Hydrogen nickel-catalyzed effect

The beneficial effect of hydrogen halides in nickel-catalyzed carboxylations was also explained as forming a hydridonickel complex as the true catalyst.155... 

Effect of Hydrogen on the Iron- and Nickel-Catalyzed Formation of Carbon from Benzene... 

As for heterogeneous catalysts, the addition of hydrogen is catalyzed by a large variety of materials, but synthetically useful procedures generally employ nickel or the platinum metals. In the latter case, the best results are obtained if the metal is finely divided over the surface of an inert support. Many materials can be used as catalyst supports, however, carbon or alumina are suitable for the majority of reactions. Calcium and barium carbonate or sulfate are also frequently used if less reactive catalysts are desired. The influence of the support is generally small compared to the effect of the metal3. The choice of metal is especially important when stereoselectivity is desired because different metals can catalyze the formation of different diastereomers upon hydrogenation. 

Chemiluminescence reactions Chemiluminescence reactions are usually redox reactions. The catalytic effect is reflected in the release of radiant energy. The best known of this type of reaction is the oxidation of luminol (5-amino-2,3-dihydrophthalazine-l,4-dione) by hydrogen peroxide, catalyzed by metal ions such as cobalt(II), copper(II), iron(II), nickel(II), chromi-um(III), and manganese(II) at pH 10-11. Detection limits of 10 to 10 mol 1 are readily achieved this way. Luminol is converted into a doubly charged anion that is subsequently oxidized to an excited singlet state that emits radiation on decomposing to... 

The uncatalyzed addition of hydrogen to an alkene although exothermic is very slow The rate of hydrogenation increases dramatically however m the presence of cer tain finely divided metal catalysts Platinum is the hydrogenation catalyst most often used although palladium nickel and rhodium are also effective Metal catalyzed addi tion of hydrogen is normally rapid at room temperature and the alkane is produced m high yield usually as the only product... 

Among the earlier studies of reaction kinetics in mechanically stirred slurry reactors may be noted the papers of Davis et al. (D3), Price and Schiewitz (P5), and Littman and Bliss (L6). The latter investigated the hydrogenation of toluene catalyzed by Raney-nickel with a view to establishing the mechanism of the reaction and reaction orders, the study being a typical example of the application of mechanically stirred reactors for investigations of chemical kinetics in the absence of mass-transfer effects. 

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