Effect of Hydroxyl Groups on Solubilization States of Alkandiols in DTAB Micelles: Application of a Differential Conductivity Technique.

The partition coefficients, Kx, of 1,2-alkanediols and α,ω-alkanediols between dodecyltrimethylammonium bromide (DTAB) micelles and water, and the change of the degree of counterion dissociation, dα/dXa(m), on DTAB micelles associated with solubilization of the alkanediols are determined by a differential conductivity technique. The standard Gibbs energy change of transfer per methylene group, ΔG(0)(CH2), is estimated from a dependence of logarithmic value of the Kx on the carbon number of alkyl chain in the alkanediols. The dα/dXa(m) is independent of the carbon number of alkyl chain in the alkanediols. Comparing the present results with those of DTAB/1-alkanols system, it is suggested that solubilization states of the alkanediols in DTAB micelles are as follows: 1,2-alkanediols are solubilized as its alkyl chain is oriented to micellar interior just like 1-alkanols, while α,ω-alkanediols are solubilized as its alkyl chain is partly located in micellar surface region.