HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY USED FOR ALKYLBENZENE LIQUID LIQUID PARTITION-COEFFICIENT DETERMINATION

Countercurrent chromatography (CCC) can be used to determine liquid-liquid partition coefficients. A hydrodynamic CCC apparatus was used to obtain methanol-water-heptane partition coefficients, P, of the homologous series of n-alkylbenzene from benzene to dodecylbenzene. The methanol-water compositions ranged from pure methanol to methanol 80%-water 20% v/v. They were used as liquid stationary phases. Heptane was the mobile phase. The partition coefficients ranged from 8 X 10(-4) to 0.95, corresponding to heptane-methanol partition coefficients ranging from 1.05 to 1250. For every methanol-water stationary phase, the linear plots Of log P versus the atom carbon number, n(c), produced the free energy of transfer, DELTA-G-degrees, for the methylene incremental group and the phenyl terminal group. Both DELTA-G-degrees energies increased linearly with the water molar fraction which allowed development of an equation giving the methanol-heptane P value of an alkylbenzene (n(c) less-than-or-equal-to 12) with water content less-than-or-equal-to 20% v/v.