Synthesis and Interfacial Properties of Monoacyl Glyceric Acids as a New Class of Green Surfactants

概要

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Glyceric acid (GA) is one of the most promising functional hydroxyl acids, and it is abundantly obtained from glycerol by a bioprocess using acetic acid bacteria. In this study, several monoacyl GAs were synthesized by esterification of GA and saturated fatty acyl chlorides (C12, C14, C16, and C18), forming a new class of bio-based surfactants. By the present method, a mixture of two isomers, namely 2-O-acyl and 3-O-acyl GAs, was produced, in which the 2-O-acyl derivatives were obtained as a major product. These isomers were isolated, and their surface-active properties were investigated for the first time. The surface tensions of 2-O-acyl GAs with different chain lengths were determined by the Wilhelmy method. At concentrations below 10–4 M, the 2-O-acyl GAs exhibited higher surface-active properties compared to commercially available synthetic surfactants. For example, 2-O-lauroyl GA reduced the surface tension of water to around 25 mN/m above the critical micelle concentration (3.0×10–4 M). In addition, 2-O-acyl derivatives showed higher surface-tension-lowering activity than 3-O-acyl GAs. The monoacyl GAs synthesized herein can potentially be used as “green surfactants.”