Synthesis Of Fluoronitrobenzene With Several [Ph₃PR]⁺X^- Type Quaternary Phosphonium Salt Catalysts

Nine kinds of [Ph₃PR]⁺X-type quaternary phosphonium salts were synthesized in this paper,which were the phase transfer catalysts in the reaction of preparation of fluoride nitrobenzene by halogen-exchange fluorination of 4-chloronitrobenzene with SD-KF.DMSO was used as solvent.Factors influencing the yield were discussed on types and dosage of quaternary phosphonium salt phase transfer catalysts,the dosage of KF,solvent select,reaction temperature and reaction time.Under the catalysis of several different quaternary phosphonium salts,in 20 m L solvent,when the molar ratio?quaternary phosphonium salt : 4-chloronitrobenzene?was 0.005⁰.05,the molar ratio?KF :4-chloronitrobenzene?was 1⁴,reaction temperature was 160²00?,reaction time was 1⁴h,the yield of fluoride nitrobenzene was 27.13⁹0.89%.The yield of the product increased with the dosage of quaternary phosphonium salt or KF in the beginning and then leveled off,and increased with the temperature or time in a certain range and then declined.The optimum reaction conditions were found as follows:[Ph₃PC₄H₉]⁺Br^-as catalyst,DMSO as solvent,reaction temperature 190?and reaction time 3 h,n?[Ph₃PC₄H₉]⁺Br^-?:n?KF?:n?4-chloronitrobenzene?=0.02:2:1,fluoride nitrobenzene was obtained with 90.01%yield.Quaternary phosphonium salts were validated by IR and 1H NMR;p-Fluoronitrobenzene products were identified by gas chromatography.The by-product of the reaction,catalyst,solvent recovery and treatment are discussed.