Synthesis and Properties of Alkoxyethyl -d-Xylopyranoside

摘要

In order to improve the water solubility of sugar-based surfactants, alkyl -d-xylopyranosides, novel sugar-based surfactants, 1,2-trans alkoxyethyl -d-xylopyranosides, with alkyl chain length n = 6-12 were stereoselectively prepared by the trichloroacetimidate method. Their properties including hydrophilic-lipophilic balance (HLB) number, water solubility, surface tension, emulsification, foamability, thermotropic liquid crystal, and hygroscopicity were investigated. The results indicated that their HLB number decreased with increase of alkyl chain, the water solubility improved since the hydrophilic oxyethene (OCH2CH2) fragment was introduced. The dissolution process was entropy driven at 25-45 degrees C for alkyl chain length n = 6-10. Octyloxyethyl -d-xylopyranoside had the best foaming ability. Nonyloxyethyl -d-xylopyranoside had the best foam stability and the emulsifying ability was better in toluene/water system than in rapeseed oil/water system. The surface tension of in aqueous solution dropped to 27.8 mNm(-1) at the critical micelle concentration, and it also showed the most distinct thermotropic liquid phases with cross pattern texture upon heating and the fan schlieren texture on cooling. Hexyloxyethyl -d-xylopyranoside possessed the strongest hygroscopicity. Based on the effective improvement of water solubility, the prepared alkoxyethyl -d-xylopyranosides showed excellent surface activity and are expected to develop their practical application as a class of novel sugar-based surfactants.