2020MNRAS.497.4486S

Based on typical physical and chemical conditions expected in massive and dense hot cores during the protostar collapse, the formation of glycolaldehyde (CH₂OHCHO) and methanol (CH₃OH) was investigated from H₂ and CO and formaldehyde (H₂CO) as an intermediate. Thermochemical properties and rate constants were obtained for gas-phase reactions using high-level electronic structure methods and chemical kinetic calculations, and the concentrations of the molecules were evolved along time. The chemical equilibrium was reached in minutes at 1500 K, a time interval much shorter than that required time for a protostar formation process. The results indicate that the formaldehyde and methanol abundances are always larger than those for glycolaldehyde, for example, at 2000 K and [H₂]₀ equals to 10²³ molecule cm^–3, the abundances of H₂CO, CH₃OH, and CH₂OHCHO relative to H₂ are equal to 3 x 10^–6, 5 x 10^–6, and 1 x 10^–12, while for [H₂]₀ equals to 10²⁰ molecule cm^–3 these abundances are 3 x 10^–9, 5 x 10^–12, and 2 x 10^–21, respectively. Considering that our results can be applied to explain the proximity of methanol and formaldehyde maser emissions, from the whole set of results, the CH₃OH abundance relative to H₂CO ranges from 10^–3 to 10².