Synthesis Of The New Phase-transfer Catalyst-N-alk Yl Quaternary Phosphonium Salts And Application In Fluorination Of Aromatic Compounds

Fluorinated aromatic compounds play an important role as intermediates or materials in preparation pharmaceuticals, pesticides and dyes last decade. Halogen exchange reaction use low-cost halogenated aromatic compounds as materials and it has been the mostly way to synthesize fluoro- aromatic compound.N-alkyl quaternary phosphonium salts are novel phase-transfer catalysts that mostly apply in fluorination of aromatic compounds, during the process they show several good characteristic, including excellent catalytic capabilities, low toxcity, perfect thermally sta ble and reuse et al. They can be used in halex reaction. Through my ameliorating meth ods, the article synthesizes mainly 5 kinds N-alkyl quaternary phosphonium salts: [(Et2N) 4P]Br, [(Et2N)(Piperdino)3P]Br,[(Et2N)(Morpholino)3P]Br,[(Et2N)(Bu2N)3P]Br,[(Et2N)2(Piperdi no)2P]Br,respestive yield is 84.2%,78.1%,83.0%,87.7% and 67.4%(according to the quali ty of PCl5), the last four phosphonium salts do not be reported in the home and the ide a of designing last four phosphonium salts is for linking different alkyl. The products w ere identified by 1HNMR, MS, IR, and the results of thermogravimetric analysis (TGA) show their decompose temperature excess 300 °C which prove above five kinds N-alkyl quaternary phosphonium salts excellently thermally stable.I research the catalytic effect of above 5 kinds PTC in halex reaction.. The synthesis of aromatic fluorides with substituted -NO2, -CN, -CF3 are studied respectively. Adopting DMSO as solvent and ladder heat, I review the influence of PTC, reaction time. Adopting GC follow up to inspect and measure, the yield of p-fluoronitrobenzene with strong electron -withdrawing group is 70.72%, and the yield of 2,6-difluorobenzonitrile with weak electron -withdrawing group is 87.87%. I get the result that N-alkyl quaternary phosphonium salts show well catalytic activity and selectivity and thermally stable in synthesis of above 2 kinds fluorinated aromatic compounds and also the three times circularly use effect of [(Et2N)(Morpholino)3P]Br and [(Et2N)(Bu2N)3P]Br was reviewed which show well catalytic activity. The synthesis of 1-fluoro-4-(trifluoromethyl)benzene is also studied fundamentally. Based on the study of reaction mechanism and the analysis of by-products, effective methods suppressing by-reaction are put forward.