Premium
Effects of sulfenyl, sulfinyl and sulfonyl groups on acidities and homolytic bond dissociation energies of adjacent C—H and N—H bonds
Author(s) -
Bordwell Frederick G.,
Liu WeiZhong
Publication year - 1998
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/(sici)1099-1395(199806)11:6<397::aid-poc10>3.0.co;2-b
Subject(s) - chemistry , bond dissociation energy , homolysis , sulfonyl , medicinal chemistry , dissociation (chemistry) , hammett equation , substituent , computational chemistry , stereochemistry , reaction rate constant , organic chemistry , radical , kinetics , alkyl , physics , quantum mechanics
Acidities and bond dissociation energies (BDEs) of the N–H bond in two phenylsulfenylamides, PhSNHBz and PhSNH‐ t ‐Bu, and four phenylsulfenylanilides, 4‐GC 6 H 4 NHSPh, where G = MeO, H, Br and CN, were measured in order to compare the effects of substituents on acidities and BDEs of N—H bonds with those of C—H bonds. The effects of PhS groups on acidities and BDEs in a series of C—H acids were found to be comparable to those on acidities and BDEs of PhS in a similar series of N—H acids. Comparisons were also made of the effects of changing the oxidation state of sulfur in the series PhS, PhSO and PhSO 2 on the acidities and BDEs of adjacent N—H and C—H bonds in weak acids. Hammett‐type plots of p K HA values for phenyl benzyl sulfones (4‐GC 6 H 4 CH 2 SO 2 Ph) and phenylsulfenylanilides (4‐GC 6 H 4 NHSPh) were linear vs σ p − values. A linear plot was obtained and explained for a plot of BDE of the N—H bonds in remotely substituted phenylsulfonylanilides with σ + values. Plots of BDEs vs E ox (A − ) were also linear for 4‐substituted phenylsulfenylanilides (4‐GC 6 H 4 NHSPh), phenylsulfonylanilides (4‐GC 6 H 4 NHSO 2 Ph) and phenyl benzyl sulfones (4‐GC 6 H 4 CH 2 SO 2 Ph). © 1998 John Wiley & Sons, Ltd.