F. Miyajima et al., Aromatic nucleophilic fluorination with KF catalyzed by polymer-supported phosphonium salts under solid-solid-liquid phase transfer conditions, REACT FUNCT, 43(3), 2000, pp. 315-324
Fluorination of 2,4-dinitrochlorobenzene (DNCB) with solid KF was conducted
in the presence of polymer-supported tetraphenylphosphonium chloride catal
yst under solid-solid-liquid (S-S-L) phase transfer conditions. The triphas
e fluorination obeyed zero-order kinetics with respect to DNCB concentratio
n and first-order kinetics with respect to the catalyst concentration. The
apparent activation energy for the fluorination was estimated as about 40 k
J/mol. On the basis of these results, the ion exchange reaction between the
Cl- ion of the supported catalyst and the F- ion of KF was concluded to be
rate-determining in this S-S-L triphase fluorination. The addition effect
of water on the triphase fluorination was discussed by means of both the pr
ompted dissolution of solid KF and the decreased reactivity of the F- ion,
induced by increased hydration. (C) 2000 Elsevier Science B.V. All rights r
eserved.