ABSTRACT
Sugar-based surfactants rank high on the list of compounds that are produced according to the principles of green chemistry [1,2]. The raw materials, mostly monosaccharides, disaccharides, fatty acids, and fatty alcohols are available from renewable sources; their production is economic because they are obtained either directly, e.g., sucrose by crystallization from concentrated sugarcane juice, or by simple processes, e.g., glucose by the enzymatic hydrolysis of starch (α-amylase and glucoamylase) [3], and fatty acids by steam-splitting of oils and fats [4]. Other raw materials that are obtained by employing straightforward, readily established processes include fatty esters, by transesteri cation of oils and fats with low molecular weight alcohols (mostly methanol and ethanol) [4]; fatty alcohols, by the catalytic reduction of the corresponding acids under high temperature/high pressure [5]; and N-alkylglucoamines by the reaction of glucose with alkylamines, followed by catalytic reduction of the intermediate imine. The economy of the production of sugar-based surfactants is assured because the reactions involved are relatively simple. Examples are the esteri - cation of the sugar by a fatty acid, by using chemical or enzymatic pathways [6,7], the Fischer and Koenigs-Knorr syntheses of alkyl glycosides from glucose and fatty alcohols [8,9], and the synthesis of N-alkanoyl-N-alkyl-1glucamines from the corresponding fatty acids and N-alkylglucoamines [10]. The relative simplicity of these reactions assures “atom economy” and reduction of waste, because all reactants are incorporated in the nal products. The ready biodegradability of the products, their compatibility with the skin, and ef ciency as surfactants, either alone or as mixtures with other “classic” surfactants are the most relevant examples of the favorable properties of sugar-based surfactants [11]. The demand for the latter is most likely to increase because the public is becoming increasingly concerned about the environmental impact of the products consumed. Additionally, the relative price advantage of petroleum-based raw materials that are employed in the detergent industry (alkenes, benzene, ethylene oxide, etc.) will probably not hold for long, because of the inexorably increased demand on crude oil, fueled by global economic expansion, not matched by an increase in oil and natural gas production. In summary, sugar-based surfactants are here to stay, and expand!
