Attempts at Solvolytic Generation of Phenyl Cations
1983; Wiley; Volume: 66; Issue: 6 Linguagem: Inglês
10.1002/hlca.19830660610
ISSN1522-2675
AutoresKenneth K. Laali, Ivanka Szele, Katsuhira Yoshida,
Tópico(s)Radical Photochemical Reactions
ResumoAbstract New substrates and reaction conditions which may be expected to yield phenyl cation intermediates have been investigated. The approaches used were: ( a ) solvolysis of PhX in fluorinated alcohols, where X = N (O) = NOTs (tosyloxyazoxy), N (O) = NONf (Nf = C 4 F 9 SO ) and OSO 2 \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^{\rm + } $\end{document} (CH 3 ) 3 ŌTf (Tf=CF 3 SO ); ( b ) solvolysis of ArBr, PhOTf and PhOSO 2 \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^{\rm + } $\end{document} (CH 3 ) 3 ŌTf (phenyl ‘betylate triflate’) in super‐acid solvents (FSO 3 H · SbF 5 , SbF 5 , AgSbF 6 ). Analysis of the product mixtures provided no evidence for the intermediacy of phenyl cations as a major pathway in any of the reactions. This result is remarkable, since the ‘betylate’, for example, is a better leaving group by a factor of at least 10 5 than the ‘super’ leaving group triflate in the solvolysis of alkyl sulfonates. These results are a further indication of the extremely low stability of phenyl cations, as well as of the very special properties of the nitrogen leaving group in arenediazonium ions.
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