View : 22 Download: 0

The alpha-effect in the SNAr reaction of 1-(4-nitrophenoxy)-2,4-dinitrobenzene with anionic nucleophiles: effects of solvation and polarizability on the alpha-effect

Title
The alpha-effect in the SNAr reaction of 1-(4-nitrophenoxy)-2,4-dinitrobenzene with anionic nucleophiles: effects of solvation and polarizability on the alpha-effect
Authors
Um, Ik-HwanKim, Min-YoungCho, Hyo-JinDust, Julian M.Buncel, Erwin
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2015
Journal Title
CANADIAN JOURNAL OF CHEMISTRY
ISSN
0008-4042JCR Link1480-3291JCR Link
Citation
vol. 93, no. 10, pp. 1109 - 1114
Keywords
alpha-effectSNAr reaction1-(phenoxy)-2,4-dinitrobenzenesolvationpolarizability
Publisher
CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
A kinetic study on SNAr reactions of 1-(4-nitrophenoxy)-2,4-dinitrobenzene (1a) with various anionic nucleophiles in 80 mol% water - 20 mol% DMSO at 25.0 degrees C is reported. The Bronsted-type plot for the reaction of 1a with a series of substituted phenoxides and HOO- results in an excellent linear correlation with beta(nuc) = 1.17. However, OH- exhibits dramatic negative deviation from the Bronsted-type plot, while N-3(-), C6H5S-, and butane-2,3-dione monoximate (Ox(-)) deviate positively from linearity. HOO- is 680-fold more reactive than OH- but does not exhibit the alpha-effect. In contrast, Ox(-) is 166-fold more reactive than isobasic 4-Cl-C6H4O- and exhibits the alpha-effect. Differential solvation effects have been suggested to be responsible for the alpha-effect in this study, i.e., Ox(-) exhibits the alpha-effect, since it is 5.7 kcal/mol less strongly solvated than 4-Cl-C6H4O- in the reaction medium, while HOO- does not show the alpha-effect due to a strong requirement for partial desolvation before nucleophilic attack. The highly enhanced reactivity of polarizable N-3(-) and C6H5S- and extremely decreased reactivity of nonpolarizable OH- are in accord with the hard-soft acid and base principle.
DOI
10.1139/cjc-2015-0073
Appears in Collections:
자연과학대학 > 화학·나노과학전공 > Journal papers
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE