Methyl 3,5-dinitrobenzoate → Methyl 3-methoxy-5-nitrobenzoate

Participants

Reaction Steps

Five (5) g (22 mmol) methyl 3,5-dinitrobenzoate (Aldrich) were suspended in 80 mL methanol (A.C.S. grade) and heated to reflux for app. 1 h under nitrogen, until a clear brown solution had formed. A simultaneously prepared sodium methoxide solution (prepared by portionwise addition of 0.76 g (33 mmol, 1.5 eq.) sodium to 10 mL methanol, the reaction flask was purged with nitrogen until all sodium had reacted) was added dropwise to the hot solution by syringe, each drop causing a deep red color. The reaction mixture was refluxed for an additional 15 h. After cooling to r.t., it was concentrated to dryness, the remaining brown-purple solid was taken up in 30 mL distilled water and acidified with 2 N HCl. The addition of ethyl acetate caused the present light orange solid to dissolve, phases were separated and extraction with ethyl acetate was repeated twice. The combined organic layers were washed with sat. aq. NaHCO3, with brine, then dried with MgSO4 and concentrated, leaving 3.7 g of a pale yellow solid. The crude product was purified by column chromatography (7:3 hexanes/ethyl acetate, Rf=0.6, UV; note: starting material coelutes but should be gone after the reaction time given) to afford 2.3 g (50%) of a light yellow solid. The procedure can be scaled up to 30 g starting material: depending on the course of the reaction, crude product material might be sufficiently pure to be carried on into the next step without further purification. mp 88-89° C. 2; 1H NMR (CDCl3) δ 8.46 (dd, J1=1.5 Hz, J2=2.4 Hz, 1H), 7.92 (t, J1=2.4 Hz, J2=2.4 Hz, 1H), 7.88 (dd, J1=1.5 Hz, J2=2.4 Hz, 1H), 3.99 (s, 3H, OCH3), 3.95 (s, 3H, OCH3); 13C NMR (CDCl3) δ 164.59, 160.00, 148.95, 132.37, 120.84, 116.36, 112.65, 56.02, 52.60.

Provenance & Evidence