We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Kinetic study on pyridinolysis of aryl benzenesulfonates: factors governing regioselectivity and reaction mechanism.
- Authors
Um, Ik-Hwan; Jung, Yoon Jae; Dust, Julian M.
- Abstract
A kinetic study is reported for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (1a–1f) and Y-substituted-phenyl benzenesulfonates (2a–2f) with Z-substituted-pyridines. The reactions proceed through S–O and C–O bond scissions competitively. The Yukawa–Tsuno plot for the reactions of 1a–1f with 4-oxypyridine (S–O bond fission) exhibits an excellent linearity. The Brønsted-type plot for the reactions of 2,4-dinitrophenyl benzenesulfonate (1d) with pyridines (S–O bond fission) is also linear with βnuc = 0.62. The Brønsted-type plot for the reactions of 2a–2f with 4-oxypyridines (S–O bond fission) is linear with βlg = –1.17. Thus, the reactions have been concluded to proceed through a concerted mechanism, in which leaving-group expulsion is significantly more advanced than bond formation between the electrophilic center and nucleophile at the transition state. The Hammett plot for the reactions of 1a–1f with 4-oxypyridine (C–O bond fission) exhibits scattered points with ρX = 0.98. The Brønsted-type plot for the reactions of 1d with Z-substituted-pyridines (C–O bond fission) results in an excellent linear correlation with βnuc = 0.38. Thus, the reactions (C–O bond fission) have been concluded to proceed through a stepwise mechanism with a Meisenheimer complex, in which expulsion of the leaving group occurs after the rate-determining step. Factors governing regioselectivity and reaction mechanism are discussed.
- Subjects
BENZENESULFONATES; REGIOSELECTIVITY (Chemistry); REACTION mechanisms (Chemistry); BENZENESULFONATE analysis
- Publication
Canadian Journal of Chemistry, 2022, Vol 100, Issue 5, p378
- ISSN
0008-4042
- Publication type
Article
- DOI
10.1139/cjc-2021-0287