Question

Which of the following reagents would convert but-2-yne to but-1-yne?
A. `HgSO_4`,`H_2SO_4`
B. Ethanilic KOH, heat
C. `NaNH_2` in mineral oil, heat
D. Ammoniacal `AgNO_3`

Answer 1

Correct Answer - C
When alkynes are heated with sodamide in an inert solvent such as paraffin the triple bond moves towards the end of the chain: But-2-yne gives the Na derivative of but-1-yne, which is converted into but-1-yne by the action of dilute acid:
`CH_2C-=C CH_3+NaNH_2overset("Paraffin")toH_2N+CH_3CH_2C-=CNaoverset(H^(+))toCH_3CH_2C-=CH`