| abstract |
PURPOSE: To recover the titled carboxylic acid having high tetracarboxylic acid content, in high efficiency, by oxidizing hydroxy-dicyclo-pentadiene with nitric acid, and carrying out the crystallization of the objective compound in two steps controlling the carboxylic acid concentration in the reaction liquid within a specific range. n CONSTITUTION: Hydroxy-dicyclopentadiene is added dropwise to a solution of nitric acid to effect the oxidation reaction of the compound, and the oxidation reaction liquid is optionally controlled to a carboxylic acid concentration of 30W 60wt% by distilling out a part of the nitric acid, and subjected to the first-stage crystallization to recover a tetracarboxylic acid mixture composed mainly of 2,3, 5-tricarboxy-cyclopentylacetic acid of formula. The filtrate of the first-stage crystallization process is adjusted to a carboxylic acid concentration of 30W60wt% by further distilling out a part of the nitric acid, and subjected to the second- stage crystallization to recover a tetracarboxylic acid mixture composed mainly of 1,2,3,4-cyclopentanetetracarboxylic acid in powdery form. n COPYRIGHT: (C)1985,JPO&Japio |