Enzymatically prepared n-alkyl esters of glucuronic acid: The effect of freeze-drying conditions and hydrophobic chain length on thermal behavior

In this work, some of the physicochemical properties of enzymatically prepared n  -alkyl esters of glucuronic acid are presented. Two questions are addressed. The first concerns the influence of post-purification freeze-drying conditions on octyl glucuronate thermotropic behavior. Depending on the amount of water added before freeze-drying, the α/βα/β anomeric ratio determined by 1H NMR is affected and differences are observed in DSC thermograms probably due to polymorphism. The second question concerns the effect of hydrophobic chain length on the thermal behavior. An increase of both transition temperature and transition enthalpy is observed by increasing the number of carbon atoms in the alkyl chain (C8 < C10 < C12 < C14). This kind of results can provide relevant information for the processing and the practical use of these nonionic surfactants.

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