The Synthesis And Purification Of Meso-1, 2, 3, 4-tetrachlorobutane

Meso-1,2,3,4-tetrachlorobutane is a very important organic intermediate in fine chemical industry. It is the raw material of Meso-1,2,3,4-tetrachloroperfluorobutane and the cross-linking agent of artificial rubber. At present there is none reports on large-scale manufacture, thus it has the potential of development and application value.First, an one-step synthesis route was established in the paper. Through comparing various possible solvents and catalysts of the reaction, ultimately dichloromethane was determined as suitable solvent, chlorine and butadiene as raw materials. Meso-1,2,3,4-tetrachlorobutane was prepared in the presence of proper solvent and catalyst by inletting of chlorine and butadiene gases with certain flow speed. Through experiments, the optimal process was obtained as follows: dichloromethane was 11.31% height of buble tray, the raw material ratio was n(Cl2):n(C4H6)=5:1, the reaction temperature was 10℃, the reaction pressure was atmosphere, the reaction time was 5h, the pyridine (5% wt of dichloromethane) was catalyst. The yield of rough product was 57.6%.Second, the rough product was disposed by means of distillation, filtration and recrystallization. The optimal technology of recrystallization was determined as follow: equivalent weight of 95% ethanol to rough crystal as the best recrystal solvent, the cooling rate was 4℃/ 15min,the terminal point of temperature was 20℃. Low speed stir was preferred in the process. The purity of the final crystal was above 99%. The structure of product was confirmed by IR, GC-MS.The possible reaction mechanism was also discussed in the paper, and verified by experimental results.