Wurtz-Fittig Reaction

Wurtz Fittig Reaction is a chemical process related to the classic Wurtz Reaction. It is primarily used to join alkyl and aryl halides, commonly chlorides, bromides, or iodides in the presence of sodium metal and dry ether. This reaction is similar to the Wurtz Reaction, and results in the formation of a new carbon-carbon bond and merge two smaller alkyl or aryl molecules into a larger one.

In this article, we will learn in detail about the Wurtz Fittig Reaction, its equation, example, uses, and comparison with the Wurtz and the Fittig Reaction.

What is Wurtz Fittig Reaction?

Wurtz Fittig Reaction, an extension of the Wurtz Reaction principles, involves the amalgamation of alkyl and aryl halide in the presence of reactive metals like sodium, leading to the synthesis of substituted aromatic compounds and the formation of sodium halide byproducts.

Learn, Wurtz Reaction

Wurtz Fittig Reaction Equation

The generalized form of the Wurtz Fittig Reaction can be expressed as:

2R−X + 2Na→R−R + 2NaX

where,

• R−X represents an Alkyl or Aryl Halide.
• Na represents Sodium.
• R−R symbolizes Desired Alkane

Wurtz Fittig Reaction Example

An example undergoing Wurtz-Fittig reaction is illustrated below:

Production of Butane from Ethyl Chloride

2CH₃CH₂Cl + 2Na → C₄H₁₀ + 2NaCl

Above example shows the coupling of two ethyl chloride molecules that yields butane, with sodium chloride produced as a byproduct in the presence of dry ether.

Wurtz-Fittig Reaction Mechanism

Mechanism of Wurtz can be best understood in the terms following two mechanism:

• Organo Alkali Mechanism
• Radical Mechanism

Organo Alkali Mechanism

In Organo Alakli Mechanism, the aryl or alkyl halide react with sodium metal to form Organo Alkali Intermediate. This is why the mechanism is named so. Let’s learn in details about the steps involved in Organo Alkali Mechanism

Step 1: Formation of a metal halide and sodium substituted aryl.

Ar−X + 2Na → Ar-Na + NaX ⁻

Step 2: Removal of the halogen from the carbon and the formation of a covalent bond with the same carbon through nucleophilic attack.

Ar-Na + R−X → Ar−R + NaX ⁻

Radical Mechanism

In Radical Mechanism, alkyl and aryl radical is formed with the help of sodium atom which then combine to form substituted aromatic compound

Step 1: Initiation – Formation of aryl radicals.

A−X + Na→Ar• + NaX⁻

Step 2: Propagation – Aryl radical reacts with another alkyl halide to form the desired product.

Ar• + R−X → Ar−R + X ⁻

Step 3: Termination – Various reactions leading to the consumption of radicals.

Ar• + R•→Ar−R

Alkene or substituted aromatic compound formation might occur as a byproduct due to the free radical mechanism.

Uses of Wurtz Fittig Reaction

Applications of Wurtz Fittig Reaction mirror those of the Wurtz Reaction:

• Facilitates the synthesis of symmetrical hydrocarbons, especially alkanes.
• Applied in ring closure reactions, particularly in forming small rings.
• Utilized in the preparation of specific compounds, like Bicyclobutane, through Wurtz coupling.
• Yields alkenes and alkynes as products based on the nature of the reactant.

Limitations of Wurtz Fittig Reaction

Wurtz Fittig Reaction has limitations:

• Exclusive synthesis of symmetric alkanes.
• Inability to synthesize methane through this method.
• Tertiary alkyl halides exhibit lower reactivity due to steric hindrance.
• Limited application in coupling aryl halides.
• Safety concerns associated with the use of highly reactive metals like sodium.

Wurtz Fittig Reaction Distinction

Wurtz Fittig Reaction closely resembles the Wurtz Reaction but has difference, particularly in its application to Aryl Halides. While the Wurtz Reaction is effective for alkyl halides, the Wurtz Fittig Reaction extends its application to Aryl Halides, allowing for the coupling of aromatic compounds in the presence of reactive metals. The mechanism remains similar, with the coupling of halides facilitated by the formation of radicals and subsequent nucleophilic attacks, but the broader scope makes the Wurtz Fittig Reaction a versatile tool in organic synthesis.

Comparison of Wurtz Reaction, Fittig Reaction, and Wurtz Fittig Reaction

A detailed comparison between Wurtz Reaction, Fittig Reaction and Wurtz Fittig Reaction is tabulated below:

Aspect	Wurtz Reaction	Fittig Reaction	Wurtz Fittig Reaction
Type of Compounds	Alkyl halides	Aryl halides	Both Alkyl and Aryl halides
Reactive Metal	Sodium or Potassium	Sodium or Potassium	Sodium or Potassium
Formation	Carbon-carbon bond between alkyl halides	Carbon-carbon bond between aryl halides	Carbon-carbon bond between alkyl and aryl halides
Applicability	Synthesis of symmetrical alkanes	Synthesis of symmetrical biaryls	Broad synthesis, coupling alkyl and aryl halides
Mechanism	Radical mechanism involving alkyl radicals	Radical mechanism involving aryl radicals	Combination of alkyl and aryl radical mechanisms

Wurtz-Fittig Reaction FAQs

What is Wurtz Fittig Reaction named after?

Wurtz Fittig Reaction is named after French Chemist Charles-Adolphe Wurtz and Wilhelm Rudolph Fittig

Is Catalyst used in Wurtz Fittig Reaction?

Typically no catalyst is used, but a strong base like sodium or potassium is required.

What does Wurtz Fittig Reaction synthesize?

Wurtz Fittig Reaction Synthesize substituted aromatic compound

What is key reagent in Wurtz Fittig Reaction?

Sodium metal act as key reagent in Wurtz Fittig Reaction

How Can Toluene be Prepared using Wurtz Fittig Reaction?

To prepare toluene with wurtz fittig reaction, we have to take a mixture of chlorobenzene and methyl chloride and react it with sodium metal in presence of dry ether