Hydrodynamic Chronocoulometric Determination of Diffusion Coefficients and Concentrations of Dioxygen in Media Containing Quinoline, Isoquinoline, and Methylquinolines

Abstract

The diffusion coefficients (DO2) and concentrations (CO2) of O2 in O2-saturated solutions (containing 0.1 M tetra(n-butyl)ammonium perchlorate as supporting electrolyte) of quinoline (Q), isoquinoline (IQ), and 2-, 3-, 4-, 6-, 7-, and 8-methylquinolines (2-Q, 3-Q, 4-Q, 6-Q, 7-Q, 8-Q) have been determined using a hydrodynamic chronocoulometry at a rotating disk gold electrode. Significant solvent effects on the values of DO2 and CO2 have been observed. A good linear correlation between the logarithm of mole fraction solubility of O2 (fO2) and the square of the Hildebrand solubility parameter (δH2) was obtained, indicating that O2 is more soluble in a solvent with a smaller solvent−solvent interaction (i.e., smaller δH2). A much higher solubility than expected from the obtained linear relation between log(fO2) and δH2 was obtained for 4-Q, which was explained on the basis of a relatively strong charge-transfer interaction between the O2 molecule and 4-Q solvent. DO2 decreases with increase in the solvent vi...