The following transformation was found to occur in areas with large NO₂ emissions. Suggest a mechanism for the reaction (J. Phys. Chem. 2013, 117, 14132–14140). [Hint: Use the fishhook arrows associated with radical reactions.]

The human body can excrete drugs and other exogenous molecules by converting them into polar, water-soluble compounds by a reaction similar to the autoxidation described in Section 11.6. Why are the following drug candidate molecules susceptible to oxidation by this pathway?

For each reaction, show which stereoisomers are obtained

1. NBS/∆/peroxide

2. Br₂/CH₂Cl₂

One danger associated with storing ether solvents is their tendency to form explosive peroxides when exposed to oxygen. Suggest a mechanism by which the hydroperoxide might form. You can assume the presence of X• to start the reaction.

Which ether is least apt to form a peroxide?

Write an equation for the reaction of vitamin E with an oxidizing radical (RO•) to give ROH and a less reactive free radical.

A student adds NBS to a solution of 1-methylcyclohexene and irradiates the mixture with a sunlamp until all the NBS has reacted. After a careful distillation, the product mixture contains two major products of formula C₇H₁₁Br.

a. Draw the resonance forms of the three possible allylic free radical intermediates.

For each compound, predict the major product of free-radical bromination. Remember that bromination is highly selective, and only the most stable radical will be formed.

(a) cyclohexane

(b) methylcyclopentane