Question

How will you obtain ethyl isothiocyanate from ethylamine $?$

Answer 1

Hint : We can obtain ethyl isothiocyanate from ethylamine by four methods. First, by treating ethyl amine and chloroform with potassium hydroxide, by pyrolyzing the complex between ethyl isothiocyanate and triethyl phosphine and lastly, by passing ethylene and hydrogen cyanide through an electric discharge.

Complete Step By Step Answer:
$-$ We can obtain isothiocyanate by treating ethyl amine and chloroform with potassium hydroxide.
The carbylamine reaction is the synthesis of an isocyanide by the reaction of a primary amine, chloroform, and base. The conversion involves the intermediacy of dichlorocarbene. It is used to prepare secondary amines.
When heated with chloroform and ethanolic potassium hydroxide, form foul-smelling isocyanides or carbylamines.
$-$ We can obtain isothiocyanate by pyrolyzing the complex between ethyl isothiocyanate and triethyl phosphine.
$-$ Also, by heating cyanocobal tic acid with ethanol.
$-$ And lastly, by passing ethylene and hydrogen cyanide through an electric discharge.
Ethylene and hydrogen cyanide was passed through these discharge tubes at a constant velocity for the period of the reaction. Two moles of hydrogen cyanide are used. A current of $60$ cycles was sent through a voltage regulator.

Note :
Remember during the pyrolysis sometimes the liquid crystallizes to a dense solid which immobilizes the stirrer if it has not been raised. The crystallization has no effect on subsequent steps except to necessitate a longer period of stirring after the potassium cyanide is added. Also, the aqueous cyanide solution can be disposed of by flushing it down the drain with a large volume of water and it is very toxic.