Bayer Aktiengesellschaft

Lanxess Deutschland Gmbh

Michael Herzhoff

Heinz U Blank

Karlfried Wedemeyer

Guido Steffan

Lutz Heuer

Erich Wolters

Otto Neuner

Bernhard Beitzke

Karl-Wilhelm Henneke

Kurt Klinkmann

Gerhard Burmeister

Uwe Boeger

Uwe Böger

The present invention relates to a process for the preparation of 4-isopropyl-3-methylphenol (p-thymol) from distillation residues of thymol production.

Method for producing parathymol

Optionally substituted benzyl-benzenes can be prepared by reaction of a benzyl alcohol of the formula ##STR1## with a benzene of the formula ##STR2## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 independently of one another denote hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, fluorine or chlorine, where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently of one another may also represent hydroxyl and R.sup.5 may additionally be C.sub.5 -C.sub.8 -alkyl,

Process for the preparation of optionally substituted benzyl-benzenes

In the preparation of 3,5-dichloro-.alpha.-methylstyrene by isopropylation of an m/p-dichlorobenzene mixture, isomerization of the resulting alkylation mixture, subsequent side chain bromination of the alkylation mixture and dehydrobromination of the resulting bromination mixture, the improvement which comprises reacting an excess of an m/p-dichlorobenzene mixture which contains at least 50% by weight of m-dichlorobenzene with isopropyl halide, isomerizing the resulting alkylation mixture under pressure in the presence of aluminum chloride until thermodynamic equilibrium has been attained, separating off the isomerized alkylation mixture from the unreacted m/p-dichlorobenzene mixture, and recycling the unreacted mixture for further reaction.

Process for preparing 3,5-dichloro-.alpha.-methylstyrene

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Michael Herzhoff