Nitric Acid → Ethyl 5-methyl-2,4-dinitrobenzoate

Participants

Reaction Steps

To a mixture of HNO3 (95%, 80 mL) and H2SO4 (98%, 80 mL) was slowly added 3-methylbenzoic acid (50 g, 0.37 mol) at 0° C. After addition, the mixture was stirred for 1.5 h while maintaining the temperature below 30° C. The mixture was poured into ice-water and stirred for 15 min. The precipitate was collected via filtration and washed with water to give a mixture of 3-methyl-2,6-dinitro-benzoic acid and 5-methyl-2,4-dinitro-benzoic acid (70 g, 84%). To a solution of this mixture in EtOH (150 mL) was added dropwise SOCl2 (53.5 g, 0.45 mol). The mixture was heated at reflux for 2 h and concentrated to dryness under reduced pressure. The residue was dissolved in EtOAc (100 mL) and extracted with 10% Na2CO3 solution (120 mL). The organic layer was found to contain 5-methyl-2,4-dinitro-benzoic acid ethyl ester while the aqueous layer contained 3-methyl-2,6-dinitro-benzoic acid. The organic layer was washed with brine (50 mL), dried over Na2SO4 and concentrated to dryness to provide 5-methyl-2,4-dinitro-benzoic acid ethyl ester (20 g, 20%).

Provenance & Evidence