Free radical reactions, strained hydrocarbons

It is now well established that the cation radicals of unsaturated and strained hydrocarbons undergo a variety of isomerization (e.g., Scheme 18) and cycloaddition reactions with much faster rates than those of the corresponding neutral molecules [162-165]. A cation radical chain mechanism analogous to Scheme 17 was reported for one-way photoisomerization of cis-stilbene (c-S) to truws-stilbene (f-S) via photoinduced electron transfer, as shown in Scheme 18 [166], Once c-S + is formed, it is known to isomerize to t-S + [167,168]. The free energy change of electron transfer... 

The free radical chain reactions (3), (4), initiated by hydroperoxides in the presence of transition metal ions and oxygen (5)-(8), continues in hydrocarbon polymers so long as oxygen is present in the system with the accumulation of abiotically stable carboxylic acids. However, in microbially active environments, carboxylic acids are bioassimilated by micoorganisms so that the carboxylic acids are in dynamic equilibrium in the system. It has been demonstrated experimentally [21,22] that pure strains of bacteria (in... 

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