Alkylglucosides with isoprenoid-type hydrophobic chains-effects of hydrophobic chain size on the aqueous phase behavior

Abstract

Aqueous phase diagrams were constructed for two new alkylglucosides with isoprenoid-type hydrophobic chains, viz. 1- O-β-(3,7-dimethyloctyl)- d-glucopyranoside, β-Glc(Ger), and 1- O-β-(3,7,11,15-tetramethylhexadecyl)- d-glucopyranoside, β-Glc(Phyt). In a low concentration regime, from 0.17 to 34 wt.% β-Glc(Ger), the β-Glc(Ger)/water system exhibits two phase, a dilute (L 1 dil) and a concentrated isotropic phase (L 1 conc), coexistence region. Above about 62 wt.% β-Glc(Ger), an Lα phase is formed. The extent of the L 1 dil+L 1 conc two-phase region decreases as temperature increases and totally disappears above 130 °C, exhibiting an upper critical temperature. The β-Glc(Phyt)/water system exhibits an Lα phase above 78 wt.% surfactant below which, an Lα + water two-phase region appears. One notable feature of these compounds is their low values of Krafft-eutectic temperature, T K, e.g. the value of T K for β-Glc(Phyt) is below 0 °C although the total number of carbon atoms in the hydrophobic chain is as large as 20.