A method for the production of pure, isomeric free dimethyl - 1 - (2 ', 4', 5 '- trichlorofluoromethane phenyl) - 2 - chlorine vinyl phosphate

摘要

1,210,630. Trichloro-α-(dichloromethyl)-aalkoxy benzoyl alcohols; pentachloroacetophenone isomers. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 3 Sept., 1969 [5 Sept., 1968 (2)]. No- 43537/69. Heading C2C. The invention comprises 2,4,5-trichloro-dichloromethyl)-α-alkoxybenzyl alcohols of the general formula in which R is a C 1 -C 4 alkyl group and their use in the separating of 2,2,2SP1/SP,4SP1/SP,5SP1/SP-pentachloroacetophenone from a mixture of the 2,2,2SP1/SP,4SP1/SP,5SP1/SP- and 2,2,2SP1/SP,3SP1/SP,6SP1/SP-pentachloro isomers The 2,2,2SP1/SP4SP1/SP,5SP1 /SP- pentachloroacetophenone is separated from such a mixture by reacting the mixture with a C 1 -C 4 alcohol in the presence of a catalytic amount of a mineral acid to form selectively an alkanol hemiketal of 2,2,2SP1/SP,4SP1/SP,5SP1 /SP- pentachloroacetophenone of the formula given above. This hemiketal crystallizes out and is separated and the 2,2,2SP1/SP,4SP1/SP,5- pentachloroacetophenone may be regenerated from the hemiketal by known methods, e.g. by heating or treatment with a base. The hemiketals referred to above may be converted to dimethyl - 1 - (2,4,5 - trichlorophenyl) - 2- chlorovinyl phosphate by reacting with trimethyl phosphate.