Dodecyl sulfates of bivalent nickel, cobalt, copper and magnesium were synthesized, and studies were carried out on the CMC values of these detergents, the effects of the added electrolytes on these CMC values, on micellar molecular weights, and on micellar charges. The CMC values of the detergents were independent of the kind of metal, and the CMC value of 1.2×10−3 mol./l. was obtained. The micellar aggregation numbers of bivalent metal dodecyl sulfates were of the order of 100, which is about twice that of sodium dodecyl sulfate. The dissociation degrees of the micelles were also evaluated from the conductivity data. The α values obtained were 0.66 for cobalt, 0.60 for copper and 0.42 for magnesium. The dissociation degree of the copper dodecyl sulfate micelle was also estimated to be 0.52 from the depression of the CMC value by the added electrolyte; this figure is approximately the same as the value of 0.60 obtained from the conductivity data. These results suggest that the fundamental factor responsible for determining the surface activities of bivalent metal dodecyl sulfates is the valency of the gegenion and that the kind of metal has little or no detectable effect on them.

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