Process for separating isomers of disubstituted benzenes and agents to be used therefor

A process for separating o, m- or p-isomers of a disubstituted benzene, comprising the steps of:

• (a) contacting a mixture of isomers of a disubstituted benzene with a substituted cyclodextrin, said disubstituted benzene selected from the group consisting of xylenes, dichlorobenzenes, chlorotoluenes, chloronitrobenzenes, nitrotoluenes, dinitrobenzenes, bromotoluenes, chlorobenzotrifluorides, aminothiophenols, divinylbenzenes, vinyltoluenes, aminobenzotrifluorides, bis(trifluoromethyl)benzenes, chlorobenzyl chlorides, flurorobenzyl chlorides, bromonitrobenzenes, fluoronitrobenzenes, difluorobenzenes, fluorotoluenes, fluoroanilines and fluorobenzonitriles, at least one of the hydrogen atoms contained in the hydroxyl groups of said cyclodextrin is substituted with a substituent selected from the group consisting of glucosyl, maltosyl, maltooligosaccharide residue, methyl, hydroxyethyl, hydroxypropyl, sulfonic acid, alkylenesulfonic acid and carboxyalkyl groups, so as to allow the isomers to form inclusion complexes with said substituted cyclodextrin in accordance with their inclusion complex-forming constants;
• and
• (b) extracting the isomers from said inclusion complexes, excluding the separation of xylene isomers with a substituted .alpha.-cyclodextrin.