Collect. Czech. Chem. Commun. 1980, 45, 330-334

Analysis of 1H-NMR spectra of cinnamaldehyde type model substances of lignin

Tibor Liptaja, Milan Remkob and Ján Polčinc

a Central NMR Laboratory, Slovak Institute of Technology, 880 37 Bratislava
b Scientific Research Institute of Pharmaceutical Faculty, Comenius University, 880 34 Bratislava
c Pulp and Paper Research Institute, 890 20 Bratislava


1H-NMR spectra of the following lignin model substances have been analyzed: cinnamaldehyde, 2-methoxycinnamaldehyde, 3-methoxycinnamaldehyde, 4-methoxycinnamaldehyde, 3,4-dimethoxycinnamaldehyde, 3-methoxy-4-hydroxycinnamaldehyde and 3,4,5-trimethoxycinnamaldehyde. From the NMR spectra analysis it follows that the studied compounds exist in solutions as trans isomers. Theoretical (PCILO) calculations in agreement with the NMR data have shown that the more stable conformer has trans orientation of C=O group with respect to the double bond of the conjugated side chain.