Answer: Ethene (elimination of both Br via zinc).
- A Ethane, formed by simple reductive removal of both bromine atoms with hydrogen
- B Ethene (elimination of both Br via zinc)
- C 1,2-ethanediol, formed by hydrolytic substitution of both bromine atoms
- D Zinc bromide only, with no organic product formed in the reaction
Correct answer: B. Ethene (elimination of both Br via zinc)
Explanation: Zinc brings about dehalogenation (removal of two adjacent halogens); the electrons push out both Br atoms and form ethene (a double bond). This is the reverse of bromination of ethene.
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.