Halogen Exchange Fluorination Preparation Of Fluoro Benzaldehyde

Fluorobenzaldehyde is important raw material and intermediate with widely applictations.Halogen-exchange fluorination is the main and efficient method to synthesis fluorinated aromatics. Halogen-exchange fluorination is the main and efficient method to synthesis fluorinated aromatics. So Halogen-exchange fluorination was applied to synthesis fluorobenzaldehyde The fluorination of 4-chlorobenzaldehyde was studied in solvents using spray-dried KF as fluorinating agent. In addition, factors influencing the yield were discussed on solvents selecting, catalytic mechanism, process optimizing, dynamical equation and by reaction control. Under the optimum reaction conditions of n(KF):n(PCAD):n(la):n(lb)=3:l:0.1:0.05, reaction temperature 210℃, reaction time 8h and nitrobenzene as solvent, yield of 4-fluorobenzaldehyde was over 80.9% and the purity was more than 99.5%This method can also be used to synthesis other fluorobenzaldehyde. Many by-products were detected in the reaction mixture and considered to be formed deriving from water, solvent and the reaction themselves. Nevertheless, the traditional Halogen-exchange fluorination needs long time and inevitably companies with serious by-reactions. So under the traditional, microwave was applied to promote greatly the reaction rate and arise the yield. The kinetic research indicated that the traditional halogen-exchange fluorination was a first order reaction, but the microwave-promoted fluorination was obviously not a first order reaction yet, which was safe to take it for "non-heat" of microwave.