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Deprotonation of Amides and Polyfunctional Imides Probed by Heteronuclear NMR and Quantum Chemical Calculations
Author(s) -
Bagno Alessandro,
Comuzzi Clara
Publication year - 1999
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199901)1999:1<287::aid-ejoc287>3.0.co;2-n
Subject(s) - chemistry , heteronuclear molecule , deprotonation , protonation , tautomer , computational chemistry , chemical shift , amide , solvation , nuclear magnetic resonance spectroscopy , organic chemistry , ion
The site of deprotonation of several types of amide acids (carboxylic amides and imides, sulfonamides, cyanamide, N ‐hydroxyurea) has been investigated by quantum chemical calculations and heteronuclear NMR measurements. Relative energies of tautomeric ions deriving from protonation at the various sites were determined both in the gas phase and in water (by the IPCM continuum solvation method). NMR properties (nuclear shielding and electric field gradient) of the involved heteronuclei were calculated and compared with experimental 14 N, 17 O and 33 S chemical shifts and relaxation rates. It is shown that the combination of theoretical and experimental tools allows a reliable prediction of spectral parameters and ultimately of the deprotonation site of polyfunctional acids.