REMOVAL OF A SMALL AMOUNT OF METHYLENE CHLORIDE IN ACETONE BY EXTRACTIVE DISTILLA-TION EMPLOYING SALT AS SEPARATING AGENT

Abstract

Vapor-liquid equilibrium data at one atmosphere are studied for the system methylene chloride-acetone-salt. The salts ZnBr₂, ZnCl₂, KSCN, MnCl₂, Nal, CuCl₂, CaCl₂, NH₄NO₃ and LiNO₃ are examined to observe the salt effect on the methylene-chloride-acetone system. Effective salts are ZnBr₂, ZnCI₂ and KSCN, which are more soluble in acetone than are MnCI₂, Nal, CuCI₂, CaCI₂, NH₄NO₃ and LiNO₃. An increase of relative volatility of methylene chloride was observed by adding these salts. By extractive distillation with zinc bromide, high-purity acetone with a methylene chloride content of 0.09 (mole %) or less was obtained.