Acidity, of sugars

Fatty acids of sugars are potentially useful and fully green nonionic surfactants, but the lipase-mediated esterification of carbohydrates is hampered by the low solubility of carbohydrates in reaction media that support lipase catalysis in general. Because the monoacylated product (Figure 10.8) is more soluble in traditional solvents than is the starting compound, the former tends to undergo further acylation into a diester. In contrast, the CaLB-catalyzed esterification of glucose with vinyl acetate in the ionic liquid [EMIm][BF4] was completely selective. The reaction became much faster and somewhat less selective when conducted in... 

Calculation can give some idea of the relative acidities of sugar hydroxyls. The deprotonation enthalpies (kJ oC ) in vacuo of the various OH groups of a-D-glucopyranose, relative to that for the anomeric hydroxyl, are 2-OH, 35.5 ... 

Bergman s essay on oxalic acid (acidum sacchari) (1776) is in the form of a thesis supported by Johann Afzelius (Arfedson see p. 200), but the real discoverer of the preparation of oxalic acid from sugar by the action of nitric acid was Scheele, mention of whom was omitted by an oversight. The acid of sugar was obtained by boiling sugar with nitric acid and crystallising the solution. Several of its salts, and the impure ethyl ester, are described. 

Bergman says the gas evolved on heating acid of sugar (oxalic acid) is half... 

He made a detailed investigation of salt of sorrel, which he supposd consisted of a peculiar acid Scheele afterwards proved that this was identical with the acid of sugar (oxalic acid) (see p. 232). Wiegleb thought the acid of sugar (oxalic acid), which he obtained by the action of nitric acid on alcohol, was nitric acid modified by the inflammable principle and he criticised the experiments of Bergman and Scheele on it. 

In 1785 de Morveau said Lavoisier had supposed that sugar when treated with nitric acid becomes acid of sugar acide saccharin) (oxalic acid) by taking up vital air, as sulphur forms vitriolic acid and phosphorus phosphoric acid (see p. 424). But if sugar enters undecomposed into acid of sugar it must exist in all other substances from which this acid is extracted by the same means, which cannot be accepted. The acid is really formed by the combination of vital air with a particular radical (radical particulier ou base acidifiable) found in numerous bodies of different kinds, in this case the radical saccharin. Thus de Morveau introduced the name radical into organic chemistry. 

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