Chemo‐enzymatic synthesis of amino acid‐based surfactants

Abstract

The application of lipases to the synthesis of amino acid-based surfactants was investigated. Low yields (2-9%) were obtained in the acylation of free amino acids, such as L-serine and L-lysine, as well as their ethyl esters and amides with fatty acids, owing in part to low miscibility of the reactants. When the N-carbobenzyloxy (Cbz)-L-amino acids were used in an effort to improve miscibility of the amino acid derivatives with the acyl donor, a dramatic improvement was observed for N-Cbz-L-serine (92% yield) but not for N α -Cbz-or N ζ -Cbz-L-lysine (7 and 2% yield, respectively). As an alternative, an efficient synthesis of N ζ -acyl-L-lysines was developed, based on the regiospecific chemical acylation of copper(II) lysinate. In pursuit of a general route to amino acid-fatty acid surfactants, the utility of a polyol linker was investigated. Thus, the glycerol ester of N α ,N ζ -di-Cbz-L-lysine was prepared and evaluated as a substrate for acylation. As expected, this and other glycer-1-yl esters of N-protected amino acids were excellent substrates for lipase-catalyzed acylation. Their reaction with myristic acid in the presence of Novozyme resulted in the regioselective acylation of the primary hydroxyl group of the glycerol moiety to afford the corresponding 1-O-(N-Cbz-L-aminoacyl)-3-O-myristoylglycerols with conversions of 50-90%. These were readily deprotected to give a range of 1-O-(aminoacyl)-3-O-myristoylglycerols with overall yields of 27-71%. JAOCS 74, 879-886 (1997).

Amino Acids, Lactic Acid and Ascorbic Acid as Raw Materials for Biocompatible Surfactants

“…The main advantages associated with the use of biocatalysts are mild reaction conditions and high enzymatic specificity, which often eliminate the need for regioselective protection of multifunctional starting materials. This point has been clearly demonstrated by a number of recent reports dealing with the application of enzymes to synthesis and/or modification of amino acids, sugar fatty acid esters, phospholipids and alkyl glycosides [40][41][42][43][44].…”

Synthesis of Surfactants Using Enzymes

“…Studies with immobilized lipases from Candida antarctica and Rhizopus miehei have shown that the enzymes could accept N -Cbz amino acids as acyl donors and catalyse the esterification with long-chain fatty alcohols with high yields [55,56]. Removal of water produced during the reaction was essential to shift the equilibrium towards ester synthesis.…”

Eco-Technologies for Obtaining Aminoacid Based Surfactants

“…The most important class of amino acid based surfactants is represented by N-acyl derivatives (acyl amino acids), comprising anionic, cationic, amphoteric or non-ionic surfactants, depending on the ionic nature of the amino acid. Synthesis methods include enzymatic [6][7][8] and chemo-enzymatic [9] processes, but mainly chemical methods due to relatively low production costs [10][11][12]. In this work we have focused on synthesis of surfactants based on hydroxyproline and glygylglycine amino acids, through processes with low environmental impact.…”