DFT study on dibenzofuran conversion to cyclohexane and benzene in gas, water and methanol solvents

Hydrodeoxygenation (HDO) of dibenzofuran is studied using density functional theory (DFT) with SMD implicit solvation model to give products like benzene and cyclohexane. Water and methanol are used as solvents, and gas-phase calculations are also performed for comparison. HDO is proposed via two major route- 1) saturation of phenyl rings followed by deoxygenation, 2) cleavage of C-O bond for oxy -removal followed by ring saturation. First, thermochemical parameters like Gibbs free energy change and enthalpy change are calculated at varying temperature in gas, water and methanol. Then, the solvation free energy is calculated for methanol and water to determine the ease of separation of products from the solvents. Finally, a Single Point Energy calculation is performed in the gas phase. It is found that water is the best solvent among three mediums and offers a significant advantage in some reactions such as the conversion of dibenzofuran to 1,2,3,4,4a,9b-hexahydrodibenzo[b,d]furan, 2-cyclohexyl phenol to bicyclo-hexan-2-ol and biphenyl to cyclohexyl benzene. Water is also found to be a better medium for separation of all the intermediates and products from the solvent over methanol. The effect of temperature was also studied, and it was found that the increase in temperature is unfavourable in all mediums for almost all reactions.