Question

How will you convert Benzene to Benzoic acid?

Answer 1

Benzene to benzoic acid:

Step 1 Freidel Craft’s alkylation reaction:

• Friedel-Crafts Alkylation is a chemical reaction in which the proton in the aromatic compound gets substituted with the alkyl group.
• In the first step, the Lewis acid catalyst Aluminium chloride (${\mathrm{AlCl}}_3$) undergoes a reaction with the Methyl chloride$\left({\mathrm{CH}}_3\mathrm{Cl}\right)$ and it results in the formation of electrophilic carbonation.
• Then the carbocation proceeds to attack the aromatic ring by forming a Cyclohexadienyl cation as an intermediate, and the aromaticity will be lost temporarily due to the breakage of the Carbon-Carbon double bond.
• Finally, the deprotonation of the intermediate leads to the reformation of the carbon-carbon double bond, restoring aromaticity to the compound. This proton goes on to form Hydrochloric acid, regenerating the ${\mathrm{AlCl}}_3$ catalyst.

Here Benzene reacts with ${\mathrm{CHCl}}_3$ along with anhydrous ${\mathrm{AlCl}}_3$, and the one Hydron atom is substituted with Methyl group and Toluene is forme

Step 2 Oxidation:

• The Toluene is oxidized in the presence of a strong oxidizing agent like ${\mathrm{KMnO}}_4$ to produce Benzoic acid.
• This Methyl group is converted into $\mathrm{COOH}$ group with the help of a strong oxidation agent ${\mathrm{KMnO}}_4$, the reaction takes place through oxidation and Benzoic acid is formed.