.3,5,6 The - Trichloropyridine - 2 - Phenol Process

3,5,6-trichloropyridin-2-ol, as one of the most important chemical material, is main intermediate for synthesizing organic phosphorus insecticide chlorpyrifos and many other fine chemicals.3,5,6-trichloropyridin-2-ol is prepared through the steps of chlorination, addition, cyclization, aromatization and acidification by using trichloroacetyl acid as raw material. For the technology of preparation, the factors influencing the yield such as the ratio of raw materials, reaction temperature, reaction time, the kind and the quantity of catalyst, etc, were studied. The optimal reaction condition was determined by orthogonal tests and confirmed by repeat experiments.In step of chlorination, trichloroacetyl chloride was synthesized using trichloroacetic acid and thionyl chloride as raw materials, pyridine as catalyst. And the steps of addition and cyclization were accomplished by one-pot process, nitrobenzene as solvent, 3,3,5,6-tetrachloro-4,4-dihydrogenpyridin-2-one was synthesized from trichloroacetyl chloride and acrylonitrile by one-pot process using the composite catalyst. Then aromatization carried out with sodium hydroxide. After the acidification, 3,5,6-trichloropyridin-2-ol was obtained.The target compound is obtained via five reactions mentioned above and the total yield is 68.6%(Base on trichloroacetic acid). The structure of 3,5,6-trichloropyridin-2-ol is identified by infrared spectra(IR), nuclear magnetic resonance(~1HNMR), and mass spectroscopy(MS). The content of trichloropyridinol determined by the High Performance Liquid Chromato-grapHy(HPLC) method is 99.3%.