Abstract:The solvent isotope effect was investigated with 1H and 2H NMR, LC MS and GC MS analyses on the reduction of H2O or CO2 with glycerine under alkaline hydrothermal conditions. The solvent isotope study results show that the H on the β C of lactate is almost exchanged by D2O, which suggests that the hydroxyl (—OH) group on the 2 C of glycerine is first transformed into a carbonyl (C=O) group and then is converted back into a —OH group to form lactate; a large amount of D is found in the produced hydrogen gas or formic acid, which shows that the water molecules act as a reactant; and D% in the produced hydrogen gas or formic acid is far more than 50%, which straight forwardly shows that acetol is formed in the first place as the most probable intermediate by undergoing a dehydration reaction rather than a dehydrogenation reaction.
