Amoco Corporation

Mark W Meszaros

Thomas G Smith

Ibrahim Ghanayem

Carl A Udovich

John M Weis

E William Breder, Jr

Thomas E Nemo

A process is provided for transaralkylating a class of starting compounds comprised of aryl-substituted lower alkanes and aryl-substituted fused alkylene ring compounds to produce derivatives of such compounds wherein benzyl substituents thereof have different alkyl substituents compared to the starting compounds. The process is carried out by admixing such a starting compound with a lower alkyl-substituted aromatic compound under liquid phase conditions in the presence of a catalytically effective amount of a Friedel-Crafts catalyst. The process makes possible new and economical routes for synthesizing desired lower alkyl-substituted benzyl group containing compounds, such as 2,2-di(lower alkyl-substituted) phenyl propanes and 1,3,3-trimethyl-1-(lower alkyl-substituted)-phenyl indans. Thus, there is provided a three-step process for making dixylylpropane from alpha methyl styrene and also a two-step process for making 1,3,3,6-tetramethyl-1-o-xylyl indan from alpha-4-dimethyl styrene. Provided also is a process for preparing 3,3',4,4'-dixylylmethane from a mixture of isomeric dixylylmethanes.

Aromatic transformation process

A regioselective process is provided for preparing 4-bromo-o-xylene in an isomer mixture of 4-bromo-o-xylene and 3-bromo-o-xylene by combining a molar excess of bromine with o-xylene. The produced 3-bromo-o-xylene isomer preferentially reacts with the excess bromine to produce dibromo-o-xylenes. The weight ratio of the 4-bromo-o-xylene to the 3-bromo-o-xylene in the product isomer mixture can be as high as about 97:3. Concurrent production of alpha-bromo-o-xylene is avoided by conducting the admixing in either darkness or in sulfur dioxide solution. The dibromo-o-xylene by products are easily separated by subsequent vacuum distillation or similar expedients.

Preparation of 4-bromo-O-xylene using excess bromine

A regioselective process is provided for preparing 4-bromo-o-xylene in an isomer mixture of 4-bromo-o-xylene and 3-bromo-o-xylene by combining bromine with o-xylene in liquid sulfur dioxide medium. A bromine to o-xylene mole ratio of about 0.4:1 to about 1:1 is utilized at a temperature in the range of about -20.degree. C. to about 40.degree. C. While preferred temperatures are in the about -15.degree. C. to about -9.degree. C. range, temperatures above about -9.degree. C. can be used by maintaining the reactant solution under pressure. A product isomer mixture can be isolated by vacuum distillation. A 92:8 weight ratio mixture of 4-bromo-o-xylene and 3-bromo-o-xylene is thus obtainable.

Preparation of 4-bromo-o-xylene in liquid sulfur dioxide

A method of separating 3,3',4,4'-tetramethyldiphenyl ether from its solid mixture with 2,3,3',4'-tetramethyldiphenyl ether.

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Batavia, IL, United States of America

Mark W Meszaros