METHOD FOR PRODUCING 1,4-DIHYDROXY-2-NAPHTHOIC ACID AND ITS ALKALI METAL SALT AND NEW CRYSTAL OF 1,4-DIHYDROXY-2- NAPHTHOIC ACID

摘要

PROBLEM TO BE SOLVED: To provide an industrially useful method for simply and efficiently producing a compound of formula (II) or its alkali metal salt without requiring high temperatures and high pressures, and an industrially useful new crystal of the compound of formula (II). ;SOLUTION: The alkali metal salt of 1,4-dihydroxynaphthalene is carboxylated with gaseous carbon dioxide in an amide solvent to produce the compound of formula (II) or its alkali metal salt. The alkali metal salt of the 1,4-dihydroxynaphthalene is obtained from the 1,4-dihydroxynaphthalene and subsequently carboxylated. The acid is then made to act on the alkali metal salt of the compound of formula (II) in the amide solvent in an amount of 1.5-2.5 pts.wt. based on 1 pt.wt. of 1,4-dihydroxynaphthalene. Thereby, the new crystal of the compound of formula (II) having 0.3-0.5 g/ml bulk density or 35-50 μm average particle diameter expressed in terms of D₅₀ (%) is produced.;COPYRIGHT: (C)2003,JPO