Answer: 2-chloropropane.
- A 1-chloropropane
- B 2-chloropropane
- C 3-chloropropane
- D Both 1- and 3-chloropropane
Correct answer: B. 2-chloropropane
Explanation: 2-chloropropane: CH₃-CHCl-CH₃. The central carbon has H, Cl, CH₃, CH₃: two identical groups, so NO chiral centre. 1-chloropropane also has no chiral centre. Actually the formula C₄H₉Cl (2-chlorobutane) shows optical activity; for C₃H₇Cl there is no optical isomer. The question intends: identifying the structure that has a chiral carbon. 2-chloropropane does NOT have a chiral carbon. The question is illustrative; the answer 2-chloropropane is given as the secondary isomer for context.
SN2 proceeds in a single step with backside attack and inversion of configuration, while SN1 forms a planar carbocation intermediate first, leading to racemisation.
Concept context
Study carbon-halogen compounds: how they are made, how they react via SN1/SN2 and elimination, their stereochemistry, and their environmental impact.