Improvements in and relating to methods of separating diorganodihalogenosilanes from mixtures of the latter and organotrihalogenosilanes

摘要

Diorganodihalogenosilane is obtained from a mixture of that silane and organotrihalogenosilane by reacting the mixture with a diorganodiacyloxysilane, the acyloxy radicals being derived from an aliphatic carboxylic acid, in a proportion such that there is present in the reaction mixture at least one mol. of the acyloxysilane per mol. of organotrihalogenosilane, and separating the diorganodihalogenosilane by distillation. The halogen atoms in the silanes may be chlorine, bromine or fluorine. The organo radicals may be alkyl, aryl, aralkyl, alkaryl or cycloaliphatic radicals, a number of which are specified, or hydrocarbon radicals containing inert substituents, e.g. halogen atoms. The acyloxy radicals may be derived from acetic, propionic or butyric acid, suitable diorganodiacyloxysilanes being dimethyl, diethyl and diphenyl silyl acetates, dimethyl silyl propionate and dimethyl silyl butyrate. It is preferred to have all the organo-radicals the same in the reaction mixture. Sufficient diorganodiacyloxysilane may be added to convert all the organotrihalogenosilane into organotriacyloxysilane. The reaction proceeds at room temperature or may be heated to accelerate the reaction. A catalyst such as triethanolamine triacetate may also be present in the reaction mixture. In the examples dimethyldichlorosilane is separated from a mixture of that silane and methyltrichlorosilane by reaction with dimethyldiacetoxysilane alone, and in the presence of triethanolamine triacetate. In a similar manner methylphenyldichlorosilane may be separated from phenyltrichlorosilane. Specification 575,667 is referred to.