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Solvolytic reactivity of pyridinium ions
Author(s) -
Jurić Sandra,
Kronja Olga
Publication year - 2015
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3412
Subject(s) - chemistry , pyridine , pyridinium , reactivity (psychology) , heterolysis , solvation , ion , chloride , solvent , medicinal chemistry , reaction rate constant , inorganic chemistry , computational chemistry , photochemistry , organic chemistry , kinetics , catalysis , alternative medicine , pathology , quantum mechanics , medicine , physics
The leaving group abilities of pyridine, 4‐methylpyridine, and 4‐chloropyridine in S N 1 solvolytic reactions have been determined by analyzing the rate constants of X,Y‐substituted benzhydrylpyridinium salts obtained in various solvents. By applying the linear free energy relationship equation, log k = s f ( E f + N f ), the nucleofuge specific parameters of 4‐substituted pyridine have been extracted. Because of solvation in the reactant ground state, the reactivity (nucleofugality, N f ) of a given pyridine decreases as the polarity of the solvent increases. High slope parameters ( s f > 1) may be due to the spread of the energy levels of the benzhydrylium ion/pyridine pair intermediates in comparison to benzhydrylium ion/chloride pairs ( s f ≈ 1). Because of slow heterolysis step of pyridinium salts in various solvents, some are stable under normal conditions. Copyright © 2015 John Wiley & Sons, Ltd.