Abstract
All positional isomers of methyl α-D-glucopyranoside mono-laurates were selectively prepared. The position of the acyl-chain of each mono-laurate isomer was confirmed by means of 1H and 13C NMR spectroscopy.
The surface tension of aqueous solutions of mono-laurates was measured at 25°C. From surface tension isotherms, the efficiency of surface tension reduction, surface excess concentration, area per molecule in the surface layer, and standard free energy of adsorption were determined. The efficiency of surface tension reduction (pC20), defined as-log Cπ=20, decreased in the order 6->4-_??_ 2->3-laurate. The order of decrease in minimum surface area per molecule (A) was 4-_??_6->2-_??_3-laurate. The standard free energy of adsorption (-Δ G) decreased in the order 6->4-_??_2->3-laurate.
The influence of the orientation of pyranoide ring on surface area per molecule and standard free energy of adsorption are discussed based on these results.
