Catalytic deuterium exchange reactions with organics. XXIII. Deformylation during the deuteration of aromatic α-hydroxy acids and related compounds

Abstract

The transition-metal catalysed exchange of aromatic a-hydroxy acids with heavy water has been studied. Benzilic acid and its 00'-dichloro- and pp'-dimethyl derivatives simultaneously deformylate with the formation of the corresponding diary1 ketones. Mandelic acid and derivatives are stable under these conditions and only deuterate, whereas 9-hydroxyfluorene-9-carboxylic acid decomposes quantitatively to 9-fluorenol and 9-fluorenone. Benzhydrol decomposes appreciably to benzophenone. The effect of catalyst (soluble Fe, Co, Ni, Ru, Rh, Pd, Ir, and Pt chlorides versus insoluble oxides) and the method of catalyst activation (hydrogen, sodium borohydride, and self-activation) on the exchange and deformylation reactions have been studied. The results are interpreted in terms of a mechanism based on π-complex adsorption.