Composition of sugar solutions

Part I. History, basic kinetics, and composition of sugar solutions, 23, 11-57... 

The question of the detailed composition of sugar solutions in various solvents together with the chemistry of the mutarotation reaction has continued to attract attention through the years. In their classical review, Mutarotation of Sugars in Solution, completed in 1969, Isbell and Pig-man have cited references to more than 320 papers and books (5, 6). The appearance of this volume justifies Isbells faith that carbohydrate chemistry continues to have a significant impact on the development of new concepts permeating all branches of chemistry and biochemistry (7). ... 

History, Basic Kinetics, and Composition of Sugar Solutions... 

Composition of Sugar Solutions as Determined by Nuclear Magnetic Resonance Measurements ... 

In some instances, nuclear magnetic resonance techniques employing trimethylsilyl ethers have provided information on the composition of sugar solutions that could not be obtained by classical methods. Thus, the formation of D-galactofuranose during mutarotation was shown by gas chromatography of the trimethylsilyl derivatives of D-galactose (from the mutarotation mixture). The products were... 

Phillips, G. O., Radiation Chemistry of Carbohydrates, 16,13-58 Pigman, Ward, and Isbell, Horace S., Mutarotation of Sugars in Solution Part I. History, Basic Kinetics, and Composition of Sugar Solutions, 23, 11-57... 

Ferlin, A. S., Action of Lead Tetraacetate on the Sugars, 14, 9-61 Perlin, a. S [Obituary of] Clifford Bur-rough Purves, 23, 1-10 Phillips, G. O., Photochemistry of Carbohydrates, 18, 9-59 Phillips, G. O., Radiation Chemistry of Carbohydrates, 16, 13-58 Pigman, Ward, and Isbell, Horace S., Mutarotation of Sugars in Solution Part I. History, Basic Kinetics, and Composition of Sugar Solutions, 23, 11-57... 

Mutarotation of sugars in solution. Part I. History, basic kinetics, and composition of sugar solutions, W. W. Pigman and H. S. Isbell, Adv. Carbohydr. Chem., 23 (1968). 

An important consequence of sucrose degradation is the development of color from degradation products. Kuridis and Mauch60 have developed an equation for the prediction of color development in model sucrose solutions. Color development was expressed as a function of temperature (90 to 120°C), time (0 to 80 min), pH (7.5 to 9.5), and composition of the solution (sucrose 20 to 60%, invert sugar 0.02 to 0.18%, and amino acids 1 to 3 g/L). The authors claimed, with caution, that the effects of an intended alteration in a unit process in the refinery can be predicted in advance. 

Although most of these forms of sugars have never been isolated, they can be detected in the n.m.r. spectra of the sugars, and their proportion in the equilibrium mixture can be measured. Before the advent of n.m.r. spectroscopy, only a rudimentary knowledge of the composition of sugars in solution was available, but, since 1961, an extensive collection of data has been built up, mainly by the use of n.m.r. spectroscopy. These data are the subject matter of this article. The composition of sugars in solution was reviewed3 in 1969, but since then, much new information has been accumulated. 

Knowledge of the composition of sugars in solution is fundamental to carbohydrate chemistry. The physical and chemical properties of the sugars in solution depend on the proportions of their various forms and their biological properties may also show such dependence. Enzymes that utilize these sugars as substrates may not be able to use each of the forms. Where only a single form is utilized, the other forms may either be converted into the reactive form or may function as inhibitors. The latter is especially important if the reactive form is present in very low proportion at equilibrium. It is possible that the substrate form is utilized faster than it is generated from the other forms the observed rate of the reaction is then that of the tautomeric interconversion.4... 

The composition of aqueous solutions of D-arahino-2-hexulose (d-fructose) has also been studied by laser-Raman spectroscopy.45 (The composition of solutions of D-fructose appears to have been determined by more methods, and more often, than that of any other sugar.20)... 

Dilute acids or bases have no noticeable effect on the composition of sugars in aqueous solution at high concentration, however, they alter it considerably. What is then observed is, in fact, not the equilibrium of the sugars themselves but that of their cations and anions, respectively, sugars being weak bases and weak acids. Thus, the a yj-pyranose ratio for D-glucose in 2,5 M DC1 was found90 to be 45 55 the same ratio was obtained when the solvent was formic acid. 

Replacement of a hydroxyl by an amino group may cause profound changes in the composition of a solution of a sugar. The extent of the change depends on whether the amino group is free, protonated, or acylated and, even more, on which hydroxyl group has been thus re-... 

Water is the only solvent in which the composition of sugars has been systematically explored. Stevens1674 has determined the composition of several aldoses in pyridine-d5 by -n.m.r, spectroscopy at 300 MHz. There are scattered data on solutions in organic solvents (mainly pyridine, dimethyl sulfoxide, and N,N-dimethylformamide), but only rarely have four (or more) components of such solutions been quantitatively determined. The data that have been encountered are collected in Table VII undoubtedly, there are others that have been missed. 

Kuhn and Grassner168 were the first to realize that the solution composition of sugars may vary considerably with a change of solvent. They stated that D-fructose in N,N-dimethylformamide exists in furanose forms to the extent of 80%. (This value is probably too high compare with Table VII.)... 

The composition of sugars in solution varies considerably with changes in the temperature (see Section III,6). It is essential, therefore, to record the temperature at which the proportions have been determined. Ideally, all of the compositions should have been listed at the same temperature, but, unfortunately, different authors have used different temperatures for their measurements. In the Tables, therefore, the temperature at which the data were obtained is recorded where no such figure appears, it was not possible to ascertain this information from the published texts, In those cases where data at several temperatures were published, those recorded closest to 25° are listed. 

The majority of the many methods used to study the composition of equilibrium solutions of carbohydrates examine the mixture without separating the individual components. With the discovery that the anomeric forms of sugars could be readily separated by gas chromatography of their tri-methylsilyl ethers, a new approach to the problem was found. A protocol was developed for the direct gas chromatographic analysis of the amount of each anomer present in an aqueous solution. The protocol can be used on the micro scale and can be used in enzyme assays such as that for mutarotase. The method has been made more effective by combining gas chromatography with mass spectrometry. It is shown how mass spectral intensity ratios can be used to discriminate anomers one from another. The application of these methods to the study of complex mutarotations is discussed. 

The Composition (%) of Aqueous Solutions of Ketoses and Amino Sugars... 

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