Ab initio Chemical Kinetics of (2-Furyl)(hydroxy)methyl with O₂

In this work, based on the ab initio method, the reaction mechanism of the low-temperature oxidation of 2-furfuryl alcohol (2FFOH) is studied. (2-furyl)(hydroxy)methyl (furylCHOH, labeled as R) and O₂ were taken as the bimolecular reactants, and the energy diagram was determined by a high-level quantum chemical method (CCSD(T)/ CBS//M05-2X/jun-cc-pVTZ). The equilibrium geometry and vibrational frequencies of the reactants, intermediates, transition states, and products were determined by the M05-2X/jun-cc-pVTZ method. Then, the Rice–Ramsperger–Kassel–Marcus/Master equation method was used to calculate the temperature- and pressure-dependent rate coefficients. O₂ addition to furylCHOH needs to overcome energy barriers of 2.35–7.26 kcal/mol to generate three kinds of peroxide radicals, 2-(2-furyl)(hydroxy)methyldioxidanyl (RO_2α), 2-2-(Z)-hydroxymethylidene-2,3-dihydro-3-furyldioxidanyl (RO_2γ) and 2-5-(Z)-hydroxymethylidene-2,5-dihydro-2-furyldioxidanyl (RO_2ε). The calculation results show that peroxide RO_2ε is the main product when the reaction temperature does not exceed 800 K at 1 atm. Moreover, furfural (P21) and HO₂ become dominant when temperature is above 800 K at 1 atm, which are formed via concerted HO₂ elimination mechanism of three peroxides. The slow reaction rate of RO_2α→INT1 via an intramolecular 1,5 H-shift indicates the trend of low oxidation reactivity of 2FFOH.