ISSN:
1434-193X
Keywords:
Ketones
;
Sulfoxides
;
Phenols
;
Steric hindrance
;
Acidity
;
Basicity
;
NMR spectroscopy
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The proton-transfer equilibrium of several bases and acids, including some sterically hindered ketones, sulfoxides, and phenols, has been investigated by means of the determination of the thermodynamics of the equilibrium, NMR 13C relaxation measurements, and quantum chemical calculations. The analysis of such data yields information about the steric effects on basicity or acidity and about the underlying reasons for the anomalous behavior of species having a sterically hindered basic or acidic site. Thus, it is demonstrated that the anomalously low basicity of two sterically hindered ketones (tBu2CO and PhCOtBu) is enthalpic in origin and stems from steric hindrance to the solvation of their protonated forms. No such effect is found for analogous sulfoxides, whereas phenols display a more complex behavior.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/1999/99105_s.pdf or from the author.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
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