| 摘要 |
PURPOSE:To obtain the titled compound useful as an intermediate for dyes, pigments, photosensitive materials, etc. in high yield, by carboxylating 1,4-naphthohydroquinone in the presence of water and an alkaline alkali metallic compound under a low pressure in a short time. CONSTITUTION:1,4-Dihydroxynaphthalene (1,4-naphthohydroquinone hereinafter abbreviated to NHQ) is reacted with gaseous carbon dioxide under pressure (preferably 1-50kg/cm<2>.G) in the presence of an alkaline alkali metallic compound, preferably an inexpensive alkaline sodium compound in an equimolar amount or more, preferably in a molar amount of 5-15 times that of NHQ expressed in terms of the alkali metal) and water (in an amount of 2 times or more, preferably 4-20 times that of NHQ) to give the aimed 1,4-dihydroxy-2- naphthoic acid. The presence of a reducing agent, e.g. a hydrosulfite, in the reaction suppresses the formation of by-products and improves the yield. The reaction temperature is within 100-200 deg.C, preferably 120-160 deg.C range. |
