SYNTHESIS, STRUCTURAL-ANALYSIS, AND PROPERTIES OF N-ALKYLGLUCOSYL(METH)ACRYLAMIDES - NEW REACTIVE SUGAR SURFACTANTS

New reactive-surfactants, N-alkylglucosylacrylamides and N-alkylglucos ylmethacrylamides, are easily prepared in two steps from glucose witho ut protection. The complete structural analysis of these compounds by 1D and 2D NMR spectroscopy shows the existence of a rotational isomeri sm that is strongly dependent on the steric hindrance of the carbonyl substituent: whatever the alkyl chain length, both endo and exo rotame rs are observed for N-alkylglucosylacrylamides 1 while the endo rotame r is the sole species observed in the case of N-alkylglucosylmethacryl amides 2. For acrylamido derivatives 1, the exo-endo equilibrium is so lvent-dependent: the endo isomer is favored in polar nonaqueous solven ts (endo-exo isomeric ratio R = 70/30) while the equilibrium is shifte d toward the exo rotamer in protic acidic medium (R = 50/50 in water a nd 80/20 in acidic medium). An intramolecular hydrogen bond is assumed to be responsible for the increased stability of the endo rotamer. Fu rthermore, for tetra-O-acetylated derivatives the exo rotamer becomes favored in aprotic solvents. Surface tension measurements demonstrate that N-octyl- to -tetradecyl-substituted compounds 1 and 2 are surfact ants with critical micelle concentrations ranging from 1.2 x 10(-2) to 1.7 x 10(-5) mol/L.