Cyclohexene from methylcyclopentane

Likewise it is possible to differentiate between substituted and unsubstituted alicycles using inclusion formation with 47 and 48 only the unbranched hydrocarbons are accommodated into the crystal lattices of 47 and 48 (e.g. separation of cyclohexane from methylcyclohexane, or of cyclopentane from methylcyclopentane). This holds also for cycloalkenes (cf. cyclohexene/methylcyclohexene), but not for benzene and its derivatives. Yet, in the latter case no arbitrary number of substituents (methyl groups) and nor any position of the attached substituents at the aromatic nucleus is tolerated on inclusion formation with 46, 47, and 48, dependent on the host molecule (Tables 7 and 8). This opens interesting separation procedures for analytical purposes, for instance the distinction between benzene and toluene or in the field of the isomeric xylenes. 

In order to produce additional evidence for the above mecheuiism for aromatization over Ga203 HZSM-5 catalysts the reactions of n-hexene, 1,5 hexadiene, methylcyclopentane, methylcyclopentene, cyclohexene, cyclohexadiene at 773 K over H-2SM-5 and Ga-HZSM-5 were comparatively studied. In these exj riments low pressure and low contact were employed to observe the primary kinetic products uncomplicated by secondary reactions. The relative rates of the formation of benzene from the various hydrocarbons cited above are listed in Table 4. 

Similar isomerization occurs in the presence of silica-alumina-thoria.104 As it might be expected, this reaction is similar to the isomerization of cyclohexane to methylcyclopentane. Both processes involve the same intermediate cyclohexyl car-bocation, which is formed, however, in different reactions. It may be formed from cyclohexane by hydride ion transfer, or by protonation of cyclohexene. Bicyclic alkenes undergo complex interconversions via carbocations over acidic catalysts.105... 

Irradiation of saturated aliphatic compounds typically results in imsaturation, polymerization, and isomerization. The radiolysis of cyclohexane illustrates all three of these processes. If the radicals are very energetic, cyclohexene can be formed by the abstraction of hydrogen from a cyclohexyl radical either by a hydrogen atom or by another cyclohexyl radical. If the radicals become thermalized, recombination of radicals can occur to give bicyclohexyl. A less frequent process is rearrangement, followed by hydrogen atom capture to yield methylcyclopentane. 

The principal products from cyclohexane are H2, cyclohexene and bicyclohexyl with yields of 5.6, 3.2 and 1.8 (100eV)"S respectively. The yield of H2 formation represents the yield of decomposition of cyclohexane molecules due to C—H scission (either by H2 elimination or otherwise). The yield of C—C scission is very small. Fragment hydrocarbons account for a yield of ca 0.2 (100 eV)", corresponding to a yield of decomposed cyclohexane molecules of around 0.03 (100 eV)" Straight-chain hydrocarbons are found with a yield of 0.46 (100 eV)" methylcyclopentane has a yield of 0.2 (100eV) and alkylcyclohexanes have a yield of ca 0.1 (100eV)" Altogether this corresponds to a yield of cyclohexane molecules decomposed by C—C scission of ca 0.8 (100 eV)- ... 

Ring contraction. Cyclohexene added dropwise at 10-12° during 55 min. from a syringe to AggO in 98%-H2S04 under 1 atm. CO 1-methylcyclopentane-carboxylic acid. Y 84%. - Similarly 1-Hexanol a,a-dimethylpentanoic acid. Y 79%. F. e., also from satd. hydrocarbons, s. Y. Souma and H. Sano, Bull. Chem. Soc. Japan 47, 1717 (1974). 

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