Synthesis Of Fluoride Aromatic With Tetrakis(Diethylamino)Phosphonium Bromide As A Phase-transfer Catalyst

Fluoride aromatic are widely used in the synthesis of pharmaceuticals, pesticide, dye and other fields,because they has excellent hydrophobic and fat soluble.Synthesis of4-fluorobenzaldehyde, p-nitrofluorobenzene and p-(trifluoromethyl)aniline was studied with Tetrakis(diethylamino)phosphonium bromide(TPB) as a phase-transfer catalyst in this paper.Synthesis of TPB was studied in this paper, it was synthesized from phosphorus pentachloride(PCl5), and were optimized with different reaction conditions and purification methods. The highest yield can reach to76.8%in mole.Synthesis of4-fluorobenzaldehyde was studied by halogen-exchange fluorination with synthesized TPB as a phase-transfer catalyst. The results showed that solvent-free method could improve the yield and reduce the cost. Under optimized reaction conditions:mole ration between p-chlorobenzaldehyde and potassium fluoride was1:1.2, mass ration of TPB was5%to p-chlorobenzaldehyde, water content was below200ppm, after reaction of16h at205℃, p-fluorobenzaldehyde could be produced with88.9%yield in mole.P-nitrofluorobenzene was synthesized from p-chlorofluorobenzene with TPB as a phase-transfer catalyst. The results proved the high stability and reaction activity of TPB. P-nitrofluorobenzene was prepared with88.2%yield in mole after reaction of10h at190℃with sulfolane as a solvent,5%TPB as a phase-transfer catalyst and excess anhydrous potassium fluoride. The catalyst was easy to recycle, and in order to keep the reaction activity, only0.5-1%TPB was needed to feed additionally.P-(trifluoromethyl)aniline was synthesized from4-trifluoromethyl benzene by aminolysis reaction with TPB as a phase-transfer catalyst. TPB could evidently improve the yield from39.6%to47.0%in mole. Under optimized conditions:equivalent weight(e.w.)2.0acetylamine as a solvent, e.w.0.062cuprous chloride and e.w.0.063TPB as a mixed catalyst, e.w.0.32sodium carbonate as a deacid reagent, and the reaction temperature was160℃, p-(trifluoromethyl)aniline was produced with47.0%yield in mole.