Synthesis and surfactant properties of symmetric and unsymmetric sulfosuccinic diesters, Aerosol-OT homologues

The synthesis and surfactant behaviour of two series of sulfosuccinic diest ers, AOT-related compounds, are described [Aerosol-OT 1: sodium bis(2-ethyl hexyl) sulfosuccinate]. The first family contains unsaturated, racemic or e nantiopure, 2-ethylhex(en)yl chains with various positions of the double bo nd. These compounds are readily prepared from the corresponding unsaturated alcohol by the standard two-step procedure: their critical micelle concent rations are higher than those of normal AOT and depend on the position of t he double bond. The second series consists of nonsymmetric homologues with two different substituents: various unsymmetrical sulfosuccinic diesters wi th two enantiopure saturated or unsaturated chains of opposite configuratio n. or with two different substituents like methyl and 2-ethylhexyl, hydroge nated and deuterated chains as well as saturated and unsaturated chains are described. These unsymmetrical sulfosuccinic diesters are readily obtained in a three-step synthetic procedure involving the regiospecific sulfonatio n of maleic monoester in aqueous medium. The structure of the sodium 4-alky l-2-sulfosuccinic acid key intermediate is unambiguously resolved by NMR co mparative analysis of the hydrogenated and deuterated derivatives. The surf actant behaviour of some unsymmetrical compounds is studied.