What is general requirement for free radical substitution reaction of ethane and halogen?
Correct answer: D. Heat and UV light
- A. Low pressure
- B. Low temperature
- C. High pressure
- D. Heat and UV light
Explanation
Initiation requires the halogen molecule to split homolytically into two radicals, and only ultraviolet light or a high temperature supplies enough energy to break that bond. In the dark and in the cold, an alkane and a halogen simply do not react, which is a standard demonstration of how unreactive alkanes are. Once started, the chain propagates on its own until two radicals combine.
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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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