Preparation of fluorobenzonitrile

PURPOSE: To efficiently obtain the subject compound at a relatively low tempera ture in a short reaction time by allowing chlorobenzonitrile to react with an alkali metal fluoride in the presence of a novel catalyst system. CONSTITUTION: A compound of formula I (wherein a is from 1 to 5; and b is from 0 to 3) is allowed to react with an alkali metal fluoride in the presence of a catalyst system comprising (A) a quaternary ammonium compound of formula II [wherein R 1 -R 3 are each formula III (wherein R 5 is H or 1-16C alkyl; m is from 1 to 10; and p is from 1 to 15), 1-30C alkyl or the like; R 4 is formula III; and X is an inorganic anion] or a mixture of component (A), (B) a quaternary ammonium salt or a phosphonium salt of formula IV (wherein R 6 -R 9 are each 1-22C alkyl, aryl or the like; and Y is N or P) and/or (C) a polyether or a crown ether of formula V (wherein R 10 and R 11 are each H or 1-16C alkyl; X is from 2 to 6; and r is from 0 to 20), at a reaction temperature of from 80 to 220°C (especially from 120 to 170°C) to obtain the objective compound. COPYRIGHT: (C)1995,JPO