Catalytic Oxidation of Ethylene Glycol by Dioxygen in Alkaline Medium. The New Example of One-Stage Oxidative Cleavage of С‒С Bond

Abstract

Reaction of low temperature oxidations of ethylene glycol (EG) by molecular oxygen in the presence of salts of bivalent copper and alkali both in water and in waterless solutions was investigated. It was found that at low (close to room) temperatures for the process carrying out in waterless solutions the basic product of EG oxidation is formic acid. Rising the temperature from 290–315 K to 350–360 K or carrying out the reaction in water-containing solutions leads to sharp change of a direction of reaction. EG in these conditions is oxidized with primary formation of glycolic acids salts. The change of direction of reaction is connected, apparently, with decrease stability of chelate complexes of Cu²⁺-ions with dianionic form of EG. The mechanism of glycolic acids formation includes, possibly, a stage of two-electronic reduction of О₂ in reaction of dioxygen with monoanionic forms of EG, coordinated on Cu²⁺-centers.

Keywords:

• Cu²⁺-ions catalysis
• ethylene glycol
• formic and glycolic acids formations
• oxidation by oxygen