A process for the preparation of 2-nitro-4-(methylsulfonyl)benzoic acid

A process for the preparation of 2-nitro-4-(methylsulfonyl)benzoic acid (NMSBA), said process comprising the following steps:

• a) reacting 1-chloro-2-nitro-4-methyl sulfonyl benzene (chloro NMSB) with a compound of Formula II by using a base in a fluid medium at a first predetermined temperature to obtain a compound of Formula III;
• wherein,
• R1 is selected from —CONH2, and —COOR3, wherein R3 is selected from C1-C4 alkyl;
• and
• R2 is a cyano group (—CN);
• b) reacting said compound of Formula III with an oxidizing agent optionally in the presence of a catalyst under stirring to obtain a mixture;
• c) optionally passing a predetermined amount of air through said mixture;
• and
• d) heating said mixture to a second predetermined temperature for a predetermined time period to obtain a product mixture comprising 2-Nitro-4-(methyl sulfonyl)benzoic acid,
• wherein a yield of 2-Nitro-4-(methyl sulfonyl)benzoic acid is greater than 75% and a purity is greater than 90%.