Hydrodynamic chronocoulometric determination of diffusion coefficients and concentrations of dioxygen in media containing quinoline, isoquinoline, and methylquinolines

摘要

The diffusion coefficients (D-O2) and concentrations (C-O2) of O-2 in O-2-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 D-O2 and C-O2 have been observed. A good linear correlation between the logarithm of mole fraction solubility of O-2 (f(O2)) and the square of the Hildebrand solubility parameter (delta H-2) was obtained, indicating that O-2 is more soluble in a solvent with a smaller solvent-solvent interaction (i.e., smaller delta H-2). A much higher solubility than expected from the obtained linear relation between log(f(O2)) and delta H-2 was obtained for 4-Q, which was explained on the basis of a relatively strong charge-transfer interaction between the O-2 molecule and 4-Q solvent. D-O2 decreases with increase in the solvent viscosity. [References: 26]