Occidental Chemical Corporation

Frank J Dinan

Willis T Schwartz

Jeffrey S Stults

Roger A Wolfe

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.

Method for the purification of dioxydiphthalic anhydride and ester

This invention relates to novel fluorinated bis-imides of the formula ##STR1## where X is H or F. The compounds are useful as additives to enhance the properties of high performance polymers such as polyimides.

Highly fluorinated bis-imides

Bis-imides of dioxydiphthalic or oxydiphthalic anhydride, are characterized by the formula ##STR1## where Z is H, alkyl of 1-12 carbon atoms, or ##STR2## A is H, Cl, F, NO.sub.2, OH, CF.sub.3, alkyl, alkoxy, alkylaryl or aryloxy, wherein the alkyl groups are 1-6 carbon atoms and the aryl groups are 6-14 carbon atoms; alkenyl or alkynyl of 2-6 carbon atoms; or benzoyl; and Y is H, Cl, F, NO.sub.2, OH, or CF.sub.3 ; X is halogen; X' is hydrogen or halogen; or X and X' together represent an oxygen atom, forming a second ether linkage.

Bis-imides of dioxydiphthalic acid

Oxydiphthalic acid esters of the formula ##STR1## where Z is H or alkyl, and X is halo, X' is H or halo, or X and X' together represent an oxygen atom; are prepared by the esterification reaction of the corresponding halo-oxydiphthalic anhydride or dioxydiphthalic anhydride with an alkanol.

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Tonawanda, NY, United States of America

Frank J Dinan