Preparation and properties of sodium alkyl β‐sulfopropionates

Abstract

Abstract A series of sodium alkyl β‐sulfopropionates containing 11 to 17 carbon atoms was prepared from β‐bromopropionic acid, sodium sulfite and even‐numbered straight chain alcohols of 8 to 14 carbon atoms. The Krafft point, critical micelle concentration (cmc), emulsifying power, calcium ion stability and resistance to acid hydrolysis were determined. Sodium alkyl β‐sulfopropionates, in which the ester linkage (hydrophilic group) is moved toward a more central position in the alkyl chain, have higher cmc values and lower Krafft points than the corresponding sodium alkyl sulfoacetates. The sodium alkyl β‐sulfopropionates were less stable toward hydrolysis than the sodium alkyl sulfoacetates because the adjacent sulfo group in the sulfoacetates protects the ester linkage through steric hindrance. The emulsifying power increases, but the calcium ion stability decreases, with increasing alkyl chain length for a series of sodium alkyl β‐sulfopropionates.