Although water is a copiously studied solvent, its role in mediating gas phase reactions remains uncertain and hard to determine precisely. Neeman et al. reexamined a previous report that water complexation accelerates the gas phase reaction of acetaldehyde with hydroxyl radicals at 60 Kelvin. Their experiments show that water instead appears to slow the reaction down, and they suggest that the earlier work may have been skewed by aldehyde dimerization at high concentration. Accompanying theory predicts that, despite lowering the energy barrier for hydrogen abstraction from CH3CHO(H2O), water complexation diminishes the dipolar attraction of the reactants.
J. Chem. Phys. 155, 034306 (2021).
