Computational Study of the Reaction between Ethylene Glycol and the CH Radical: Competition between Carbon Addition and Dehydrogenation

TL;DR

This study explores how ethylene glycol reacts with the CH radical in space, revealing which products form under low-temperature conditions.

Contribution

The paper identifies the most likely reaction pathways and products under interstellar conditions using computational methods.

Findings

Five isomers of C2H4O2 and six of C3H6O2 are formed from the reaction.

2-methoxyacetaldehyde + H is the least stable product but forms fastest due to low temperatures.

Glycolaldehyde + CH3 is the most prominent product, followed by methyl formate + CH3.

Abstract

The gas-phase reaction between ethylene glycol ((CH2OH)2) and the methylidyne radical (CH) has been
investigated
with the aim of understanding the competition between carbon addition
and dehydrogenation processes under interstellar conditions. The former
type of reaction increases the molecular complexity and leads to the
formation of members of the C3H6O2 family (with the hydrogen atom as coproduct), while the latter somewhat
decreases the chemical complexity but opens the way toward the gas-phase
production of C2H4O2 isomers (together
with the CH3 radical as coproduct). An accurate investigation
of the reactive potential energy surface indicates the formation of
five isomers belonging to the C2H4O2 family and six species belonging to the C3H6O2 one. From a thermochemical point of view, the most
stable product is acetic acid + CH3, while 2-methoxyacetaldehyde
+ H is the least stable. However, because of the low temperatures
of the interstellar medium, reactivity is ruled by kinetics. Kinetic
simulations turn the tide, with the formation of 2-methoxyacetaldehyde
becoming the fastest process. The title reaction also produces glycolaldehyde
+ CH3, followed by the formation of methyl formate + CH3 and methyl acetate + H to a lesser extent.

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