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Transient Spectroscopy of Ninhydrin ¶
Author(s) -
Kleinman Mark H.,
Telo João P.,
Vieira Abel J. S. C.,
Bohne Cornelia,
NettoFerreira José Carlos
Publication year - 2003
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2003)0770010tson2.0.co2
Subject(s) - ketyl , chemistry , photochemistry , flash photolysis , radical , hydrogen atom abstraction , protonation , radical ion , triplet state , electron paramagnetic resonance , hydroxylamine , ion , ninhydrin , benzophenone , organic chemistry , reaction rate constant , kinetics , molecule , biochemistry , physics , nuclear magnetic resonance , quantum mechanics , amino acid
The photochemistry of ninhydrin in benzene and water was studied by laser flash photolysis and electron paramagnetic resonance. Its photochemistry was shown to be dependent on the solvent. In benzene, a triplet excited state was observed, which underwent hydrogen abstraction reactions or reduction to the radical anion. In water, the radical anion of ninhydrin was formed within the laser pulse (15 ns) at neutral pH, whereas the neutral ketyl radical was formed by protonation of the radical anion at low pH. A pK a of 0.77 was determined for the protonation equilibrium. The formation of hydrindantin is proposed to occur through the dimerization of the ketyl radical or the radical anion (or both). In addition, ninhydrin was shown to be a poor precursor for the photogeneration of hydroxyl radicals.