Organic reactions in low melting mixtures based on carbohydrates and L-carnitine-a comparison

A new L-carnitine/urea melt was developed and compared to previously reported sugar and sugar alcohol melts using several organic reactions for benchmarking. Physicochemical properties of the new L-carnitine melt, including the melting point and the polarity were determined by differential scanning calorimetry (DSC) and solvatochromatic measurements, respectively. The L-carnitine melt shows a very high polarity. Heck and Sonogashira cross-couplings, Diels-Alder reactions and Cu-catalysed 1,3-dipolar cycloadditions proceed cleanly in sugar and L-carnitine based melts, but the applicability of L-carnitine melts for standard organic reactions is limited by their lower thermal stability.