Problem 160 - A Complete Resource Book in Chemistry for JEE Main

Question

In the chemical reactions, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2}+\mathrm{CHCl}_{3}+3 \mathrm{KOH} \longrightarrow\) (a) \(+(\mathrm{b})+3 \mathrm{H}_{2} \mathrm{O}\) the compounds (a) and (b) are respectively: (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CONH}_{2}\) and \(3 \mathrm{KCl}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NC}\) and \(\mathrm{K}_{2} \mathrm{CO}_{3}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NC}\) and \(3 \mathrm{KCl}\) (d) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{CN}\) and \(3 \mathrm{KCl}\)

Step-by-Step Solution

Answer

The products are (c) \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{NC}\) and \(3 \mathrm{KCl}\).

Step 1: Identify the reaction type

The given reaction is a type of rearrangement reaction where chloroform \(\mathrm{CHCl}_3\) reacts with a primary amine \(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{NH}_2\) and potassium hydroxide \(\mathrm{KOH}\) to form an isocyanide compound. This specific reaction is known as the carbylamine reaction.

Step 2: Determine the main product (compound a)

According to the carbylamine reaction, an aliphatic primary amine reacts with chloroform and a strong base to produce an isocyanide (or carbene) compound. The primary amine ethylamine \(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{NH}_2\) will form isocyanide \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{NC}\).

Step 3: Identify the byproduct (compound b)

Within the reaction, for each mole of chloroform, three moles of \(\mathrm{KOH}\) are used, and three moles of \(\mathrm{KCl}\) are produced as byproducts. Hence, the other compound (b) is \(3 \mathrm{KCl}\).

Step 4: Match the products to the given options

Based on the reaction products: (a) \(\mathrm{C}_2 \mathrm{H}_5 \mathrm{NC}\) and (b) \(3\mathrm{KCl}\), we compare this with the provided options. Option (c) matches exactly with the identified products from the carbylamine reaction.

Key Concepts

Rearrangement Reaction

Rearrangement reactions play a crucial role in organic chemistry. They involve the reorganization of atoms within a molecule to form a new molecular structure. In the context of the Carbylamine Reaction, a rearrangement allows the transformation of an amine into an isocyanide.

The importance of rearrangement reactions lies in their ability to transform complex molecules and synthesize important chemical products. The rearrangement process often involves changes in the connectivity of atoms and can lead to unexpected products.

• Involves internal structural changes.
• Yields new products with different properties.
• Can be reversible or irreversible.

. Understanding these can help predict reaction outcomes and design efficient pathways for chemical synthesis.

Isocyanide Formation

Isocyanides, also known as carbylamines, are unique compounds with notable pungent odors. The formation of isocyanides exemplifies a classic transformation in organic synthesis known as the Carbylamine Reaction.

This reaction involves a primary amine reacting with chloroform (\(\mathrm{CHCl}_{3}\) in the presence of a strong base like potassium hydroxide (\(\mathrm{KOH}\)). Isocyanides are valuable in organic synthesis and are characterized by the functional group –NC, a staple in various chemical applications.

• Primary amines act as starting materials.
• Chloroform provides the necessary carbon atom.
• Strong bases promote the reaction conditions.

. Isocyanides are crucial intermediates that interact in further chemical pathways, highlighting the versatility of synthetic chemistry.

Chemical Reaction Analysis

Analyzing chemical reactions is key to understanding the interactions within a chemical system. In the Carbylamine Reaction, analyzing the reactants and products helps us comprehend the mechanism at play.

A comprehensive analysis involves examining the reaction's stoichiometry, balancing the equation, identifying reactants, intermediates, products, and byproducts.

• Potassium hydroxide reacts with chloroform to form dichlorocarbene.
• Dichlorocarbene then attacks the primary amine to yield an isocyanide.
• Potassium chloride forms as a byproduct from the neutralization process.

. This detailed analysis assists in predicting products and optimizing conditions for maximum yield, an essential skill in chemistry. Understanding these elements helps chemists design better experiments and interpret complex reactions effectively.