Preparation and Properties of Nonionic Surfactants with One Alkyl Chain and Two Sugar-Amide Head Groups

Abstract

Nonionic surfactants each bearing one alkyl chain and two gluconamides, maltobionamides, lactobionamides, or maltotrionamides were prepared by the monoalkylation of malononitrile with alkyl bromide, reduction of two nitrile groups with LiAlH4/AlCl3, and reaction of the alkyldiamine thus produced with the sugar lactone. The surfactants possessed good water solubility. That the surfactants bearing two gluconamide groups showed higher water solubility than the conventional N-alkylgluconamide [RNHCO (CHOH) 4CH2OH] or dialkylbisgluconamide [R2C (CH2NHCO (CHOH) 4CH2OH) 2] with the same alkyl chain length is of particular interest. The critical micelle concentrations (cmcs) of the surfactants decreased with increase in carbon number of the alkyl chain, while the number of sugar unit in hydrophilic portions had little effect on cmcs. Surfactants bearing terminal glucopyranoside residues had remarkable binding affinity toward the sugar-binding protein, Concanavalin A (Con A), while the one with terminal galactopyranoside residues did not. Terminal sugar residues in the surfactants are thus specifically distinguished by Con A.