Answer: CCl 4.
- A CCl<sub>4</sub>
- B CH<sub>2</sub>Cl<sub>2</sub>
- C CHI<sub>3</sub>
- D CHCl<sub>3</sub>
Correct answer: A. CCl<sub>4</sub>
Explanation: Carbon tetrachloride (CCl<sub>4</sub>), sold as pyrene, was used to smother fires as its dense vapour cuts off oxygen.
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.