Correspondence between homogeneous and heterogeneous reactions

It took some time to adopt a similar view of other heterogeneous elimination and substitution reactions. Most efficient experimental tools have been found in stereochemical studies, correlation of structure effects on rates and measurement of deuterium kinetic isotope effects. The usual kinetic studies were not of much help due to the complex nature of catalytic reactions and relatively large experimental error. The progress has been made possible also by the studies of surface acid—base properties of the solids and their meaning for catalysis (for a detailed treatment see ref. 5). 

The analogy between homogeneous and heterogeneous eliminations and substitutions has been pursued further. Joint action of an acidic and a basic site, suggested quite early for the heterogeneous dehydration of alcohols [6], has been gradually accepted as a general mode of operation 

On solid acid—base catalysts, beside elimination, addition and substitution, some other reactions also proceed. Of these, especially skeletal isomerisation of hydrocarbons and double bond shift should be mentioned. The latter can influence the product composition in olefin-forming eliminations and thus distort the information on orientation being sought. 

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