The Use of γ-Radiation for the Preparation of Supported Metal Complex Catalysts I. The Grafting of 4-Vinylpyridine to Polypropylene

The potential advantages of catalysts in which transition metal complexes are linked to inert supports have been outlined by many authors including ourselves1. Foremost amongst these is the greater ease of separation of the supported catalyst from the reaction mixture, as compared to its homogeneous counterpart. However, whilst some results obtained with supported catalysts have been very encouraging, for example in some instances the presence of the support has increased the specificity of the catalyst2–4, in general the activities of supported catalysts have been lower than those of their homogeneous counterparts. Again there have been exceptions to this5–9, which together with the increased specificity found in certain instances have encouraged an increasing number of workers to join in the search for supported catalysts. It is apparent from previous work that the factors that lead to high activity and high selectivity are generally fairly subtle, so that a large series of closely related, yet each slightly different, supported catalysts is essential if a thorough study is to be made of the factors involved. The technique of γ-irradiation grafting offers a potentially very convenient route for the preparation of such a series of supported catalysts due to the realtive ease with which different amounts of complex can be introduced into different regions of the polymer by modifying the radiation conditions.