Structure-reactivity relationships in the pyridinolysis of N-methyl-N-arylcarbamoyl chlorides in dimethyl sulfoxide

Citation
I. Lee et al., Structure-reactivity relationships in the pyridinolysis of N-methyl-N-arylcarbamoyl chlorides in dimethyl sulfoxide, J ORG CHEM, 66(25), 2001, pp. 8549-8555
Citations number
42
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry & Analysis","Organic Chemistry/Polymer Science
Journal title
JOURNAL OF ORGANIC CHEMISTRY
ISSN journal
0022-3263 → ACNP
Volume
66
Issue
25
Year of publication
2001
Pages
8549 - 8555
Database
ISI
SICI code
0022-3263(200112)66:25<8549:SRITPO>2.0.ZU;2-G
Abstract
Nucleophilic substitution reactions of N-methyl-N-arylcarbamoyl chlorides ( YC6H4N(CH3)COCl) with pyridines (XC5H4N) have been investigated in dimethyl sulfoxide at 45.0 degreesC. A striking trend in the selectivity parameters is that they are constant within experimental errors, rho (X) = -2.25 +/- 0.03, beta (X) = 0.42 +/- 0.01, and rho (Y) = 1.10 +/- 0.06, with changing reactivities of the electrophiles (delta sigma (Y)) and nucleophiles (delta sigma (X)), respectively, and this leads to a vanishingly small cross-inte raction constant, rho (XY) approximate to beta (XY) approximate to 0. The r ate data can be expressed in the Ritchie N+ type equation. Based on this an d other results, the mechanism of nucleophile (pyridine) addition to the re sonance- stabilized carbocation is proposed. It has been shown from the def inition of beta (XY) (and rho (XY)) together with the Marcus equation that the high intrinsic barrier, DeltaG(0)(double dagger), in the intrinsic-barr ier controlled reaction series is a prerequisite for such reactions in whic h the cross-interaction vanishes and the N+ relationship holds.