A hypothetical alternative mechanism for the halogenation of methane has the following propagation steps.
(i) X∙ + CH4 → CH3X + H∙
(ii) H∙ + X2 → HX + X∙
(a) Using DH° values from appropriate tables, calculate ∆H° for these steps for any one of the halogens.
(b) Compare your ∆H° values with those for the accepted mechanism (Table 3-5). Do you expect this alternative mechanism to compete successfully with the accepted one?