Process for preparing 2,5-diphenylterephthalic acid by oxidation
AssigneeEastman Chemical Company
InventorsCharles E. Sumner, Jr., Bruce L. Gustafson, Ernest W. Arnold, III, Eric J. Fugate, Dewey W. Fuller, Jr.
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Abstract
Provided is a process for preparing 2,5-diphenylterephthalic acid, which is useful in preparing certain polyesters, especially liquid-crystalline polyesters. In this process, p-xylene is di-alkylated with cyclohexene to provide 2,5-dicyclo-hexyl-p-xylene, which is in turn dehydrogenated to provide 2,5-diphenylxylene. 2,5-Diphenylxylene is then oxidized to provide 2,5-diphenylterephthalic acid by utilization of a cobaltous/manganous/bromide oxidation system.
Claims5
A process for preparing 2,5-diphenylterephthalic acid, optionally substituted with one group selected from the group consisting of C.sub.1 -C.sub.10 alkyl, halo, nitro, a group of the formula --CO.sub.2 R.sup.4, and --OR.sup.4, wherein R.sup.4 is C.sub.1 -C.sub.4 alkyl;
- which comprises
- (a) di-alkylation of a compound of the formula ##STR4## wherein R.sup.3 is hydrogen, C.sub.1 -C.sub.10 alkyl, halo, nitro, or a group of the formula --CO.sub.2 R.sup.4 or --OR.sup.4, wherein R.sup.4 is C.sub.1 -C.sub.4 alkyl;
- with cyclohexene in the presence of an acid catalyst, to provide a compound of the formula ##STR5## wherein R.sup.1 is cyclohexyl;
- followed by (b) dehydrogenation in the presence of a Group VIII or Group IB catalyst, at a temperature of about 100.degree. C. to 500.degree. C., and at a pressure of about 0.01 to 30 atmospheres, to provide a compound of the formula ##STR6## wherein R.sup.2 is phenyl;
- followed by (c) oxidation in the presence of air or oxygen and a cobaltous bromide oxidation catalyst system, at a temperature of about 75.degree. C. to 250.degree. C., and at a pressure of about 10 to 1000 psig.
Dependencies are inferred from the claim text.