Acid-base equilibria in ethylene glycol--II: autoprotolysis constants and acid-base properties of ethylene glycol and its mixtures.
The acid-base behaviour of ethylene glycol and its mixtures with water (1, 5 and 10%), methanol, ethanol, isopropanol, nitromethane (each 10%) and ethyl methyl ketone-chloroform (5 + 5%) have been investigated by potentiometric titration, in a cell without liquid junction, equipped with a glass and a silver-silver chloride electrode. The autoprotolysis as well the protolysis constants of phthalic acid were determined for each mixture. The added solvents improve the properties of ethylene glycol, decreasing the viscosity without changing the acid-base behaviour of the ethylene glycol itself, which is favourable for the titration of weak bases. Water increases the basic, and nitromethane the acidic, properties of the mixture. Small quantities of water (ca. 1%) do not impair the titration conditions.
Zikolov
P
P
Faculty of Pharmacy, Academy of Medicine, Ekz. Josif No. 15, Sofia, Bulgaria.
Astrug
A
A
Budevsky
O
O