GB857128A - Production of alpha-hydroxy-beta, beta-dimethyl-gamma-butyrolactone - Google Patents

Abstract

a -Hydroxy-b , b -dimethyl-g -butyrolactone is purified by dissolving it in a water-immiscible solvent, adding thereto a quantity of alkali at least sufficient to produce the salt of the corresponding acid, separating the phases, adding an acid to the aqueous phase and heating to reform the lactone and recovering same, the amount of acid being sufficient to convert the salt to the lactone. The crude lactone may be in the form of an aqueous solution in which case the pH is first preferably adjusted with alkali to 6,5 to 6,8 before adding the solvent and the aqueous layer is preferably discarded before adding the alkali. The treatment with alkali is preferably effected below room temperature and a 5-20% solution may be used. The pure lactone may be recovered by adjusting the pH of the acidified aqueous solution to about 6,5 and extracting with an organic solvent. Suitable solvents for both stages include methylene chloride, ethylene chloride, isopropyl acetate and benzene. The lactone may be prepared by condensing isobutyraldehyde with formaldehyde in a solution comprising a mixture of water and a watermiscible organic solvent, e.g. a lower alkanol, in the presence of aqueous alkali cyanide in an amount sufficient to form formoisobutyraldol and at the same time provide cyanide requisite for the subsequent conversion of said formoisobutyraldol to its p cyanhydrin, thereafter adding an acidic substance more acid than HCN, e.g., HCl, substantially to neutralise the reaction mixture and promote the conversion to cyanhydrin. If the acid is considerably more acidic than HCN, e.g. at a pH of about 1-2, the cyanhydrin formation and its hydrolysis to lactone are carried out simultaneously. Otherwise the hydrolysis is effected subsequently with an acid at a pH of about 1-2.