CS228499B1 - Process for the preparation of (3-bromopropyl) trichlorosilane and (3-bromopropyl) methyldichlorosilane - Google Patents

Abstract

The invention relates to a method for the production of (3-bromopropyl)trichlorosilane and (3-bromopropyl)methyldichlorosilane by the addition of trichlorosilane and methyldichlorosilane to allyl bromide under catalysis by chloroplatinic acid in the presence of a ligand of the general formula R4R2R3M, where R1 represents an alkyl C1 to C10 group, or an aryl C6 to C10 group or cyclohexyl and R2, R3 a hydrogen atom or R1, M a nitrogen or phosphorus atom. The reaction is carried out in the presence of an organosilicon cocatalyst of the general formula HSiR4R5R6, where R4 represents an alkyl or cycloalkyl to C10 group, an aryl C6 to C10 group, or an alkoxyl C1 to C8 group and R5, R8 a hydrogen atom or R4. After isolation of the non-polymeric starting and final substances, the catalytic system is reused in the next batch. The resulting (3-bromopropyl) substituted organosilicon silanes serve mainly as intermediates for the preparation of coupling agents between organic and inorganic substances and as raw materials for the preparation of some carbofunctional polysiloxanes.

Description

The invention relates to a process for the preparation of (3-bromopropylpropyl) trichlorosilane and (3-bromopropylpropyl) methyldichlorosilane by addition of trichlorosilane and methyldichlorosilane to allyl bromide under catalysis with chloroplatinic acid in the presence of a ligand of the formula

R ⁴ R ² R ³ M wherein R ¹ represents an alkyl C 1 -C 10 group, or an aryl C 6 -C 10 group or cyclohexyl and R ² , R ³ is hydrogen or R ¹ ,

M represents a nitrogen or phosphorus atom.

The reaction is carried out in the presence of an organosilicon cocatalyst of the formula HS ¹ R ⁴ R ⁵ R ⁶ , wherein R ⁴ represents an alkyl or cycloalkyl to C 10 group, an aryl C 6 to C 10 group,

A C 10 group, or an alkoxy C 1 -C 8 group, and R ⁵ , R ^{8 are} hydrogen or R ⁴ . After isolation of the non-polymeric starting and final materials, the catalyst system is reused in a subsequent batch.

The resulting (3-bromopropyl) substituted organosilicon silanes serve primarily as intermediates for the preparation of linkers between organic and inorganic substances and as raw materials for the preparation of some carbofunctional polysiloxanes.

The present invention relates to a process for the preparation of (3-bromopropyl) trichlorosilane and (3-bromopropylpropylmethyldichlorosilane) by adding trichlorosilane and methyldichlorosilane to allyl bromide in the presence of chloroplatinic acid, a nitrogen or phosphorus containing ligand and an alkyl- or aryl-substituted organosilicon cocatalyst.

It is known that hydrosilylation of allyl bromide with trichlorosilane or dichloromethylsilane is difficult due to the easy dehalogenation of allyl bromide to give propene and bromotrichlorosilane or bromodichloromethylsilane. This undesirable reaction is usually suppressed by the very slow addition of trichlorosilane to allyl bromide, so 72 hours are needed to complete one batch [J. Amer. Chem. Soc., 89, 1144 (1967)] and despite this arrangement the yields of (3-bromopropyl) trichlorosilane do not exceed 60%.

The process of the invention overcomes these drawbacks by increasing the yields of the desired (3-bromoalkyl) substituted organosilicon compounds while substantially reducing the reaction time. It has been found that (3-bromopropylpropyl) trichlorosilane and (3-bromopropyl) methyldichlorosilane can be prepared by adding trichlorosilane or methyldichlorosilane to allyl bromide under catalysis with chloroplatinic acid in the presence of a ligand of formula (I)

R ⁴ R ² R ³ M, (I) wherein R ¹ represents an alkyl C 1 to C 10 group, or an aryl C 6 to C 10 group or cyclohexyl and R ² , R ³ is hydrogen or R ¹ , M is nitrogen or phosphorus, The reaction is carried out in the presence of an organosilicon cocatalyst of formula II

HSiR ⁴ R ⁵ R ⁶ 6, (Π), wherein R ⁴ represents an alkyl or cycloalkyl to C 10 group, an aryl C 6 to C 10 group or an alkoxy L ^{1 to} C ⁵ group, R ⁵ , R ⁶ hydrogen or R ⁴ .

The addition can also be carried out by using the catalyst system again in the next batch after isolation of the non-polymeric final and starting materials.

The ratio of the reactants is governed by the stoichiometry of the reaction. Although it is preferred to use an equimolar mixture of allyl bromide and silane, an excess of one of the reactants may be employed. Chloroplatinic acid as a catalyst is used in mol. ratio to alkyl bromide in the range of 1: 10 ⁴ to 1: 10 ⁶ , is usually used in the form of an isopropanol solution, but other solvents may also be used. The relative molar ratio of chloroplatinic acid to ligand is preferably 1: 10 to 10: 1. the ratio of chloroplatinic acid to alkyl- or aryl-substituted organosilicon cocatalyst is preferably 1: 1 to 1: 1000.

The described reaction may optionally be carried out in the presence of a solvent, at normal pressure, or at the vapor temperature of the reaction components, or even at elevated initial pressure by the addition of an inert gas.

The resulting (3-bromopropyl) substituted organosilicon strong serves primarily as intermediates for the preparation of coupling agents between organic and inorganic substances and as raw materials for the preparation of some carbofunctional polysiloxanes.

The following examples illustrate the process of the invention without limiting or limiting it. The weights of the reaction components are given in molar parts.

Example 1

To the stirred reaction vessel was charged 0.02 parts of chloroplatinic acid as a 0.1 M solution in isopropanol, 0.02 parts of triethylamine. as a 0.01 M solution in toluene and 1 part diphenylsilane. After the catalyst solution was heated to 70 ° C, a mixture of 650 parts of allyl bromide and 700 parts of trichlorosilane was added dropwise over 2 hours. The reaction proceeded without an induction period and, after completion of the dropwise addition, the reaction mixture was kept under gentle boiling for a further 2 hours. After cooling, a yield of 72% (3-bromopropyl) trichlorosilane was found by gas chromatography.

Example 2

From the reaction mixture prepared according to Example 1, the low-boiling substances and (3-bromopropylpropyl) trichlorosilane were distilled off and the remaining catalyst solution was used in the next batch carried out according to Example 1, after which a 70% yield of (3-bromopropyl) trichlorosilane was found.

Example 3

Example 1 was repeated except that methyldichlorosilane was used instead of trichlorosilane. The reaction mixture showed (3-bromopropylpropylmethyldichlorosilane in 68% yield).

Examples 4 and 5

Example 1 was repeated except that other types of ligand were used instead of triethylamine. The yields of (3-bromopropyl) trichlorosilane are given in the table below:

Example Ligand Yield 4 methyldecylamine 74% 5 diphenylnaphthylphosphine 67% 5a cyclohexylamine % 89

Examples 6 to 9

Example Cocatalyst Yield Dimethyldecylsilane 65% Phenylnaphthylsilane 73% Triethoxysilane 60% Tripentoxysilane 61%

Claims (2)

Process for the preparation of (3-bromopropyl) trichlorosilane and (3-bromopropyl) methyldichlorosilane by addition of trichlorosilane and methyldichlorosilane to allyl bromide under catalysis with chloroplatinic acid in the presence of a ligand of the general formula I R 1 R ² R ³ M (I) wherein R ¹ represents an alkyl C 1 -C 10 group, or an aryl C 6 -C 10 group or cyclohexyl, and R ² , R ³ is hydrogen or R ¹ , M is nitrogen or phosphorus, The process according to claim 1, characterized in that the reaction is carried out in the presence of an organosilicon cocatalyst of the formula II HSiR ⁴ R ⁵ R ⁶ (II) wherein R ⁴ represents an alkyl or cycloalkyl to C 10 group, an aryl C 6 to C 10 group or an alkoxy C 1 to C 5 group and R 5, R 6 is hydrogen or R ⁴ . 2. Process according to claim 1, characterized in that after the isolation of the non-polymeric starting and final substances, the catalyst system is used again in a subsequent batch.