Carbohydrates, physical properties sucrose

It should also be remembered, as illustrated by the artifacts in the sucrose studies, that vacuum calculations could potentially be inadequate. Most carbohydrates are found in aqueous environments, and the influence of solvent upon conformation might be significant. Since physical properties are determined by free energies rather than mechanical energies, it may be necessary in some cases to compute (, ) maps of the potential of mean force from solution MD studies, which would include the solvent contribution. 

Polarimetry is extremely useful for monitoring reactions of optically active natural products such as carbohydrates which do not have a useful UV chromophore, and samples for study do not need to be enantiomerically pure. Nevertheless, compared with spectrophotometry, the technique has been applied to relatively few reactions. It was, however, the first technique used for monitoring a chemical reaction by measuring a physical property when Wilhemy investigated the mutarotation of sucrose in acidic solution and established the proportionality between the rate of reaction and the amount of remaining reactant [50]. The study of a similar process, the mutarotation of glucose, served to establish the well-known Bronsted relationship, a fundamental catalysis law in mechanistic organic chemistry. 

A one-stage procedure involving sodium catalysed transesterification between raffinose undeca-acetate and methyl esters of long-chain fatty acids (derived, for example, from salad oil) has been employed to produce raffinose fatty acid polyesters in excellent yields (>96%) their physical properties are described as similar to those of analogous sucrose polyesters." Certain carbohydrate esters of fatty acids, e.a.. sucrose mono-laurate, -palmitate, and -stearate, have been found to enhance the activity of thiabendazole, a fungicide used against Penicillium dioitatum infections of citrus fruit. The mechanism of this action remains to be clarified. ... 

By the middle of the nineteenth century, a number of relatively pure carbohydrates such as sucrose, cellulose from cotton, starch, glucose, fructose, mannose, and lactose were known to the chemists of Europe, especially in Germany, who were studying natural products [3]. These chemists were investigating the physical and chemical properties of carbohydrates. The following is a summary of what was known about carbohydrates in the nineteenth century. 

---