RADIOTRACERS IN FLUORINE CHEMISTRY .17. CESIUM AND POTASSIUM FLUORIDES SUPPORTED ON FLUORINATED GAMMA-ALUMINA

Exhaustive fluorination of CsF or KF supported on gamma-alumina, by SF 4 or OSF2, nominally at room temperature, is an effective process for the removal of hydroxy groups and/or strongly bound H2O from the surfa ce of these materials. Anhydrous HF and OCF2 are less effective reagen ts; the former can be used however if the surface is pretreated with S O2. The physical properties of CsF and KF supported on fluorinated gam ma-alumina and the behaviour of these materials towards SF4 and CIF, l abelled with sulphur-35 and chlorine-36 respectively, indicates that t he Lewis base character of the surfaces, which is ascribed to surface MF, M=Cs or K, particles, is retained after fluorination. Although the surface areas of the materials are reduced compared with their unfluo rinated counterparts, they are greater than those for the unsupported fluorides.