GB1215012A - THE PRODUCTION OF alpha-HYDROXY CARBOXYLIC ACIDS - Google Patents

Abstract

1,215,012. α-Hydroxy carboxylic acids. IMPERIAL CHEMICAL INDUSTRIES Ltd. 25 March, 1968 [5 April, 1967], No. 15686/67. Heading C2C. α-Hydroxy carboxylic acids are produced by contacting with free oxygen at a pressure to maintain the components in a liquid phase a solution comprising an aldehyde of formula RCH 2 CHO in which R is a hydrocarbon group containing at most 10 carbon atoms in which each of the carbon atoms is saturated or is contained in an aromatic ring; a heterocyclic aromatic compound containing a nitrogen atom in its aromatic ring; cupric ions; and water or a saturated alcohol having at most 4 carbon atoms, the solution being free from any base which has a pK value (in water at 20‹ C., at a concentration of 0À05 N) of less than 4. The cupric ions may be provided in the form of any cupric salt soluble in the reaction mixture, e.g. cupric sulphate, nitrate, chloride, bromide, iodide, acetate or benzoate or a soluble cupric carboxylate. The alcohol may be mono- or dihydric. The reaction may be carried out at a temperature between 30 and 130‹ C. and a pressure of 0À5 to 50 atmospheres may be employed. Preferably the solution should contain a low concentration of aldehyde, at most 50% by weight, which is fed into the reaction medium continuously during the course of the reaction to achieve a low standing concentration of aldehyde. In the examples the aldehydes used are n-butyraldehyde and propionaldehyde. Lactic acid and pyruvic acid are produced in minor amounts when the aldehyde used is nbutyraldehyde. The methylester of 2-hydroxy n-butyric acid is formed by reaction of 2- hydroxy n-butyric acid with diazomethane in Example 1. In Example 2 the product lactic acid is esterified with diazomethane to give methyl lactate.