Novel mannitol based non-ionic surfactants from biocatalysis

Two new mannitol ester based non-ionic surfactants were synthesised using immobilised lipases. The synthesis started from mannitol derivatives having two of the six hydroxyls protected by an isopropylidene group. In the acylation step five different immobilised lipases were compared, for efficiency of substrate conversion. The commercial immobilised lipase from Candida antarctica B (Novozym 435) gave the highest conversion in the shortest time for both substrates. Selective hydrolysis of the isopropylidene group yielded 1-O-lauroyl-d-mannitol and 1,6-di-O-lauroyl-d-mannitol. Characterisation of the products was performed by 13C NMR. enzymatic step it has been thought that it is mainly the primary hydroxyl groups that are esterified. However, as detected from 13C NMR, also other isomers were found. The formation of these isomers may be due to the non-specificity of the lipase, and to the acyl migration phenomenon.