Purification of pphydroxybenzaldehyde

TLDR: In this article, an aqueous solution or solid of crude p-hydroxybenzaldehyde obtained by various processes, is dissolved in an organic solvent which is insoluble or slightly soluble in water and is a good solvent of the p -hydroxy benzaldehyde (e.g. diethyl ether, methyl isobutyl ketone).

Abstract: PURPOSE:To prepare the title compound useful as an intermediate of drugs, in high purity and yield, by treating an alkaline aqueous solution of p-hydroxybenzaldehyde successively with an organic solvent which is insoluble or slightly soluble in water, and with an alkaline aqueous solution, and crystallizing the objective compound at a specific pH. CONSTITUTION:An aqueous solution or solid of crude p-hydroxybenzaldehyde obtained by various processes, is dissolved in an organic solvent which is insoluble or slightly soluble in water and is a good solvent of the p-hydroxybenzaldehyde (e.g. diethyl ether, pref. methyl isobutyl ketone). The pH of the solution is adjusted to >=10 by adding an alkaline aqueous solution. After separating the mixture into two phases, the alkaline aqueous solution layer is added with a mineral acid to attain a pH value of 4-7, pref. 5.5-6.5. The crystallized p-hydroxybenzaldehyde is separated and purified.