.2,3,4 - Trifluoroaniline Synthesis Process

Fluorine-contained medicine and pesticides are characteristic of small dosage,low toxicity,high efficiency,powful metabolism,etc.,which make its application in the new drugs increasing continuously. 2,3,4-trifluoronitrobenzene,which is an important organic fine chemical and medicine intermediate,is mainly applied to the production of medicines,pesticides and so on.In this text,1,2,3-trichlorobenzene was used as the raw material. Firstly,the 2,3,4-trifluoronitrobenzene was produced through nitration, ultrasonic promoted fluoro-substitution of 1,2,3-trichlorobenzene.Then the process of the electro-reduction of 2,3,4-trifluoronitrobenzene to yield 2,3,4-trifluoroaniline was studied.Plentiful and substantial conclusions were obtained,which are listed as follows:The process of producing 2,3,4-trifluoronitrobenzene was studied under ultrasonic radiation after the nitration of 1,2,3-trichlorobenzene by hybrid acids(H₂SO₄ and fuming HNO₃).And the optimized reaction conditions are:the molar ratio of fuming HNO₃ with 1,2,3-trichlorobenzene is 1.3:1;the reaction temperature is 55～60℃;and the reaction time is 2h.Keeping the molar ratio 1:4 of 2,3,4-trichloronitribenzene/anhydrous potassium fluoride as a constant, we also optimized the ultrasonic fluoro-substitute process:the reaction time is 20 min;the temperature is 60℃,the power of the ultrasonic equipment is 375W.The cathodic reduction behaviors and kinetic characteristics of 2,3,4-trifluoronitrobenzene in sulfuric acid-ethanol system was studied by cyclic voltammetry.The results showed that 2,3,4-trifluoronitrobenzene have good electrochemical reduction behavior on copper electrode,and its reduction potential is -0.2～0.6V,which is more positive than that of hydrogen,so the 2,3,4-trifluoronitrobenzene can reduced before hydrogen evolution.Moreover,it was found that the reduction process which controlled by diffusion is irreversible.The influential factors,such as temperature,concentration of 2,3,4-trifluoronitrobenzene and electric quantity of electro-reaction,for the yielding of 2,3,4-trifluoro-aniline on Cu electrode in sulfuric-ethanol system was studied with fixed potential.The optimal experimental conditions were obtained:the electric quantity is 85%of the theoretical value;the apparent concentration of 2,3,4-trifluoronitrobenzene is 0.2mol/L while the concentration of medium is 0.1 mol/L;and the reaction temperature is 45℃.The average yielding of 2,3,4-trifluoro-aniline could reach 70.3%with this experimental conditions...