Question

What is(are) true about free radical chlorination of a alkane ?

• A. Taking a large excess of alkane over chlorine minimizes the chances of dechlorination and polychlorination.
• B. Propagation is preferred over termination because the radicals are highly reactive.
• C. Major product is always formed at the carbon where the most stable free radical is formed in the intermidiate step.
• D. Reaction is usually carried out in aqueous medium.

Answer 1

Answer: (A), (B)

The correct options are
A Taking a large excess of alkane over chlorine minimizes the chances of dechlorination and polychlorination.
B Propagation is preferred over termination because the radicals are highly reactive.

a)Taking large excess of alkane increases the probability of H-abstaction from alkane rather than product alkyl halide in the propagation step,hence minimises the chance of dichlorination
b) Progagation is preferred over termination because free radicals are highly reactive, immediately reacts rather than recombine in termination steps.

Hence options A & B are correct.