Study On The Synthesis Of Trifluoromethyl Compounds And Its Derivative

Many trifluoromethylated compounds have shown remarkable biological activity, and they have been widely used in a variety of fields ranging from medicinal to agricultural applications. At present the technology to preparing trifluoromethylated compounds is monopolized by Japanese company and American company in the main. Some internal universities have studied synthesis of the intermediate, but only a few approaches to the synthesis of trifluoromethylated compounds have been developed. Therefore, more convenient and effective synthetic methods to prepare trifluoromethylated compounds are increasingly required. The article relates to a method of trifluoromethyl compounds by fluorination of trichloromethyl compounds.Trichloromethylbenzene is reacted with anhydrous hydrogen fluoride by using mercuric oxide as catalyst to form the trifluoromethylbenzene at -20 . Its yield is more than 95% and its purity is 98%. 2-Chloro-5-trichloromethylpyridine is reacted with anhydrous hydrogen fluoride by using mercuric oxide as catalyst to form 2-chloro-5-trifluoromethylpyridine at 20 . Method for preparation of 2, 3-dichloro-5-trifluoromethylpyridine is also studied. Their yields are more than 90% and purities are above 98%. The structures of these productions have been confirmed by elemental analyst, IR, !H-NMR which showed that the structures of these compounds are the same as desired. Trichloromethylbenzene is reacted with anhydrous hydrogen fluoride by using recycling mercuric oxide as catalyst to form the product which contain 84% trifluoromethylbenzene at -20 癈 for 22 hours. Additionally, recycling of hydrogen fluoride is studied, which indicate that hydrogen fluoride can be recycled. Many other catalysts such as Hgp2, AgO, AgFi, et al of the fluorination have been studied also.2-Phenoxy-5-trifluoromethylpyridine is obtained from the reaction of 2-chloro-5-trifluoromethylpyridme and phenol in the presence of potassium carbonate in the dimethyl sulphoxide at 125. The structures of the production has beenconfirmed by elemental analyst, IR. The effects of the reaction conditions on the yield are investigated and reacting conditions optimized.