Ion-Pair Partition Mechanism of Methyl orange with Aminoalkanols and Alkylamines

抄録

Ion-pair partition of methyl orange anion with aminoalkanol and alkylamine cations between n-octanol and buffer solution was studied under various conditions. Transfer of methyl orange from the aqueous to the octanol phase increased with increase in the concentration of amines, and with increase in their alkyl chain length. The ion-pair partition consists of two steps : formation of the ion-pair complex in the aqueous phase and its transfer into the octanol phase. Although the ion-pair formation constant was almost independent of alkyl chain length of the amine and temperature, the ion-pair partition coefficient increased with increase in the chain length, both of these parameters being greater with alkylamines than with aminoalkanols. From the values of thermodynamic parameters, the mechanism of ion-pair partition of methyl orange with amine cation was discussed.