Process for preparing imidazoles.

摘要

1. Process for the preparation of imidazoles of the formula (I) see diagramm : EP0018568,P6,F1 in which R**1 and R**2 denote hydrogen atoms or aliphatic, aromatic, araliphatic or cycloaliphatic radicals and R**3 denotes a hydrogen atom or an aliphatic, aromatic or heterocyclic radical, wherein acetalized alpha-dicarbonyl compounds of the formulae see diagramm : EP0018568,P6,F2 or see diagramm : EP0018568,P6,F3 in which R**4 represents an alkyl radical are treated with a strong acid and an aldehyde of the formula R**3 -CHO (IV) in the presence of water at temperatures of up to 100 degrees C, ammonia and/or ammonium salts are added to the acid mixture such that the pH value of the mixture is between 1 and 4, the reaction mixture is heated to from 20 to 140 degrees C, the pH value is brought to above 8.5 by addition of bases, and the imidazole formed is extracted from the aqueous reaction solution with an organic solvent.