Process for the preparation of aromatic methoxycarboxylic acid methyl esters

US5763641A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Willi Streicher · Krefeld, DE
• Hans-Joachim Laakmann · Leichlingen, DE

Key dates

• Filing date: Jan 17, 1997
• Grant date: Jun 9, 1998
• Expiry date: Jan 17, 2017

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C67/31
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

In a process, improved in respect of yield, purity and simple procedure, for the preparation of aromatic methoxycarboxylic acid methyl esters by methylation of the corresponding aromatic hydroxycarboxylic acids with dimethyl sulfate in the presence of water and a base, a procedure is followed in which the water, base and aromatic hydroxycarboxylic acid are initially introduced into the reaction vessel, 1 to 2.5 times the molar amount of dimethyl sulfate (based on the methylatable hydroxyl and carboxyl groups) is metered in and, during this procedure, the pH of the reaction mixture is controlled by addition of an aqueous base in finely divided form.