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1H and 13C NMR spectra and isomerism of 3-aminoacroleins

✍ Scribed by Antonio Gómez-Sánchez; Rocío Paredes-León; Juan Cámpora

Publisher
John Wiley and Sons
Year
1998
Tongue
English
Weight
248 KB
Volume
36
Category
Article
ISSN
0749-1581

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✦ Synopsis

A set of 3-alkylaminoacroleins (R1NHCHxCHCHxO, R1 \ alkyl) were studied by 13C and 1H NMR spectroscopy in solutions of di †erent solvents and, for the simplest representative of the series, 3methylaminoacrolein, at di †erent temperatures. The equilibrium solutions of these compounds consists of mixtures of the chelated ZZE form (Z geometry around the xCÈCxO single bond and the CxC bond, and E geometry around the CÈN bond) and the two E conÐgurational isomers having the E disposition around the xCÈCxO single bond and di †ering in the disposition around the CÈN bond (EEZ and EEE forms). The relative proportions of the three isomers depend on solvent polarity, concentration, bulk of substituent R1 and temperature. The EEZ isomer is the most abundant in polar solvents, while the concentration of the ZZE form increases in non-polar solvents and when increasing the bulk of R1. A lineshape 1H NMR study for 3-methylaminoacrolein in gave CDCl 3 a *G" value of 66.0 kJ mol~1 at 303 K for the EEZ ] EEE conversion. The presence of other tautomeric forms was not observed.

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