The Study On Orientation Chlorination Technology Of Pyridine

Pyridine and chloro-pyridines are very useful chemical materials,chemical intermediate, medical and pesticide intermediates. In recent years, the study on synthesizing diversified chloro-pyridines has been a hotspot in chemical field.In this paper, according to a great deal of references, pentachloropyridine, 2,3,5,6-tetrachloro pyridine ,2,3,5-trichloropyridine,3,5-dichloropyridine and 3,5,6-trichloropyridine-2-ol had been synthesized successfully.In the study of synthesizing pentachloropyridine, the pyridine by the gas-solid chlorine craft of preparing pentachloropyridine of catalysis of the fixed bed had been studied, the reaction device and the catalyzer had been improved, the optimistic conditions of this craft was attained. The result showed the catalyst (70%CoCl220%LaCl2) was a high active one for pyridine chlorination. About this catalyst the optimum react conditions were the fitting react temperature:380℃, ratio of chlorine to pyridine : 8.5:1, contact time : 8s, pyridine moles of consistence in the row material :6%. Under these conditions, the yield was about 90%, the purity of the products was 99%. The catalyst had good activity and selectivity after continuous working 160h. On the base of it, a notional industrial design of pentachloropyridine with annual production 2000 tons was built.In the study of 2,3,5,6-tetrachloropyridine, pentachloropyridine as a row material,reduced by zinc dust, proton provided by NH4Cl, one chlorine atom on the contraposition of nitrogen atom had been replaced by hydrogen atom. The influence of several factors ,such as the dosage of zinc dust, the adding time of NH4Cl, the reaction time, had been studied. The optimistic conditions were ratio of zinc to pyridine : 1.5:1, reaction time of this process: 2.5h, adding time of NH4Cl: 45min. Under these conditions, the yield was about 95%, the purity of the products was beyond 96%.In the study of 2,3,5-trichloropyridine, pentachloropyridine as a row material,reduced by zinc dust, proton provided by water, in base condition,two chlorine atoms on the contraposition and adjacent position of nitrogen atom had been replaced by hydrogen atoms. The influence of several factors ,such as the dosage of zinc dust, the consistence of NaOH, the reaction temperature ,the reaction time, had been studied. The optimistic conditions were ratio of zinc to pyridine : 4:1, the consistence of NaOH:25%, reaction temperature :90℃,reaction time of this process: 8h. Under these conditions, the yield was about 62.3%, the purity of the products was beyond 95%.In the study of 3,5-trichloropyridine, pentachloropyridine as a row material,reduced by zinc dust, proton provided by acetic acid, three chlorine atoms on the contraposition and adjacent positions of nitrogen atom had been replaced by hydrogen atoms. The influence of several factors ,such as the dosage of zinc dust, the reaction temperature ,the reaction time, had been studied. The optimistic conditions were ratio of zinc to pyridine : 7:1, reaction temperature :100℃,reaction time of this process: 10h. Under these conditions, the yield was about 66.53%, the purity of the products was beyond 98%.In the study of 3,5,6-trichloro pyridine-2-ol, 2,3,5,6-tetrachloropyridine hydrolyzed in KOH solution,then reduced by 50% vitriol solution. The influence of several factors , the reaction temperature ,the reaction time, the consistence of KOH,had been studied. The optimistic conditions were reaction temperature :95℃,reaction time of this process: 20h,the consistence of KOH:15%. Under these conditions, the yield was about 95%, the purity of the products was...