Process for the preparation of dichlorobenzenes

摘要

A process for separating ortho-, meta-, and/or para-dichlorobenzene from an isomeric mixture thereof which comprises: A. in a first step, distilling said isomeric mixture to distill over meta- and/or para-dichlorobenzene to leave behind ortho-dichlorobenzene which is separated off as bottoms product; B. in a second step, cooling the distillate from step A to a temperature of 10 DEG to 40 DEG C. whereby para-dichlorobenzene as a solid phase is obtained and separating said solid phase from liquid phase with which it is in admixture; C. in a third step, further cooling said liquid phase from step B to a temperature of -40 DEG to -5 DEG C. whereby to precipitate a second solid phase and separating said second solid phase from the liquid phase with which it is in admixture; D. in a fourth step, distilling the liquid phase from step C whereby to obtain an isomeric mixture as bottoms and an isomeric mixture as distillate; and E. removing m-dichlorobenzene from the distillate of step D.