Hydrochloric Acid → 2-Methyl-5-nitrobenzoyl chloride

Participants

Reaction Steps

Part A. A 1-L flask equipped with a reflux condenser and a nitrogen sweep to an HCl gas scrubber was charged with 2-methyl-5-nitrobenzoic acid (200 g, 1.10 mol). The reaction vessel was cooled in an ice bath and thionyl chloride (307 mL, 4.20 mol) was added in one portion. The ice bath was removed, and the reaction mixture was refluxed overnight. The excess thionyl chloride and the SO2 and HCl reaction side-products were removed by vacuum distillation to afford 2-methyl-5-nitrobenzoyl chloride as a solid residue, which was used without further purification. This material was immediately dissolved in methylene chloride (100 mL) and added dropwise with stirring to a commercial 40% dimethylamine solution (500 mL, 4.45 mol) which was maintained at 0° to 12° by periodic immersion in a dry ice-acetone bath. After complete addition, the reaction mixture was stirred for 30 minutes at room temperature. The reaction mixture was diluted with water and extracted with methylene chloride. The combined organic extracts were washed with water, dried, and concentrated. The resulting material was distilled under vacuum to afford 5-nitro-N,N,2-trimethylbenzamide (189.9 g, 0.91 mol, 83% yield) as a solid: mp 98°-99°; bp 156°-170° (0.5 torr); MS m/e 209(M+ +H); 1H NMR(CDCl3) δ 8.00-8.17(m,2H), 7.40(d,J=8 Hz,1H), 3.17(s,3H), 2.88 (s,3H), 2.41(s,3H). Anal. Calcd for C10H12N2O3 : C,57.69; H,5.81; N,13.45. Found: C,57.72; H,5.84; N,13.49.

Provenance & Evidence