Process for preparing substituted phthalic anhydrides

Details Process for preparing substituted phthalic anhydrides Process for preparing substituted phthalic anhydrides

1987-07-27

1988-11-15

Raymond, Richard L.

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

549243, 549244, 549245, 549247, C07D30789

Patent

active

047851201

ABSTRACT:
Yield and assay (purity) improvements in the reaction of bromine and the Diels-Alder addition product of maleic anhydride and a conjugated diene in the presence of a nitrogenous acid acceptor are realized in the instant process. The heating time after completion of bromine addition is increased to more completely eliminate hydrogen bromide from the reaction medium and thereby drive the reaction to completion. Also, the type of catalyst selected for use is one which will yield a phthalimide by-product impurity having a boiling point which differs enough from the boiling point of the desired product to allow for distillative separation of the impurity and desired product.

REFERENCES:
patent: 4559405 (1985-12-01), Telschow
patent: 4560773 (1985-12-01), Telschow
Neuman et al., J. Am. Chem. Soc., vol. 63 (1941) pp. 1542-1544.

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