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Ethane reacts with bromine under ultraviolet light. Bromoethane is one product, and the reaction proceeds by a radical chain mechanism.
Write the two propagation equations for the reaction of ethane with bromine.
Write a termination equation involving two ethyl radicals.
State one reason why a mixture of organic products can form.
State two features of alkanes that contribute to their low reactivity.
The alkane shown reacts with under UV light. Which sequence shows initiation followed by the two propagation steps in which one H atom at C2 is replaced by Cl? A dot denotes one unpaired electron.
Answer: C. UV light causes homolytic fission of producing two chlorine radicals. A chlorine radical abstracts H from C2, forming and This radical reacts with to form and regenerate sustaining the chain. A: abstracts H at a terminal carbon, so the product is 1-chloropropane. B: uses radical–radical combination, a termination step that consumes the radicals rather than regenerating one. D: shows heterolytic fission, producing ions rather than the radicals needed to initiate the chain. Remember: a propagation step consumes one radical and produces another.
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