PREPARATION OF BENZALDEHYDEESULFONIC ACID

摘要

PURPOSE:To obtain the title compound which is a raw material for synthesis of dyes and pigments, by oxidizing a toluene derivative in the liquid phase in the presence of a bromide ion donor in a saturated lower fatty acid solvent under specific conditions to terminate the reaction at a conversion <= 70%. CONSTITUTION:A toluene derivative having one or two sulfonic acid groups directly bonded to the benzene nucleus is converted to a salt soluble in the reaction mixture. The salt is then oxidized with a molecular oxygen-containing gas in the liquid phase in the presence of a bromide ion donor in a solvent, e.g. a saturated lower fatty acid, preferably 2-4C, using a soluble cobalt salt in an amount of 0.005 the molar amount of the raw material, and the reaction is terminated at a conversion <= 70% to give benzaldehyde-sulfonic acid.