Process for producing pyromellitic dianhydride

Details Process for producing pyromellitic dianhydride Process for producing pyromellitic dianhydride

1990-06-26

1993-07-06

Bereh, Mark L.

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C07D49304

Patent

active

052255727

ABSTRACT:
Pyromellitic dianhydride, useful as raw material for the manufacture of polyimides, is prepared in high yield and purity by the reaction of benzene derivatives such as ethylbenzene, diethylbenzenes, and triethylbenzenes with an ethylating agent in the presence of a Friedel-Crafts catalyst, the separation of tetraethylbenzenes from the reaction products by distillation, the separation of 1,2,4,5-tetraethylbenzene from other tetraethyl benzenes by differential centrifugal precipitation at -10 to -30 degrees Celsius, and the catalytic vapor-phase oxidation of tetraethyl benzenes, using a catalyst containing vanadium pentoxide and titanium dioxide.

REFERENCES:
patent: 3769360 (1973-10-01), Harper
patent: 3848012 (1974-11-01), Applegath
patent: 3925425 (1975-12-01), Draguez de Hault
patent: 4185040 (1980-01-01), Ward
patent: 4665200 (1987-05-01), Nakanishi et al.
Fessenden et al., "Organic Chemistry," second ed. pp. 474-483 (1982).
Ault, "Techniques and Experiments for Organic Chemistry, 4th ed." Allyn & Bacon (1983) pp. 62-85.
"Advanced Organic Chemistry, 3rd ed." Jerry Mar. (1985) pp. 479-484.
Chemical Abstracts, vol. 75 97929u (1971).

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