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8.2.1 A Convention for Moving Electrons in Reaction Mechanism Diagrams

Before delving into rearrangement chemistry, it should be emphasized that in ion decomposition chemistry, one often has free radicals as products. Therefore, one must consider the 'unpairing' of electrons during the course of a reaction, and this should be indicated in the mechanism diagram. To do this, we adapt McLafferty's convention of using a double barbed arrow, $\rightarrow$, to indicate movement of a pair of electrons (such as an entire bonding pair). On the other hand, a single barbed arrow, such as $\rightharpoonup$, is used to indicate a single electron. {insert figure}

John S. Riley, DSB Scientific Consulting