Question

$C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{C}H}-C{H}_3$(excess)+$B{r}_2\stackrel{hv}{\to }C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{\underset{Br}{\underset{|}{C}}}}-C{H}_3+C{H}_3-\stackrel{C{H}_3}{\stackrel{|}{C}H}-C{H}_2-Br$

The relative reactivity of $1^{o}H,2^{o}H$ and $3^{o}H$ in bromination reaction has been found to be 1:82:1600 respectively. In the reaction the percentage yields of the products (A) and (B) are expected to be

• A. 99.4%, 0.6%
• B. 50%, 50%
• C. 0.6%, 99.4%
• D. 80%, 20%

Answer 1

The correct option is A 99.4%, 0.6%

The product A is formed by replacement of a tertiary hydrogen atom. Product B is formed by replacement of a primary hydrogen atom. The relative reactivity of tertiary H atom is much higher than the relative reactivity of primary H atom.
Hence, the proportion of product A in the product mixture should be much higher than the proportion of product B. Hence, the percentage yields of the products (A) and (B) are expected to be 99.4% and 0.6%.