Process for the preparation of ring-fluorinated aromatic 6-membered ring nitrogen heterocycles

摘要

Aromatic ring-fluorinated 6-membered ring nitrogen heterocycles of the formulae <IMAGE> in which R3 = H, CH3, C2H5, Cl, Br; R4 = H, CH3 Cl; R5 = H, CH 3, C2H5, ClCH2, Cl2CH, Cl3C, CF3; R6 = H, CH3, C2H5, ClCH2 , Cl2CH are obtained almost quantitatively, by reacting the corresponding ring-chlorinated compounds with anhydrous hydrofluoric acid under pressure, if the reaction is carried out with up to 10 mol of excess hydrofluoric acid per mol of ring-chlorinated starting compound and at temperatures between 50 and 200 DEG C and at a pressure between 2 and 40 bar and if the excess hydrofluoric acid, after completion of the reaction time, is distilled off, without cooling the reaction mixture, by gradual depressurisation of the reactor.