Synthesis and properties of alkoxyethyl 2-acetamido-2-deoxy-α-D-glucopyranoside

Abstract

A class of novel sugar-based surfactants named alkoxyethyl 2-acetamido-2-deoxy-α-D-glucopyranosides were constructed by the introduction of oxyethene fragment (-OCH2CH2-) in the traditional alkyl glycoside structure. Such alkoxyethyl 2-acetamido-2-deoxy-α-D-glucopyranosides with different length of alkyl chain were synthesized, and their single configurations were confirmed to be α-anomer by 1H NMR and HRMS analysis. Their water solubility, surface tension, emulsification, foaming and thermal stability were investigated, and the effect of alkyl chain length on their surface property was also compared. The water solubility of alkoxyethyl 2-acetamido-2-deoxy-α-D-glucopyranoside was significantly superior to that of alkyl 2-acetamido-2-deoxy-α-D-glucopyranoside without an oxyethene fragment. Their dissolution process was an endothermic process and was driven by entropy increment as well. Alkoxyethyl 2-acetamido-2-deoxy-α-D-glucopyranoside was disclosed to reduce significantly the surface tension of water. For both of CMC and γCMC, there was a decreasing trend with increasing of alkyl chain length. As increasing of alkyl chain length, the maximum surface adsorption (Γmax) increased and the molecular cross-sectional area (Amin) decreased. They adsorbed preferentially on the solution surface and then formed spontaneously micelles in solution by the hydrophobic effect. Nonyloxyethyl 2-acetamido-2-deoxy-α-D-glucopyranoside had the best foaming and emulsifying properties. All glycosides are thermally stable below 270°C. In view of the improvement of the water solubility and maintainance of surface activity with the introduction of the hydrophilic spacer, the novel alkoxyethyl 2-acetamido-2-deoxy-α-D-glucopyranoside should be expected to develop further its multiple applications as a class of novel water-soluble sugar-based surfactants in the future.