Method B. To a solution of potassium nitrate (100 g, 0.99 mol) in sulfuric acid (250 mL, 96%) was added s-triazolo [3, 4-a]-phthalazine (30 g, 0.176 mol). A slight exotherm was noted as the reaction mixture turned light orange. After stirring overnight, the pale yellow reaction mixture was worked up as in method A to give the crude nitro product 21.2 g of yellow solid. The isomers were separated by column chromatography on silica gel eluting with 2% ...
