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Question: \(C{{H}_{3}}N{{H}_{2}}+CHC{{l}_{3}}+KOH\to \) The nitrogen-containing compound formed is: (A) \[...

CH3NH2+CHCl3+KOH→C{{H}_{3}}N{{H}_{2}}+CHC{{l}_{3}}+KOH\to
The nitrogen-containing compound formed is:
(A) CH3−C≡NC{{H}_{3}}-C\equiv N
(B) CH3−NH−CH3C{{H}_{3}}-NH-C{{H}_{3}}
(C) CH3−N−≡C+C{{H}_{3}}-{{N}^{-}}\equiv {{C}^{+}}
(D) CH3−N+≡C−C{{H}_{3}}-{{N}^{+}}\equiv {{C}^{-}}

Explanation

Solution

According to carbylamine reaction which is based on electrophiles, when a primary amine is heated with chloroform in the presence of alcoholic potassium hydroxide, then the reaction tends to form a product i.e. isocyanide or a carbylamine.

Complete step by step solution:
Due to the presence of lone pair of electrons on the nitrogen atom, animes like ammonia are good nucleophiles and hence react with a variety of electrophiles (electron-deficient compounds) such as metal ions, acid halides like acid chlorides, acid anhydrides like chloroform, etc.
When a primary amine is reacted with chloroform, the reaction is called a “carbylamine reaction” as a carbylamine or isocyanide is formed as a product. This reaction is also used as an isocyanide test.
According to this reaction, both aliphatic and aromatic primary amines when warmed with chloroform and an alcoholic solution of KOHKOH, it produces an isocyanide or a carbylamine which will have a very unpleasant smell.
When primary amine reacts with chloroform, it forms an alkyl isocyanide. The general reaction is shown below,
R−NH2+CHCl3+3KOH→HeatR−N≡C+3KCl+3H2OR-N{{H}_{2}}+CHC{{l}_{3}}+3KOH\xrightarrow{Heat}R-N\equiv C+3KCl+3{{H}_{2}}O
As per the given question, methylamine (a primary amine) with chemical formula CH3NH2C{{H}_{3}}N{{H}_{2}}, is being reacted with chloroform i.e. CHCl3CHC{{l}_{3}}and potassium hydroxide i.e. KOHKOH. Hence, it will form methyl isocyanide with three moles of potassium chloride and three moles of water. This can be understood by the following balanced chemical reaction shown,
CH3NH2+CHCl3+KOH→CH3−N+≡C−+3KCl+3H2OC{{H}_{3}}N{{H}_{2}}+CHC{{l}_{3}}+KOH\to C{{H}_{3}}-{{N}^{+}}\equiv {{C}^{-}}+3KCl+3{{H}_{2}}O
So, the product formed is CH3−N+≡C−C{{H}_{3}}-{{N}^{+}}\equiv {{C}^{-}}.

Hence, the correct option is D.

Additional information:
The carbylamine reaction is not given by secondary and tertiary amines (both aliphatic and aromatic compounds). Therefore, it is used to distinguish primary amines from secondary and tertiary amines.

Note: The possible mistake is, you may get confused between options C and D because their chemical formulas are the same but the difference is, they are having different bonding. This reaction is a specific type of reaction which forms the only isocyanide. So, while writing the reaction, keep in mind that by-products should be correct.