4-Iodo-2-nitro benzoic acid can be synthesized by taking benzene as starting material using the following path. The reaction can be completed in four steps.
Step 1: Conversion of Benzene molecule to Toluene molecule
Benzene undergoes Friedel Craft Alkylation when reacted with methyl chloride (CH3Cl) and aluminum chloride (AlCl3) to give Toluene.
Step 2: Conversion of Toluene to p-iodo Toluene
Toluene undergoes iodination when reacted with iodine in the presence of ferric chloride (FeCl3). The methyl group is ortho and para-directing. But, the ortho position is comparatively hindered so iodination takes place at the para position.
Step 3: Nitration of p-iodo toluene with the nitrating mixture
p-iodo toluene reacts with concentrated nitric acid in the presence of concentrated sulfuric acid to give a nitro group at the ortho position of p-iodo toluene. Nitration happens on the ortho position to the methyl group since para is already occupied by iodine.
Step 4: Oxidation of Methyl group of toluene
The Methyl group can be directly oxidized to the carboxylic acid group by heating with a strong oxidizing agent such as acidic KMnO4.