GB300040A - Improvements in the production of pure ª‡-hydroxycarboxylic acids - Google Patents

Abstract

300,040. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). Dec. 28, 1927. Cyanhydrins;a-hydroxycarboxylic acids.-The manufacture of a-hydroxycarboxylic acids bv the acid saponification of the corresponding nitrile is performed with a sufficient amount of water in the presence of an inert organic solvent or organic solvent mixture which is capable of dissolving the reagents and the reaction products, except the resulting ammonium salt. Suitable organic solvents are dioxane, ethyl ether, tetrachlorethane, chloroform. The nitriles may be prepared (by reaction of hydrocyanic acid with the correspond - ing aldehyde or ketone) in the inert, solvent afterwards required in the saponification, the water necessary for the saponification being added before or after the nitrile synthesis. In one example, acetaldehyde is led into a cooled mixture of dioxane, caustic soda solution, water, and hydrocyanic acid; the nitrile of lactic acid is formed and, when the reaction is complete, hydrogen chloride is led in to saponify the nitrile. The deposited ammonium chloride is filtered off and the dioxane is removed from the filtrate by distillation. In other examples, conducted similarly, benzaldehyde and propionaldehyde are used instead of acetaldehyde and the products are mandelic acid and a-hydroxybutyric acid respectively.