Question

3 Explain the following reaction with example.
(1) Wurtz reaction
(2) Friedel craft reaction
(3) Wurts-fitting reaction
(4) Kolbe's electrolysis process
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Answer 1

Answer:

1. The reaction in which alkyl halides on treatment with sodium metal in dry ethereal (free from moisture) solution give higher alkanes is known as Wurtz reaction and is used for the preparation of higher alkanes containing even number of carbon atoms.
2. A Friedel-Crafts reaction is an organic coupling reaction involving an electrophilic aromatic substitution that is used for the attachment of substituents to aromatic rings. The two primary types of Friedel-Crafts reactions are the alkylation and acylation reactions.
3. Wurtz fittig reaction is the chemical reaction of aryl halides with alkyl halides and sodium metal in the presence of dry ether to give substituted aromatic compounds. Aryl halides are also known as haloarene. ... An example of this reaction is as follows: We can see that alkyl chain and an aromatic ring is joined.
4. Kolbe's reaction. Kolbe reaction: When sodium phenoxide is treated with carbon dioxide under pressure (4 to 7. atom) and at 400 K, sodium salicylate is formed, which on further reaction gives salicyclic acid. This reaction is known as Kolbe's reaction.

Answer 2

Explanation:

(a) Wurtz reaction

Alkyl halides react with sodium in presence of dry ether to form higher alkanes. For example, methyl bromide reacts with sodium in presence of dry ether to form ethane.

CH

3

−Br+2Na+Br−CH

3

dry ether

CH

3

−CH

3

+2NaBr

(b) Wurtz-Fittig reaction

Aryl halides react with alkyl halides in presence of sodium to form substituted aromatic compounds. For example, bromobenzene reacts with methyl iodide in presence of sodium to form toluene.

C

6

H

5

−Br+2Na+I−CH

3

→C

6

H

5

−CH

3

+NaBr+NaI