Bayer Aktiengesellschaft

Volkmar Handschuh

Heinz U Blank

Heinz-Ulrich Blank

Bernhard Beitzke

Gunter Rauchschwalbe

Crude 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)propane (=tetramethyl-bisphenol A=TMBPA) can be purified by recrystallization, if C.sub.1 -C.sub.4 -monoalcohols with a water content of 2 to 40% by weight relative to the total weight of alcohol and water are used in an amount of 70 to 250% by weight, relative to the amount of TMBPA and the recrystallization is carried out at a temperature of 65.degree. to 150.degree. C.

Process for the purification of crude

A process for the preparation of cinnamic acid is provided by the present invention in which an optionally substituted benzaldehyde and alkali metal salt of carboxylic acid and/or alkali metal (bi) carbonate, as condensing agents, are heated up to a temperature of 100.degree.-220.degree. C. and thereafter there is introduced into the so heated mixture acetic anhydride in at least a stoichiometric amount based upon the amount of optionally substituted benzaldehyde employed. The process can be carried out by heating up a reaction mixture to 100.degree.-220.degree. C. which is free of acetic anhydride or one which contains acetic anhydride but less than a stoichiometric amount thereof based upon the amount of optionally substituted benzaldehyde.

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Burscheid, Germany

Volkmar Handschuh