Purification of substituted phthalic anhydrides

Details Purification of substituted phthalic anhydrides Purification of substituted phthalic anhydrides

1985-12-20

1987-03-17

Raymond, Richard L.

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

549243, 549245, 549246, C07D30789

Patent

active

046508805

ABSTRACT:
A process for purifying crude substituted phthalic anhydrides, e.g. 4-methylphthalic anhydride, derived from the dehydrogenation in the presence of bromine of a Diels-Alder addition product of a conjugated diene, e.g. isoprene, and maleic anhydride. In this process, a mixture of the crude, liquid substituted phthalic anhydride, e.g. 4-methylphthalic anhydride, and an alkali is heated to a temperature effective to reduce the impurities present in the crude substituted phthalic anhydride. Suitable alkalis can include sodium hydroxide and sodium carbonate. Mild alkalis are heated to a higher temperature, e.g. 130.degree. C. for sodium carbonate, whereas stronger alkalis are heated to a lower temperature, e.g. 90.degree. C. for sodium hydroxide.

REFERENCES:
patent: 2671054 (1954-03-01), Bump et al.

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