In the monochlorination of 2,3-dimethylbutane the relative reactivity per hydrogen is 1 deg : 3 deg = 1 : 5. The ratio (moles of 1-chloro-2,3-dimethylbutane) : (moles of 2-chloro-2,3-dimethylbutane) in the product is

JEE Advanced levelSingle correct optionDifficulty 3 of 3g3148

In the monochlorination of 2,3-dimethylbutane the relative reactivity per hydrogen is $1^{\circ} : 3^{\circ} = 1 : 5$ . The ratio (moles of 1-chloro-2,3-dimethylbutane) : (moles of 2-chloro-2,3-dimethylbutane) in the product is

2,3-Dimethylbutane has 12 primary H and 2 tertiary H. Primary product

\propto 12 \times 1 = 12

and tertiary product

\propto 2 \times 5 = 10

. The ratio is

12 : 10 = 1.2 : 1

. The 5-fold preference per H is overcome by the six-fold statistical factor.