Summary Mandelic acid, labelled C14 in the a-position, was obtained from similarly labelled phenylglyoxal on treatment with alkali, thus demonstrating that no rearrangement of the carbon skeleton occurs and consequently that the reaction proceeds by a shift of the aldehydic hydrogen atom. The similar reaction of a, a-dibromoacetophenone with aqueous alkali has also been shown to occur without rearrangement.
