Hydrogen Bromide → Methyl 2-amino-5-bromo-3-methylbenzoate

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Reaction Steps

A solution of methyl 2-amino-3-methylbenzoate (142.1 g, 0.843 mol, purity: 98% quantitative NMR) in 240 mL of H2O is gradually admixed at 30° C. with hydrogen bromide (48% of H2O, 149.2 g, 0.885 mol) added dropwise. The suspension obtained is admixed with hydrogen peroxide (30% in H2O, 105.1 g, 0.927 mol) added dropwise over 2 h, and the temperature is kept below 70° C. After 1 hour of subsequent stirring, NaHSO3 (39% in H2O, 33.7 g, 0.126 mol) is added a little at a time (peroxide test was negative). The suspension obtained is adjusted to pH7-8 with Na2CO3 (0.1 eq., 9.0 g, 0.084 mol), which is added a little at a time. Following filtration and drying in a vacuum drying cabinet, methyl 2-amino-5-bromo-3-methylbenzoate is isolated as a pale brown solid. Yield: 204.2 g, 97.7% of theory, purity: 98.5% quantitative NMR).

Provenance & Evidence