PROCESS FOR SEPARATING ORGANIC CHLOROPHOSPHINES

1,181,343. Resolving a mixture of organic chlorophosphines. KNAPSACK A.G. 10 May, 1968 [11 May, 1967], No. 22316/68. Heading C2C. A mixture of lower alkyl mono- and dichlorophosphines having from 1 to 3 carbon atoms, is resolved by saturating the mixture with hydrogen chloride, separating the resulting two liquid phases I and II, and isolating the dichlorophosphine from the lighter phase I and the monochlorophosphine from the heavier phase II by distillation. The monochlorophosphine-containing phase II may be further purified before distillation by saturating once again with hydrogen chloride and extracting once or twice with an inert solvent to give phases IIIa and IVa, and in the latter case, IIIb and IVb. The lighter phases IIIa and IIIb may then be added to phase I for distillation. The heavier phases IVa and IVb are mixed again with the inert solvent and boiled until the hydrogen chloride ceases to be evolved. Thereafter, the mixture is fractionally distilled to obtain two further liquid phases V and VI, the former being rejected or combined with the phases IVa and IVb, and the latter being distilled to obtain the pure monochlorophosphine. Inert solvents may be aromatic, aliphatic or cycloaliphatic hydrocarbons or halogenated hydrocarbons which are miscible with dichlorophosphine but which do not dissolve the HCl-addition product of the monochlorophosphine, e.g. toluene, xylene, cumene, heavy gasoline, decalin and chlorobenzene.