Facilitated synthesis of inulin esters by transesterification

Inulin, the polydisperse polyfructose, extracted from chicory, has been modified via transesterification, using fatty acid methyl esters (FAME). The grafting of an alkyl chain onto the inulin backbone under different conditions for the development of potential tensio-active derivatives is described. The modification of the biopolymer was performed in polar organic solvents, such as dimethyl sulfoxide (DMSO) and N-methylpyrrolidinone (NMP). Depending on the type of solvent, different catalytic systems, such as DMSO-Na+, NaH, and NaOMe, were used and compared in reaction efficiency and reproducibility. Therefore the synthesized derivatives were characterized by H-1- and C-13 NMR. The methods using NaH had a mean reaction efficiency of 80%, whereas the one using NaOMe showed a slight decrease in reaction efficiency to 75%. However, the method using NaOMe in NMP proved to be the preferred way to graft the inulin backbone with FAME on a bigger scale. The methods using DMSO as a solvent were not attractive since the end products had a specific bad smell.