1,2-Dibromopropane on treatment with X moles of NaNH_2` followed by treatment with ethyl bromide gave a pentyne. The value of X is

Options

A. One
B. Two
C. Three
D. Four

Answer

C

Explanation

i) `CH_3CHBr - CH_2Br + 2NaNH_2 to CH_3C -= CH + 2NaBr + 2NH_3`
ii) `CH_3 C -= CH + NaNH_2 to CH_3C -= C^(-) Na^(+) + NH_3`
iii) `CH_3C -= C^(-) Na^(+) + CH_3CH_2 Br to CH_3C -= C CH_2 CH_3 + NaBr`
Thus 3 mole of `NaNH_2` is used .