Recent Advances in the Synthesis of Sugar-based Surfactants

Abstract

New challenges have to be faced in the field of surfactants. Green processes and products are increasingly demanded: green syntheses, natural building blocks as starting materials, products of high biodegradability and devoid of toxicity, low costs. Sugar-based surfactants successfully fit all these requirements and thus they are at the centre of the research of new green surfactants with specific properties. Most of the syntheses published in the literature from 2008 to 2014 are about new structures presenting variations on the sugar moiety, the hydrophobic chain, and the introduction of spacer arms between the polar head and the lipophilic tail. Carbohydrates offer a wide diversity of monomers and dimers that can be cyclic (furanose, pyranose) or acyclic to be used as a polar head. Among all the available hydroxyl groups of a sugar unit, two are particularly suitable for substitution: primary alcohols and the hydroxyl at the anomeric position. The hydrophobic chain can be more complex than the classical alkyl chain, as chemists are looking for new properties that can be brought by the use of fluoroalkyl chains or polysiloxanes. This chapter reviews recent bibliography and reports (patents excluded) on the synthesis of sugar-based surfactants, including chemical and chemoenzymatic methods.