1. Reaction pathways of methylglyoxal oligomerization
Glyoxal and methylglyoxal are the two most common di-aldehydes that can contribute to secondary organic aerosol formation. However the observed oligomerization products are quite different. While glyoxal favors oligomers with hydrated 5-membered dioxolane rings, methylglyoxal yields a wide range of products depending on the experimental setup and conditions. What is going on?
Unlike glyoxal where hydrated dioxolane rings are both the thermodynamic and kinetic sink; acetals, dioxolanes, and even monomeric species have similar relative energies. In addition, the fully hydrated species are not the most favorable.
Aldol condensation products (not accessible in glyoxal), while most favorable thermodynamically, are harder to access kinetically.
Jeremy Kua
Dept. of Chemistry
& Biochemistry
(All numerical values are solution phase free energies in kcal/mol. Barriers in parentheses.)