Enzymatic preparation of polyethylene glycol esters of castor oil fatty acids and their surface‐active properties

Abstract

AbstractThis study concerns the preparation and evaluation of nonionic surfactants prepared from polyethylene glycol (PEG) esters of castor oil fatty acid, a source of hydroxy fatty acid. A lipase‐catalyzed esterification reaction has been employed to prepare PEG esters of hydroxy acid to overcome problems associated with chemical processes. Castor oil fatty acid (85% ricinoleic acid) was mixed with PEG of different molecular weight. Rhizomucor miehei lipase was added as catalyst (10% level) and the reaction was continued at 60°C under 2 mm Hg pressure for 360 min. Conversion of PEG to esters was in the range of 86–94%, depending on the molecular size of PEG. The products were isolated and examined for surface activity by surface tension measurement. Surface tension values measured at 25°C were about 36–37 dynes/cm.