Detection and Characterization of a Transient Zwitterion, the 9-Carboxylate-9-fluorenyl Cation, and Its Conjugate Acid

Download
  1. Get@NRC: Detection and Characterization of a Transient Zwitterion, the 9-Carboxylate-9-fluorenyl Cation, and Its Conjugate Acid (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1021/ja962066t
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
TypeArticle
Journal titleJACS: Journal of the American Chemical Society
ISSN0002-7863
Volume118
Issue48
Pages1206612073; # of pages: 8
AbstractLaser flash photolysis of 9-hydroxy-9-fluorenecarboxylic acid in hexafluoro-2-propanol (HFIP) generates a transient with 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 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 ? 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.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Institute for Chemical Process and Environmental Technology; NRC Steacie Institute for Molecular Sciences
Peer reviewedYes
Identifier10072378
NPARC number12329167
Export citationExport as RIS
Report a correctionReport a correction
Record identifiere2c3a6d9-5eb3-4bf1-9399-4cc827ba4ae8
Record created2009-09-10
Record modified2017-03-17
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)