PURPOSE: To obtain the titled compound useful as an oxidation reduction type agent in high purity without isolating intermediates, by heat-treating benzophenone-2,4-dicarboxylic acid, etc. with a dehydrating and condensing agent and a sulfonating agent one after another.
CONSTITUTION: Benzophenone-2,4-dicarboxylic acid, benzophenone-2,5-dicarboxylic acid or 2-(p-carboxybenzoyl)benzoic acid is heated with a dehydrating and condensing agent, e.g. fuming sulfuric acid, and the resultant reaction mixture is subsequently heated with a sulfonating agent, e.g. fuming sulfuric acid, without isolating the formed 2-carboxyanthraquinone to give the aimed compound expressed by the formula (M is H, Na, K or ammonium). The isomers of the aimed compound are only two 2-carboxyanthraquinone-6-sulfonic acid and 2- carboxyanthraquinone-7-sulfonic acid, and the control in the preparation, purity analysis in use, etc. are easily carried out.
MITA RIYUUICHI
KATOU TOSHIO
HIGUCHI CHIYOUJIROU
MURAKAMI NAOMICHI
