Process for the separation of mixtures of m- and p-dichlorobenzene

摘要

Mixtures of m- and p-dichlorobenzene can be separated by treatment of such mixtures with a pentasil zeolite in the presence of a solvent combination at from 20 to 250 DEG C, a filtrate enriched with m-dichlorobenzene being taken off and the p-dichlorobenzene being recovered by extraction from the pentasil zeolite using the same solvent combination. The pentasil zeolites can contain protons, cations of the first or second main group of the Periodic Table (Mendeleev), cations of the rare earth metals or a mixture of a plurality thereof as exchangeable cations. The solvent combination comprises at least two different solvents originating from two groups A and B respectively, of which the representatives of the group A are substituted benzenes containing a halogen atom and one or two further substituents or at least two halogen atoms and optionally one further substituent and the representatives of the group B are substituted benzenes containing only one halogen atom and optionally one further substituent. For the representatives of the group A, 4-chlorotoluene and the dichlorobenzenes are excepted.