ESTERIFICATION OF HALOSILANES

1359312 Esterifying halosilanes UNION CARBIDE CORP 7 Sept 1971 [8 Sept 1970] 41697/71 Heading C3S Halosilanes are esterified by reacting them with a sufficient amount of a monohydric alcohol to esterify at least 80% of the halogen atoms present in a reaction zone having a temperature sufficient to maintain both the reactants and the reaction products in the vapour state, and removing the said reaction products from the reaction zone in the vapour state. The reaction zone temperature is preferably at least 5‹ C. greater then the reaction product having the highest boiling point, working pressure is preferably atmospheric and contact time is preferably of the order of 0À1 to 40 seconds. Occluded hydrogen halide may be removed by condensing the reaction product into a solvent under reflux conditions, by condensing the reaction product and bubbling through it an inert gas, or by condensing the reaction product through a porous plate or packed porous bed which are subsequently sparged with an inert gas. Suitable preparation and recovery apparatus is described. In examples methyl trichlorosilane is esterified with methanol to give a mixture of methyl vichloromethoxysilane and methylchlorodimethoxysilane; trichlorosilane is esterified (a) with methanol to give a mixture of trimethoxy- and tetramethoxysilanes, (2) with ethylene glycol monoethylether to give a mixture of HSi(OC 2 H 4 OCH 3 ) 3 and Si(OC 2 H 4 OCH 3 ) 4 , (3) with ethanol to give a mixture of triethoxy and tetraethoxysilanes, (4) with butanol to give a mixture of tributoxy and tetrabutoxysilanes, and (5) with propanol to give a mixture of tripropoxy and tetrapropoxysilanes; beta-cyanoethyltrichlorosilane is esterified with ethanol to give a mixture of NC.CH 2 CH 2 SiCl(OC 2 H 5 ) 2 and vinyltrichlorosilane is esterified with propanol to give a mixture of vinyltripropoxy and vinylchlorodipropoxysilanes ; gamma - isocyanatopropyltrichlorosilanes esterified with methanol to give a mixture of and with minor amounts of (where n is 1 or 2); and phenyltrichlorosilane is esterified with ethanol to give a mixture of phenyltriethoxy and phenylchlorodiethoxysilanes.