PROCESS FOR THE TREATMENT OF METHANOLIC-AQUEOUS RESIDUES AS A RESULT OF THE SYNTHESES WITH TRIPHENYL-PHOSPHONIUM SALTS

摘要

A process for treating residues which result from the Wittig synthesis of olefins and which consist principally of methanol, triphenylphosphine oxide, salts and organic by-products, by steam-stripping the volatile constituents, with partial condensation of the steam, and separating the resulting aqueous-organic mixture at 80 DEG -100 DEG C. into a saline aqueous phase and an organic phase containing principally triphenylphosphine oxide. Using this process provides a simple method of freeing, from triphenylphosphine oxide and other organic impurities, the effluent from syntheses which result in the formation of triphenylphosphine oxide, and thereby on the one hand substantially facilitates the purification of the effluent and on the other hand provides a simple method of recovering the triphenylphosphine oxide. The latter compound, which is easily purified by distillation or recrystallization, can then be used, for example, to prepare the triphenylphosphine required for Wittig syntheses or to prepare the triphenylphosphine dichloride required for the synthesis of pesticides.