Synthesis of β-hydroxyalkyl ethers of inulin in aqueous surfactant media

Abstract

The synthesis of long chain hydrophobic β-hydroxyalkyl ethers of inulin in aqueous surfactant media is described. β-hydroxyalkyl ethers of inulin were obtained in reaction media containing 40% inulin and 1 M KOH at 80 °C. Several parameters such as the amount and structure of two cationic surfactants (dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB)) and a non-ionic surfactant (β-hydroxydodecyl ether of inulin (EC12)) as well as the amount and epoxide chain length (C6–C18/26) on the reaction efficiency (RE) were examined through NMR analysis. We can state that the etherification of inulin in aqueous media with 1,2-dodecylepoxide was dependent on the surfactant used. The non-ionic surfactant, EC12, did not have any effect on the etherification reaction. On the contrary, adding a cationic surfactant such as CTAB or DTAB increased the RE significantly. The effect of DTAB micelles on this reaction could be attributed to both electrostatic (inulin/DTAB) and hydrophobic (epoxide/DTAB) interactions. A micellar catalysis mechanism is proposed to explain these interactions. Efficiencies did not increase more than 50% and were not related to variations in the epoxide alkyl chain.