Properties of aqueous solutions of several salts of α,ω-alkanediol disulfates

Several salts of α,ω-sulfates, MO₃SO(CH₂)_n OSO₃M(n=12, 14, 16, 18, and M=Li, Na, and K) were prepared from the corresponding α,ω-alkane diols. The Krafft points of these α,ω-sulfates with common counterion as estimated by electroconductivity measurements increased with the increase of the hydrocarbon chain length, and the effect of the counterions on the Krafft points of the α,ω-sulfates with the same hydrocarbon chain length was in the order : Li<Na<K. Solutions of the α,ω-sulfates, except disodium dodecanediol disulfate, showed two break points corresponding to the first and second critical micelle concentration in each plot of the electroconductivity as a function of the concentration. The existence of the second break point suggested that another aggregation of rearrangement of the existing aggregates occurs in α,ω-sulfate solutions in addition to the usual micelle formation. The first and second break points of α,ω-sulfates with sodium counterion decreased logarithmically with increasing total number of methylene groups. The relationships were given as follows: log(first break point)=−0.138Nc−0.095; log(second break point)=−0.104Nc−0.251. The effect of the counterions upon the break points of α,ω-sulfates with the same hydrocarbon chain length was in accordance with their positions in the lyotropic series.