PURPOSE: A mixture resulting from the self-condensation reaction of a succinic dialkyl ester is combined with an alkali metal bicarbonate and neutralized to produce the titled compound used as a starting material of quinacridone pigments with no side reaction in high yield.
CONSTITUTION: The self-condensation reaction of succinic dialkyl ester such as dimethyl succinate is effected in an organic solvent such as benzene or hexane in the presence of an alkali metal alcoholate such as methylate and the reaction mixture is pre-treated with an alkali metal bicarbonate. The reaction mixture is stood for cooling and the salt of succinosuccinic dialkyl ester is collected by filtration. The salt is neutralized by dropping it into an acidic aqueous solution to produce the objective succinosuccinic dialkyl ester, i.e., cyclohexa-1,4-diene-2,5-diol-1,4-dicarboxylic dialkyl ester.
IKEDA KASAKU
KOGA KUNITOSHI
HISAYUKI TERUMI
YAMAZAKI YOSHINORI
