Oxidation in the Witten-Hercules process for preparing dimethyl terephthalate

US5869736A · kind A · utility

Assignee

• Huels Aktiengesellschaft · DE

Inventors

• Stefan Jelko · Haltern am See, DE
• Anton Schoengen · Witten, DE
• Hermann-Josef Korte · Haltern, DE
• Gerhard Franz · Marl, DE
• Hans-Guenther Srebny · Coesfeld, DE
• Thomas Jostmann · Dülmen, DE
• Frank Steding · Marl, DE

Key dates

• Filing date: Oct 14, 1997
• Grant date: Feb 9, 1999
• Expiry date: Oct 14, 2017

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C67/39
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process is provided for the oxidation of p-xylene and methyl p-tolulate with oxygen-containing gases in the Witten-Hercules process for preparing dimetyl terephthalate in at least two sequentially arranged stages and in the presence of a catalyst, wherein the process involves oxidizing p-xylene and methyl p-toluate with oxygen containing gases in at least two sequential stages in the presence of a catalyst, wherein the at least two sequential stages include at least one p-xylene rich stage and at least one methyl p-toluate rich stage, wherein at least one of the following steps (a) and (b) occurs: PA1 (a) in the at least one p-xylene rich stage at least a portion of p-xylene present is oxidized in the presence of 5 to 30% by mass of methyl p-toluate, based on a total amount of oxidation mixture in the at least one p-xylene rich stage; or PA1 (b) in the methyl p-toluate rich stage at least one of methyl p-toluate or p-toluic acid is oxidized in the presence of 2 to 30% by mass of p-xylene, based on a total amount of methyl p-toluate and p-toluic acid in the methyl p-toluate rich stage.