In the free radical substitution of methane, the initiation step is
Correct answer: D. the homolytic splitting of a chlorine molecule into two chlorine radicals by ultraviolet light
- A. the reaction of a chlorine radical with methane
- B. the combination of two methyl radicals
- C. the reaction of a methyl radical with chlorine
- D. the homolytic splitting of a chlorine molecule into two chlorine radicals by ultraviolet light
Explanation
Initiation is the step that creates radicals where there were none, and only the chlorine to chlorine bond is weak enough to be broken by ultraviolet light. Propagation steps then consume one radical and produce another, so the chain continues, while termination removes radicals by combining them. Identifying which step is which by counting radicals on each side is the reliable method.
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About Free Radical Substitution
Free radical substitution explains how alkanes react with halogens under ultraviolet light or heat through initiation, propagation and termination steps. The mechanism involves homolytic bond fission and radical intermediates, while product formation depends on the relative stability of radicals and differs from ionic substitution.
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