Cycloalkanes product distributions

Adsorption modes and hydrogenolysis were also correlated with other metal-catalyzed reactions. Gault noticed striking similarities in product distributions of isomerization and ring opening of cycloalkanes. Kinetic and tracer studies provided useful data252 268 to arrive at the conclusion that a common surface intermediate is... 

Little is known of the chemistry of alkyl-substituted cycloalkanes such as C6H11CH3. The presence of one tertiary C—H bond will not noticeably increase the overall rate of radical attack because of the abundance of secondary C—H bonds. Attack at a ring C—H position will tend to give a similar product distribution to that observed for cyclohexane with high yields of the various isomeric cyclohexenes at most temperatures between 600 and 1000 K. Loss of a hydrogen atom at the /3 position to the R group would induce homolysis to give cyclohexene and R radicals, particularly at temperatures above 800 K. 

As developed in the introduction, a number of important features in hydrogenolysis of cycloalkanes on platinum-charcoal catalysts emerges from the work of the Soviet school of catalysis. In a different approach, the hydrogenolysis of methyl- and 1,3-dimethylcyclopentanes was investigated on a series of platinum-alumina catalysts with various metal loadings (0.2-20%) (84, 85). It was found that the product distribution changed substantially with the percentage of platinum on the carrier. An almost selective... 

The important catalysts applied in this process are Lewis acids (promoted by hydrogen halide) and protic acids (61,77). Hydrogen fluoride and sulfuric acid are the preferred catalysts because they are handled more conveniently and can be reused. Of the reactants, alkanes and cycloalkanes with tertiary carbon atoms are the most reactive in the alkane-alkene reaction. The process may yield alkylates of markedly different product compositions, depending on the reactants, catalysts, and reaction conditions. Superacids may also be used as catalysts with signiflcant and characteristic differences in product distribution (63). 

Excited-state Mg atoms react with methane and other alkanes via H atom abstraction in the gas phase (equation 1). By studying the vibrational states of the MgH product, information on the mechanism has been inferred. It has been found that regardless of the alkane, RH (and thus the C—H bond strength), the vibrational state distributions are essentially identical. This suggests that long-lived vibrationaUy excited [RMgH] complexes are not intermediates for equation 1 in the gas phase. The situation is quite different for excited-state Mg atoms reacting with methane under matrix conditions, where the insertion product (equation 2) is sufficiently stable for analysis via infrared spectroscopy ". Calcium atoms have been shown to insert into the C—H bonds of cycloalkanes. ... 

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