
%0 Journal Article
%A Davis, KP 
%A Garnett, JL 
%T A comparison of homogeneous and heterogeneous platinum as catalysts for the deuteration of polyphenyl aromatic hydrocarbons
%J Australian Journal of Chemistry
%D 1975/08/01
%V 28
%N 8
%P 1713-1723
%K 
%R https://doi.org/10.1071/CH9751713
%U https://www.publish.csiro.au/paper/CH9751713 
%X Polyphenyl aromatic compounds exchange with heavy water in the presence of both homogeneous and heterogeneous platinum with high M values. Diphenyl, m- and p-terphenyls exhibit similar isotope orientations during initial rates in both catalytic systems whereas o-terphenyl does not. The first three compounds show ortho steric effects and appear to exchange by n-dissociative processes. In m- and p-terphenyls, the deactivated ortho protons exchange heterogeneously at rates which may be directly related to their degrees of steric hindrance. With o- terphenyl, all ortho hydrogens are deactivated in homogeneous exchange whereas heterogeneously, all centre ring ortho hydrogens exchange readily. A novel catalytic intermediate has been proposed to explain this orientation. These results show that o-terphenyl is a unique compound for differentiating between homogeneous and heterogeneous metal catalysed exchange processes. The data from the polyphenyls and the condensed polycyclics support the &#960;-complex theory of catalysis. 
