Surfactants from glucamines and α-epoxides : Syntheses and studies of surface-active properties

The synthesis of sugar-based surfactants by ring opening of α-epoxides with aminopolyols based on glucose is described. By reacting α-epoxides with chain lengths of C 4 -C 18 or styrene oxide with N-methyl glucamine, N-dodecyl glucamine or glucamine under mild conditions in methanol or mixtures of methanol and water, N-2-hydroxyalkyl-N-methyl glucamines, N-2-hydroxyalkyl-N-dodecyl glucamines and N,N-bis-(2-hydroxyalkyl) glucamines were obtained in good yields (70-100 %) with purities > 95 %. Depending on the glucamine used, the products may have a linear structure or Y-type structure with two hydrophobic alkyl chains of equal or differing chain length. Studies of these surfactants and their hydrobromides, which were obtained by acidification, demonstrate different surface properties in aqueous solutions. Measurements of the c.m.c. (critical micelle concentration) were successful for several of the products. Some of the c.m.c. values are in a range between 2 and 500 mg/l. Some of the synthesized sugar-based surfactants reduce the surface tension of water down to 25 mN/m (N-2-hydroxydodecyl-N-methyl glucamine and N,N-bis-(2-hydroxydodecyl) glucamine at pH = 2). Most of the ring-opening products are rather poor foamers, whereas some of the corresponding hydrobromides show good foaming properties.