IONIZATION OF ORGANIC COMPOUNDS: IV. STUDIES OF ETHANOL AND ETHYL ETHER IN SULPHURIC ACID BY NUCLEAR MAGNETIC RESONANCE

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Abstract
The chemical shift of the methyl protons relative to the methylenic protons of an ethyl group attached to a basic center increases with the acidity of the medium. This increase may be attributed to two effects: over a relatively narrow range of acidity function (H0) values, to protonation of the basic center; over the complete H0 range investigated, to a general solvent effect, which may be due to changing strengths of hydrogen bonds between the basic center or its conjugate acid and solvent water molecules. Protonation constants [Formula: see text] of −1.1 for propionamide and −6.9 for propionic acid have been calculated, in good agreement with values obtained by the ultraviolet spectrophotometric method; the constants calculated for diethyl ether (−6.2) and ethanol (−4.8) are much less certain, because of the greater magnitude of the solvent effect with these compounds.