Sketch potential-energy/reaction-coordinate diagrams for the two propagation steps of the mono-bromination of benzene (Problem 24).
Problem 24
Write a mechanism for the radical bromination of the hydrocarbon benzene, C6H6 (for structure, see Section 2-3). Use propagation steps similar to those in the halogenation of alkanes, as presented in Sections 3-4 through 3-6. Calculate ∆H° values for each step and for the reaction as a whole. How does this reaction compare thermodynamically with the bromination of other hydrocarbons? Data: DH° (C6H5-H) = 112 kcal mol-1; DH° (C6H5-Br) = 81 kcal mol-1. Note the Caution in Exercise 3-5.