STUDIES ON PERCENT DISTRIBUTION OF TERTIARY AMINE DRUGS

This is a further study on solvent extraction on the basis of previous reports. The results are presented as follows:1. Solvent: The percent distribution (PD) of tertiary amines became larger with increasing dieleetrie constant of the mixed solvent.2.Extractant. The effect of the addition of sulfate substituent was that the PD increased with increasing lipophilic character of the substituted group. Addition of different inorganic salts did not change the pattern of PD curves, nor the pH value of the rising point of these curves, but their height was affected. The effect of salts on the PD of tertiary amines was:ClO₄^->Br^->NO₃^->Cl^->SO₄⁼>PO₄^≡; monobasie acid salt>dibasic acid salt>tribasic acid salt. When monobasic acid salts were added, the PD decreased with, decreasing molecular weight of these acid radicals. Addition of organic acid salts to water phase caused the PD to increase and the pH value with which the PD reached to 100% to decrease. Increasing the hydrophilie group or electronegative group in the molecule of either the extractant or tertiary amines enabled the PD to become smaller, and increasing lipophilic group or the number of carbon atoms enabled it to become larger. The pKa of tertiary amine played a role only at such a stage (weak acidic aqueous phase)that its ionic form was changing to the molecular form. However, it was still affected by lipophilie or hydrophilie groups. In addition, the effect of aqueous phase on PD at different Acidic and basic stages and the relationship between different cases of solvent extraction are discussed.