Science and Mathematics Faculty Publications
Base-Catalyzed Hydrogen-Deuterium Exchange of N-Substituted Pyridinium Ions. Inductive Effects and Internal Return
Document Type
Article
Publication Date
12-1970
Journal Title
Journal of the American Chemical Society
Volume
92
Issue
26
First Page
7547
Last Page
7552
Abstract
Rates of hydrogendeuterium exchange of N-substituted pyridinium ions in DzO at 75.0" were obtained by the use of an nmr method. Deprotonation is catalyzed by deuteroxide ion. Catalysis by buffer bases is negligible, Relative rates of exchange for substituents 0-, CH2CsH5, CH3, CsH5, ND2, and OCH, are 1.0, 1.1 X 102, 1.4 x 102, 5.3 x 102, 2.7 x 103, and 1.3 x 106, respectively. Rates show a good correlation with the Taft uI inductive parameter; pr is 15. The substituent rate factor for positively charged nitrogen is estimated to be about 1014-'6. The absence of substantial buffer base catalysis for these reactions giving pyridinium ylide intermediates is consistent with internal return during exchange. Generalizations concerning the structure of carbon acids, general base catalysis, and internal return are given.
Keywords
Hydrogen-deuterium, Pyridinium
Recommended Citation
Helmick, L. S. (1970). Base-Catalyzed Hydrogen-Deuterium Exchange of N-Substituted Pyridinium Ions. Inductive Effects and Internal Return. Journal of the American Chemical Society, 92, 7547-7552.
