Four Different C8G1Alkylglucosides. Anomeric Effects and the Influence of Straight vs Branched Hydrocarbon Chains

Abstract

In this work some of the physical-chemical properties of four different alkylglucosides are presented. The four alkylglucosides are 2-ethylhexyl α-d-glucoside, 2-ethylhexyl β-d-glucoside,n-octyl α-d-glucoside, andn-octyl β-d-glucoside. Two questions are addressed. The first concerns the general influence on surfactant properties of the type of linkage, α or β, between the glucose head group and the surfactant tail. The second question concerns the difference in properties between straight and branched hydrocarbon chains. The binary phase diagrams (temperature vs concentration) and the properties of the one-phase regions have been determined. In the micellar regions,1H NMR self-diffusion experiments have been performed to determine the micellar sizes in the temperature range from 25 to 55°C. The melting enthalpies of the pure substances have been determined by means of DSC to obtain information about differences in the crystal stability between molecules with α- or β-linkage. A general result of this work is that the α-linkage gives rise to an increased crystal stability and, as a consequence, an increased Krafft boundary. In the two cases with straight hydrocarbon chains several different liquid crystal phases appear, whereas in the two cases with branched hydrocarbon chains there is only a lamellar phase.