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Aminoxyl radical addition to arylketenes
Author(s) -
Acton Austin,
Allen Annette D.,
Fedorov Andrei V.,
HenryRiyad Huda,
Tidwell Thomas T.
Publication year - 2006
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.1036
Subject(s) - chemistry , reactivity (psychology) , ketene , substituent , nucleophile , electrophile , reaction rate constant , medicinal chemistry , hammett equation , photochemistry , kinetics , organic chemistry , catalysis , medicine , physics , alternative medicine , pathology , quantum mechanics
Kinetic studies of the addition of the aminoxyl radical TEMPO (2,2,6,6‐tetramethylpiperidinylaminoxyl, TO·) to the 4‐substituted phenylketenes 8 (4‐RC 6 H 4 CHCO, R = NO 2 , CN, Cl, H, CH 3 , CH 3 O) and to 3‐pyridylketene ( 15 ) reveal a correlation of log k 2 (TEMPO) with the Hammett sigma parameters of the substituents (including the aza substituent of 15 ), with rho = 1.58 ( r = 0.94). A better correlation is obtained with the rate constants for hydration of the same substrates: log k 2 (TEMPO) = 1.64log k (H 2 O)−5.76 ( r = 0.98). These results fit within a previously established correlation of ketene hydration reactivity with aminoxyl radical reactivity, and confirm that the reactivity of TEMPO in additions to ketenes is dominated by the nucleophilic character of the aminoxyl oxygen, with a strong trend of increasing reactivity for more electrophilic ketenes. Copyright © 2006 John Wiley & Sons, Ltd.