Mechanism of hydrogenolysis

The values of the adsorption coefficient of hydrogen for both reactions were practically identical (1.9 and 2.1 atm-1). Here, the selectivity of the branched reactions depends on the partial pressure of methylcyclopentane. This difference may be accounted for by assuming that either the cleavage of the C—C bond of methylcyclopentane in the (3-position and in the 7-position with respect to the methyl group does not take place on the same sites of the surface of platinum (or on the sites of the same activity), or that the mechanism of hydrogenolysis is more complex than that ex-... 

A further consideration in the mechanism of hydrogenolysis of hydrocarbons is the structure of the chemisorbed species that undergoes scission of the carbon-carbon bond. In the case of ethane hydrogenolysis, one readily visualizes bonding of the two carbon atoms in the species C2H to adjacent metal surface atoms. It is convenient to refer to the adsorbed C2H as a... 

Mechanism of hydrogenolysis of thiophene on bimetallic sulfide catalysts 92UK332. 

The first approach to the cyclic mechanism of isomerization was the finding that the interconversion of n-hexane and methylpentanes takes place under the conditions where the nonselective mechanism of hydrogenolysis (Mechanism A) is the only one operating that is, on 0.2% Pt/AljOj (32). The identical product distributions in isomerization of hexanes and hydrogenolysis of methylcyclopentane suggested that both reactions involve a common intermediate with a methylcyclopentane structure. It was then proposed that the species responsible for dehydrocyclization of hexanes are a,j8, -triadsorbed species involving a single metal atom (55) (Scheme 40). 

Hence, three different dehydrocyclization mechanisms, corresponding to the three mechanisms of hydrogenolysis of methylcyclopentane, may be characterized ... 

Despite of the popularity of benzyl as a protective group there is a lack of fundamental studies on the mechanism of hydrogenolysis [9]. It is probable that hydrogenolysis occurs via two reaction routes. The first mechanism is characteristic of Pd and Pt and proceeds mainly with inversion of configuration at the carbon atom, whereas the second occurs with Ni and Cu and configuration is retained [11]. With unsymmetrically substituted oxiranes the two mechanisms have different regio-selectivity-the sterically less hindered bond is cleaved on Pt and Pd, whereas the more hindered bond is ruptured on Ni and Cu [11]. At the same time cis-... 

Activation can be moderate or quite substantial (up to 10-fold increase in catalyst productivity). The most likely mechanism of hydrogenolysis is the direct insertion of H2 into the metal—carbon bond (Scheme... 

Scheme 18.7 Proposed mechanism of hydrogenolysis of tin tetra-alkyl by a Pt/silica surface covered with hydrogen [113],...

Kinetics and Mechanism of Hydrogenolysis of Propylene in the Presence of Deuterium... 

The kinetics and mechanism of hydrogenolysis of propylene to give ethylene and methane were investigated in a flow reactor made of quartz, at temperatures between 675 and 800 C. The molar ratio of deuterium or hydrogen to propylene employed was up to approx. 10. 

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