The fluorenylcation is a textbook example for a 4π antiaromatic cation. However, contrasting results have been published on how the annelated benzene rings compensate the destabilizing effect of the 4π antiaromatic five‐membered ring in its core. Whereas previous attempts to synthesize this cation in superacidic media resulted in undefined polymeric material only, we herein report that it can be generated
A kinetic study of the photosolvolysis of 9-fluorenol
作者:Elizabeth Gaillard、Marye Anne Fox、Peter Wan
DOI:10.1021/ja00188a036
日期:1989.3
both heterolytic and homolytic cleavage via the singlet excited state. The partitioning between homolysis and heterolysis is controlled by solvent composition, the rate constant for cation formation being a function of the solvent dielectric constant. The rate constants of intersystem crossing, fluorescence, and singlet-derived radical formation are linear functions of the mole fraction of water.
McClelland, Robert A.; Cozens, Frances L.; Li, Jianhui, Journal of the Chemical Society. Perkin transactions II, 1996, # 8, p. 1531 - 1544
作者:McClelland, Robert A.、Cozens, Frances L.、Li, Jianhui、Steenken, Steen
DOI:——
日期:——
Cozens, Frances; Li, Jianhui; McClelland, Robert A., Angewandte Chemie, 1992, vol. 104, # 6, p. 753 - 755
作者:Cozens, Frances、Li, Jianhui、McClelland, Robert A.、Steenken, Steen
DOI:——
日期:——
Detection and Characterization of a Transient Zwitterion, the 9-Carboxylate-9-fluorenyl Cation, and Its Conjugate Acid<sup>1</sup>
作者:C. S. Q. Lew、B. D. Wagner、Mark P. Angelini、E. Lee-Ruff、J. Lusztyk、L. J. Johnston
DOI:10.1021/ja962066t
日期:1996.1.1
Laser flash photolysis of 9-hydroxy-9-fluorenecarboxylic acid in hexafluoro-2-propanol (HFIP) generates a transient with lambda(max) at 495 nm that reacts with nucleophiles such as methanol and bromide and is insensitive to oxygen. In the presence of 0.15 M trifluoroacetic acid, a different transient with lambda(max) at 560 nm that also reacts with nucleophiles is formed. The 495 and 560 nm species are identified as a zwitterion (the 9-carboxylate-9-fluorenyl cation) and its conjugate acid (the 9-carboxy-9-fluorenyl cation), respectively. The assignment of the zwitterion is supported by the observation of infrared absorptions in the carboxylate region that are quenched by nucleophiles with rate constants similar to those obtained by UV-visible detection. Both the zwitterion and its protonated form are observed at intermediate acid concentrations, leading to an estimate of 1 x 10(-2) M(-1) for the equilibrium constant for the ionization of the 9-carboxy-9-fluorenyl cation in HFIP. Absolute rate constants for reaction of the zwitterion with alcohols, anionic nucleophiles, and substituted aromatics are reported and compared to data for other 9-fluorenyl cations.