1H NMR study of deuteroexchange in styrene under the conditions of hydrocarboxylation catalyzed by palladium complexes

By the method of deuteroexchange in the process of styrene hydrocarboxylation, catalyzed by the complex PdCl2(Ph3P)2 (11O deg, carbon oxide pressure 2.0 MPa) it has been ascertained that terminal protons of unreacted substrate are to a noticeable extent replaced by deuterium, whereas no exchange of protons in α-position as to phenyl group is observed. Decrease of pressure and introduction of SnCl2 leads to proton exchange in both carbon atoms of vinyl group of styrene. The results obtained are interpreted as regards hydride mechanism of the process