New methods to obtain carboxylic acids by oxidation reactions of 1,2-ethanediol with metallic nitrates

The oxidation reactions of 1,2 ethanediol (ethylene glycol, EG) with some metallic nitrates in diluted acid solutions were investigated. Under specific working conditions, the reactions take place by the oxidation of EG to glyoxylic acid or to oxalic acid, coordinated as glyoxylate anion or oxalate anion respectively, to the metal (II) cation, with the simultaneous isolation of some homopolynuclear coordination compounds. In order to separate and identify the ligand, the synthesized coordination compounds, having the composition formula [ML(H2O)x·yH2O]n and [ML′(H2O)·zH2O]n respectively, where L is the glyoxylate anion, L′ the oxalate anion and M one of the following metals (M = Mg, Co, Ni, Cu), have been treated with R–H cationite (Purolite C-100). After the retention of the metal cation, the glyoxylic acid or oxalic acid obtained have been subjected to analysis by specific reactions and spectroscopic methods.