Sodium Dithionite → Methyl 4-amino-3-(methylamino)benzoate

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Reaction Steps

Add an aqueous solution of sodium hydrosulfite (17.4 g, 100 mmol in 80 mL of water) to methyl-3-(methylamino)-4-nitrobenzene carboxylate (855 mg, 4.75 mmol) in tetrahydrofuran (70 mL) and ethanol (30 mL) at 0° C. The orange solution turned to an orange suspension upon addition. Stir the mixture at room temperature for 2 hours. The orange suspension turned to a yellow suspension over this time. Add saturated sodium bicarbonate (100 mL) then the yellow suspension turned colorless. Extract the mixture with ethyl acetate (2×100 mL). Wash the combined organics with brine (30 mL). Dry over magnesium sulfate, filter, concentrate, and dry under high vacuum to yield methyl 4-amino-3-(methylamino)benzoate (586 mg, 68%) as a yellow oil. The resulting oil began to crystallize upon standing after 10 minutes. 1H NMR (400 MHz, CDCl3) δ ppm 2.89 (s, 3H), 3.37-3.81 (m, 2H), 3.85 (s, 3H), 6.67 (d, J=8.01 Hz, 1H), 7.33 (d, J=1.37 Hz, 1H), 7.44 (dd, J=8.11, 1.66 Hz, 1H).

Provenance & Evidence