Whether reactions take place by ionic or radical mechanisms is unclear in some cases.

The reaction requires t-butyl hydroperoxide and generally a metal and proceeds through a radical mechanism.

The stepwise chlorination occurs via an order-independent radical mechanism.

The reaction is insensitive to radical scavengers and therefore a free radical mechanism can be ruled out.

This reaction operates via a free radical mechanism.

In 1992, Niemi et al. proposed a radical mechanism, shown in Figure 6(top).

For example, hydrogen and oxygen can be combined to form water through a free radical mechanism commonly referred to as combustion.

The free radical mechanism is one of the first methods to be used.

On the other hand, experiments with radical traps and the observation of racemization during substitution suggest a radical mechanism.

Reactions which are generally accepted to proceed by a radical mechanism are known however.