Hydrocarbon production from lignocellulosic biomass via liquid phase processing depends strongly on obtaining high yields of glucose and its main reaction intermediates such as hydromethylfurfural (HMF). However, glucose possesses multiple reaction pathways during chemical processing in solution. Fundamental understanding of glucose reaction mechanisms, and determining their associated barriers and free energies would be critical in order to achieve high conversion of liquid fuels. Car-Parrinello based ab initio molecular dynamics simulations (CPMD) coupled with metadynamics (MTD) simulations were used to determine glucose reaction mechanisms and associated free energy landscapes in acidic solvent and solvent mixtures. Solvent and solvent structures are found to play an important role in glucose reactions. The theoretical results were validated by the complementary experiments. The insight obtained will shed significant light on optimizing biomass conversion to biofuels.