The Studies On Synthesis Technology And Thermodynamic Properties Of 4-Nitropyridine N-Oxide

The synthesis process of 4-nitropyridine-N-oxide and the thermodynamic property of the intermediate were studied in this paper. Pyridine was oxidized to be pyridine N-oxide by hydrogen peroxide in the presence of phosphotungstic acid, which was used as a catalyst in the reaction. The investigation of the reaction conditions were obtained through orthogonal experiment. The results showed that the factors are material ratio, temperature, the quantity of catalyst and reaction time in influence sequence. Moreover, the preparation methods were evaluated by single-factor selecting experiment.Solid super acid SO42-ZrO2 was prepared by using zirconium oxychloride as raw material. The solid super acid that obtained under different conditions was analyzed by IR spectroscopy and X-ray diffraction. The result showed that the calcine temperature had significantly effect on the crystallite structure. The solid super acid, instead of sulfuric acid, was used as catalyst during the nitration of pyridine N-oxide, and the relationship of catalytic activity and crystallite structure of the catalyst was preliminarily studied.The vapor pressure of pyridine N-oxide was measured using a boiling point method at different temperature from (389.02 to 546.33) K. The Antoine equation has been used to describe the experimental data with an average absolute deviation (AAD) of 1.30%。On the basis of Antoine equation and Clausius-Clapeyron equation, the enthalpy of vaporization of pyridine N-oxide at normal boiling point was obtained. Based on Othmer's method, the standard enthalpy of vaporization was obtained by using pyridine and benzene as the standard substances, respectively. Furthermore, Watson equation was employed to verify the reliability of the value and the results demonstrate that the value of the standard enthalpy of vaporization was acceptable.