Sodium sulfosuccinate esters

Sodium sulfosuccinate esters are organic compounds with the formula NaO₃SCH(CO₂R')CH₂CO₂R where R and R' can be H or alkyl groups. They comprise a large class of surfactants and emulsifiers used in cosmetics, pharmaceuticals, and cleaning agents. They are colorless salts. These materials can be further classified into monoesters (R' = H, R = alkyl) and diesters (R and R' = alkyl).^[1][2]

Structure of sodium sulfosuccinate esters.

Synthesis

They are produced by treatment of maleic anhydride with alcohols. The resulting mono or diesters are then treated with sodium sulfite, which, concomitant with protonation, adds to the C=C bond.

Application

A high volume example is sodium bis(2-ethylhexyl) sulfosuccinate. This is perhaps best known as the laxative docusate, however its main use is as a surfactant for which it finds common use in personal-care and household-care products, often under the name Aerosol-OTs.^[1] It is unusual in that it is able to form microemulsions without the use of co-surfactants, and it has a rich variety of aqueous-phase behavior including multiple liquid crystalline phases.^[3]