Nitric Acid → 2-Methyl-6-nitro-3-pyridinol

Participants

Reaction Steps

While maintaining a temperature of 0-5° C. with external ice cooling, 3-hydroxy-2-methyl pyridine (10.00 g, 91.63 mmol) was added gradually to concentrated sulfuric acid (65.00 ml). A mixture of concentrated sulfuric acid (8.50 ml) and nitric acid (6.50 g, 103.16 mmol) was added over 2 h. The resulting mixture was poured onto ice. Addition of a few milliliters of saturated ammonium hydroxide caused precipitation of crude 2-methyl-6-nitro-pyridin-3-ol. This was collected by filtration and recrystallized from methanol/water to yield pure 2-methyl-6-nitro-pyridin-3-ol (1.37 g, 10%). Basification of the mother liquors to pH 3-4 triggered precipitation of the isomeric 2-methyl-4-nitro-pyridin-3-ol (major component), which was discarded.

Provenance & Evidence