Organic chemistry carbohydrates

Organic Chemistry. Carbohydrates, E. L. Hirst and S. Peat, Annu. Rep. Prog. Chem., Chem. Soc. London, 32, 272 (1935). 

As in other areas of organic chemistry, carbohydrate nomenclature is under constant review. However, the compendiirai of rules published in 1963 (96) is a good place to begin. 

Phenylhydrazine on exposure to light slowly darkens and eventually becomes deep red in colour salts of the base share this property but to a lesser degree, the sulphate and acetate (of the common salts) being most stable to light. Phenylhydrazine is largely used in organic chemistry to characterise aldehydes and ketones as their phenyl-hydrazones (pp. 342, 345), and carbohydrates as their osazones (pp. 136-140). It is readily reduced thus in the process of osazone formation some of the phenylhydrazine is reduced to aniline and ammonia. On the... 

The task of relating carbohydrate configurations to names requires either a world class memory or an easily recalled mnemonic A mnemonic that serves us well here was pop ularized by the husband-wife team of Lours F Fieser and Mary Fieser of Harvard Uni versity m their 1956 textbook Organic Chemistry As with many mnemonics it s not clear who actually invented it and references to this particular one appeared m the chem ical education literature before publication of the Fiesers text The mnemonic has two features (1) a system for setting down all the stereoisomeric d aldohexoses m a logical order and (2) a way to assign the correct name to each one... 

Carey Organic Chemistry I 25 Carbohydrates Fifth Edition... 

A quote from a biochemistry text is instructive here. "This is not an easy reaction in organic chemistry. It is, however, a very important type of reaction in metabolic chemistry and is an integral step in the oxidation of carbohydrates, fats, and several amino acids." G. L. Zubay, Biochemistry, 4th ed., William C. Brown Publishers, 1996, p. 333. 

The [ 2 + 4]-cycloaddition reaction of aldehydes and ketones with 1,3-dienes is a well-established synthetic procedure for the preparation of dihydropyrans which are attractive substrates for the synthesis of carbohydrates and other natural products [2]. Carbonyl compounds are usually of limited reactivity in cycloaddition reactions with dienes, because only electron-deficient carbonyl groups, as in glyoxy-lates, chloral, ketomalonate, 1,2,3-triketones, and related compounds, react with dienes which have electron-donating groups. The use of Lewis acids as catalysts for cycloaddition reactions of carbonyl compounds has, however, led to a new era for this class of reactions in synthetic organic chemistry. In particular, the application of chiral Lewis acid catalysts has provided new opportunities for enantioselec-tive cycloadditions of carbonyl compounds. 

These Recommendations expand and replace the Tentative Rules for Carbohydrate Nomenclature [1] issued in 1969 jointly by the IUPAC Commission on the Nomenclature of Organic Chemistry and the IUB-IUPAC Commission on Biochemical Nomenclature (CBN) and reprinted in [2]. They also replace other published JCBN Recommendations [3-7] that deal with specialized areas of carbohydrate terminology however, these documents can be consulted for further examples. Of relevance to the field, though not incorporated into the present document, are the following recommendations ... 

The present Recommendations deal with the acyclic and cyclic forms of monosaccharides and their simple derivatives, as well as with the nomenclature of oligosaccharides and polysaccharides. They are additional to the Definitive Rules for the Nomenclature of Organic Chemistry [13,14] and are intended to govern those aspects of the nomenclature of carbohydrates not covered by those rules. 

Not all problems were solved, however, and different usages were encountered on the two sides of the Atlantic. A joint British-American committee was therefore set up, and in 1952 it published Rules for Carbohydrate Nomenclature [18]. This work was continued, and a revised version was endorsed in 1963 by the American Chemical Society and by the Chemical Society in Britain and published [19]. The publication of this report led the IUPAC Commission on Nomenclature of Organic Chemistry to consider the preparation of a set of IUPAC Rules for Carbohydrate Nomenclature. This was done jointly with the IUPAC-IUB Commission on Biochemical Nomenclature, and resulted in the Tentative Rules for Carbohydrate Nomenclature, Part I, 1969 , published in 1971/72 in several journals [1]. It is a revision of this 1971 document that is presented here. In the present document, recommendations are designated 2-Carb-n, to distinguish them from the Carb-n recommendations in the previous publication. 

March J (1992) Advanced Organic Chemistry, 4th edn. Wiley, New York, p 659 March J (1992) Advanced Organic Chemistry, 4th edn. Wiley, New York, p 393 Samaranayake G, Glasser WG (1993) Carbohydr Res 22 1... 

Comprehensive Organic Chemistry , Pergamon, Elmsford, NY, 1979, is a six-volume treatise on the synthesis and reactions of organic compounds. The first three volumes cover the various functional groups, vol. 4, heterocyclic compounds, and vol. 5, biological compounds such as proteins, carbohydrates, and lipids. Probably the most useful volume is vol. 6, which contains formula, subject, and author indexes, as well as indexes of reactions and... 

Because of its importance to carbohydrate technology, biochemistry, and physical organic chemistry, the hydrolytic cleavage of glycosides has been extensively studied with respect to both acid and enzymic catalysis. Reviews on the acid-catalyzed hydrolysis have been presented by BeMiller, Capon, ... 

The death of Francisco Garcia Gonzalez, Emeritus Professor of Organic Chemistry at the University of Seville, Spain, deprived carbohydrate chemistry of a long-lived and enthusiastic researcher. Professor Garcia Gonzalez was a pioneer in carbohydrate research in Spain, and a leader for many years of an active school of research that has now spread to several universities and research centers in that country. 

HMF is an important versatile sugar derivative and is a key intermediate between bio-based carbohydrate chemistry and petroleum based industrial organic chemistry (1, 2). The most coimnon feedstock for HMF is fructose and reactions are carried out in water-based solvent systems using acid catalysis (3,4). HMF is unstable in water at low pH and breaks down to form levulinic acid and formic acid, resulting in an expensive HMF recovery process. In strongly polar organic co-solvents, such as dimethylsulfoxide (DMSO), levuhnic acid formation is reduced and HMF yields are improved (5). 

Silica-supported reagents have been exploited as nontoxic, inexpensive, reusable, and environmentally acceptable catalysts for developing stoichiometric reaction methods in organic chemistry and specifically in carbohydrate chemistry. Apart from being easy to handle and to store, these systems allow facile workup, the catalyst being removed by simple filtration, and the reaction products isolated by chromatographic purification, if necessary. 

The use of water or of an aqueous solvent as the reaction medium is a characteristic of periodate oxidation, as performed in this field. This situation is ideal for most work on carbohydrates, but imposes on applications to other fields of organic chemistry a limitation which, nevertheless, has been partially circumvented in a number of ways. 

---