jp7b06102_si_001.pdf (12.03 MB)
Dimethyl Sulfoxide Complexes Detected at Ambient Conditions
journal contribution
posted on 2017-07-17, 00:00 authored by Anne S. Hansen, Henrik G. KjaergaardDimethyl sulfoxide (DMSO) is an important
intermediate in the atmospheric
oxidation of dimethyl sulfide (DMS). DMS, emitted from the ocean,
is the main natural sulfur source, and its oxidation products are
essential in the formation of sulfate aerosols. The high atmospheric
concentration of water makes hydrogen bonding with DMS and its oxidation
products likely. Through hydrogen bonding, water can potentially catalyze
and affect the steps of the oxidation. We investigate binary hydrogen-bound
complexes involving DMSO. Both water·DMSO and methanol·DMSO
complexes are identified in an Ar matrix, and at room temperature,
a Gibbs free energy of 0.7 kJ/mol for the formation of the methanol·DMSO
complex is determined. Assuming a similar Gibbs free energy of the
hydrate, it would suggest a relatively high abundance of the DMSO
hydrate relative to the monomer in the atmosphere. The effect of changing
the atom divalently bound to the hydrogen bond accepting oxygen, from
S to C (DMSO to acetone), is found to significantly decrease the equilibrium
constant of complex formation.