Fraenkel, Gideon and Niemann, Carl (1958) The Mode of Protonation of Amides. Proceedings of the National Academy of Sciences of the United States of America, 44 (7). pp. 688-671. ISSN 0027-8424 http://resolver.caltech.edu/CaltechAUTHORS:FRApnas58
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The relative basicities of oxygen versus nitrogen in amides is a problem which has not been satisfactorily resolved. However, it might be anticipated from considerations of resonance and structural parameters that in strongly acidic solutions the proton will attach to oxygen rather than to nitrogen, to give [structure] I rather than [structure] II. It is generally recognized that amides are monoprotonated in 100 per cent sulfuric acid. For example, O'Brien and Niemann  reported i-factors of 2.0, 2.7, 2.0, 2.9, and 1.9 for benzamide, glycinamide, trichloroacetamide, benzoylglycinamide, and phthalimide, respectively, in this solvent. Similarly, in this study we have found the i-factors of N,N-dimethylformamide, N,N-dimethylacetamide, and acetamide to be 2.1, 2.1, and 2.0, respectively. Thus the problem is to locate the locus of protonation in singly protonated primary, secondary, and tertiary amides.
|Additional Information:||Copyright © 1958 by the National Academy of Sciences. Communicated May 16, 1958. The authors are indebted to Professor J.D. Roberts for his assistance during the course of this investigation. Gates and Crellin Laboratories of Chemistry, Contribution No. 2337.|
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|Deposited On:||21 Apr 2008|
|Last Modified:||26 Dec 2012 09:58|
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