Dimethylcyclohexanes, from dimethylcyclohexenes

Figure 7.15. Formation of Z-l,2-dimethylcyclohexane from 1,2-dimethylcyclohexene the latter is shown as the jr-adsorbed state, which is converted to the half-hydrogenated state having the same geometry as the final product.

If the hydrogenation reaction consisted solely of the one-sided addition of hydrogen to a double bond, then pure cfs-1,2-dimethylcyclohexane should be obtained from 1,2-dimethylcyclohexene however, only 77% of the expected isomer was formed. Conceivably, the introduced olefin might isomerize to one in which the groups are trans or to an olefin which can yield the trans isomer by a one-sided addition of hydrogen, for example,... 

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