Abstract: A process for preparing hexamethylcyclo-trisilazane by heating octamethylcyclotetra-silazane in the presence of a catalyst such as a Lewis acid or a sulfur compound of the following formula ##STR1## wherein M represents Ca, Mg, Al, Fe or NH.sub.4, R represents OH, a phenyl group or a substituted phenyl group, x is 0, 1 or 2 and y is 0, 1, 2 or 3 provided that x and y are not zero at the same time, and z is 0, 1, 2 or 3.

Abstract: Hexamethylcyclotrisilazane is prepared by reacting dimethyldichlorosilane with ammonia at a temperature between -20.degree. C. and 20.degree. C. Preferably, ammonia is blown into dimethyldichlorosilane at the temperature, and the reaction mixture is washed with 20% or higher alkaline water within one hour from the end of reaction for removing ammonium chloride by dissolving it in the water. Then hexamethylcyclotrisilazane of high purity is prepared in high yields. The method can be scaled up for commercial manufacture.

Abstract: The inventive compound 4-chloromethylphenyl methyl dichlorosilane is a novel compound not known in the prior art. The silane compound can readily be prepared by the chlorination of 4-tolyl methyl dichlorosilane with sulfuryl chloride as the chlorinating agent. The novel silane compound is useful as a component of an organochlorosilane mixture as the starting material of various kinds of silicone products or, in particular, silicone resins capable of exhibiting high performance, e.g. sensitivity for radiation-induced curing, not obtained by any combinations of known organochlorosilanes.