Synthesis of 4-substituted phthalic anhydrides

Details Synthesis of 4-substituted phthalic anhydrides Synthesis of 4-substituted phthalic anhydrides

1993-05-28

1994-06-21

Dentz, Bernard

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

560 80, 560 83, 560 86, 560 96, 562480, 562488, C07D30789

Patent

active

053229541

ABSTRACT:
Disclosed is a method of making a 4-substituted phthalic anhydride. A halomaleic (including halofumaric anhydride (or the acid or ester thereof) is made by the reaction of-maleic anhydride with chlorine or bromine. The halomaleic anhydride is reacted with a conjugated diene to form a first cycloadduct having the formula ##STR1## The first cycloadduct is heated to eliminate HX and produce a second cycloadduct having the formula ##STR2## The second cyclo adduct is dehydrogenated to produce a 4substituted phthalic anhydride which has the formula ##STR3## where R.sub.1, R.sub.2, and R.sub.4 are preferably H and R.sub.3 is preferably Cl or F.

REFERENCES:
patent: 4978760 (1990-12-01), Spohn
patent: 5003088 (1991-03-01), Spohn et al.
patent: 5049682 (1991-09-01), Tang et al.
patent: 5059697 (1991-10-01), Fertel et al.
Bergmann, J. Appl. Chem., 3, pp., 145-146 (1953).

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