Problem 66 - A Complete Resource Book in Chemistry for JEE Main

Question

Ethyl chloride on heating with AgCN forms a compounds \(X\). The functional isomer of \(X\) will be (a) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NC}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{CN}\) (d) none of these

Step-by-Step Solution

Answer

(b) C_2H_5NC

Step 1: Understanding the Reaction

When ethyl chloride ( C_2H_5Cl ) reacts with silver cyanide ( AgCN ), the usual outcome is the formation of an isonitrile (isonitrile group: -N=C).

Key Concepts

Functional Isomers

In organic chemistry, the concept of functional isomers plays a pivotal role in understanding how compounds with the same molecular formulas can have different properties due to variations in their functional groups. Functional isomers occur when two or more compounds have the same chemical formula but differ in the type of functional group present in the molecule.

One well-known example is the difference between alcohols and ethers, which both have the general formula C_2H_6O. While alcohols contain an -OH group, ethers contain an -O- linkage.

This variation leads to significant differences in physical and chemical properties. Functional isomerism is crucial for synthesizing different compounds and understanding their behavior in chemical reactions. It demonstrates the importance of structural arrangement in defining a compound's reactivity and interaction.

Ethyl Chloride Reactions

Ethyl chloride (C_2H_5Cl) is a versatile compound in organic reactions, frequently used in the formation of various products. Its reactions often involve the substitution of the chlorine atom.

When ethyl chloride reacts with silver cyanide (AgCN), the typical product formed is an isonitrile. This reaction pathway is common due to the nucleophilic nature of the cyanide ion, which readily attacks the carbon atom bonded to chlorine.

The reaction of ethyl chloride with potassium cyanide (KCN) would typically result in the formation of an aliphatic nitrile, as the attack occurs via the nitrogen atom. However, with AgCN, the product is often the isonitrile (NC-), highlighting the different outcomes based on the metal cyanide used. These reactions illustrate how ethyl chloride can lead to various compounds depending on reaction conditions.

Isonitrile Formation

The formation of isonitriles is an interesting outcome in organic synthesis and is critical in advancing the versatility of organic compounds. Isonitriles, also known as isocyanides, have a unique -N=C functional group. This is distinct from the nitrile group (-C≡N), where the carbon atom shares a triple bond with nitrogen.

In reactions with silver cyanide (AgCN), such as when combined with ethyl chloride, the isocyanide pathway is favored, resulting in the production of an ethyl isocyanide. Such isonitriles are characterized by their distinctively strong and pungent smell.

Isonitriles are valuable in organic synthesis due to their ability to participate in various chemical reactions, providing pathways to synthesize a vast array of compounds. Their distinct formation involves a shift from the typical cyanide behavior, leading to intriguing applications in synthetic frameworks.