Theoretical Characterization of Hydroxyfuranones Related to Biomass Burning and Their Tautomers

The formation of hydroxyfuranones has been observed in biomass plumes and suggested as an indicator of their temporal evolution. This work focuses on the characterization of three different hydroxyfuranones and their open-chain tautomers. The relationship between the thermal stability and structures is studied using density functional theory (DFT) calculations. Furthermore, harmonic and anharmonic IR vibrational frequencies calculated using generalized second-order perturbation theory (GVPT2) are compared with several experimental IR spectra. We find good agreement for the most important vibrational modes. It is also shown that the thermodynamic stability depends on substituent positioning and structural features like intramolecular hydrogen bonding. The DFT + GVPT2 approach was successfully used to distinguish between different tautomers.