| abstract |
PROBLEM TO BE SOLVED: To provide a method for producing a specific 2-arylbenzimidazolesulfonic acid useful as an ultraviolet filter in one step. SOLUTION: An o-phenylenediamine is reacted with an aryl carboxylic acid or an aryl carboxylic acid derivative in the presence of oleum dissolved in concentrated sulfuric acid to give a compound of the formula I (Wherein, Ar is a substituted or unsubstituted phenyl or naphthyl group, R is a C 1-8 alkyl or alkoxy group, n is 1, 2, 3, or 4, m is 1, 2, or 3, and o is 0. , 1 or 2) for producing 2-arylbenzimidazolesulfonic acid. |