Problem 6 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The Wurtz-Fittig reaction involves condensation of : (a) two molecules of aryl halides (b) one molecule of each of aryl-halide and alkyl-halide. (c) one molecule of each of aryl-halide and phenol. (d) two molecules of aralkyl-halides.

Step-by-Step Solution

Answer

(b) one molecule of each of aryl-halide and alkyl-halide.

Step 1: Understanding the Wurtz-Fittig Reaction

The Wurtz-Fittig reaction involves the reaction between aryl halides and alkyl halides in the presence of sodium metal to form alkylarenes.

Step 2: Analyzing the Options

We need to determine which pair of molecules is involved in the Wurtz-Fittig reaction. Looking at the options, (a) involves two aryl halides, (b) involves one aryl halide and one alkyl halide, (c) involves one aryl halide and phenol, and (d) involves two aralkyl halides.

Step 3: Identifying the Correct Reaction

The key aspect of the Wurtz-Fittig reaction is the presence of one aryl halide and one alkyl halide. This reaction leads to the formation of alkylarenes, which is consistent only with option (b).

Key Concepts

Aryl Halides

Aryl halides are a special class of organic compounds where a halogen atom is directly bonded to an aromatic ring. These compounds are significant in the field of organic chemistry due to their stable structures and unique reactions. Aryl halides do not readily participate in simple substitution reactions because the aromatic ring makes the carbon-halogen bond quite strong and stable.
One of the notable features of aryl halides is their potential to undergo specific reactions like the Wurtz-Fittig reaction. This reaction involves an aryl halide's transformation into more complex aromatic compounds.
Key Characteristics of Aryl Halides:

• High stability due to resonance within the aromatic ring.
• Lower reactivity in nucleophilic substitution compared to alkyl halides.
• Used as starting materials for more complex synthetic reactions like the Wurtz-Fittig reaction.

Understanding these features helps in predicting how aryl halides can interact in various chemical reactions, especially those that involve forming new carbon-carbon bonds.

Alkyl Halides

Alkyl halides, also known as haloalkanes, are compounds in which a halogen atom replaces one hydrogen atom in an alkane. Unlike aryl halides, alkyl halides are more reactive and readily participate in both nucleophilic substitution and elimination reactions.
In the Wurtz-Fittig reaction, alkyl halides act as one of the reactants, combining with aryl halides in the presence of sodium to produce alkylarenes. This highlights their versatile nature as intermediates in organic synthesis.
Core Characteristics of Alkyl Halides:

• Highly reactive, making them suitable for a variety of substitution and elimination reactions.
• Used extensively in the synthesis of other organic compounds.
• Serve as key players in the formation of carbon-carbon bonds in synthetic chemistry.

By understanding the reactivity patterns of alkyl halides, chemists can effectively leverage their properties to synthesize a wide array of organic structures, including complex aromatic compounds.

Alkylarenes Formation

The formation of alkylarenes is a crucial goal in various organic synthesis processes, particularly through the Wurtz-Fittig reaction. This reaction specifically involves the fusion of an aryl halide with an alkyl halide in the presence of sodium, resulting in the creation of alkylarenes.
Alkylarenes are valuable due to their presence as structural units in many chemicals, including pharmaceuticals and polymers.
Important Aspects of Alkylarenes Formation:

• The process begins with the reaction of sodium with the halide groups, creating intermediate radicals.
• The subsequent coupling of these radicals forms a new carbon-carbon bond linking the aromatic ring to the alkyl group.
• This synthesis route is particularly useful for producing complex aromatic compounds with various applications.

The successful formation of alkylarenes in reactions like the Wurtz-Fittig highlights the importance of understanding electron behavior and bond formation in organic chemistry. It opens pathways to synthesize diverse products with significant practical applications.