Question

Butanenitrile may be prepared by heating:
A. propyl alcohol with KCN
B. butyl alcohol with KCN
C. butyl chloride with KCN
D. propyl chloride with KCN

Answer 1

Hint: Butanenitrile’s formula is \[{C_4}{H_7}N\]. It is also called butyronitrile. It is miscible with most polar solvents. Butanenitrile can be obtained by heating certain chemical substances with KCN.

Complete step by step solution:
- React butyl alcohol with KCN, the reaction will not occur because KCN cannot react with the hydroxyl group of butyl alcohol. So, reaction will not occur at all.
- Same way, propyl alcohol cannot react with KCN as hydroxyl groups cannot react with cyanide ions.

- KCN is a salt and it can easily displace the halogen atom from alkyl halides. So, the resultant product will be corresponding cyanides.
- React butyl chloride with KCN, the reaction will be:
\[C{H_3}C{H_2}C{H_2}C{H_2} - Cl\xrightarrow{{KCN}}\mathop {C{H_3}C{H_2}C{H_2}C{H_2}CN}\limits_{{\text{Pentane nitrile}}} + KCl\], the obtained product is pentane nitrile.

- React propyl chloride with KCN, the reaction will be:
\[C{H_3}C{H_2}C{H_2} - Cl\xrightarrow{{KCN}}\mathop {C{H_3}C{H_2}C{H_2}CN}\limits_{{\text{Butyronitrile}}} + KCl\], the obtained product is butanenitrile.
So, from above we can conclude that option D is correct.

Additional Information:
- Butanenitrile or propyl cyanide is a nitrile with a formula ${{\text{C}}_{\text{4}}}{{\text{H}}_{\text{7}}}{\text{N}}$.
- It is colorless liquid which is miscible with most polar organic solvents but soluble in benzene.
- Its molar mass is 69.107.
- It is used as a precursor to the poultry drug Amprolium.
- So many isomers of butanenitrile are presents such as 1-amino-3-butyne, 1-isocyano propane, 2-isocyano propane, 2-methylpropanenitrile, 3-pyrroline, butanenitrile, n-methylpropargylamine and pyrroline.

Note: Apart from the listed process, we can also obtain butanenitrile by the ammoxidation of n-butanol. The reaction can be given as below.
\[C{H_3}C{H_2}C{H_2}C{H_2}OH + N{H_3} + {O_2} \to C{H_3}C{H_2}C{H_2}CN + 3{H_2}O\]
Mainly this process of making butanenitrile by the ammoxidation of n-butanol is followed in industry.