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Kinetic Study on Alkaline Hydrolysis of Y-substituted Phenyl X-substituted Benzenesulfonates: Effects of Changing Nucleophile from Azide to Hydroxide Ion on Reactivity and Transition-State Structure.
- Source :
-
Bulletin of the Korean Chemical Society . Jun2015, Vol. 36 Issue 6, p1563-1568. 6p. - Publication Year :
- 2015
-
Abstract
- Second-order rate constants () for alkaline hydrolysis of 2,4-dinitrophenyl X-substituted benzenesulfonates ( 1a-1f) and Y-substituted phenyl 4-nitrobezenesulfonates ( 2a-2g) have been measured spectrophotometrically. Comparison of with the values reported previously for the corresponding reactions with has revealed that OH is only 103-fold more reactive than , although the former is 11 p Ka units more basic than the latter. The Yukawa-Tsuno plot for the reactions of 1a-1f results in an excellent linear correlation with ρX = 2.09 and r = 0.41. The Brønsted-type plot for the reactions of 2a-2g is linear with βlg = −0.51, which is typical for reactions reported to proceed through a concerted mechanism. The Yukawa-Tsuno plot for the reactions of 2a-2g exhibits excellent linearity with ρY = 1.85 and r = 0.25, indicating that a partial negative charge develops on the O atom of the leaving group in the transition state. Thus, the alkaline hydrolysis of 1a-1f and 2a-2g has been concluded to proceed through a concerted mechanism. Comparison of the ρX and βlg values for the reactions with ions suggests that the reactions with hydroxide ion proceed through a tighter transition-state structure than those with azide ion. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 02532964
- Volume :
- 36
- Issue :
- 6
- Database :
- Academic Search Index
- Journal :
- Bulletin of the Korean Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 103345484
- Full Text :
- https://doi.org/10.1002/bkcs.10297