Intramolecular kinetic isotope effect in hydride transfer from dihydroacridine to a quinolinium ion. Rejection of a proposed two-step mechanism with a kinetically significant intermediate.
The intramolecular kinetic isotope effect (KIE) for hydride transfer from 10-methyl-9,10-dihydroacridine to 1-benzyl-3-cyanoquinolinium ion has been found to be 5-6 by both (1)H NMR and mass spectrometry. This KIE is consistent with other hydride transfers. It is inconsistent with the high intermolecular KIEs derived by fitting to a two-step mechanism with a kinetically significant intermediate complex, and it is inconsistent with the strong temperature dependence of those KIEs. We therefore reject the two-step mechanism for this reaction, and we suggest that other cases proposed to follow this mechanism are in error.
Perrin
Charles L
CL
Department of Chemistry, University of California, San Diego La Jolla, California 92093-0358, USA. cperrin@ucsd.edu
Zhao
Chen
C
D000166:Acridines / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D007554:Isotopes / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011806:Quinolinium Compounds / Q000737:chemistry*
D000166:Acridines; D007477:Ions; D007554:Isotopes; D011806:Quinolinium Compounds; D006859:Hydrogen