| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing in a single step a specific 2- arylbenzimidazolesulfonic acid useful as an ultraviolet filter. SOLUTION: This method for producing a 2-arylbenzimidazolesulfonic acid of the formula (I) [wherein, Ar is a (substituted) phenyl or naphthyl; R is a 1-8C alkyl or alkoxy; n is 1, 2, 3 or 4; m is 1, 2 or 3; and o is 0, 1 or 2] comprises reaction between o-phenylenediamine and an arylcarboxylic acid or a derivative thereof in the presence of an oleum dissolved in concentrated sulfuric acid.
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