Ion-pair extraction of multi-OH compounds by complexation with organoboronate

Ion-pair extraction with organoboronate has been investigated as a regenerable means of removal and recovery of multi -OH compounds from aqueous solution. The extractant utilized was 3-nitrophenylboronate (NPB[sup [minus]]), paired with Aliquat 336 as cation (A336[sup +]). The solubility of 3-nitrophenylboronic acid (NPBA) in water at 25[degree]C was measured as 0.45 [+-] 0.02 g/100 g H[sub 2]O. The 1:1 complexation stability constant for 1,2-propanediol with NPB[sup [minus]] was measured by the buffer-capacity method through the Antikainen model as 3.2, 2.3 and 1.95 mol/l[sup [minus]1] at 25[degree], 35[degrees] and 44.8[degree]C, respectively. The A336[sup +]NPB[sup [minus]] ion pair was prepared by repeated washing of a mixture of Aliquat 336, NPBA and diluent with aqueous NaOH and then water. Equilibria were measured for extraction of fructose, glycerol, and sorbitol from aqueous solution into the ion-pair extractant in a diluent of 2-ethylhexanol. 21 refs., 4 figs., 3 tabs.