Problem 54 - A Complete Resource Book in Chemistry for JEE Main

Question

Chloroform reacts with acetone to yield (a) insecticide (b) hypnotics (c) analgesic (d) isocyanide

Step-by-Step Solution

Answer

The reaction yields (d) isocyanide.

Step 1: Identify the Reactants

The reactants in this chemical reaction are chloroform (CHCl_3) and acetone ((CH_3)_2CO). The product is the result of a chemical interaction between these substances.

Step 2: Recognize the Conditions

This reaction often occurs in the presence of a base, such as NaOH, which helps deprotonate chloroform and initiate the reaction with acetone.

Step 3: Determine the Reaction Type

Chloroform reacting with acetone in basic conditions typically leads to the formation of a compound that can rearrange to create an isocyanide, through a complex mechanism known as the Carbylamine reaction.

Step 4: Identify the Product

Given the reaction conditions and the typical outcome of this reaction, the product formed is isocyanide, the choice (d).

Step 5: Conclusion

The reaction between chloroform and acetone under basic conditions yields an isocyanide.

Key Concepts

Chloroform

Chloroform is a colorless, sweet-smelling organic compound with the formula \( ext{CHCl}_3 \). It's primarily known as a solvent in the laboratory and was once used as an anesthetic in surgeries. Though it is no longer used in medical practices due to its potential health risks, it still plays a significant role in chemical reactions.
In the context of the Carbylamine reaction, chloroform acts as a reactant that partakes in complex interactions to yield other chemicals. When used in reactions, chloroform often requires a suitable base to proceed, facilitating the deprotonation and promoting interactions with other reagents like acetone.

Acetone

Acetone is a simple organic compound with the formula \( ( ext{CH}_3)_2 ext{CO} \). It is a colorless, flammable liquid often used as a solvent in many industrial applications. You might recognize acetone from its common use in nail polish remover.
In chemical reactions, acetone can act as a reactant that participates in forming new products. When it reacts with chloroform in the presence of a base, one of the possible outcomes is the formation of an isocyanide through a sequence of reactions. Acetone contributes its carbonyl group to participate in the reaction, leading to the rearrangement needed for product formation.

Isocyanide

Isocyanides, or isonitriles, are a class of organic compounds containing the \( ext{NC} ext{-} \) group, which is a functional group that can be considered a carbon-nitrogen triple bond connected to an organic moiety. These compounds have a strong, often unpleasant odor and are notable for their role in specialized chemical syntheses.
The formation of isocyanides is a hallmark of the Carbylamine reaction, where reactants like chloroform and acetone interact under basic conditions. The product, an isocyanide, results from a series of shifts and structural reorganizations in the molecular framework. Despite their smell, isocyanides are invaluable in organic chemistry for the development of complex molecular architectures.

Chemical Reaction Mechanism

A chemical reaction mechanism describes the step-by-step process by which reactants transform into products. It offers insight into the individual events and molecular rearrangements occurring throughout the reaction sequence.
In the case of the Carbylamine reaction, the mechanism involves several stages:

• Deprotonation: Initiated by a base, chloroform loses a hydrogen atom, setting the stage for the reaction.
• Nucleophilic attack: The deprotonated chloroform can now interact with acetone, initiating bond formation.
• Rearrangement: The intermediates formed undergo structural changes, leading to the formation of an isocyanide.

Understanding the chemical reaction mechanism is crucial as it explains not only what happens during a reaction but also why certain conditions or catalysts are necessary.