4 - Hydroxy-pyridine

4-Nitropyridine N-oxide was prepared at first from pyridine by oxidation and nitration. Then,the denitration of 4-Nitropyridine N-oxide gave the product 4-Hydroxypyridine N-oxide.At last,the target product 4-Hydroxypyridine was gaven by reduction of 4-Hydroxypyridine N-oxide using zinc and Ammonium Formate as catalysts.The influences of reaction conditions such as mole ratios between materials,reaction time,the kind of solvent and temperature were described.Optimum conditions of oxidation were obtained as follows:the volume ratio of pyridine to hydogen peroxide to acetic acid was 1:2.5:2.5,reaction 12 h under 80℃,the yield was 95%.Optimum conditions of nitration were obtained as follows:the molar ratio of pyridine N-oxide to nitric acid was 1:3.5,the molar ratio of nitric to vitriol was 1:1.5,reaction 14 h under 90℃,the yield was 85%.Optimum conditions of hydroxylation were obtained as follows:the volume of 4-Nitropyridine N-oxide,N,N-dimethylanilin-e and acetic anhydride are 4 g,5 mL and 16 mL,reaction 2.5 h under 85℃,the yield was 70%.Optimum conditions of deoxidize were obtained as follows:the molar ratio of 4-Hydroxypyridine N-oxide to zinc to Ammonium Formate is 1:2.5:3.5,reaction 7 h under refluxing temperature.,the yield was 85%.The total yield was 48%.