Hydrochloric Acid → 8-Chloronaphthalene-2-sulfonic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 8-amino-2-naphthalenesulfonic acid (Aldrich, 1.00 g, 4.48 mmol) in water (3.0 mL) and conc. HCl (7.0 mL) was cooled to 0° C. A solution of NaNO2 (143 μL, 4.48 mmol) in water (3.0 mL) was added dropwise while maintaining the temperature below 5° C. The reaction mixture was stirred at 0° C. for 1 h. In a separate flask, CuCl (214 μL, 8.96 mmol) was dissolved in conc. HCl (7.0 mL) and the solution was cooled to 0° C. The copper solution was added to the diazonium solution at 0° C. in portions to control the gas evolution. The reaction mixture was allowed to stir at 0° C. for 1 h and then at room temperature for 12 h. The reaction mixture was then diluted with 10% aq. NH4Cl solution and extracted with EtOAc (3×). The combined organic extracts were washed again with aq. 10% NH4Cl solution, dried over Na2SO4, filtered and concentrated in vacuo to give the title compound (740 mg, 65%). 1H NMR (DMSO-d6) δ 8.43 (s, 1H), 7.95 (dd, J=17.1, 8.5 Hz, 2H), 7.80 (dd, J=8.4, 1.5 Hz, 1H), 7.71 (dd, J=7.5, 1.1 Hz, 1H), 7.57-7.45 (m, 1H); MS(ESI−) m/z 241.2 (M−H)−.

Provenance & Evidence