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:
Mar. 25, 1986
Filed:
Apr. 18, 1980
Dynamit Nobel Aktiengesellschaft, Troisdorf, DE;
Abstract
A process for the production of a crude dimethyl terephthalate suitable for hydrolyzing into a fiber grade terephthalic acid involves separating a crude ester obtained from the production of dimethyl terephthalate by the Witten process by vacuum distillation at elevated pressure in a three-column series arranged distillation system. In the first distillation column of the system the crude is separated into a methyl p-toluate-rich fraction as head product; in a second column of the series, into a fraction rich in methyl ester of terephthalaldehydic acid as head product; and in a third distillation column, a crude dimethyl terephthalate fraction. The crude dimethyl terephthalate fraction has a methyl ester of terephthalaldehydic acid content of 0.01-0.1% by weight as a head product.