FT-IR and 29Si, 27Al, and 19F MAS NMR studies of the adsorption of CdF2, ZnF2, and CuF2 onto montmorillonite K10; activity towards Friedel–Crafts alkylation

Abstract

ZnF2, CdF2, and CuF2 have been adsorbed onto the surface of montmorillonite K10, and the infrared and 19F, 27Al, and 29Si MAS NMR spectra of the resulting reagents over a range of loadings and activation temperatures have been obtained. CuF2 was observed to attack the SiO2 layer and form the complex CuSiF6, ZnF2 tends to attack the aluminium oxide layer, in which Zn isomorphously replaces Al, and forms AlF3 and AlF4− complexes. The spectroscopic evidence rules out the formation of any Al–F and (or) Si–F species as CdF2 is adsorbed on the surface of montmorillonite K10. The reactivity of MF2–K10 reagents towards the Friedel–Crafts reaction of benzene with benzyl chloride varies from one reagent to another. ZnF2–K10 was observed to be the most reactive and CuF2 was the least reactive.