ISOMERIZATION OF DICHLOROTOLUENE

PURPOSE:To obtain 2,6-dichlorotoluene useful as an intermediate for pharmaceuticals, agricultural chemicals, dyes, etc., at an industrially usable concentration by an industrial process comprising the isomerization of a mixture of dichlorotoluene isomers using a specific zeolite catalyst. CONSTITUTION:A mixture of dichlorotoluene(DCT) isomers, especially a mixture of 2,4- and 2,5-DCT isomers produced in considerable amount as a by-product in the production of 2,6-DCT by the ring-chlorination of toluene or o- chlorotoluene is isomerized in the presence of a zeolite-based catalyst. The above process is carried out by using a TPZ-3 zeolite as the isomerization catalyst and isomerizing the isomers to 2,6-DCT at 200-550 deg.C, preferably 250-500 deg.C to convert the above byproduct into 2,6-DCT and effectively reuse the by-products. 2,6-DCT can be produced by the most effective industrial process comprising the ring-chlorination of toluene or o-chlorotoluene.