Use the information in Table 4-2 to explain why toluene (PhCH₃) has a very high octane rating of 111. Write an equation to show how toluene reacts with an alkyl free radical to give a relatively stable radical.

a. Which of the hydrogens in the structure in the margin is the easiest for a chlorine radical to remove?

b. How many secondary hydrogens does the structure have?

Rank the following radicals in decreasing order of stability. Classify each as primary, secondary, or tertiary.

a. The isopentyl radical,

b. The 3-methyl-2-butyl radical,

c. The 2-methyl-2-butyl radical,

d.

Use the information in Table 4-2 (p. 167) to rank the following radicals in decreasing order of stability.

For each set of reactive intermediates, rank them in order of reactivity (1 = most reactive).

(b)

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.

b. Rank these three intermediates from most stable to least stable.

Explain the dramatic difference in rotational energy barriers of the following three alkenes. (Hint: Consider what the transition states must look like.)

The following ethers are ranked according to their ability to form explosive peroxides. Explain this ranking based on your knowledge of the reaction mechanism.

Based on the stability of the radicals produced, predict which bond in each pair would have the higher bond-dissociation energy.

(a)