Consider the bromination of (S)-2-chlorobutane under radical conditions (). What is the expected product distribution and stereochemical outcome at the major substitution site?
- Substitution primarily at C-3 giving (S)-2-chloro-3-bromobutane with retention of configuration
- Substitution primarily at C-2 giving racemic 2-bromo-2-chlorobutane due to planar radical intermediate
- Substitution primarily at C-3 giving racemic 2-chloro-3-bromobutane due to loss of stereochemistry (correct answer)
- Equal substitution at C-2 and C-3 with retention of configuration at the original stereocenter
Explanation: Radical bromination shows selectivity for tertiary > secondary > primary positions. The most reactive site is C-3 (secondary). Radical abstraction at C-3 creates a planar radical intermediate that can be attacked by Br₂ from either face, leading to racemization at that position. The original stereocenter at C-2 is not directly involved and retains its configuration. Choice A incorrectly suggests retention at the reaction site. Choice B identifies wrong reaction site. Choice D incorrectly suggests equal reactivity at different carbon types.