THE PREPARATION OF a, a-DISUBSTITUTED GLYCOLIC ACIDS

摘要

Several methods for the synthesis of glycolic acids of the type RR'C(0H)C0sub2H, 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 4,4,di-(dimethylamino)benzophenone1[Michler's ketone]. The con¬version of l,l-di-(parachlorophenyl)-l,2,2,2-tetrachloroethane to 4,4'dichlorobenzil in a 98.5% yield was effected by the action of sulfuric acid at from 65 degrees to 75 degrees C. A 39$ 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 l-cyclopentyl-l-phenyl-2-propyn-l-ol. 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 benzoin.