Spontaneous formation of tetramethylethylene π-radical cations on adsorption of alkenes onto H-mordenite

Abstract

Following the adsorption of propene on H-mordenite at 195 K, electron spin resonance (ESR) spectra were recorded at 298 K that are assigned to a mixture of the tetramethylethylene (TME) radical cation and its π dimer (Me 2C CMe 2) .+ 2. From 3,3-dimethylbut-1-ene (DMB), the TME .+ radical cation was again observed; results for this alkene in solid freon matrices suggest that the DMB .+ radical cation is stable to rearrangement at the temperatures employed in these experiments and that a proton-catalysed process occurs in the zeolite, forming DMB which is then oxidised to its radical cation.