Glyoxal, dioxolane (1,3-dioxacyclopentane), and 1,4-dioxane are
the industrially most important secondary products of ethylene
glycol.
Gboxal is manufactured from glycol with yields of 70-80% in
a gas-phase oxidation with air. The reaction takes place at over
300°C in the presence of Ag or Cu catalysts and small amounts
of halogen compounds to prevent total oxidation: