Method for the purification of dioxydiphthalic anhydride and ester intermediate made therein
AssigneeOccidental Chemical Corporation
InventorsWillis T. Schwartz, Frank J. Dinan, Jeffrey S. Stults
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Abstract
Crude mixtures of dioxydiphthalic anhydride containing alkali metal salts are purified by treating the crude mixture with an alkanol, such as n-butanol, to form the dioxydiphthalic acid diester; removing the insoluble alkali metal salts by filtration; removing the excess alkanol; and reconverting the dioxydiphthalic acid diester to dioxydiphthalic anhydride.
Claims13
A process for the purification of dioxydiphthalic anhydride which comprises
- (A) treating a crude mixture of dioxydiphthalic anhydride and alkali metal salts with an alkanol selected from C.sub.3 -C.sub.5 alkanols, to form the dioxydiphthalic acid diester thereof, the alkanol being present in sufficient excess to dissolve the diester;
- (B) removing the insoluble alkali metal salts from the crude reaction product of step (A);
- and
- (C) converting the dioxydiphthalic acid diester to dioxydiphthalic anhydride.
A process for the purification of a crude dioxydiphthalic anhydride mixture containing alkali metal salts which comprises:
- (A) treating a crude mixture of dioxydiphthalic anhydride and one or more potassium metal salts selected from the group consisting of potassium carbonate, potassium fluoride and potassium chloride, by reaction with n-butanol at a temperature of from about 70.degree. Celsius to reflux temperature to form the n-butyl diester of dioxydiphthalic acid and dissolve the n-butyl diester to produce a crude reaction product comprising a solution of the n-butyl diester of dioxydiphthalic acid in admixture with insoluble potassium salts;
- (B) filtering the crude reaction product of step (A) at a temperature of 100.degree. to 120.degree. to remove the potassium salts;
- and
- (C) converting the n-butyl ester of dioxydiphthalic acid to dioxydiphthalic anhydride.
A dioxydiphthalic acid ester characterized by the formula:
- ##STR6## where Z is n-butyl, one of R.sup.1 and R.sup.2 is H and one of R.sup.1 and R.sup.2 is n-butyl.
Dependencies are inferred from the claim text.