The oxidation proceeds via dinitrogen trioxide, which is formed according to (1) of nitrogen monoxide and oxygen and then reacts according to (2) with methanol forming methyl nitrite:[6] In the next step of dicarbonylation (3) carbon monoxide reacts with methyl nitrite to dimethyl oxalate in the vapor phase at atmospheric pressure and temperatures at 80-120 °C over a palladium catalyst: The sum equation: This method is lossless with respect to methyl nitrite, which acts practically as a carrier of oxidation equivalents.

[7] For example, diethyl oxalate condenses with cyclohexanone to give the diketo-ester, a precursor to pimelic acid.

Quinoxalinedione is produced by condensation of dimethyloxalate and o-phenylenediamine: Hydrogenation gives ethylene glycol.

[9] Dimethyl oxalate can be converted into ethylene glycol in high yields (94.7%)[10][11] The methanol formed is recycled in the process of oxidative carbonylation.

[12] Other plants with a total annual capacity of more than 1 million tons of ethylene glycol per year are planned.