ALKALI-METAL FLUORIDES SUPPORTED ON GAMMA-ALUMINA - SURFACE-REACTIONS INVOLVING F-18 LABELED AND S-35 LABELED SULFUR-TETRAFLUORIDE AND THIONYL FLUORIDE, S-35 LABELED SULFUR-DIOXIDE, F-18 LABELED AND C-14-LABELED CARBONYL FLUORIDE AND C-14-LABELED CARBON-DIOXIDE

Reactions between the Lewis acids, SF4, F2SO, SO2, F2CO and CO2, radiolabelled with C-14, F-18 and S-35 as appropriate, and CsF or KF supported on gamma-alumina have been studied under heterogeneous conditions at room temperature. Fluorine-containing Lewis acids react in two ways, with surface F- anions to form Lewis acid-base complexes and to fluorinate surface hydroxyl groups. Maximum surface F- anion activity occurs at a metal fluoride loading of 5.5 mmol g-1. The reaction between CsF or KF and gamma-alumina to give hexafluoroaluminate salts, which occurs during the impregnation process, becomes more important as the metal fluoride loading increases over the range 0.6-20.0 mmol g-1. This reaction is accompanied by dehydroxylation of the surface of the support, but there is no evidence for the presence of free hydroxide anions.