Hydrogen-transfer reactions activation

Catalyst activity. An increase in catalyst activity will increase della coke. As catalyst activity increases so does the number of adjaceni sites, which increases the tendency for hydrogen transfer reactions to occur. Hydrogen transfer reactions are bimolecular and require adjacent active sites. 

The pulse experiments demonstrated that active sites for propane dehydrogenation are formed upon exposure of the oxide form of gallium modified ZSM-5 to propane itself. A constant 1 1 ratio of hydrogen produced to propane consumed is attained after a number of pulses with little propene formation, which suggests that, after propane dehydrogenation to propane, aromatization proceeds through hydrogen transfer reactions. 

Catalytic Activity of Cp Iridium Complexes in Hydrogen Transfer Reactions... 

I 5 Catalytic Activity of Cp Iridium Complexes in Hydrogen Transfer Reactions Table 5.3 Transfer hydrogenation of ketones and imines catalyzed by ll. "... 

The mechanism operating in rhodium-catalyzed and iridium-catalyzed hydrogen transfer reactions involves metal hydrides as key intermediates. Complexes such as [ M(p.-C1)(L2) 2], [M(cod)L2](Bp4) (M = Rh, Ir L2 = dppp, bipy), and [RhCl(PPh3)3] are most likely to follow the well-established mechanism [44] via a metal alkoxide intermediate and elimination to generate the active hydride species, as shown in Scheme 2. 

The procedure for getting the polymer-bound ligands is very easy to reproduce. Three jS-functionalized aromatic ketones were successfully reduced to the corresponding alcohols by heterogeneous asymmetric hydrogen transfer reaction with formic acid-triethylamine azeotrope as the hydrogen donor. One of the product alcohols (19c) is an intermediate for the synthesis of optically active fluoxetine. 

In order to distinguish between the dihydridic and the monohydridic routes in hydrogen-transfer reactions, Backvall and coworkers developed an optically active a-deuterated alcohol. If the dihydridic route was occurring the deuterium would be scrambled between carbon and oxygen atoms whereas if the monohydridic... 

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