Innovation Of Technics For Producing 2-Chloro-5-chloromethylpyridine

2-Chloro-5-chloromethylpyridine is the crucial intermediate of pesticide and medicine. And another crucial intermediate of pesticide and medicine,2-Chloro-5-amino methylpyridine can be also derivated from it.The innovation of technology synthesizing 2-Chloro-5-chloromethylpyridine is a subject of which aims at working out the problem of low yield and much pollution from the current cyclization technology. In this paper, the cyclization reaction has been optimized, and the method of crystallization was used for purifying the aim product on the basis of preliminary experiments. So the technology is simplified for synthesizing 2-Chloro-5-chloromethylpyridine and cut down the operating costs. The pure 2-Chloro-5-chloromethylpyridine can be obtained by repetitious recrystallization. The melting enthalpy is observed to be-15294.42 J/mol of 2-Chloro-5-chloromethylpyridine by DSC scan. At the same time, the saturate characteristics of 2-Chloro-5-chloromethylpyridine were detemined in water and in some organic solvents, and the proper solvent was be taken as a choice from among several. They provide the thermodynamics basic data for industrial produce 2-Chloro-5-chloromethylpyridine.In this paper, single-factor test, which influence the 2-chloro-5-chloromethyl pyridine cyclization reaction,separation and purification of the factors that directly using 2-chloro-2-chloromethyl-4-cyanobutyraldehyde-N,N-Dimethyl formamide solution as raw material, not to add other solvents, optimization of the cyclization reaction of the better conditions are n(2-chloro-2-chloromethyl-4-cyanobutyral dehyde):n(phosphorus oxychloride)= 1:0.6, the temperature of cyclization reation is 90℃, and the reaction time is 8 hours. At this procedure, the yield of 2-Chloro-5-chloromethylpyridine is observed to be 77.91%. At the control of stirring, the solvent is added at the dosage of 5mL per gram reaction solution, and the crystallization temperature is 3～6℃. The crystallization procedure demands 4 hours. The purity of 2-Chloro-5-chloromethylpyridine exceed 90%, and the purification rate exceeds 83%. The technics meets the needs of industry production becauce of avoiding the decomposing of 2-Chloro-5-chloromethylpyridine on the basic of distillation technics.The solubility data of the binary systems of 2-Chloro-5-chloromethylpyridine in water, methanol, ethanol, ethyl acetate, acetone,trichloromethane and toluene are measured at the temperature range of 275.85 K to 309.15K by using laser detection technique at atmospheric pressure, respectively. To testify the uncertainty of the measurement, a comparison with the literature values for the solubility of benzoic acid in water was made. It can be seen that the relative deviation in the mole fraction solubility is less than 2%. These data fill up the blank of the solid-liquid equilibrium data of 2-Chloro-5-chloromethylpyridine.The solubility model of the Ideal solution equation, Apelblat eqution and Wilson equation are proposed, and calculated solubilities by the model show good agreement with experimental data. At the same time, the related parameters are obtained in these models. The maximum error of Ideal eqution, Apelblat eqution and Wilson eqution were 1.22%,1.06% and 3.65%, respectively. The overall error is small by comparing between calculated results and experiment results. So it is appropriate that the solubility models are applied for relationship the solubility with temperature at the experimental range of temperature and concentration.