PROCESS FOR PREPARING P-CHLOROTOLUENE AND/OR M- CHLOROTOLUENE

• Main Authors: ARPE, HANS-JUERGEN, MAYER, NORBERT, LITTERER, HEINZ
• Format: Patent
• Language: English; French
• Published: 21.07.1987
• Edition: 4
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; APPARATUS THEREFOR; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; GENERAL METHODS OF ORGANIC CHEMISTRY; METALLURGY; ORGANIC CHEMISTRY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; THEIR RELEVANT APPARATUS; TRANSPORTING

of the disclosure: The invention relates to a process for preparing p-chlorotoluene and/or m-chlorotoluene by ring-chlorina-tion of toluene by using the following two stages a) and b) when further processing the toluene chlorination product composed of mixed isomers: a) Isolation of p-chlorotoluene from a mixture of o-, mand p-chlorotoluene by selective adsorption of p-chloro-toluene onto a mesoporous or macroporous zeolite and subsequent desorption of p-chlorotoluene b) Treatment of an o-chlorotoluene-rich mixture of isomers with an isomerization catalyst. For the exclusive preparation of p-chlorotoluene first p-chlorotoluene is isolated and removed from the toluene chlorination product in stage a). The remaining mixed isomers are then treated in stage b) to increase their content of m- and p-isomers and then returned into stage a). For the preparation of m-chlorotoluene and, if appropriate, additionally of p-chlorotoluene first the toluene chlorination product is treated in stage b) to increase its content of m- and, if appropriate, p-isomer. p Chlorotoluene is then isolated in stage a) and returned to stage b), or, if appropriate, removed. The remaining mixture essentially comprising o- and m-isomers is separated by distillation or adsorption and o-chlorotoluene is then returned into stage b) and m-chlorotoluene is removed.