Ammonium Chloride → Oxybuprocaine Impurity 4

Participants

Reaction Steps

A solution of methyl 3-butoxy-4-nitrobenzoate (2.5 g, 9.9 mmol) in methanol (100 mL) was added an aqueous solution (50 mL) of NH4Cl (5.3 g, 99 mmol), followed by activated zinc (Aldrich, 6.5 g, 99 mmol). The reaction mixture was stirred at room temperature for 1 h. The mixture was filtered through a short pad of celite. The mixture was concentrated. The residue was partitioned between ethyl acetate and water. The organic layer was separated, and aqueous layer was extracted with ethyl acetate. The combined organic extract was washed with water, brine, dried over MgSO4, and concentrated to give 4-amino-3-butoxy-benzoic acid methyl ester as a yellow solid (1.8 g, 82%).

Provenance & Evidence