THE PREPARATION OF ALPHA,ALPHA-DISUBSTITUTED GLYCOLIC ACIDS

Several methods for the synthesis of glycolic acids of the type RRCOHCO2H, in which R and R are aryl, alkyl, or cycloalkyl groups equal or different, were investigated to find a practicable route not requiring use of Grignard reagents. Benzilic acid, 9-fluorenol-9 -carboxylic acid, and potassium 4,4-di-dimethylamino benzilate were obtained in yields of 82.5, 93.4, and 45.5, respectively, by the carbonation in dioxane of benzophenone disodioketyl, fluorenone disodioketyl, and dipotassioketyl of 4,4di-dimethylamino benzophenoneMichlers ketone. The conversion of 1,1-di-parachlorophenyl-1, 2,2,2-tetrachloroethane to 4,4dichlorobenzil in a 98.5 yield was effected by the action of sulfuric acid at from 65 degrees to 75 degrees C. A yield of 4,4-dichlorobenzilic acid was obtained by the benzilic acid rearrangement of 4, 4-dichlorobenzil. Cyclopentylphenylglycolic acid in 30 yield resulted from oxidation of 1-cyclopentyl-1-phenyl-2-propyn-1-o1. This method is unsatisfactory, however, because of poor yield and hazards encountered in the preparation of the propynol from acetylene and ketone. With desired-product yield only 18, the synthesis of a mixed acyloin as a glycolic acid precursor was unsatisfactory when aqueous potassium cyanide acted on an equimolar mixture of an acyloin and a benzoil.