Réaction #631978

Équation de réaction

NaNO2

3-Amino-2-methylbenzoic acid

HBr

HBr

→

3-bromo-2-methylbenzoic acid

Solvants

H2O

Conditions de réaction

Traitement

1. 1
   workup.ADDITIONAfter the addition
2. 2
   Filtrationfiltered
3. 3
   FiltrationThe recovered filter cake
4. 4
   Lavagewas washed first with water
5. 5
   Séchagewith 10% HCl, and dried in air

Mode opératoire

3-Amino-2-methylbenzoic acid (6.16 g) was heated at reflux for 30 minutes in concentrated HBr. The mixture was cooled to 0° C. and treated with a solution of NaNO2 at 0° C. (2.8 g in 5.6 mL H2O). The resultant diazonium salt solution was slowly added to a preheated (60-70° C.) solution of CuBr (3.8 g) in 3.2 mL concentrated HBr. After the addition, the mixture was stirred overnight at room temperature and filtered. The recovered filter cake was washed first with water and then with 10% HCl, and dried in air to yield 6.93 g of 3-bromo-2-methylbenzoic acid as a light purple powdery solid. This material was dissolved in ethyl acetate, washed twice with 5% HCl dried over Na2SO4, and recrystallized from 4:1 hexanes:ethyl acetate first at room temperature and then under refrigeration. 1H NMR (DMSO, 200 MHz), δ (ppm): 7.72 (dd, 2H), 7.2 (t, 1H), 2.5 (s, 3H).

Source