorillonite, and the like, which have protic hydrogen atoms or elements of Groups 3 to 15 in the periodic table, as well as inorganic solid acids supported on silica gel, heteropolyacids, carbon-based materials, and the like.
There is no limitation on the type of Group 3 to Group 15 elements in these solid acids, and specific examples of Group 3 to Group 15 elements include those listed above. Among these, Group 3, Group 8, or Group 12 to Group 14 elements are preferred, and Group 8, Group 13, or Group 14 elements are more preferred. Among these elements, iron, aluminum, indium, or tin are preferred, and iron, aluminum, or tin are more preferred.

Among inorganic solid acids, solid acids having regular pores and/or layered structures such as zeolite, mesoporous silica, and montmorillonite are preferred in terms of catalytic activity, selectivity to products, and the like, and solid acids such as zeolite and montmorillonite are more preferably used.
Although there is no particular limitation on the type of regular pores and/or layered structure of the inorganic solid acid, in consideration of the ease of diffusion of reacting or produced molecules, the pore size of a solid acid catalyst having a pore structure is usually 0.2 to 20 nm, preferably 0.3 to 15 nm, and more preferably 0.3 to 10 nm. Also, in a solid acid catalyst having a layered structure, the interlayer distance is usually 0.2 to 20 nm, preferably 0.3 to 15 nm, and more preferably 0.3 to 10 nm.

When using zeolite as an inorganic solid acid catalyst having a regular pore structure, various types of zeolites having a basic skeleton such as USY type, Y type, beta type, ZSM-5 type, mordenite type, SAPO type, etc. can be used. Also preferably used are 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) (for details of USY-type, see, for example, "Molecular Sieves", Advances in Chemistry, Volume 121, American Chemical Society, 1973, Chapter 19, etc.).

In terms of reaction rate, among these zeolites, USY type, beta type, Y type, ZSM-5 type, and mordenite type are preferred, USY type, beta type, and Y type are more preferred, USY type and beta type are even more preferred, and USY type is particularly preferred.

As for these zeolites, various types of zeolites can be used, such as Bronsted acid type zeolites having protic hydrogen atoms and Lewis acid type zeolites having elements of Groups 3 to 15 of the periodic table. Among these, proton type zeolites having protic hydrogen atoms are represented by H-Y type, H-SDUSY type, H-SUSY type, H-beta type, H-mordenite type, H-ZSM-5 type, etc. In addition, ammonium type zeolites such as NH ₄ -Y type, NH ₄ -VUSY type, NH ₄ -beta type, NH ₄ -mordenite type, NH ₄ -ZSM-5 type, etc., which are calcined to convert them to proton type can also be used.
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 to 1,000, preferably 3 to 800, more preferably 5 to 600, and even more preferably 5 to 400.

Various types of zeolites, including commercially available products, can be used. Specific examples of commercially available products include USY-type zeolites such as CBV760, CBV780, CBV720, CBV712, and CBV600, which are commercially available from Zeolite Co., Ltd. Examples of Y-type zeolites include HSZ-360HOA and HSZ-320HOA, which are commercially available from Tosoh Corporation. Examples of beta zeolites include CP811C, CP814N, CP7119, CP814E, CP7105, CP814CN, CP811TL, CP814T, CP814Q, CP811Q, CP811E-75, CP811E, and CP811C-300, etc., available from Zeolite Co., Ltd.; HSZ-930HOA and HSZ-940HOA, etc., available from Tosoh Corporation; and UOP-Beta, etc., available from UOP Co., Ltd. Examples of mordenite zeolites include CBV21A and CBV90A, etc., available from Zeolite Co., Ltd.; and HSZ-660HOA, HSZ-620HOA, and HSZ-690HOA, etc., available from Tosoh Corporation. Examples of ZSM-5 zeolites include CBV5524G, CBV8020, and CBV8014N, which are commercially available from Zeolite.

In addition to the above inorganic solid acids, organic solid acids having acidic functional groups can also be effectively used. The organic solid acid is a polymer having an acidic functional group. Examples of the acidic functional group include a sulfo group, a carboxy group, and a phosphoryl group, and examples of the polymer include a tetrafluoroethylene skeleton polymer having a perfluoro side chain, a styrene-divinylbenzene copolymer, and the like. Specific examples of the polymer having an acidic functional group include Nafion (registered trademark, available from DuPont), Dowex (registered trademark, available from Dow Chemical Company), Amberlite (registered trademark, available from Rohm & Haas Company), and Amberlyst (registered trademark, available from Dow Chemical Company), which have a sulfo group. More specifically, there can be mentioned Nafion NR50, Dowex 50WX2, Dowex 50WX4, Dowex 50WX8, Amberlite IR120, Amberlite IRP-64, Amberlyst 15, Amberlyst 36, and the like.
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, etc.) can also be used, and a combination of inorganic solid acids and organic solid acids can also be used.

The amount of catalyst relative to the silanol or carboxylic anhydride can be determined as desired, but the molar or weight ratio is usually about 0.00001 to 10, preferably about 0.0001 to 8, and more preferably about 0.0001 to 6.

In this embodiment, the reaction in the reaction step can be carried out in a liquid phase or gas phase state depending on the reaction temperature or reaction pressure. In addition, the reaction can be carried out in various conventionally known forms such as a batch type or a flow type reactor.
The reaction temperature is usually −20° C. or higher, preferably −10 to 300° C., and more preferably −10 to 200° C. When the reaction is carried out at room temperature in order to control the reactivity of the carboxylic acid anhydride, the temperature range of the 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 from 0.1 to 100 atm, preferably from 0.1 to 50 atm, and more preferably from 0.1 to 10 atm.
The reaction time depends on the amount of the raw material, the amount of the catalyst, the reaction temperature, the shape of the reaction apparatus, etc., but in consideration of productivity and production efficiency, it is usually 0.1 to 1200 minutes, preferably 0.1 to 600 minutes, more preferably about 0.1 to 300 minutes, even more preferably 5 to 200 minutes, and particularly preferably 5 to 120 minutes.

When the reaction is carried out in a liquid phase system, it can be carried out with or without a solvent. When a solvent is used, 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, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene; and ethers such as tert-butyl methyl ether and dibutyl ether. Two or more types can also be mixed and used. When the reaction is carried out in a gas phase, it can be carried out by mixing an inert gas such as nitrogen.

The reaction in the reaction step in this embodiment can also be carried out under microwave irradiation. In this reaction system, the dielectric loss coefficients of the raw materials, such as the carboxylic acid anhydride and acid catalyst, are relatively large 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.

In the microwave irradiation reaction, various commercially available devices equipped with contact or non-contact temperature sensors can be used. The microwave irradiation output, the type of cavity (multi-mode, single mode), the irradiation form (continuous, intermittent), etc. can be arbitrarily determined according to the scale, type, etc. of the reaction. The microwave frequency is usually 0.3 to 30 GHz. Among them, the IMS frequency band allocated for use in the industrial, scientific, or medical fields is preferable, and among them, the 2.45 GHz band, the 5.8 GHz band, etc. are more preferable.

In addition, in microwave irradiation reactions, a heating material (susceptor) that absorbs microwaves and generates heat can be added to the reaction system in order to heat the reaction system more efficiently. As the type of heating material, various types of materials known in the art, such as activated carbon, graphite, silicon carbide, and titanium carbide, can be used. In addition, a molded catalyst can be used that is made by mixing the catalyst and heating material powder described above and calcining the mixture using an appropriate binder such as sepiolite or hormite.

The reaction process in this embodiment can proceed in a closed reaction apparatus, but the reaction can also proceed more efficiently by making the reaction apparatus an open system and continuously removing the reaction products from the reaction system.

When a solid acid catalyst is used in the production method according to this embodiment, the catalyst can be easily separated and recovered after the reaction step by a method such as filtration or centrifugation.
Furthermore, the acyloxysilane produced can be easily purified by means commonly used in organic chemistry, such as distillation, recrystallization, column chromatography, etc.

The manufacturing method according to this embodiment may include a modification step in which, after producing acyloxysilane, the acyloxy group of the obtained acyloxysilane is converted to another functional group. The modification step can be performed using not only purified acyloxysilane, but also unpurified acyloxysilane. In other words, it is possible to convert the acyloxy group to another substituent in one pot by adding a modifying agent to a reaction solution containing acyloxysilane.

The modifying agent used in the modification step is not particularly limited as long as it reacts with an acyloxy group. For example, by using an alcohol as the modifying agent, the acyloxy group can be converted into an alkoxy group.
The alcohol may, for example, be an alcohol represented by the following general formula (IV). By reacting with the alcohol, the acyloxy group is converted to an alkoxy group represented by the following general formula (V).
R ⁵ OH (IV)
^-OR5 (V)

In the general formulas (IV) and (V), R ⁵ is an alkyl group having 1 to 6 carbon atoms. The number of carbon atoms of the alkyl group is preferably 1 to 4, more preferably 1 to 3. Specific examples of R ⁵ include a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, a pentyl group, and a hexyl group. Specific examples of the alcohol of the general formula (IV) having such a group include methanol, ethanol, isopropanol, tert-butanol, pentanol, and hexanol. Specific examples of the alkoxy group represented by the general formula (V) having such a group include a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, a pentyloxy group, and a hexyloxy group.

In the modification step, the reaction can be carried out in the presence of a basic compound or the like in order to promote the reaction. As such a basic compound, organic and inorganic basic compounds can be used. Specific examples of organic basic compounds include triethylamine, tripropylamine, diisopropylethylamine, dicyclohexylmethylamine, pyridine, and dimethylaniline. Specific examples of inorganic basic compounds include sodium carbonate, potassium carbonate, cesium carbonate, and potassium phosphate.
In the modification step, it is not necessary to isolate and purify the acyloxysilane produced in the reaction step, and the modification step and the reaction step can be carried out consecutively as a one-pot operation.

The amount of modifying agent can be selected at will, but the molar ratio relative to one acyloxy group in the acyloxysilane is usually 1 to 30, preferably 1 to 20, and more preferably 1 to 10. The reaction temperature can also be selected at will, but is usually -20°C or higher, preferably -10 to 300°C, and more preferably -10 to 200°C. The reaction time depends on the amount of acyloxysilane, the amount of basic compound, the reaction temperature, the form of the reaction apparatus, etc., but considering productivity and efficiency, it is usually about 1 minute to 72 hours, preferably 1 minute to 48 hours, and more preferably 1 minute to 24 hours.

The acyloxysilane provided by the production method according to the present embodiment has a highly reactive acyloxy group, and therefore is believed to be capable of efficiently carrying out reactions under mild conditions when used as a synthetic intermediate, a surface treatment agent, a sol-gel material, etc., and is therefore highly useful as a functional chemical.
For example, the surface treatment agent can rapidly treat the surface of solid materials such as glass under mild conditions at room temperature for a few minutes, and the hydrophilicity or hydrophobicity of the solid material surface can be easily controlled depending on the type of acyloxysilane used.
The acyloxysilane produced by the production method according to the present embodiment may be used as a surface treatment agent either alone or in combination of two or more kinds.
Furthermore, the method for producing acyloxysilane according to the present embodiment can easily produce various acyloxysilanes under mild conditions, and therefore the reaction solution containing acyloxysilanes can be used as a surface treatment agent as is without purification, which is also a feature of the method for producing acyloxysilane according to the present embodiment.
When an acyloxysilane is used as the surface treatment agent, it may be diluted with an organic solvent that does not react with acyloxysilane, such as toluene or hexane, if necessary.
Examples of methods for treating the surface of a solid material with an acyloxysilane-containing surface treatment agent include various conventional methods such as a dipping method, a casting method, a spin coating method, and a spray coating method.

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.
The main analytical instruments 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 Corporation GC-2014
Gas chromatograph mass spectrometry (hereinafter sometimes referred to as GC-MS): Shimadzu Corporation GCMS-QP2010Plus
Microwave irradiation reaction: Initiator 8 manufactured by Biotage

Example 1
Trimethylsilanol (Me ₃ SiOH) 1 mmol, acetic anhydride (Ac ₂ O) 2 mmol, iron (III) perchlorate hexahydrate (Fe (ClO ₄ ) _{3.6H 2} O) 0.005 mmol
The resulting mixture was placed in a reaction vessel and stirred at about 25° C. (room temperature) for 10 minutes. The product was analyzed by GC, GC-MS, and NMR, and the product yield was determined by NMR. As a result, (acetoxy)
It was found that trimethylsilane (Me ₃ SiOAc) was produced in yields of ≧99% (see Table 1-1).

(Examples 2 to 31, Comparative Examples 1 and 2)
The reaction and analysis were carried out in the same manner as in Example 1, but the reaction conditions (raw materials, catalyst, temperature, time, etc.) were changed. The product yields were measured by NMR, and the results are shown in Tables 1-1 to 1-3.

The notes in Tables 1-1 to 1-3 are as follows:
1) Me ₃ SiOH: Trimethylsilanol
_Et3SiOH : Triethylsilanol
_Ph2Si (OH) ₂ : Diphenylsilanediol
2) _Ac2O : acetic anhydride,
(EtCO) _2O : Propionic anhydride
(PhCO) _2O : Benzoic anhydride
3) Fe( _ClO4 ) _3.6H2O : Iron(III) _perchlorate hexahydrate
_FeCl3 : Iron(III) chloride
_FeBr3 : Iron(III) bromide
_RuCl3 · _H2O : Ruthenium(III) chloride hydrate
CBV780: USY zeolite (manufactured by Zeolist)
Sn4 ⁺ -mont: Sn4 ⁺ ion-containing montmorillonite (prepared by adding _SnCl4 to Na ⁺ ion-containing montmorillonite (Kunipia F, manufactured by Kunimine Industries Co., Ltd.) in water and exchanging the cations)
Amberlyst 15: H ⁺ type cation exchange resin (Dow Chemical Company)
4) The units are mmol if the catalyst is a homogeneous catalyst (Fe(ClO ₄ ) ₃ ·6H ₂ O, FeCl ₃ , FeBr ₃ , RuCl ₃ ·H ₂ O) and mg if the catalyst is a heterogeneous catalyst (solid acid catalyst, CBV780, Sn ⁴⁺ -mont, Amberlyst 15).
5) DCB: 1,2-dichlorobenzene.
6) 25°C indicates the reaction temperature at room temperature. For reactions at temperatures higher than room temperature, an oil bath (Riko Kagaku MH-5D) was used.
7) Me ₃ SiOAc: Acetoxytrimethylsilane
Me ₃ SiOCOEt: Trimethyl(propionyloxy)silane
_Et3SiOAc : Acetoxytriethylsilane
Me ₃ SiOCOPh: (benzoyloxy)trimethylsilane
AcO( _SiPh2O ) _mAc (m=1): Diacetoxydiphenylsilane
AcO( _SiPh2O ) _mAc (m=2): 1,3-diacetoxy-1,1,3,3-tetraphenyldisiloxane
AcO( _SiPh2O ) _mAc (m=3): 1,5-diacetoxy-1,1,3,3,5,5-hexaphenyltrisiloxane
AcO( _SiPh2O ) _mAc (m=4): 1,7-diacetoxy-1,1,3,3,5,5,7,7-octaphenyltetrasiloxane
8) Yield by NMR (yield of acyloxysilane product relative to silanol)
9) A microwave irradiation device (Biotage Initiator 8) was used.
10) Yield of siloxane product relative to carboxylic acid anhydride
11) A mixture of compounds having two acetoxy groups (monomer (m=1), dimer (m=2), trimer (m=3), and tetramer (m=4)). The figures in parentheses indicate the ratio of the monomer to tetramer compounds. Also,
The yield indicates the total yield.

(Example 32)
0.08 mL of the reaction solution containing 0.12 mmol (moles per SiPh ₂ O) of AcO(SiPh ₂ O) _m Ac (m=1-4, ratio of monomer to tetramer compounds was 38:51:8:3) obtained in Example 25 was dissolved in 0.4 mL of deuterated acetonitrile, and 1.2 mmol of methanol and 3.6 mmol of triethylamine were added thereto, followed by allowing to stand at room temperature for about 2 hours. The product was analyzed by GC, GC-MS, and NMR, and the product yield was measured by NMR, revealing that MeO(SiPh ₂ O) _m Me (m=1-4, ratio of monomer to tetramer compounds was almost the same as before the reaction) was produced in a yield of ≧99%.

^{The 29} Si-NMR and GC-MS measurement data of the acyloxysilanes and alkoxysilanes obtained in Examples 1 to 32 above are shown in Table 2.

The notes in Table 2 are as follows:
1) The names of the compounds are as described in footnote 7 of Tables 1-1 to 1-3 and below.
MeO( _SiPh2O ) _mMe (m=1): Dimethoxydiphenylsilane
MeO( _SiPh2O ) _mMe (m=2): 1,3-dimethoxy-1,1,3,3-tetraphenyldisiloxane
MeO( _SiPh2O ) _mMe (m=3): 1,5-dimethoxy-1,1,3,3,5,5-hexaphenyltrisiloxane
MeO( _SiPh2O ) _mMe (m=4): 1,7-dimethoxy-1,1,3,3,5,5,7,7-octaphenyltetrasiloxane
2) ^29Si NMR chemical shift values. _C6D6 was used as the NMR solvent. Cr( _acac ) ₃ (chromium(III) acetylacetonate) was added as a relaxation agent.
3) GC-MS: Gas chromatograph mass spectrometer, EI method: Electron impact ionization method (70 eV).
4) _CDCl3 was used as the NMR solvent.

In the production method of the present invention, the reaction proceeds efficiently by using a catalyst, and therefore the reaction proceeds easily even at low temperatures such as room temperature.
For example, in the reaction of trimethylsilanol ( _Me3SiOH ) with acetic anhydride ( _Ac2O ) in the absence of a catalyst, as shown in Comparative Examples 1 and 2, the yield of acetoxytrimethylsilane ( _Me3SiOAc ) was 0% or 1%, respectively, at 25°C for 160 minutes or at 80°C for 60 minutes, and almost no acyloxysilane was obtained.
On the other hand, in the method of the present invention using a catalyst, as shown in Example 1, Me 3 SiOAc could be obtained in a high yield of 99% or more in the presence of a catalytic amount ( _0.5 mol%) of Fe(ClO _{4 )} 3.6H ₂ O at 25° C. for 10 minutes.
These results demonstrate that the production method of the present invention makes it possible to efficiently produce acyloxysilanes in a short period of time even at room temperature.

Furthermore, in the production method of the present invention, the reaction can be accelerated by heating using microwave irradiation.
For example, in Example 18, in which the reaction was carried out using an oil bath heating device, trimethylsilanol (Me ₃ SiOH) and benzoic anhydride ((PhCO) ₂ O) in a molar ratio of 1:1 were reacted in the presence of 0.5 mol% Fe(ClO ₄ ) _{3.6H 2} O relative to the benzoic anhydride at 120° C. for 10 minutes to obtain (benzoyloxy)trimethylsilane (Me ₃ SiOCOPh) in a yield of 70%. In addition, in Example 20, in which the reaction was carried out in the same manner as in Example 18 except that the molar ratio of trimethylsilanol (Me ₃ SiOH) and benzoic anhydride ((PhCO) ₂ O) was 1:0.8 and the amount of catalyst was 0.6 mol% relative to the benzoic anhydride, (benzoyloxy)trimethylsilane (Me ₃ SiOCOPh) was obtained in a yield of 72%.
On the other hand, in Examples 19 and 21, the reactions were carried out under the same conditions as in Examples 18 and 20, respectively, except that a microwave irradiation device was used instead of an oil bath heating device. As a result, the yields of Me ₃ SiOCOPh were 74% and 77%, respectively.
These results show that the production method of the present invention can be carried out efficiently using a method that uses normal heating such as oil bath heating, but can be carried out even more efficiently by using microwave heating.

The manufacturing method of the present invention makes it possible to efficiently and safely produce acyloxysilanes, which are useful as functional chemicals, from silanols, making the present invention highly valuable and of great industrial significance.

Claims (10)

A method for producing an acyloxysilane having a Si-OCO bond (OCO represents an oxycarbonyl group, O-C(=O)), comprising a reaction step of reacting a silanol having a Si-OH bond with a carboxylic acid anhydride in the presence of a catalyst,
The method for producing acyloxysilane, wherein the catalyst is an acidic catalyst selected from the following (1) and (2):
(1) Perchlorates , bis (trifluoromethanesulfonylimide) salts, hexafluorophosphates , or bromides of elements selected from the elements of Groups 3 to 15 of the periodic table.
(2) Zeolite . The method according to claim 1, wherein the acid catalyst (1) is a compound containing a group 8 element. The method according to claim 2, wherein the Group 8 element is an element selected from iron and ruthenium. The method according to any one of claims 1 to 3 , wherein the silanol having a Si-OH bond is a silanol represented by the following general formula (I):
R ¹ _a R ² _b R ³ _c Si(OH) _4-(a+b+c) (I)
(In the formula, a, b, and c each independently represent an integer of 0 to 3; a+b+c represents an integer of 0 to 3; R ¹ , R ² , and R ³ each independently represent 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 having 1 to 24 carbon atoms may be substituted with a group that does not participate in the reaction.) The method according to any one of claims 1 to 4 , wherein the carboxylic acid anhydride is a carboxylic acid anhydride represented by the following general formula (II):
( ^R4CO ) _2O (II)
(In the formula, R ⁴ 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.) The method according to any one of claims 1 to 3, wherein the silanol having a Si-OH bond is a silane monool represented by the following general formula (I'), the carboxylic acid anhydride is a carboxylic acid anhydride represented by the following general formula (II), and the acyloxysilane produced is an acyloxysilane represented by the following general formula ( IIIA ):
R ¹ R ² R ³ Si(OH) (I')
(In the formula, 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.)
( ^R4CO ) _2O (II)
(In the formula, R ⁴ 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.)
^R1R2R3Si ( ^{OCOR4 )} ( ^IIIA )
(In the formula, R ¹ , R ² , R ³ , and R ⁴ are defined as above.) The method according to any one of claims 1 to 3, wherein the silanol having a Si-OH bond is a silanediol represented by the following general formula (I''), the carboxylic acid anhydride is a carboxylic acid anhydride represented by the following general formula (II), and the generated acyloxysilane is an acyloxysilane represented by the following general formula (IIIB):
^R1R2Si ( ^OH ) ₂ (I'')
(In the formula, R ¹ and R ² each independently represent 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 having 1 to 24 carbon atoms may be substituted with a group that does not participate in the reaction.)
( ^R4CO ) _2O (II)
(In the formula, R ⁴ 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 having 1 to 24 carbon atoms may be substituted with groups that do not participate in the reaction.)
( ^R4CO )O( ^{SiR1R2O )} _m ( ^COR4 ) (IIIB)
(In the formula, R ¹ , R ² , and R ⁴ are defined as above; and m is an integer of 1 to 20.) The method according to any one of claims 1 to 7 , wherein the reaction is carried out under microwave irradiation. 9. A method for producing an alkoxysilane, comprising: an acyloxysilane production step of producing an acyloxysilane by the production method according to any one of claims 1 to 8 ; and a modification step of reacting the acyloxysilane with an alcohol represented by the following general formula (IV) to convert an acyloxy group of the acyloxysilane into an alkoxy group:
R ⁵ OH (IV)
(In the formula, ^R5 is an alkyl group having 1 to 6 carbon atoms.) an acyloxysilane production process for producing an acyloxysilane having a Si-OCO bond (OCO represents an oxycarbonyl group, O-C(=O)), which comprises a reaction process of reacting a silanol having a Si-OH bond with a carboxylic acid anhydride in the presence of a catalyst; and
The method includes a modification step of reacting the acyloxysilane with an alcohol represented by the following general formula (IV) to convert the acyloxy group of the acyloxysilane into an alkoxy group,
The catalyst in the acyloxysilane production process is selected from the following (1) and (2):
The method for producing alkoxysilanes is characterized in that the acid catalyst is
R ⁵ OH (IV)
(Wherein, R ⁵ is an alkyl group having 1 to 6 carbon atoms.
(1) A perchlorate, trifluoromethanesulfonate, bis(trifluoromethanesulfonylimide) salt, hexafluorophosphate, chloride, or bromide of an element selected from the elements of Groups 3 to 15 of the periodic table; an inorganic acid; or an organic acid.
(2) Inorganic or organic solid acid compounds.