Nitric Acid → Methyl 5-chloro-2-ethyl-3-nitrobenzoate

Participants

Reaction Conditions

Reaction Steps

A solution of methyl 5-chloro-2-ethylbenzoate (5.12 g, 25.77 mmol) in concentrated H2SO4 (31 ml, 587 mmol) was cooled to −5° C. in an acetone/ice bath in air. A mixture of concentrated nitric acid (2.15 ml, 33.51 mmol) and concentrated H2SO4 (2 ml, 37.52 mmol) was added drop wise to the reaction mixture at −5 to 0° C. over 15 minutes. The pale yellow reaction mixture was stirred at −5 to 0° C. for 1 hour before being poured onto ice (500 ml) and this was extracted with EtOAc (3×100 ml). The combined organic phases was washed with deionized water (100 ml) and then brine (100 ml). The organic phase was dried over MgSO4, filtered and concentrated under reduced pressure. LCMS and NMR showed ˜30% hydrolysis of the ester. The crude material was dissolved in Methanol (30 ml) and cooled to 0° C. under nitrogen where SOCl2 (2.25 ml, 30.93 mmol) was added slowly. The reaction mixture was then heated to reflux for 6 hours before being concentrated under reduced pressure to give 6.18 g (98.4%) of methyl 5-chloro-2-ethyl-3-nitrobenzoate as an orange oil. Product contained 1:1 mixture of 3-nitro:6-nitro isomers along with some ethyl ester which was suitable for use without any further purification.

Provenance & Evidence