Lipase‐mediated synthesis of alkyl ricinoleates and 12‐hydroxy stearates and evaluation of the surfactant properties of their sulfated sodium salts

An efficient and simple lipase‐mediated synthesis of alkyl ricinoleates and 12‐hydroxy stearates was performed by transesterification of methyl ricinoleate/12‐hydroxy stearate and various alcohols in a solvent‐free system without estolide formation. The reaction conditions were optimized by varying the temperature, pressure, and dosage of lipase. Sulfates of alkyl ricinoleates/12‐hydroxy stearates were evaluated for surfactant properties such as surface tension, critical micelle concentration, emulsifying properties, foaming power, and calcium tolerance. The surfactant properties of sulfated alkyl ricinoleates were found to be superior to the sulfated alkyl 12‐hydroxy series. The surfactant properties of the above two series of compounds were then compared with sodium dodecyl sulfate, and the properties of sulfated dodecyl ricinoleate and sulfated dodecyl 12‐hydroxy stearate were found to be comparable with sodium dodecyl sulfate.