Method for producing cyclic silazane compound

Abstract

To provide a method for producing a cyclic silazane compound, which achieves a high reaction rate in a short time.SOLUTION: Provided is method for producing a cyclic silazane compound represented by the following general formula (2) (in the formula, R1 to R2 each independently represent a C1-10 unsubstituted primary hydrocarbon group; R3 represents a C1-10 primary hydrocarbon group which may have an amino group or an alkoxysilyl group; and m is 0, 1, or 2), comprising intramolecularly cyclizing an organoxysilane compound having a secondary amino group represented by the following general formula (1) (in the formula, R1 to R3 and m represent the same meanings as described above) in the presence of an equimolar or more basic compound selected from an organometallic compound or an organometallic amide compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a cyclic silazane compound. [Background technology]

[0002] The nitrogen-containing organoxysilane compounds are useful as silane coupling agents, surface treatment agents, resin additives, paint additives, and the like. Known examples of such nitrogen-containing organoxysilane compounds include organoxysilane compounds having a primary amino group such as aminopropyltrimethoxysilane, organoxysilane compounds having a secondary amino group such as N-phenylaminopropyltrimethoxysilane, and organoxysilane compounds having a tertiary amino group such as dimethylaminopropyltrimethoxysilane. Among these, organoxysilane compounds having a secondary amino group (hereinafter also referred to as "secondary aminosilane compounds") in particular can be derived into cyclic silazane compounds by intramolecular cyclization at the amino group and alkoxysilane moiety in the molecule.

[0003] Cyclic silazane compounds can reduce the amount of alcohol generated during hydrolysis compared to the corresponding secondary aminosilane compounds. In addition, since they do not have active hydrogen on the nitrogen, they are useful because they can provide a stable composition even when mixed with a resin having a functional group that can react with an amino group, as long as they are not in contact with alcohol or moisture. In addition, the Si-N structure in the cyclic silazane compound is highly reactive and is known to react quickly with moisture in the air or hydroxyl groups in the compound to open the ring, and therefore can be used as a surface treatment agent by reacting quickly with reactive hydroxyl groups on a metal surface, for example.

[0004] When a cyclic silazane compound is used as a surface treatment agent, various functions can be imparted to the object to be treated depending on the type of the substituent on the nitrogen. For example, hydrophobicity can be imparted in the case of a cyclic silazane compound having a hydrocarbon group such as a butyl, octyl, or phenyl group, hydrophilicity can be imparted in the case of a cyclic silazane compound having a hydrophilic functional group such as an amino group, and crosslinkability can be imparted in the case of a cyclic silazane compound having an alkoxysilyl group. Furthermore, since the cyclic silazane compound reacts quickly with moisture in the air, it also has excellent hydrolysis properties, and as a result of the progress of hydrolysis and condensation, a hardened coating can be formed.

[0005] As a method for synthesizing such a cyclic silazane compound, a method has been proposed in which a secondary aminosilane compound is distilled in the presence of a catalytic amount of an acid or a basic compound, and the alcohol generated by intramolecular cyclization is removed from the system under reduced pressure (Patent Documents 1 and 2). For example, in Patent Document 1, an intramolecular cyclization reaction is carried out in the presence of a basic substance, sodium methoxide, and in Patent Document 2, an intramolecular cyclization reaction is carried out in the presence of a basic substance, sodium amide or sodium methoxide. Also proposed is a method of intramolecularly cyclizing a secondary aminosilane compound in the presence of a catalytic amount of an acidic compound and a silylamine compound such as hexamethyldisilazane (Patent Document 3). This is an efficient synthesis method that can suppress reverse reactions by capturing the alcohol generated by intramolecular cyclization with the silylamine compound. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-102267 A [Patent Document 2] Chinese Patent No. 110862408 [Patent Document 3] JP 2015-160811 A Summary of the Invention [Problem to be solved by the invention]

[0007] The methods described in Patent Documents 1 and 2 change the equilibrium relationship between the secondary aminosilane compound and the cyclic silazane compound by physically removing the alcohol. However, these methods have the problem that the efficiency of removing the alcohol decreases with scale-up, and it takes time to produce the cyclic silazane compound, and the conversion rate from the secondary aminosilane compound to the cyclic silazane compound is not sufficient. In addition, in order to isolate the target cyclic silazane compound, it is necessary to separate the cyclic silazane compound from the raw secondary aminosilane compound by distillation purification, so there are problems that the isolation yield is not sufficient and distillation purification takes time, and there is also a problem that it cannot be applied to compounds that are unstable under acidic or basic conditions because it is heated for a long time in the presence of an acid or basic catalyst.

[0008] In particular, the method described in Patent Document 2 uses solid metal amide compounds (sodium amide, potassium amide, etc.) that are highly reactive and require careful handling. These reagents are poorly soluble in general organic solvents, and it is possible that a sufficient reaction rate will not be reached in a short time. In addition, metal amide compounds easily react with moisture in the air and are decomposed into metal hydroxides and ammonia. This metal hydroxide decomposes the cyclic silazane compound, while ammonia can react with the cyclic silazane compound or secondary aminosilane compound to polymerize, which may reduce the yield and purity. Furthermore, the metal amide compound reacts with the alcohol generated in the reaction to generate the cyclic silazane, and is decomposed into metal alkoxides and ammonia, and the generation of ammonia may also lead to a decrease in yield and purity.

[0009] In the method described in Patent Document 3, the equilibrium relationship between the secondary aminosilane compound and the cyclic silazane compound is changed by chemically converting the alcohol by reacting it with a silylamine compound. However, in order to increase the production rate of the cyclic silazane compound, it is necessary to remove the reaction product of the silylamine compound and the alcohol from the reaction solution, which has the same problem as Patent Document 1. In addition, since heating is performed under acidic conditions for a long period of time, the method cannot be applied to compounds that are unstable under acidic conditions, and a reaction product between a silylamine compound and an alcohol produced as the reaction proceeds reacts with a cyclic silazane compound, resulting in the problem that the target cyclic silazane compound cannot be obtained or the purity is reduced.

[0010] 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 producing a cyclic silazane compound which achieves a high reaction rate in a short period of time. [Means for solving the problem]

[0011] As a result of intensive research aimed at solving the above problems, the present inventors have found that a cyclic silazane compound can be efficiently obtained in a short time by intramolecularly cyclizing a secondary aminosilane compound in the presence of an equivalent or more of a basic compound obtained from an organometallic compound and an organometallic amide compound, and have thus completed the present invention.

[0012] That is, the present invention provides 1. The following general formula (1) [ka] (In the formula, R 1 and R 2 each independently represents an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms; R 3 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms which may have an amino group or an alkoxysilyl group, and m is 0, 1, or 2. Intramolecular cyclization of an organoxysilane compound having a secondary amino group represented by the following general formula (2): [ka] (In the formula, R 1 ~R 3 and m have the same meaning as above. A method for producing a cyclic silazane compound represented by the formula: 2. The method for producing a cyclic silazane compound according to claim 1, wherein the metal is at least one selected from the group consisting of lithium, sodium, potassium and magnesium. 3. A cyclic silazane compound having an alkoxysilyl group represented by the following general formula (3): [ka] (In the formula, R 1 and R 2 each independently represents an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms; R 4 and R 5 each independently represents an unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, m is 0, 1 or 2, and n is 0, 1 or 2. to provide. Effect of the Invention

[0013] According to the method for producing a cyclic silazane compound of the present invention, not only can a cyclic silazane compound be obtained simply and in a short time with a high reaction rate, but also a cyclic silazane compound having a structure that is difficult to synthesize by conventional methods can be synthesized. Furthermore, the resulting cyclic silazane compound can be used for various purposes depending on the substituent on the nitrogen. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 shows an IR spectrum of 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane obtained in Example 7. [Diagram 2] FIG. 1 shows the 1H-NMR spectrum of 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane obtained in Example 7. [Diagram 3] FIG. 1 shows an IR spectrum of 2,2-dimethoxy-N-trimethoxysilylmethyl-1-aza-2-silacyclopentane obtained in Example 9. [Figure 4]FIG. 1 shows the 1H-NMR spectrum of 2,2-dimethoxy-N-trimethoxysilylmethyl-1-aza-2-silacyclopentane obtained in Example 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be specifically described below. The method for producing a cyclic silazane compound represented by the following general formula (2) (hereinafter referred to as "compound (2)") of the present invention comprises intramolecularly cyclizing an organoxysilane compound having a secondary amino group represented by the following general formula (1) (hereinafter referred to as "compound (1)") in the presence of an equivalent or more of a basic compound selected from organometallic compounds and organometallic amide compounds.

[0016] [ka] (In the formula, m is 0, 1 or 2.)

[0017] Generally, when compound (1) is converted to compound (2), an alcohol is generated, but if the generated alcohol remains in the system, it will react with compound (2) to generate compound (1). In other words, as shown in the following scheme, compound (1) and compound (2) are in equilibrium. In the present invention, the compound (2) is subjected to intramolecular cyclization in the presence of a basic compound, and the alcohol generated from the compound (2) is converted into a metal alkoxide (R 1 O - ), making it difficult for the reverse reaction from compound (2) to compound (1) to occur. This shifts the equilibrium in favor of the production of compound (2), allowing compound (2) to be obtained.

[0018] [ka] (In the formula, m is 0, 1 or 2.)

[0019] In the above general formula (1), R1 and R 2 are each independently an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms. R 1 and R 2 The monovalent hydrocarbon group may be linear, branched, or cyclic, and specific examples thereof include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, and decyl groups; branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, neopentyl, thexyl, and 2-ethylhexyl groups; cyclic alkyl groups such as cyclopentyl and cyclohexyl groups; alkenyl groups such as vinyl, allyl, propenyl, butenyl, pentenyl, and octenyl groups; aryl groups such as phenyl and tolyl groups; and aralkyl groups such as benzyl and phenethyl groups. Among these, from the viewpoint of ease of procurement of raw materials, a methyl group and an ethyl group are preferred.

[0020] R 3 is a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms, which may have an amino group or an alkoxysilyl group. As the monovalent hydrocarbon group, R 1 Among these, from the viewpoint of ease of procurement of raw materials, a propyl group, a butyl group, an octyl group, an octenyl group, and a phenyl group are preferable.

[0021] R 3 When the monovalent hydrocarbon group contains an amino group, examples of the monovalent hydrocarbon group include aminoalkyl groups such as aminoethyl, aminopropyl, and aminooctyl groups; alkylaminoalkyl groups such as methylaminoethyl, ethylaminoethyl, butylaminoethyl, and tert-butylaminoethyl groups; dialkylaminoalkyl groups such as dimethylaminoethyl, diethylaminoethyl, morpholinoethyl, piperazinoethyl, and methylpiperazinoethyl groups; aminoalkylaminoalkyl groups such as aminoethylaminoethyl groups; and bis(trialkylsilyl)aminoalkyl groups such as bis(trimethylsilyl)aminoethyl groups. Among these, from the viewpoint of ease of procurement of raw materials, an aminoalkyl group is preferred, and an aminoethyl group is more preferred.

[0022] R 3 When the alkoxysilyl group is contained, examples of the monovalent hydrocarbon group include trialkoxysilylalkyl groups such as trimethoxysilylpropyl, triethoxysilylpropyl, trimethoxysilylmethyl, triethoxysilylmethyl, trimethoxysilyloctyl, triethoxysilyloctyl, trimethoxysilylethylphenylmethyl, and triethoxysilylethylphenylmethyl groups; alkyldialkoxysilylalkyl groups such as methyldimethoxysilylpropyl and methyldiethoxysilylpropyl groups; and dialkylalkoxysilyl groups such as dimethylmethoxysilylpropyl and dimethylethoxysilylpropyl groups. Among these, from the viewpoint of ease of procurement of raw materials, a trimethoxysilylpropyl group and a triethoxysilylpropyl group are preferred, and from the viewpoint of usefulness of the product, a trimethoxysilylpropyl group, a triethoxysilylpropyl group, a trimethoxysilylmethyl group and a triethoxysilylmethyl group are preferred.

[0023] Specific examples of compound (1) include alkylaminopropyltrialkoxysilane compounds such as butylaminopropyltrimethoxysilane, octylaminopropyltrimethoxysilane, allylaminopropyltrimethoxysilane, octenylaminopropyltrimethoxysilane, phenylaminopropyltrimethoxysilane, butylaminopropyltriethoxysilane, octylaminopropyltriethoxysilane, allylaminopropyltriethoxysilane, octenylaminopropyltriethoxysilane, and phenylaminopropyltriethoxysilane; butylaminopropylmethyldimethoxysilane, octylaminopropylmethyldimethoxysilane, allylaminopropylmethyldimethoxysilane, and octenylaminopropyltriethoxysilane; alkylaminopropyl alkyldialkoxysilane compounds such as propylmethyldimethoxysilane, phenylaminopropylmethyldimethoxysilane, butylaminopropylmethyldiethoxysilane, octylaminopropylmethyldiethoxysilane, allylaminopropylmethyldiethoxysilane, octenylaminopropylmethyldiethoxysilane, and phenylaminopropylmethyldiethoxysilane; alkylaminopropyl dialkylalkoxysilane compounds such as butylaminopropyldimethylmethoxysilane, octylaminopropyldimethylmethoxysilane, allylaminopropyldimethylmethoxysilane, octenylaminopropyldimethylmethoxysilane, and phenylaminopropyldimethylmethoxysilane;Aminoethyl aminopropyl trimethoxysilane, aminoethyl aminopropyl triethoxysilane, aminoethyl aminopropyl methyl dimethoxysilane, aminoethyl aminopropyl methyl diethoxysilane, aminopropyl aminopropyl trimethoxysilane, aminopropyl aminopropyl triethoxysilane, aminopropyl aminopropyl methyl dimethoxysilane, aminopropyl aminopropyl methyl diethoxysilane, dimethylaminoethyl aminopropyl trimethoxysilane, diethylaminoethyl aminopropyl trimethoxysilane, morpholinoethyl aminopropyl trimethoxysilane, piperazinoethyl aminopropyl trimethoxysilane, methylpiperazinoethyl aminopropyl trimethoxysilane, aminoethyl aminoethyl aminoalkylalkoxysilane compounds such as aminoethylaminopropyltrimethoxysilane and aminoethylaminopropyltriethoxysilane; bis(alkoxysilylalkyl)amines such as bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)amine, (trimethoxysilylpropyl)(trimethoxysilylmethyl)amine, (trimethoxysilylpropyl)(dimethylmethoxysilylmethyl)amine, (triethoxysilylpropyl)(triethoxysilylmethyl)amine, (triethoxysilylpropyl)(dimethylethoxylmethyl)amine, (trimethoxysilylpropyl)(trimethoxysilyloctyl)amine, and (triethoxysilylpropyl)(triethoxysilyloctyl)amine;

[0024] The basic compound used in the production method of the present invention is selected from organometallic compounds and organometallic amide compounds. Specific examples of the organometallic compound include organolithium reagents such as n-butyllithium, tert-butyllithium, and phenyllithium; and organomagnesium reagents including Grignard reagents such as isopropylmagnesium chloride, sec-butylmagnesium chloride, tert-butylmagnesium chloride, and thexylmagnesium chloride.

[0025] Specific examples of the organometallic amide compound include lithium amides such as lithium diisopropylamide, lithium isopropyl tert-butylamide, lithium di(tert-butyl)amide, and lithium hexamethyldisilazide; sodium amides such as sodium diisopropylamide, sodium isopropyl tert-butylamide, sodium di(tert-butyl)amide, and sodium hexamethyldisilazide; potassium amides such as potassium hexamethyldisilazide; and magnesium amides such as chloromagnesium diisopropylamide, chloromagnesium hexamethyldisilazide, and bromomagnesium hexamethyldisilazide. These organometallic compounds and organometallic amide compounds may be used alone or in combination of two or more. The basic compounds may be used alone or in combination of two or more.

[0026] Among these basic compounds, tert-butylmagnesium chloride, sodium hexamethyldisilazide, and chloromagnesium hexamethyldisilazide are preferred from the standpoint of reactivity and ease of handling.

[0027] The basic compound may be a commercially available product as it is, or may be prepared just before the reaction. However, in order to prevent the deactivation of these compounds, it is preferable to use a compound prepared just before the reaction. In this case, the preparation method of the basic compound can be a known method. For example, in the case of an organometallic compound, it can be prepared by mixing a metal such as lithium or magnesium with an alkyl halide and causing a metal-halogen exchange reaction. On the other hand, in the case of an organometallic amide compound, it can be prepared by mixing a metal, a metal hydride, an organometallic compound, or the like with an amine compound.

[0028] In the production method of the present invention, the basic compound may be used as a solution. The solvent used in this case is not particularly limited as long as it does not react with compound (1) and compound (2) and does not inactivate the basic compound, and examples thereof include aromatic hydrocarbon solvents such as toluene and xylene; ether solvents such as diethyl ether, tetrahydrofuran, cyclopentyl methyl ether, 4-methyltetrahydropyran, and methyl-tert-butyl ether, and the like. These solvents may be used alone or in combination of two or more. In particular, tetrahydrofuran, cyclopentyl methyl ether, and 4-methyltetrahydropyran are preferred from the viewpoints of reactivity and yield. The amount of the solvent used is not particularly limited, but is preferably 100 to 3000 g, and more preferably 300 to 1000 g from the standpoints of economy and reactivity, relative to 1.0 mole of compound (1).

[0029] In addition to the above solvents, (iso)paraffin compounds such as hexane, octane, isooctane, decane, dodecane, isododecane, etc. may be used in combination. By using these compounds, the polarity of the reaction solution decreases, and the salt generated as the reaction proceeds is more likely to precipitate.

[0030] The amount of the basic compound used in the production method of the present invention is preferably 1.0 to 2.0 mol, more preferably 1.0 to 1.5 mol, and even more preferably 1.0 to 1.2 mol, per 1.0 mol of compound (1) from the viewpoint of reactivity.

[0031] The reaction temperature is not particularly limited, but is preferably from -10 to 150°C, more preferably from 0 to 100°C. The reaction time is not particularly limited, but is preferably 1 to 40 hours, and more preferably 1 to 20 hours. The above reaction is preferably carried out in an inert gas atmosphere such as nitrogen or argon in order to prevent hydrolysis of compound (1), compound (2) and the basic compound.

[0032] In addition, the metal alkoxide (R 1 O- ) can be further reacted to make the reaction proceed more efficiently. Specific examples of compounds capable of reacting with metal alkoxides include 2-chloropyridine, 2-bromopyridine, 2-chloropyrazine, 2-bromopyrazine, methyl 2-chlorobenzoate, ethyl 2-chlorobenzoate, 2-chloronitrobenzene, 4-chloronitrobenzene, 2-bromonitrobenzene, and 4-bromonitrobenzene.

[0033] When a compound capable of reacting with a metal alkoxide is used, the amount used is not particularly limited, but is preferably 1 to 1.5 mol, more preferably 1.05 to 1.2 mol, based on the generated alkoxide.

[0034] The above-mentioned manufacturing method of the present invention can produce a cyclic silazane compound having an alkoxysilyl group represented by the following formula (3) (hereinafter referred to as "compound (3)"). This compound (3) has an aminomethylalkoxysilyl structure in the molecule, which is much more reactive than an aminopropylalkoxysilyl structure, and therefore has a very high hydrolysis property, and is expected to be applied to fast-curing materials, etc.

[0035] [ka] (In the formula, R 1 , R 2 and m have the same meaning as above, and n is 0, 1 or 2.

[0036] In formula (3), R 4 and R 5 each independently represents an unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. Specific examples of this monovalent hydrocarbon group include the above-mentioned R 1 Among the groups exemplified above, those having 1 to 6 carbon atoms can be mentioned, with alkyl groups having 1 to 3 carbon atoms being preferred, and methyl and ethyl groups being more preferred.

[0037] Specific examples of compound (2) (including compound (3)) obtainable by the production method of the present invention include 2,2-dimethoxy-N-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-octyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-phenyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-allyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-octenyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-styryl-1-aza-2-silacyclopentane, and 2,2-dimethoxy-N-butyl-1-aza-2-silacyclopentane. -Aza-2-silacyclopentane, 2-methoxy-2-methyl-N-butyl-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-octyl-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-phenyl-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-allyl-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-octenyl-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-styryl-1-aza-2- Silacyclopentane, 2,2-diethoxy-N-butyl-1-aza-2-silacyclopentane, 2,2-diethoxy-N-octyl-1-aza-2-silacyclopentane, 2,2-diethoxy-N-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-N-allyl-1-aza-2-silacyclopentane, 2,2-diethoxy-N-octenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-N-styryl-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N cyclic silazane compounds having a hydrocarbon group, such as 2-butyl-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N-octyl-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N-phenyl-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N-allyl-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N-octenyl-1-aza-2-silacyclopentane, and 2-ethoxy-2-methyl-N-styryl-1-aza-2-silacyclopentane;2,2-dimethoxy-N-(aminoethyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-(aminoethyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-N-(aminoethyl)-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N-(aminoethyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(aminopropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(aminoethylaminoethyl)-1-aza-2-silacyclopentane, 2 Cyclic silazane compounds having amino groups, such as 2,2-dimethoxy-N-(dimethylaminoethyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(diethylaminoethyl)-1-aza-2-silacyclopentane, and 2,2-dimethoxy-N-(morpholinoethyl)-1-aza-2-silacyclopentane; 2,2-dimethoxy-N-(trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(trimethoxysilylmethyl)-1-aza-2-silacyclopentane, and 2,2-dimethoxy-N -(trimethoxysilyl octyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-(trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-(trimethoxysilyl octyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-N-(triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-N-(triethoxysilylmethyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-N-(triethoxysilyl octyl)-1-aza-2-silacyclopentane cyclic silazane compounds having a trialkoxysilylalkyl group, such as 2-ethoxy-2-methyl-N-(triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N-(triethoxysilyloctyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(trimethoxysilylthioethyl)-1-aza-2-silacyclopentane, and 2-methoxy-2-methyl-N-(trimethoxysilylthioethyl)-1-aza-2-silacyclopentane;2,2-dimethoxy-N-(methyldimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(methyldimethoxysilylmethyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(methyldimethoxysilyloctyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-(methyldimethoxysilyloctyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-N-(methyldiethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy -Alkyl dialkoxysilanes such as N-(methyldiethoxysilylmethyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-N-(methyldiethoxysilyl octyl)-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-N-(methyldiethoxysilyl octyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(methyldimethoxysilylthioethyl)-1-aza-2-silacyclopentane, and 2-methoxy-2-methyl-N-(methyldimethoxysilylthioethyl)-1-aza-2-silacyclopentane. Cyclic silazane compounds having alkyl alkyl groups; 2,2-dimethoxy-N-(dimethylmethoxysilylmethyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(dimethylmethoxysilyl octyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-(dimethylmethoxysilyl octyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(diethylmethoxysilyl octyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-(diethylmethoxysilyl octyl)-1-aza-2-silacyclopentane, Examples of the cyclic silazane compounds include cyclic silazane compounds having a dialkylalkoxysilylalkyl group, such as aza-2-silacyclopentane, 2,2-dimethoxy-N-(diphenylmethoxysilylhexyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-N-(diphenylmethoxysilyloctyl)-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-N-(diphenylmethoxysilyloctyl)-1-aza-2-silacyclopentane, and 2,2-diethoxy-N-(dimethylethoxysilylmethyl)-1-aza-2-silacyclopentane.

[0038] By the above series of reactions, a mixture of compound (2), a salt derived from a basic compound, and a solvent, and in some cases, a mixture further containing compound (1), is obtained. To isolate and purify the target compound (2) from this mixture, a purification method appropriately selected from those commonly used in organic synthesis, such as filtration, distillation, vacuum stripping, various types of chromatography, and treatment with an adsorbent, can be used. Among these, purification by distillation is preferred because it can highly purify the target product, and it is particularly preferred to filter out salts derived from metal compounds before distillation. EXAMPLES

[0039] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the examples and comparative examples, the reaction rate was determined by the following calculation from the area values ​​of the raw materials and the products obtained by gas chromatography analysis (hereinafter also referred to as GC analysis). (area value of compound 3) / (area value of compound 1 + area value of compound 3) x 100

[0040] [Example 1] Synthesis of 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane [ka] (In the formula, Me represents a methyl group. The same applies hereinafter.)

[0041] The inside of a four-necked glass flask equipped with a stirrer, a thermometer, and a reflux condenser was replaced with nitrogen, and 24.1 g of sodium hexamethyldisilazide (40% by mass solution in tetrahydrofuran (hereinafter abbreviated as "THF"), 0.0526 mol) was charged and cooled to 5°C. 17.1 g (0.0500 mol) of bis(trimethoxysilylpropyl)amine was added dropwise over 20 minutes and stirred at the same temperature for 5 minutes. Gas chromatography analysis of the reaction solution (hereinafter referred to as "GC analysis") showed that 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane was produced with a reaction rate of 99%.

[0042] [Example 2] Synthesis of 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane The inside of a four-necked glass flask equipped with a stirrer, thermometer, and reflux condenser was replaced with nitrogen, and 85.7 g of chloromagnesium hexamethyldisilazide (30% by mass solution of methyltetrahydropyran (hereinafter abbreviated as "MTHP"), 0.116 mol) was charged and heated to 60°C. 34.1 g (0.100 mol) of bis(trimethoxysilylpropyl)amine was added dropwise over one hour, and the mixture was aged at the same temperature for one hour. It was then aged at 100°C for one hour. GC analysis of the reaction solution showed that 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane had been produced with a reaction rate of 93%.

[0043] [Example 3] Synthesis of 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane The inside of a four-necked glass flask equipped with a stirrer, thermometer, and reflux condenser was replaced with nitrogen, and 76.2 g of tert-butyl magnesium chloride (18 mass% THF solution, 0.117 mol) was charged and heated to 60°C. 34.1 g (0.100 mol) of bis(trimethoxysilylpropyl)amine was added dropwise over one hour and aged at the same temperature for one hour. Then, it was aged under reflux for one hour. GC analysis of the reaction solution showed that 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane was produced at a reaction rate of 85%.

[0044] [Example 4] Synthesis of 2,2-dimethoxy-N-butyl-1-aza-2-silacyclopentane [ka]

[0045] The inside of a four-necked glass flask equipped with a stirrer, thermometer, and reflux condenser was replaced with nitrogen, and 58.1 g of sodium hexamethyldisilazide (40 mass% THF solution, 0.0127 mol) was charged. 31.0 g (0.124 mol) of N-butyl(trimethoxysilylpropyl)amine was added dropwise over 1 hour. The mixture was then stirred at 60°C for 2 hours. GC analysis of the reaction solution revealed that 2,2-dimethoxy-N-butyl-1-aza-2-silacyclopentane had been produced with a reaction rate of 92%.

[0046] [Example 5] Synthesis of 2,2-dimethoxy-N-(aminoethyl)-1-aza-2-silacyclopentane [ka]

[0047] The inside of a four-necked glass flask equipped with a stirrer, thermometer, and reflux condenser was replaced with nitrogen, and 58.1 g of sodium hexamethyldisilazide (40 mass% THF solution, 0.0127 mol) was charged. 22.4 g (0.100 mol) of aminoethylaminopropyltrimethoxysilane was added dropwise over one hour. The mixture was then stirred at 60°C for two hours. GC analysis of the reaction solution revealed that 2,2-dimethoxy-N-(aminoethyl)-1-aza-2-silacyclopentane had been produced with a reaction rate of 60%.

[0048] [Example 6] Synthesis of 2,2-diethoxy-N-triethoxysilyl octyl-1-aza-2-silacyclopentane [ka] (In the formula, Et represents an ethyl group, and the same applies below.)

[0049] The inside of a four-necked glass flask equipped with a stirrer, thermometer, and reflux condenser was replaced with nitrogen, and 73.0 g of sodium hexamethyldisilazide (40 mass% THF solution, 0.159 mol) was charged and cooled to 5°C. 72.1 g (0.145 mol) of (triethoxysilyl octyl) (triethoxysilylpropyl) amine was added dropwise over 1 hour and stirred at the same temperature for 1 hour. GC analysis of the reaction solution showed that 2,2-diethoxy-N-triethoxysilyl octyl-1-aza-2-silacyclopentane was produced with a reaction rate of 88%.

[0050] [Example 7] Synthesis of 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane [ka]

[0051] The inside of a four-necked glass flask equipped with a stirrer, a thermometer, and a reflux condenser was replaced with nitrogen, and 126.1 g of sodium hexamethyldisilazide (40 mass% THF solution, 0.2752 mol) was charged and cooled to 5° C. 99.3 g (0.250 mol) of (triethoxysilylmethyl)(triethoxysilylpropyl)amine was added dropwise thereto over 1 hour, and the mixture was stirred at the same temperature for 1 hour. GC-MS analysis of the reaction solution revealed that 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane was produced with a reaction rate of 97%. The reaction solution obtained was filtered and then distilled to obtain 54.0 g of 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane as a fraction with a boiling point of 105°C / 0.4 kPa. The compound obtained was analyzed by IR, 1 H-NMR analysis was performed, and the results are shown in Figures 1 and 2.

[0052] [Example 8] Synthesis of 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane The inside of a four-necked glass flask equipped with a stirrer, thermometer, and reflux condenser was replaced with nitrogen, and 85.7 g of chloromagnesium hexamethyldisilazide (30 mass% MTHP solution, 0.116 mol) was charged and heated to 60°C. 39.7 g (0.100 mol) of (triethoxysilylpropyl)(triethoxysilylmethyl)amine was added dropwise over one hour, and the mixture was aged at 100°C for one hour. GC analysis of the reaction solution showed that 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane had been produced with a reaction rate of 98%.

[0053] [Example 9] Synthesis of 2,2-dimethoxy-N-trimethoxysilylmethyl-1-aza-2-silacyclopentane [ka]

[0054] The inside of a four-necked glass flask equipped with a stirrer, a thermometer, and a reflux condenser was replaced with nitrogen, and 85.7 g of chloromagnesium hexamethyldisilazide (30% by mass MTHP solution, 0.116 mol) was charged and heated to 60°C. 31.3 g (0.100 mol) of (trimethoxysilylpropyl)(trimethoxysilylmethyl)amine was added dropwise over 1 hour, and the mixture was aged at 100°C for 1 hour. GC-MS analysis of the reaction solution revealed that 2,2-dimethoxy-N-trimethoxysilylmethyl-1-aza-2-silacyclopentane was produced at a reaction rate of 100%. The reaction solution obtained was filtered and then distilled, and 47.0 g of 2,2-dimethoxy-N-trimethoxysilylmethyl-1-aza-2-silacyclopentane was obtained as a fraction with a boiling point of 109°C / 0.8 kPa. The obtained compound was analyzed by IR, 1 H-NMR analysis was performed, and the results are shown in Figures 3 and 4.

[0055] [Comparative Example 1] Synthesis of 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane The inside of a three-necked glass flask equipped with a thermometer, a reflux condenser, and a distillation column was replaced with nitrogen, and 170.5 g (0.500 mol) of bis(trimethoxysilylpropyl)amine and 0.27 g (0.0050 mol) of sodium methoxide were charged. The mixture was then heated at 0.6 kPa and refluxed for 5 hours while collecting methanol in a deep-cold trap. The reaction solution was analyzed by GC, and the reaction rate was found to be 51%.

[0056] [Comparative Example 2] Synthesis of 2,2-dimethoxy-N-trimethoxysilylpropyl-1-aza-2-silacyclopentane The inside of a four-necked glass flask equipped with a stirrer, thermometer, and reflux condenser was replaced with nitrogen, and 170.5g (0.500 mol) of bis(trimethoxysilylpropyl)amine and 0.82g (0.0025 mol) of dodecylbenzenesulfonic acid were charged and heated to 130°C. 89.7g (0.500 mol) of N-trimethylsilyl-N-methylaniline was added dropwise over 1 hour, and the mixture was aged at the same temperature for 2 hours. At this point, the reaction solution was analyzed by GC to determine the reaction rate, which was 75%. The reaction mixture was then transferred to a three-necked glass flask equipped with a thermometer, reflux condenser, and distillation column, and aged for two hours while extracting the low-boiling component trimethylmethoxysilane. The reaction mixture was analyzed by GC, and the reaction rate was found to be 85%.

[0057] [Comparative Example 3] Synthesis of 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane The inside of a three-necked glass flask equipped with a thermometer, reflux condenser, and distillation column was replaced with nitrogen, and 99.3g (0.250 mol) or 99.4g (0.250 mol) of (triethoxysilylmethyl)(triethoxysilylpropyl)amine and 0.17g (0.0025 mol) of sodium ethoxide were charged. The mixture was then heated at 0.5 kPa and refluxed for 5 hours while collecting ethanol in a deep-cold trap. The reaction solution was analyzed by GC to determine the reaction rate, which was 33%. In addition, some of the raw materials had decomposed, producing low-boiling point compounds.

[0058] [Comparative Example 4] Synthesis of 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane The inside of a four-necked glass flask equipped with a stirrer, thermometer, reflux condenser, and distillation column was replaced with nitrogen, and 39.7g (0.100 mol) of (triethoxysilylmethyl)(triethoxysilylpropyl)amine, 0.33g (0.0010 mol) of dodecylbenzenesulfonic acid, and 44g of toluene were charged and heated to 130°C and refluxed. 17.9g (0.100 mol) of N-trimethylsilyl-N-methylaniline was added dropwise over 1 hour, and the trimethylethoxysilane produced at the same time was extracted together with toluene. The reaction solution was analyzed by GC, and the reaction rate was found to be 8%. In addition, as the reaction progressed, trimethylethoxysilane was produced, and disiloxane compounds were generated by reacting with the raw material (triethoxysilylmethyl)(triethoxysilylpropyl)amine or the product 2,2-diethoxy-N-triethoxysilylmethyl-1-aza-2-silacyclopentane.

[0059] Comparing Examples 1 to 3 with Comparative Examples 1 and 2, it can be seen that the production method of the present invention achieves a high reaction rate in a short time. In particular, in Comparative Example 1, the cyclization rate is insufficient, so it is necessary to separate the desired cyclic silazane compound from the raw material by distillation purification. In addition, in Comparative Example 2, a high conversion rate is not achieved unless an additional operation is performed to remove the low boiling point components generated by the reaction. Comparing Examples 7 and 8 and Comparative Examples 3 and 4, it can be seen that the production method of the present invention produces the target product with a good reaction rate, whereas the conventional method produces a very low reaction rate or causes side reactions.

[0060] In particular, the cyclic silazane compounds obtained in Examples 8 and 9 have an aminomethylalkoxysilyl structure in the molecule, which is known to be much more reactive than an aminopropylalkoxysilyl structure, and are therefore expected to be used in fast-curing materials due to their extremely high hydrolysis properties.

Claims

1. The following general formula (1) 【Chemistry 1】 (In the formula, R 1 and R 2 each independently represents an unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms; R 3 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms which may have an amino group or an alkoxysilyl group, and m is 0, 1, or 2. In the presence of an equivalent or more of a basic compound selected from an organometallic compound and an organometallic amide compound, an organoxysilane compound having a secondary amino group represented by the following general formula (2) is subjected to intramolecular cyclization, and an alcohol produced by the intramolecular cyclization is converted into a metal alkoxide: 【Chemistry 2】 (In the formula, R 1 ~R 3 and m have the same meaning as above. A method for producing a cyclic silazane compound represented by the formula:

2. 2. The method for producing a cyclic silazane compound according to claim 1, wherein the metal is at least one selected from the group consisting of lithium, sodium, potassium and magnesium.

3. The method for producing a cyclic silazane compound according to claim 1, wherein the basic compound is at least one selected from the group consisting of n-butyllithium, tert-butyllithium, phenyllithium, isopropylmagnesium chloride, sec-butylmagnesium chloride, tert-butylmagnesium chloride, thexylmagnesium chloride, lithium diisopropylamide, lithium isopropyl tert-butylamide, lithium di(tert-butyl)amide, lithium hexamethyldisilazide, sodium diisopropylamide, sodium isopropyl tert-butylamide, sodium di(tert-butyl)amide, sodium hexamethyldisilazide, potassium hexamethyldisilazide, chloromagnesium diisopropylamide, chloromagnesium hexamethyldisilazide and bromomagnesium hexamethyldisilazide.

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