Process for preparing 2-arylbenzimidazole-5-sulfonic acids

US5473079A · kind A · utility

Assignee

• Merck Patent GmbH · DE

Inventors

• Ulrich Heywang · Darmstadt, DE
• Ingeborg Stein · Langen (Hessen), DE
• Ulrich Fechtel · Darmstadt, DE
• Michael Casutt · Pfungstadt, DE
• Gerald Faller · Bensheim, DE
• Hartmut Hartner · Weiterstadt, DE

Key dates

• Filing date: Oct 1, 1993
• Grant date: Dec 5, 1995
• Expiry date: Oct 1, 2013

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61P29/00
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

The invention relates to an improved process for preparing 2-arylbenzimidazole-5-sulfonic acids of the formula I, ##STR1## in which Ar is unsubstituted phenyl or phenyl substituted by one or more C.sub.1 -C.sub.6 alkyl or alkoxy groups and PA1 m is 1, 2 or 3, PA1 wherein o-phenylenediamine is reacted in the presence of sulfuric acid at between room temperature and 250.degree. C. with a benzoic acid derivative of the formula II EQU Ar(--X).sub.m II PA1 in which Ar and m are as above, and X is COO-alkyl, where alkyl is n-alkyl having from 1 to 6 C atoms, COOH, COCl, COBr or CN, and new arylbenzimidazole acids of the formula Ia ##STR2##