Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
6-(Triphenylphosphonio-3′-cyclopentadienyl)-2,3,5-trihalocyclohexa-2,5-diene-1,4-diones (2) are a new class of phosphorus containing dyes that behave as weak bases. Mono-protonation occurs at the cyclopentadiene ring leading to three isomers as assessed by NMR. The kinetics of the protonation were studied by the stopped-flow technique in aprotic media. The activation energies and deuterium isotope effects suggest that the rate-limiting step is the addition of trifluoroacetic acid to the quinone ring rather than direct protonation of the cyclopentadiene ring. © 1997 John Wiley & Sons, Inc.
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