Cyclobutanes, isomerization, product distributions

The oxidation of cyclobutanemethanol and a,a-dimethylcyclobutanemethanol with lead tetra-acetate in benzene gave the same product distributions within the isomeric homoallylic, cyclobutyl and cyclopropylmethyl actates. The distribution was the same in the oxidation of cyclobutane carboxylic acid, suggesting that alcohol p-cleavage and acid decarboxylation gave rise to the same radical species. 

The occurrence of mechanism A on 0.2% Pt/Al2O3 was confirmed for several substituted cyclopentanes and cyclobutanes (Table IV). On the other hand, while Mechanism C, which seems to occur on 10% platinum catalysts at high temperatures, could not be isolated on account of the fast consecutive isomerization of acyclic products that occurs above 320°C, Mechanism B was associated with the distribution of methylpentanes obtained at 220°C... 

At least five plausible structures for C4Hg ions can be envisioned, which correspond to the structures of the isomeric neutral molecules, namely 1-butene, 2-butene, isobutene, methylcyclopropane, and cyclobutane. Experiments utilizing the technique of neutral product analysis have been performed to determine the structure(s) of the C4Hg ions formed in various systems. In all cases, conclusions based on the distributions of various D2"-transfer products and charge-transfer products gave internally consistent results. 

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