Beta scission rule

The secondary free radical can crack on either side of the carbon carrying the unpaired electron according to the beta scission rule, and a terminal olefin is produced. 

If R = H in the above example, then according to the beta scission rule (an empirical rule) only route b becomes possible, and propylene would be a product ... 

Such a cleavage, known as the beta-scission, is based on the principles developed by F. C. Whitmore in his early work on the carbonium-ion systems. This beta rule is the rule of least rearrangement since it involves the shifting of electrons only ... 

ViUano SM, Huynh LK, Carstensen HH, Dean AM. High-pressure rate rules for alkyl + O2 reactions. 2. The isomerization, cychc ether formation, and beta-scission reactions of hydroperoxy alkyl radicals./Phys Chem A. 2012 116 5068-5089. ViUano SM, Huynh LK, Carstensen HH, Dean AM. High-pressure rate rules for alkyl + 02 reactions. 1. the dissociation, concerted elimination, and isomerization channels of the alkylperoxy radical. / Phys Chem A. 2012 115 13425-13442. 

---