PURPOSE: After 3-nitrophthalic anhydride is subjected to chlorination, benzoylation and dehydrative ring closure with concentrated sulfuric acid, the reaction mixture is diluted with water until the concentration of sulfuric acid reaches a prescribed level and the product is selectively extracted with a solvent to produce the titled compound used as an intermediate of threne dyes.
CONSTITUTION: The reaction of 3-nitrophthalic anhydride with chlorine affords 3-chlorophthalic anhydride, which is subjected to condensation reaction with benzene in the presence of anhydrous aluminum chloride to give 2-benzoyl-3-chlorobenzoic acid. The dehydrative ring closure of the product is effected in concentrated or fuming sulfuric acid and the reaction mixture is diluted with water until the concentration of sulfuric acid becomes 75W90, preferably 80W83%. Then, 1-chloroanthraquinone is selectively extracted with a solvent such as chloroethylene. Further, after benzoylation and decomposition of the complex with diluted hydrochloric acid, the refluxing of the slurry together with an excessive amount of benzene and filtration after cooling give the objective compound of much improved quality.
YATABA TOORU
OOTA JIYOUSUKE
YAMAGUCHI TOYOHIKO
SUGAI CHEMICAL IND CO LTD
Next Patent: MANUFACTURE OF ORGANIC SATURATED FATTY ACID MONOCARBOXYLIC ACID