Novel Technology On Synthesising Sodium 3,5,6-Trichloropyridin-2-ol

In China,the main method for synthesizing Sodium 3,5,6-trichloropyridin-2-ol (STCP) is Trichloroacetyl Chloride (TCAC) route:trichloroacetyl chloride and acrylonitrile are used as the starting material fistly synthesizing 3,3,5,6-tetrachloro-3,4-dihydropyridin-2-one,then alkalized to STCP.The yield of STCP in this route is low, about 60%.For increasing the yield of STCP we modified the trichloroacetyl chloride route. The new process is like this:(1) TCAC and methanol firstly react to synthesis methyl trichloroacetate (MTCA); (2) With the presence of CuCl as the atalyst,MTCA then to react with acrylonitrile (AN) for ethyl 2,2,4-trichloro-4-cyanobutyrate(MTCB); (3) 2,3,5,6-tetrachloropyridine (TCP) was prepared by the cyclization of MTCB in the solvent of POCl3; (4) TCP is alkalized for STCP.The influencing factors of every step such as the ratio of raw materials, reaction temperature, and time were investigated systematically. The mechanism of the reactions was also discussed. Under optimized reaction conditions the best yield of the four steps were 100%,88%,93%,95%. The total yield of STCP reached 77%.In this novel process of synthesizing STCP, under mild conditions every reaction got a higher yield. It is of momentous significance for raising the yield of STCP.