Method for preparing monohalogenosilanes

Abstract: This invention relates to a method for preparing a monohalogenosilane, R¹R²R³SiX which comprises the step of subjecting, to a rearrangement reaction, an organodisiloxane, (R¹R²R³Si)₂O and a polyhalogenosilane, R⁴ n SiX 4-n in the presence of active carbon or an ammonium salt, R⁵R⁶R⁷R⁸NY as a catalyst (wherein R¹, R², R³ and R⁸ each represents a hydrogen atoms or a monovalent hydrocarbon group; R⁴, R⁵, R⁶ and R⁷ each represents a monovalent hydrocarbon group, a part or whole of the hydrogen atoms in each hydrocarbon group may be substituted with other atoms or groups; X represents a halogen atom; Y represents a monovalent anion; n is 0, 1 or 2). The method permits the easy preparation of monohalogenosilanes, in a high yield, which are useful as starting materials for use in making silylating agents as well as a variety of organosilicon compounds without using any harmful hexaalkylphosphoric acid triamide type catalyst.

Description: The present invention relates to a method for preparing monohalogenosilane which is useful as a starting material for synthesizing a silylating agent or a variety of organosilicon compounds. Japanese Patent Provisional Publication 52-65226 discloses a method for preparing a monohalogenosilane from non-halogenated disiloxane. This method comprises the step of reacting a non-halogenated disiloxane, i. e., non-halogenodisiloxane with a polyhalogenosilane in the presence of a hexaalkylphosphoric acid triamide hydrochloride. However, it has recently been recognized that the hexamethylphosphoric acid triamide is a powerful carcinogenic substance and as a result, it becomes difficult to get and handle the same and to handle the waste liquor originated from the reaction. It is an object of the present invention to provide a method for easily preparing a monohalogenosilane in a high yield without using such hexaalkylphosphoric acid triamides which suffer from the foregoing disadvantages. The foregoing object of the present invention can effectively be achieved by providing a method for preparing a monohalogenosilane represented by the following general formula (IV): R¹R²R³SiX (IV) which comprises the step of subjecting, to a rearrangement reaction, an organodisiloxane represented by the following general formula (I): (R¹R²R³Si)₂O (I) and a polyhalogenosilane represented by the following general formula (II): R⁴ n SiX 4-n (II) in the presence of active carbon or an ammonium salt represented by the following general formula (III): R⁵R⁶R⁷R⁸NY (III) as a catalyst. The method of the present invention can be represented by the following reaction scheme: Wherein R¹, R² and R³ each independently represents a hydrogen atom or a monovalent hydrocarbon group in which a part or whole of the hydrogen atoms may be substituted with other atoms or groups; R⁴ represents a monovalent hydrocarbon group in which a part or whole of the hydrogen atoms may be substituted with other atoms or groups; X represents a halogen atom; n is O, 1 or 2; R⁵, R⁶ and R⁷ each independently represents a monovalent hydrocarbon group and R⁸ represents a hydrogen atom or a monovalent hydrocarbon group, a part or whole of the hydrogen atoms of the hydrocarbon group being optionally substituted with other atoms or groups; and Y represents a monovalent anion. The method for preparing a monohalogenosilane according to the present invention permits the easy preparation of monohalogenosilanes, in a high yield, which are useful as starting materials for use in making silylating agents as well as a variety of organosilicon compounds without using any harmful hexaalkylphosphoric acid triamide type catalyst. The present invention will hereinafter be explained in more detail with reference to the following preferred embodiments. In the organodisiloxane represented by the general formula (I) used as one of the starting materials, hydrogen atom or the monovalent hydrocarbon group represented by R¹, R² and R³. The monovalent hydrocarbon group is, for instance, a saturated or unsaturated non-cyclic aliphatic hydrocarbon group, cyclic aliphatic hydrocarbon group, aryl group or aralkyl group in which a part or whole of the hydrogen atom(s) may further be substituted with, for instance, halogen atoms and/or cyano group. Specific examples of such organodisiloxanes represented by the general formula (I) having substituents R¹, R² and R³ are 1,1,3,3-tetramethyldisiloxane, 1,1,3,3-tetradiisopropyldisiloxane, hexamethyldisiloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 1,3-diethynyl-1,1,3,3-tetramethyldisiloxane, 1,3-cyclohexyl-1,1,3,3-tetramethyldisiloxane, 1,3-dicyanoethyl-1,1,3,3-dimethyldisiloxane and 1,3-dimethyl-1,1,3,3-tetraphenyldisiloxane. In the polyhalogenosilane represented by the general formula (II) used as the other starting material, the monovalent hydrocarbon group in the definition of R⁴ is the same as those defined above in connection with R¹, R² and R³ of the organodisiloxane represented by the general formula (I). X represents a halogen atom and n is 0, 1 or 2. Specific examples of the polyhalogenosilanes used herein are dimethyldichlorosilane, dimethyldibromosilane, methyltrichlorosilane, diphenyldichlorosilane, phenyltrichlorosilane, methylphenyldichlorosilane, methylvinyldichlorosilane and tetrachlorosilane. In the ammonium salt represented by the general formula (III) used as the catalyst, R⁵, R⁶ and R⁷ each independently represents a monovalent hydrocarbon groups, and R⁸ represents a hydrogen atom or a monovalent hydrocarbon group. The monovalent hydrocarbon group is the same as those defined above in connection with R¹, R² and R³ of the organodisiloxane represented by the general formula (I). Examples of Y which represents a monovalent anion are chlorine, bromine, sulfate and perchlorate ions. Specific examples of the ammonium salts are tertiary ammonium salts such as trimethylamine hydrochloride, triethylamine hydrochloride, tri-n-butylamine hydrochloride and dimethylphenylamine hydrobromide; and quaternary ammonium salts such as tetra-n-butylammonium chloride, tetra-n-butylammonium bromide and tetramethylammonium sulfate. Examples of the subject compounds represented by the foregoing general formula (IV) include dimethylchlorosilane, dimethylvinylchlorosilane, allyldimethylchlorosilane, ethynyldimethylchlorosilane, cyanoethyldimethyldichlorosilane, methyldiphenylchlorosilane, diisopropylchlorosilane and trimethylbromosilane. The foregoing reaction is carried out by introducing, into a flask, an organodisiloxane and a polyhalogenosilane together with active carbon or an ammonium salt, adding a small amount of water and stirring the resulting reaction mixture for several hours. The reaction solution is then distilled to recover a monohalogenosilane. In this reaction, the amount of the active carbon or the ammonium salt used as the catalyst may widely vary, and it is in general added to the reaction system in an amount ranging from 0.001 to 80% by weight, preferably 0.1 to 10% by weight on the basis of the total weight of the starting materials. Moreover, the reaction temperature is desirably controlled to the range of from 0 to 200 °C, preferably 20 to 150 °C. This rearrangement reaction easily proceeds under an acidic condition and, therefore, it is effective, when the reaction proceeds at a slow rate, to add a small amount of water or a proton-type solvent to the reaction system to thus cause a reaction with the halogenosilane to give an acid. When a tertiary ammonium salt is used as the ammonium salt of the foregoing general formula (III), it is also possible to introduce, into a reactor, the ammonium salt in the form of a tertiary amine together with the foregoing two kinds of starting materials. In this case, the amine can be converted into the tertiary ammonium salt in vitro by adding an acid or water or a compound such as an alcohol which can generate an acid through the reaction with the polyhalogenosilane. The present invention will hereunder be explained in more detail with reference to the following non-limitative working Examples. Example 1: Preparation of Trimethylchlorosilane To a 1ℓ volume four-necked flask equipped with a stirring machine, a reflux condenser, a dropping funnel and a thermometer, there were added 324.8g (2.0 moles) of hexamethyldisiloxane, 271.0g (2.1 moles) of dimethyldichlorosilane and 10g of active carbon, followed by the dropwise addition of 1.8g (0.1 mole) of water through the dropping funnel at room temperature and stirring the mixture at that temperature for 5 hours. The reaction solution was then distilled to give 349.0g (yield = 80.3%) of trimethylchlorosilane. This substance was confirmed in terms of IR spectra, NMR spectra and mass spectra. NMR spectra is as follows; ¹HNMR(CDCl₃) : δ (ppm) (CH₃)₃SiCl (C H ₃)₃ ··· 0.40 (9H,s) Example 2: (1) Preparation of Dimethylvinylchlorosilane To a 1ℓ volume four-necked flask equipped with a stirring machine, a reflux condenser, a dropping funnel and a thermometer, there were added 372.8g (2.0 moles) of 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, 271.0g (2.1 moles) of dimethyldichlorosilane and 11.1g (0.05 mole) of tri-n-butylamine hydrochloride, followed by the dropwise addition of 1.8g (0.1 mole) of water through the dropping funnel at room temperature and stirring the mixture at that temperature for 5 hours. The reaction solution was then distilled to give 396.7g (yield = 82.2%) of dimethylvinylchlorosilane. This substance was confirmed in terms of IR spectra, NMR spectra and mass spectra. NMR spectra is as follows; ¹HNMR(CDCl₃) : δ (ppm) (CH₂=CH)(CH₃)₂SiCl (C H ₃)₂ ··· 0.44 (6H,s) (C H ₂=C H ) ··· 5.55 - 6.57 (3H,m) Example 3: (2) Preparation of Dimethylvinylchlorosilane The same procedures as those used in Example 2 were repeated except that 9.3g (0.05 mole) of tri-n-butylamine was substituted for the tri-n-butylamine hydrochloride used in Example 2 to give 388.8g (yield = 80.6%) of dimethylvinylchlorosilane. This substance was confirmed in terms of IR spectra, NMR spectra and mass spectra. NMR spectra is as follows; ¹HNMR(CDCl₃) : δ (ppm) (CH₂=CH)(CH₃)₂SiCl (C H ₃)₂ ··· 0.44 (6H,s) (C H ₂=C H ) ··· 5.55 - 6.57 (3H,m) Example 4: Preparation of Dimethylchlorosilane To a 1ℓ volume four-necked flask equipped with a stirring machine, a reflux condenser, a dropping funnel and a thermometer, there were added 268.7g (2.0 moles) of 1,1,3,3-tetramethyldisiloxane, 271.0g (2.1 moles) of dimethyldichlorosilane and 16.1g (0.05 mole) of tetra-n-butylammonium bromide, followed by the dropwise addition of 1.8g (0.1 mole) of water through the dropping funnel at room temperature and stirring the mixture at that temperature for 5 hours. The reaction solution was then distilled to give 283.5g (yield = 74.9%) of dimethylchlorosilane. This substance was confirmed in terms of IR spectra, NMR spectra and mass spectra. NMR spectra is as follows; ¹HNMR(CDCl₃) : δ (ppm) (CH₃)₂(H)SiCl (C H ₃)₂ ··· 0.49 (6H,d) ( H ) ··· 4.81 (1H,q) Example 5: Preparation of Allyldimethylchlorosilane To a 1ℓ volume four-necked flask equipped with a stirring machine, a reflux condenser, a dropping funnel and a thermometer, there were added 428.9g (2.0 moles) of 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 209.3g (1.4 moles) of methyltrichlorosilane and 5.5g (0.05 mole) of tetramethylammonium chloride, followed by the dropwise addition of 1.8g (0.1 mole) of water through the dropping funnel at room temperature and stirring the mixture at that temperature for 5 hours. The reaction solution was then distilled to give 415.4g (yield = 77.1%) of allyldimethylchlorosilane. This substance was confirmed in terms of IR spectra, NMR spectra and mass spectra. NMR spectra is as follows; ¹HNMR(CDCl₃) : δ (ppm) (CH₂=CHCH₂)(CH₃)₂SiCl (C H ₃)₂ ··· 0.40 (6H,s) (CH₂=CHC H ₂) ··· 1.71 - 1.84 (2H,m) (CH₂=C H CH₂) ··· 5.37 - 6.07 (1H,m) Example 6: Preparation of Cyanoethyldimethylchlorosilane To a 1ℓ volume four-necked flask equipped with a stirring machine, a reflux condenser, a dropping funnel and a thermometer, there were added 480.9g (2.0 moles) of 1,3-dicyanoethyl-1,1,3,3-tetramethyldisiloxane, 271.0g (2.1 moles) of dimethyldichlorosilane and 9.3g (0.05 mole) of tri-n-butylamine, followed by the dropwise addition of 1.8g (0.1 mole) of water through the dropping funnel at room temperature and stirring the mixture at 50 °C for 2 hours. The reaction solution was then distilled to give 407.6g (yield = 69.0%) of cyanoethyldimethylchlorosilane. This substance was confirmed in terms of IR spectra, NMR spectra and mass spectra. NMR spectra is as follows; ¹HNMR(CDCl₃) : δ (ppm) (CN-CH₂CH₂)(CH₃)₂SiCl (C H ₃)₂ ··· 0.48 (6H,s) (CN-CH₂C H ₂) ··· 1.17 (2H,t) (CN-C H ₂CH₂) ··· 2.40 (2H,t)

Claims: A method for preparing a monohalogenosilane represented by the following general formula (IV): R¹R²R³SiX (IV) (wherein R¹, R² and R³ each independently represents a hydrogen atom or a monovalent hydrocarbon group in which a part or whole of the hydrogen atoms may be substituted with other atoms and/or groups and X represents a halogen atom) comprising the step of subjecting, an organodisiloxane represented by the following general formula (I): (R¹R²R³Si)₂O (I) (wherein R¹, R² and R³ each independently represents a hydrogen atom or a monovalent hydrocarbon group in which a part or whole of the hydrogen atoms may be substituted with other atoms and/or groups) and a polyhalogenosilane represented by the following general formula (II): R⁴ n SiX 4-n (II) (R⁴ represents a monovalent hydrocarbon group in which a part or whole of the hydrogen atoms may be substituted with other atoms and/or groups; and X represents a halogen atom; and n is 0, 1 or 2) in the presence of active carbon or an ammonium salt represented by the following general formula (III): R⁵R⁶R⁷R⁸NY (III) (R⁵, R⁶ and R⁷ each independently represents a monovalent hydrocarbon group and R⁸ represents a hydrogen atom or a monovalent hydrocarbon group, a part or whole of the hydrogen atoms of the hydrocarbon group being optionally substituted with other atoms and/or groups; and Y represents a monovalent anion) as a catalyst. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the active carbon or the ammonium salt is used in an amount ranging from 0.1 to 10% by weight on the basis of the total weight of the organodisiloxane and the polyhalogenosilane. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the reaction temperature ranges from 20 to 150 °C. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the reaction is carried out under an acidic condition. The method for preparing a monohalogenosilane as set forth in claim 1 wherein, in the general formula (I), the substituent R¹, R² and R³ each represents a monovalent hydrocarbon group and the hydrocarbon group is a member selected from the group consisting of saturated or unsaturated non-cyclic aliphatic groups, cyclic aliphatic groups, aryl groups and aralkyl groups. The method for preparing a monohalogenosilane as set forth in claim 5 wherein a part of the hydrogen atoms of the hydrocarbon group is substituted with halogen atoms and/or cyano groups. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the organodisiloxane represented by the general formula (I) is a member selected from the group consisting of 1,1,3,3-tetramethyldisiloxane, 1,1,3,3-tetradiisopropyldisiloxane, hexamethyldisiloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 1,3-diethynyl-1,1,3,3-tetramethyldisiloxane, 1,3-cyclohexyl-1,1,3,3-tetrametyldisiloxane, 1,3-dicyanoethyl-1,1,3,3-dimethyldisiloxane and 1,3-dimethyl-1,1,3,3-tetraphenyldisiloxane. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the substituent R⁴ of the polyhalogenosilane represented by the general formula (II) is a hydrocarbon group selected from the group consisting of saturated or unsaturated non-cyclic aliphatic groups, cyclic aliphatic groups, aryl groups and aralkyl groups. The method for preparing a monohalogenosilane as set forth in claim 8 wherein a part of the hydrogen atoms of the hydrocarbon group is substituted with halogen atoms and/or cyano groups. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the polyhalogenosilane represented by the general formula (II) is a member selected from the group consisting of dimethyldichlorosilane, dimethyldibromosilane, methyltrichlorosilane, diphenyldichlorosilane, phenyltrichlorosilane, methylphenyldichlorosilane, methylvinyldichlorosilane and tetrachlorosilane. The method for preparing a monohalogenosilane as set forth in claim 1 wherein, in the general formula (III), the substituents R⁵, R⁶, R⁷ and R⁸ each represents a monovalent hydrocarbon group and it is a member selected from the group consisting of saturated or unsaturated non-cyclic aliphatic groups, cyclic aliphatic groups, aryl groups and aralkyl groups. The method for preparing a monohalogenosilane as set forth in claim 11 wherein a part of the hydrogen atoms of the hydrocarbon group is substituted with halogen atoms and/or cyano groups. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the substituent Y in the general formula (III) is a member selected from the group consisting of chlorine, bromine, sulfate and perchlorate ions. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the ammonium salt represented by the general formula (III) is a member selected from the group consisting of tertiary ammonium salts such as trimethylamine hydrochloride, triethylamine hydrochloride, tri-n-butylamine hydrochloride and dimethylphenylamine hydrobromide; and quaternary ammonium salts such as tetra-n-butylammonium chloride, tetra-n-butylammonium bromide and tetramethylammonium sulfate. The method for preparing a monohalogenosilane as set forth in claim 1 wherein the monohalogenosilane represented by the general formula (IV) is a member selected from the group consisting of dimethylchlorosilane, dimethylvinylchlorosilane, allyldimethylchlorosilane, ethynyldemithylchlorosilane, cyanoethyldimethyldichlorosilane, methyldiphenylchlorosilane, diisopropylchlorosilane and trimethylbromosilane.

Inventors: ENDO MIKIO SHIN-ETSU CHEMICAL, ISHIHARA TOSHINOBU SHIN-ETSU C, KUBOTA TOHRU SHIN-ETSU CHEMICA, KUROSAKI TADAO SHIN-ETSU CHEMI, ENDO, MIKIO, SHIN-ETSU CHEMICAL CO., LTD., ISHIHARA, TOSHINOBU, SHIN-ETSU CHEMICAL CO., LTD., KUBOTA, TOHRU, SHIN-ETSU CHEMICAL CO., LTD., KUROSAKI, TADAO, SHIN-ETSU CHEMICAL CO., LTD.
Applicants: SHINETSU CHEMICAL CO, SHIN-ETSU CHEMICAL CO., LTD.
Application year: 1991
Main classification: C07F7
IPC codes: B01J21, B01J31, C07F7, C07B61