Experimental and quantum chemical study of biosynthetic lignin models — dehydropolymers

Abstract

Using IR Fourier transform spectroscopy we consider biosynthetic lignin models, namely, dehydropolymers. Quantum chemical calculations of IR spectra of model lignin structures were carried out within the framework of the density functional theory with the B3LYP functional in the 6-31+G(d,p) basis. The IR spectrum of a dimer with the C(8)—O—C(4) fragment describes well the specific features of the spectrum of the dehydropolymer synthesized from coniferyl alcohol. The presence of dimeric structures with double bonds in aliphatic chains and ether bonds between aromatic rings was determined in dehydropolymers from ferulic acid. The results of theoretical and experimental studies were shown to be in agreement with each other.