PURIFICATION OF 1,2-DIHYDROXYBENZENE-3,5-DISULFONIC ACID ALKALI METAL SALT

摘要

PURPOSE:To obtain the objective compound in high purity and yield, by adding a polyaminocarboxylic acid to an aqueous solution of crude 1,2- dihydroxybenzene-3,5-disulfonic acid alkali salt, heating and concentrating the mixture, cooling the product and repeating recrystallization procedure. CONSTITUTION:Crude 1,2-dihydroxybenzene-3,5-disulfonic acid sodium salt is dissolved in water, adjusted to 4.0-4.0pH e.g. with sodium hydroxide and added with a polyaminocarboxylic acid. The mixture is concentrated by heating and cooled to obtain 1,2-dihydroxybenzene-3,5-disulfonic acid sodium salt as white crystal. A chelating agent such as ethylenediaminetetraacetic acid can be used as the polyaminocarboxylic acid and its amount is =10% of the starting raw material.