Substituent effect on IR, 1H and 13C NMR spectral data in n-(substituted phenyl)-2-cyanoacetamides: A correlation study

• Main Authors: Marinković Aleksandar D., Brkić Dominik, Martinović Jelena S., Mijin Dušan Ž., Milčić Miloš, Petrović Slobodan D.
• Format: Article
• Language: English
• Published: Association of the Chemical Engineers of Serbia 2013-01-01
• Series: Chemical Industry and Chemical Engineering Quarterly
• Subjects: N-(substituted phenyl)-2-cyanoacetamides; LFER analysis; IR and NMR spectra; SCS shift; Hammett equation
• Online Access: http://www.doiserbia.nb.rs/img/doi/1451-9372/2013/1451-93721200044M.pdf

Linear free energy relationships (LFER) were applied to the IR, 1H and 13C NMR spectral data of N-(substituted phenyl)-2-cyanoacetamides. A variety of substituents were employed for phenyl substitution and fairly good correlations were obtained using the simple Hammett and the Hammett-Taft dual substituent parameter equations. The correlation results of the substituent induced 13C NMR chemical shifts (SCS) of the C1, C=O and N-H atom indicated different sensitivity with respect to electronic substituent effects. A better correlation of the SCSC=O with a combination of electrophilic and nucleophilic substituent constants indicated a significant contribution of extended resonance interaction (π-delocalization) within the π1-unit. The conformations of the investigated compounds were studied using the DFT B3LYP/6-311G method and, together with the results of 13C NMR and IR spectroscopic studies, a better insight into the influence of such a structure on the transmission of electronic substituent effects was obtained.