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Alkylα-D-galactopyranosides are sugar-based nonionic surfactants, and it is necessary to research their structure–property relationships since it is not quite clear that the change of the alkyl chain length has effects on a series of physicochemical properties. Here, alkylα-D-galactopyranosides were prepared by galactose and alcohols through three steps including acetylation, coupling with alcohols in the presence of a catalyst stannic chloride, and deprotection. Furthermore, their water solubility and other properties were investigated. Alkylα-D-galactopyranosides (4a ∼ 4e,n = 6 ∼ 10) were water soluble, and their dissolution process in water was an endothermic process. Nonylα-D-galactopyranoside (4d) showed excellent foaming ability and foam stability. Octylα-D-galactopyranoside (4c) had the strongest emulsifying ability for toluene and nonylα-D-galactopyranoside (4d) had the strongest emulsifying ability for rapeseed oil. The critical micelle concentration (CMC) values and surface tension at the CMC were decreasing with increasing alkyl chain length. Their standard free energy of adsorption (ΔGads) was more negative than their standard free energy of micellization (ΔGmic). The moisture-absorption abilities were weakening with increasing alkyl chain length. Alkylα-D-galactopyranosides (4a ∼4f) were thermally stable below 280°C. Alkylα-D-galactopyranosides (4c ∼4f) had the optical texture of the thermotropic liquid crystal smectic A phase. [ABSTRACT FROM PUBLISHER]

Graphical abstract Highlights • Alkoxyethyl β - D -glucopyranosides in anomerically pure were prepared. • Their water solubility was higher than that of alkyl β - D -glucosides due to an introduction of the hydrophilic spacer. • The synthesized glucopyranosides had excellent surface properties. • They had thermotropic liquid crystalline property. • They were thermal stable below 230 °C. Abstract Alkyl glycosides as modern industrial manufactured products are important. Furthermore, the better water solubility should make them a greater potential application value. In this study, an improvement of water solubility has been realized by adding the oxyethene fragment (−OCH 2 CH 2) as a hydrophilic spacer to the conventional alkyl glucoside structure, and the excellent surface properties of the alkyl glucoside were still maintained. The amphipathic properties of the prepared alkoxyethyl β - D -glucopyranoside can be adjusted by the alkyl chain length (n). Alkoxyethyl β - D -glucopyranosides were found to be water soluble with n ≤ 10. For both of CMC and γ CMC , there was a monotonous decreasing trend with increasing the alkyl chain length. Such amphipathic molecules adsorbed preferentially on the solution surface and then formed spontaneously micelles in the aqueous solution by the hydrophobic effect. Nonyloxylethyl β - D -glucopyranoside exhibited the finest foaming property, as well as the strongest emulsifying capacities in the rapeseed oil/water system and the toluene/water system. In addition, alkoxylethyl β - D -glucopyranoside (n = 9–14) had thermotropic liquid crystal property and thermal stability below 230 °C. Alkoxyethyl β - D -glucopyranoside, as a class of sugar-based surfactants, will be expected to be developed in a variety of practical application. [ABSTRACT FROM AUTHOR]