Acetic Anhydride → 4-(Acetylamino)-3-methylbenzoic acid

Reaction equation

[NH2:1][C:2]1[CH:10]=[CH:9][C:5]([C:6]([OH:8])=[O:7])=[CH:4][C:3]=1[CH3:11].C(N(CC)CC)C.[C:19](OC(=O)C)(=[O:21])[CH3:20]>C(Cl)Cl>[C:19]([NH:1][C:2]1[CH:10]=[CH:9][C:5]([C:6]([OH:8])=[O:7])=[CH:4][C:3]=1[CH3:11])(=[O:21])[CH3:20]

Participants

Procedure

To a suspension of 4-amino-3-methylbenzoic acid (60 g, 0.40 mol) in methylene chloride (800 mL) was added triethylamine (121 g, 1.19 mol). The solution became clear. Then, acetic anhydride (81 g, 0.79 mol) was added and the reaction mixture was stirred for 60 h at room temperature. The solvent was evaporated. The residue was diluted with water (400 mL) and extracted with ethyl acetate (3×600 mL). The combined organic extracts were dried over magnesium sulfate, filtered and evaporated to give the title compound as a tan solid (43 g, 56% yield). 1H-NMR (d6-DMSO, 300 MHz) δ 9.36 (s, 1H), 7.77 (s, 1H), 7.10 (s, 2H), 2.27 (s, 3H), 2.10 (s, 3H). LC/MS: tR=1.22 min, 194 (MH)+.