Very recently, we have developed a new technique to efficiently produce glyceric acid (GA) from crude glycerol using a new microbial process. GA is an attractive building-block compound due to its three functional groups and an asymmetrical carbon. In this study, we tried to prepare GA fatty acid esters as novel green surfactants and investigated their surface-active properties.
Several GA fatty acid monoesters were selectively synthesized from GA and C12, C14 and C16 fatty acyl chlorides. Their structures were confirmed by 1H-NMR and elemental analysis. Surface tension lowering activities of these monoesters were measured by the Wilhelmy method. The critical micelle concentration (CMC) and the surface tension at CMC of these monoesters were estimated to be 1.28x10-4 M and 29.5 mN/m (C12), 4.26x10-5 M and 32.3 mN/m (C14), 2.20x10-5 M and 34.1 mN/m (C16), respectively.
On these monoesters, the CMC value increased with an increase of the hydrocarbon chain-length of fatty acid. In addition, the sodium salts of GA monoesters showed higher water solubility compared to the acidic forms, retaining excellent surface-tension lowering activity. Accordingly, the newly prepared GA monoesters have great potential as novel green surfactants.