The discovery of complex organic molecules (COMs) such as methyl formate, dimethyl ether and the most recent detection of chiral propylene oxide represents a challenge for astrochemical modelers. Qualitatively, the astrochemistry models reproduce the whole range of simple molecules identified in the ISM at temperatures ≥30 K, for example, ions formed from ion-molecule reactions, radicals and isomers, and mainly unsaturated hydrocarbons produced by recombination reactions dissociative. However, the way in which these COMs are formed in cold environments (≤20 K), cannot reproduce the observed abundances using previously developed models. Methanol is one of the key precursors of COMs revealing evidence of gas phase and dust grain chemistry reactions. A recent observational work reported lines arising from methyl mercaptan (CH3SH), formic acid (HCOOH), propynal (HCCCHO), acetaldehyde (CH3CHO), dimethyl ether (CH3OCH3), methyl formate (CH3OCOH), and the formyl radical (HCO) toward B1-b. The experiment showed the formation of CH3OCH3 and probably CH3CHO-. Therefore, the confirmation/detection of the Methoxy radical (CH3O) and the hydroxymethyl radical (CH2OH) by photodesorption still needed to confirm. In order to understand this process, in this work, we have carried out a simulation of a decamer of methanol reacting with the hydroxyl ion as a projectile, at the Bohr-Oppenheimer Molecular Dynamics level of theory (1600 timesteps with wb97x/6-31+g(d,p). The projectile was vibrationally excited with different energies, from 10 eV up to 22 eV. As a preliminary result, a new chemical network of all reactions involved in the impact of OH- with methanol was found. The reactions studied here at 10 eV revealed the methoxy radical as a primary product (CH3O). We also found the methylene glycol and hydroxymethyl radicals, and other interesting COMs. We discuss here the chemical reactions on icy mantles, the availability of reactants and the mobility of these reactants on ice and grain surfaces. We have pointed out that the exothermicity of chemical reactions into the ejection of products from the surface plays a key role to give a new explanation of COMs synthesis along stellar sources.

Methanol-containing ice mantle on collision with OH-: A dust grain reaction through quantum ab initio molecular dynamic

255th National Meeting (2018)

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