Niculescu, M; Dumitru, R; Magda, A; Pode, V
The paper presents the experimental results of the investigations concerning the oxidation reactions between 1,3-propanediol (1,3-PG) and metal nitrates, in weak acid solutions. These reactions occurs, under some working conditions, with the oxidation of 1,3-propanediol to 3-hydroxypropionic acid, coordinated as 3-hydroxypropionate anion to the metal(II) cation (M(II) = Co(II), Ni(II), Cu(II)), with simultaneous isolation of some homopolynuclear coordination compounds. In order to separate and identify the ligand, the synthesized coordination compounds, having the formula: [Co-2(OH)(2)L(H2O)(2)](n), [Ni-2(OH)(2)L-2(H2O)(2). 0.5H(2)O](0), [Co-2(OH)(2)L(H2O)(2)](n) where L is 3-hydroxypropionate anion, HO-CH2-CH2-COO-, have been treated with R-H cationite (Purolite C-100). After the retention of the metal cation, the resulted 3-hydroxypropionic acid has been identified by specific reactions and physical properties measurement. The work also presents the results concerning the mechanism of the oxidation reaction of 1,3-propanediol with d type metal nitrates, in weak acid solutions. A mechanism which involves nitrosonium ion, NO+, as the active oxidizing agent has been proposed.