Formation of the interstellar sugar precursor, (Z)-1,2-ethenediol, through radical reactions on dust grains

TL;DR

This study computationally investigates how (Z)-1,2-ethenediol, a prebiotic molecule detected in space, forms on dust grains through radical reactions involving vinyl alcohol and water ice, revealing a non-selective pathway influenced by reactant adsorption modes.

Contribution

It introduces a detailed reaction pathway for (Z)-1,2-ethenediol formation on dust grains, considering all possible radical reactions and their stereoselectivity, which was not previously characterized.

Findings

Formation pathway involves OH addition and H abstraction reactions.

Reaction pathway is non-selective, producing multiple products.

Adsorption modes influence stereoselectivity of reactions.

Abstract

In recent years, the continued detection of complex organic molecules of prebiotic interest has refueled the interest on a panspermic origin of life. The prebiotic molecule glyceraldehyde is proposed to be formed from (Z)-1,2-ethenediol, a molecule recently detected towards the G+0.693-0.027 molecular cloud at the galactic center. In this work, we computationally simulate the formation of (Z)-1,2-ethenediol from vinyl alcohol on the surface of amorphous solid water in a two-step synthesis involving a OH addition and a H abstraction reaction. In total, we considered all reaction possibilities of the 1,1 and 1,2-OH addition to vinyl alcohol followed by H-abstraction or H-addition reactions on the resulting radicals. The combination of these reactions is capable of explaining the formation of (Z)-1,2-ethenediol provided a suprathermal diffusion of OH. We also conclude that our proposed formation pathway is not selective and also yields other abstraction and addition products. Key in our findings is the connection between the adsorption modes of the reactants and intermediates and the stereoselectivity of the reactions.