The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 16, 1994
Filed:
Nov. 04, 1993
Hermann-Josef Korte, Niederkassel, DE;
Anton Miletic, Troisdorf, DE;
Hans U Neutzler, Wetter, DE;
Anton Schoengen, Witten, DE;
Johann H Schroeder, Dortmund, DE;
Ralf Wirges, Niederkassel, DE;
Huls Aktiengesellschaft, Marl, DE;
Abstract
The invention relates to a process for the production of a DMT intermediate product as well as its working up to fibregrade DMT and to medium pure and pure terephthalic acid. The DMT intermediate product is moreover produced by combined oxidation of a predominantly para-xylene (p-X) and para-toluic acid methyl ester (p-TE) containing mixture in liquid phase with an oxygen containing gas, esterification of the acids being produced with methanol, distillative or rectificative separation of the esterification products being produced into a p-TE rich fraction I, a fraction II containing more than 99% by weight DMT and its isomers and a high boiling residue fraction III as well as feeding back the p-TE fraction I into the oxidation, with the residue fraction III having a DMT content of 15 to 70% by weight and the DMT fraction II being purified by single solvent recrystallisation in methanol to form the DMT intermediate product to such an extent that the amounts of hydroxymethylbenzoic acid methyl ester (HM-BME) and terephthalic acid methyl ester (TAE) in the DMT intermediate product amount together to less than 200 ppm.