Publisher Summary This chapter provides an overview of the 13 Carbon-nuclear magnetic resonance ( 13 C-NMR) spectroscopy of monosaccharides. The 13 C-NMR spectroscopy has become increasingly important as a tool for the characterization and structural elucidation of sugars and their derivatives. Although 13 C-NMR is closely related to 1 H-NMR spectroscopy, especially when both types of spectra are recorded with Fourier-transform instruments, the two techniques are sufficiently different to be valuable complements to each other. In many cases, in particular when dealing with complex molecules such as polysaccharides, the amount of information obtainable from 1 H-NMR spectra is limited as compared to that revealed by 13 C- NMR spectra. This chapter provides an almost complete collection of 13 C- NMR chemical shifts of monosaccharides, their methyl glycosides, and acetates, along with the examples of shift data for as many different types of monosaccharide derivative as possible. It also provides details on sampling techniques and assignment techniques, and discusses the identity of monosaccharides, their structure determination, and conformational analysis .

Carbon-13 Nuclear Magnetic Resonance Spectroscopy of Monosaccharides

Metabolite profiling by one- and two-dimensional NMR analysis of complex mixtures

Publisher Summary This chapter discusses the composition of reducing sugars in solution. Reducing sugars differ from most other organic compounds in one characteristic property. When a pure organic compound that is not a reducing sugar is dissolved in a solvent, it is certain that the solution will usually contain only one compound; but when a reducing sugar, above an aldotetrose or a 2-pentulose, is dissolved in water, a solution is obtained that always contains at least six compounds: two pyranoses, two furanoses, and an acyclic (open-chain) carbonyl form and its hydrate. There are also minute proportions of septanoses and dimers. Very few of these many compounds that are present in the equilibrium solutions of sugars have ever been isolated. The only method for separating them from the equilibrium mixture is by crystallization and that depends on the fortuitous presence of seed crystals. The chapter details about the pyranose form, the furanose form, and the septanose form. It also discusses the composition of aldoses, ketoses, and substituted and derived sugars in aqueous solution.

The composition of reducing sugars in solution

Carbon-13 with a natural abundance of only 1.1% and a smaller magnetic moment than 1H (and hence a weaker NMR signal) was for many years a nucleus relatively inaccessible to NMR spectroscopists. However, with the advent in recent years of pulsed NMR and Fourier Transform (FT) analysis, 13C-NMR spectroscopy has become more readily available. As a result the past five years have seen a dramatic increase in the number of publications on, or involving, 13C-NMR spectroscopy of flavonoids. For example major compilations include those of Ternai and Markham (1976), Markham and Ternai (1976), Markham et al. (1978), Wagner et al. (1976), Chari et al (1977a), Pelter et al (1976) and Wenkert and Gottlieb (1977). The increasing availability and sensitivity of modern FT-NMR spectrometers is assurance that this powerful technique will become a major tool for the structure elucidation of flavonoids and their glycosides.

Lawrence Jr. Que

Papers

13C nuclear magnetic resonance spectra and the tautomeric equilibria of ketohexoses in solution.