Dehydration mechanisms involving hydride transfer, pinacol rearrangement, or substitution reactions have barriers between 20 and 25 kcal mol (-1). Revision D.01 2009.DOI:10.1159/000348293 In this reaction, a six-membered cyclic transition state (TS5) structure was obtained, with an energy barrier of ΔG533,TS5 = 236.4 kJ mol-1, which is lower than that for four-membered cyclic transition states. Entry 2 shows how the change of carrier gas from N2 to H2 increases the selectivity toward HA followed by a decrease in glyceraldehyde and pyruvaldehyde formation. These metrics are regularly updated to reflect usage leading up to the last few days. However, due to the hydrogen-rich environment used in Entry 2, the extension of hydrogenation reaction can promote the formation of 1,2-propanediol from HA. Her research interests include: molecular modeling of combustion reactions, catalytic systems such as catalytic cracking, gas phase atmospheric reactions and bio-oils upgrading. The formation of glycidol is the rate limiting step of the overall decomposition process. The transition structures for the epoxidation of ethylene and propene with peroxyformic acid and of ethylene with dioxirane and dimethyldioxirane calculated at the B3LYP level as well as at the QCISD and CCSD levels are symmetrical with nearly identical C-O bond distances, whereas the MP2 calculations favor unsymmetrical transition structures. Particularly, for these two hydrogenation reactions similar transition structures were found as can be observed in ( eq. Palabras-clave: mecanismo de formación de hidroxiacetona; deshidratación de glicerol; deshidrogenación de glicerol; conversión de glicerol; valorización de biomasa. ORCID: 0000-0002-9916-7614, C. Batiot-Dupeyrat, received the PhD degree in applied chemistry in 1994, from the University of Poitiers, France. For this elementary reaction, the energy barrier is lower than the one obtained for ( eq. Acid catalyzed first dehydration of glycerol at the secondary site: The effect of glycerol conformation. in Chemistry in 2002, and the PhD degree in Chemical Sciences in 2007, both from the Institute of Chemistry, University of Antioquia, Medellin, Colombia. HA= hydroxyacetone, Pyr= pyruvaldehyde, Gly= glyceraldehyde, Others = 1,2-propanediol, ethylene glycol, methanol, and glycidol, a = N2 atmosphere, b = H2 atmosphere. [22], suggested the use of a copper-based type-perovskite as basic catalyst due to its lower activity for C-C bond cleavage compared to Ni-based type-perovskite. Mechanisms of Propylene Glycol and Triacetin Pyrolysis. The initial products of decomposition were carbon monoxide, acetaldehyde and acrolein. Applied Catalysis B: Environmental, 160-161, pp. 3) Evaluate subsequent dehydration/dehydrogenation reactions using pure HA and, in a different experiment employing 10 % (w/w) glyceraldehyde-glycerol solution as starting substrates. This property makes the copper-based catalyst a potential candidate to be used in mild reaction conditions, reducing thereby the formation of decomposition products. 5351-5357, 2000. They proposed a dehydration reaction mechanism for neutral and protonated glycerol based on the results of energy barriers (Ea). The mechanism of the dehydration reaction was found to be very complex, depending on the crystal size and water vapor pressure. These results compared to those obtained for six-membered cyclic transition state would suggest that the energy barrier of the hydrogenation steps depends strongly on the transition state geometry. On the other hand, the ( eq. This suggests that both pathways are thermodynamically feasible.