Catalysts reversed micelle stabilized

The borohydride reduction of nickel decanoate in cyclohexane also produced a reversed micelle stabilized nickel boride cateilyst.37 The most active catalyst was formed using a 3 1 BH4 Ni ratio. This gave a catalyst that was about as active as the P-2 catalyst for alkene hydrogenation. The use of other BH4 Ni ratios gave less active catalysts. 

In abroad sense, the model developed for the cobaloxime(II)-catalyzed reactions seems to be valid also for the autoxidation of the alkyl mercaptan to disulfides in the presence of cobalt(II) phthalocyanine tetra-sodium sulfonate in reverse micelles (142). It was assumed that the rate-determining electron transfer within the catalyst-substrate-dioxygen complex leads to the formation of the final products via the RS and O - radicals. The yield of the disulfide product was higher in water-oil microemulsions prepared from a cationic surfactant than in the presence of an anionic surfactant. This difference is probably due to the stabilization of the monomeric form of the catalyst in the former environment. 

As shown by the data in Fig. 12.4 these micelle stabilized catalysts were considerably more active for alkene hydrogenation than the P-2 nickel borides. The hydrogenation run using a preformed P-2 catalyst in a reversed micelle medium proceeded at a faster rate than the reaction run over P-2 nickel boride in... 

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