The Polarographic Behavior of the Condensation Products of o-Phenylenediamine with Glycolaldehyde and with Glyceraldehyde, and Its Application to the Determination of Glycolaldehyde and Glyceraldehyde

Abstract Glycolaldehyde and glyceraldehyde condense with o-phenylenediamine (OPD) in a buffered solution (pH 2–10) containing an excess of the latter to produce the corresponding condensation products. Both condensation products give a single diffusion-controlled oxidation wave E1⁄2:−0.08 V vs. SCE for both aldehydes at pH 6.0) at the dropping mercury electrode, and their electrode reactions are irreversible over all the pH range studied (pH 2—10). The limiting currents of both waves show their maximum values at pH values of about 6 and decrease either with an increase or a decrease in the pH from about 6. From the results of the present polarographic investigations, it has been deduced that the condensation products of OPD with glycolaldehyde and with glyceraldehyde are probably benzimidazoline derivatives. The equilibrium constants for the condensation reaction of glycolaldehyde and glyceraldehyde with OPD were calculated to be 551 and 294 l/mol respectively at 25°C. A linear relationship between the limiting current of the condensation product and the concentration [(0.5–30)×10−4m] of glycolaldehyde or glyceraldehyde was obtained under the following conditions, which are recommended for the practical determination: 5.5–6.5 for pH, 2×10−2m for the concentration of OPD, 25°C for the temperature, and 5–60 min for the condensation time. The present method was applied to the determination of the glycolaldehyde present as an impurity in a commercially-available ethylene glycol.