Weaving a web of reliable thermochemistry around lignin building blocks: Vanillin and its isomers

Vanillin and its isomers are a promising biobased building blocks for monomer synthesis. Extensive experimental thermochemical studies of these compounds have been carried out, including combustion calorimetry, vapor pressure measurements, and differential scanning calorimetry. We have collected available primary experimental results on enthalpies of formation and vapour pressures as well as on phase transitions liquid–gas, liquid–solid, crystal-liquid. These data were evaluated using empirical, semi-empirical and quantum chemical methods. The consistent sets of evaluated thermodynamic data were used to design the method for predicting enthalpies of vaporization and enthalpies of formation of di- and tri-substituted benzenes. It is expected that parameters and pairwise interactions will be transferable to predict the thermochemical properties of poly-methoxy-substituted and poly-hydroxy-substituted benzenes that appear in reaction products of lignin transformations in the value-adding chemicals and materials.