Generation and Direct Observation of the 9-Fluorenyl Cation in Non-acidic Zeolites

✍ Scribed by Melanie A O'Neill; Frances L Cozens; Norman P Schepp

• Book ID: 104202844
• Publisher: Elsevier Science
• Year: 2000
• Tongue: French
• Weight: 146 KB
• Volume: 56
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(00)00518-4

✦ Synopsis

Alkyl-9-¯uorenyl cations and the parent 9-¯uorenyl cation are generated via photoheterolysis of the corresponding 9-¯uorenols within alkali metal zeolites such as LiY, NaY and Nab, and observed directly using nanosecond laser ¯ash photolysis. The observation of the highly reactive and highly unstable 9-¯uorenyl cation under these conditions provides a remarkable example of the extraordinary ability of non-proton exchanged zeolites to provide kinetic stabilisation for electrophilic guests. The reactivity of the carbocations is found to be highly in¯uenced by the nature of the alkali metal counterion as well as the inclusion of cosolvents within the zeolite matrix. The availability of several reaction pathways, other than heterolysis, to photoexcited 9-¯uorenols within the zeolite cavities is also demonstrated and shown to be modi®ed by co-adsorbed protic reagents in a manner consistent with solvent-assisted dehydroxylation.