4-Nitropyridine was synthesized, extracted and separated by using chloroform as extraction solvent. The influences of the pH of the solvent, extraction temperature and time of extraction etc. on the extraction process were investigated. The experimental results show that the extraction process is a fast extraction process The distribution ratio increases with the increase of pH of the aqueous solution and reaches its maximum when pH=9-10; then it decreases with further increase of pH. It was found that ammonium phosphite and ammonium chloride in the aqueous solution have the salting-out effect which can enhance the distribution ratio, and the extraction temperature has only a little effect on the extraction process. The distribution equilibrium relation of 4-nitropyridine with chloroform in aqueous and organic solution with pH=9-10 was determined, and the extraction enthalpy of 5.410 kJ·mol-1 was obtained by experimental measurement. When the volume ratio of organic to aqueous phase is 3, the recovery yield of 5-stage cross-flow extraction is above 95%, and when the volume ratio reaches to 5, the recovery yield of 7-stage counter-flow extraction can be above 96%.

An improved synthesis method of hexachlorocyclotriphosphazene was reported.It was made from ammonium chloride and phosphorus pentachloride using pyridine as an acid-captor in a two-step process.Pyridine could absorb hydrogen chloride produced in the reaction,so the reaction speed was accelerated greatly.The factors affecting the preparation of hexachlorocyclotriphosphazene were investigated.The yield reached 89.4% at optimal conditions.The product was characterized by IR and melting point method.

The uses of 2-fluoropyridine in medicine synthesis,biotechnology,functional material, etc.,and the synthesis methods were reviewed.It is believed that the halogen exchange reaction of 2- chloropyridine with KHF_2 is a potential method for the commercialization.Perspectives of the synthe- ses of fluoropyridines and their applications in the future were given.