Question

Write a short note on the following.

Mustard oil reaction

Answer 1

When primary amines are treated with carbon disuiphide (CS₂), N-alkyldithio carbamic acid is formed which on subsequent treatment with HgCI₂, gives an alkyl isothiocyanate.

\[\begin{array}{cc}
\phantom{}\ce{S}\phantom{........................}\ce{S}\phantom{...............................}\\
\phantom{}||\phantom{........................}||\phantom{...............................}\\
\ce{CH3 - N - H + C = S -> \underset{(N-methyl dithiocarbamic acid)}{CH3 - NH - C - SH} ->[HgCl2] \underset{\underset{(Mustard oil smell)}{Methyl isothiocyanate}}{CH3 - N = C = S} + HgS + 2HCl}\\
|\phantom{..........................................................................}\\
\ce{\underset{(Methylamine)}{H}}\phantom{..........................................................................}
\end{array}\]