The synthesis of higher-carbon sugar alcohols via indium-mediated acyloxyallylation as potential phase change materials.

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In recent years, sugar alcohols have gained significant attention as organic phase change materials (PCMs) for thermal energy storage due to their comparably high thermal storage densities up to 350 J/g. In a computational study, outstandingly high values of up to ~ 450-500 J/g have been postulated for specific higher-carbon sugar alcohols. These optimized structures feature an even number of carbon atoms in the backbone and a stereochemical configuration in which all hydroxyl groups are in an 1,3--relationship, as found in the natural hexitol d-mannitol. However, these -configured higher-carbon sugar alcohols have not been experimentally investigated as PCMs yet and described synthetic routes are elaborate multiple steps syntheses. Therefore, we aimed to synthesize sugar alcohols of the -series with a concise synthetic protocol based on the indium-mediated acyloxyallylation (IMA) of aldoses. En route the C2-epimers were easily accessible, namely -configured sugar alcohols, bearing one set of hydroxyl groups in a suboptimal 1,3--realtionship. The synthesized compounds were found to possess thermal properties consistent with the predicted values, and the "perfect" higher-carbon sugar alcohol with eight carbon atoms was found to have indeed an outstanding high latent heat of fusion of ~ 380 J/g with a melting point of 260 °C.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00706-023-03136-6.