Protonation acidity constants for some benzamides, acetamides, and lactams

Protonation acidity constants for 27 benzamides, acetamides, and lactams have been determined. Ultraviolet, and 13 C and 1 H nmr, spectroscopic methods were used; almost all the spectra were found to be subject to medium effects, some quite severe, as the sulfuric acid concentration was increased. D...

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Published inCanadian journal of chemistry Vol. 59; no. 11; pp. 1568 - 1573
Main Authors Cox, Robin A, Druet, Linda M, Klausner, Adi E, Modro, Tomasz A, Wan, Peter, Yates, Keith
Format Journal Article
LanguageEnglish
Published Ottawa, Canada NRC Research Press 01.06.1981
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ISSN0008-4042
1480-3291
DOI10.1139/v81-231

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Summary:Protonation acidity constants for 27 benzamides, acetamides, and lactams have been determined. Ultraviolet, and 13 C and 1 H nmr, spectroscopic methods were used; almost all the spectra were found to be subject to medium effects, some quite severe, as the sulfuric acid concentration was increased. Despite this, the excess acidity (X-function) method gave accurate and m* values. In all cases protonation, followed by a medium shift in the spectrum of the protonated form, was the only process taking place; protonation was essentially complete in 60% H 2 SO 4 . The results for the different bases are interpreted in terms of the resonance, inductive, and steric effects in operation in the acid and base forms.
ISSN:0008-4042
1480-3291
DOI:10.1139/v81-231