Sodium Hydroxide → 1-methyl-1H-1,2,3-triazole-5-carboxylic acid

To a solution of 1-methyl-1H-1,2,3-triazole-5-carbaldehyde (Preparation 33, 5 g, 45 mmol) and sodium hydroxide (8.59 g, 215 mmol) in water (120 ml) at 15° C. was added dropwise a solution of potassium permanganate (5.83 g, 36.9 mmol) in water (120 ml). The reaction was stirred at room temperature for 30 minutes and then heated to reflux for 1 hour. The reaction was filtered and the filtrate acidified to pH 3 with concentrated HCl before extracting with ethyl acetate (3×100 ml). The combined organic extracts were washed with saturated aqueous brine, dried over Na2SO4 and concentrated in vacuo to afford the title compound.