Cleavage preferential

By changing from the simplest to larger aliphatic and cyclic ketones, structural factors may be introduced which favor alternative unimolecular primary photoprocesses or provide pathways to products not available to the simple model compound. In addition, both the increase in molecular size and irradiation in solution facilitate rapid vibrational relaxation of the electronically excited reactant as well as the primary products to thermally equilibrated species. In this way the course of primary and secondary reactions will also become increasingly structure-selective. In a,a -unsym-metrically substituted ketones, the more substituted bond undergoes a-cleavage preferentially. 

Tertiary amines undergo /3-cleavage, preferentially in the longest hydrocarbon chain. If more than three carbon atoms... 

In both of these studies, the solvents used promoted glycol-cleavage preferentially. 

Cleavage of cycloalkanones. Diesters are the major products. The cleavage preferentially occurs at the less highly substituted C—<2 bond. 

Where will the a-bond cleavage preferentially occur in 2-methylbutane ... 

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