Nitric Acid → 3-Methyl-5-nitroisoquinoline

Participants

Reaction Steps

3-Methylisoquinoline (2.14 g, 14.9 mmol) was added portionwise to ice-cooled concentrated H2SO4 (10 ml) keeping the internal temperature below 10° C. A nitrating mixture of concentrated H2SO4 (2 ml) and fuming nitric acid (2 ml) was then added dropwise keeping the internal temperature below 15° C. After stirring for 30 minutes, TLC indicated reaction was complete. The acid was neutralized by adding the mixture to an excess of 4N aqueous NaOH (180 ml) with ice-cooling. The mixture was extracted with dichloromethane (2×150 ml), then dried (Na2SO4) and evaporated to give the crude product (2.69 g) as a yellow solid. Flash column chromatography using as eluant 5% methanol in dichloromethane gave a pure sample of the title compound (660 mg) and a sample (1.95 g) containing ca. 10% of the 8-nitro isomer.

Provenance & Evidence