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. 10, 1999
Filed:
Jan. 27, 1998
John Barry Henshall, Urmston, GB;
John Whitworth, Audenshaw, GB;
Ciba Specialty Chemicals Corporation, Tarrytown, NY (US);
Abstract
The invention provides a process for the preparation of 3-(N,N-dimethylamino)benzoic acid which comprises subjecting an aqueous solution of an alkali metal salt or ammonium salt of 3-aminobenzoic acid to reductive methylation in the presence of a supported transition metal catalyst, by the controlled and continuous addition of a solution of formaldehyde over a period of 0.5 to 20 hours with a hydrogen pressure between 1 bar and 40 bar and with the temperature of the reaction mass gradually raised during the reduction, the reaction being carried out within the temperature range of 20.degree. C. to 120.degree. C., and wherein a buffering agent is added such that the pH of the reaction mass after reductive methylation is from 6.5 to 9.5.