INEXPENSIVE, ACTIVE KF FOR NUCLEOPHILIC AROMATIC DISPLACEMENT-REACTIONS

The simple, and inexpensive process, of recrystallizing KF from a methanol solution by slow evaporation of the solvent followed by drying at 100 degrees C, results in a highly active form of KF. The surface area was increased 20 fold by this process. This pre-treated KF proved to be considerably more efficient as a source of fluoride ion than untreated KF in the conversion of 2,4-dichloronitrobenzene to 2,4-difluoronitrobenzene. It was observed to be more efficient than spray dried KF but was less efficient than KF supported on CaF2. The results of a kinetic analysis of the above reaction using the pre-treated KF point towards a solid-liquid interfacial mechanism.