Monosaccharide production influences

With some oligosaccharides, periodate studies may be complicated by different rates of oxidation of the constituent monosaccharides, by hydrolysis, and by overoxidation. In such cases, the periodate consumption and yields of products are strongly influenced by the reaction conditions, and the interpretation of results obtained should, therefore, be undertaken with great care. 

Parenteral formulations often contain excipients considered to be chemically stable and inert however, all excipients in a formulation may influence the photochemical stability of the product. Dextrose and sodium chloride are used to adjust tonicity in the majority of parenteral formulations. Sodium chloride can affect photochemical processes by influencing solvation of the photoreactive molecules (see Section 14.2.3). The ionic strength is reported to affect the photochemical decomposition rate of minoxidil until a saturation level is reached (Chinnian and Asker, 1996). The photostability of L-ascorbic acid (vitamin C) in aqueous solution is enhanced in the presence of dextrose, probably caused by the scavenging effect of the excipient on hydroxyl radicals mediated by the photolysis of ascorbic acid sucrose, sorbitol, and mannitol have the same effect (Ho et al., 1994). Monosaccharides (dextrose, glucose, maltose, and lactose), disaccharides (sucrose and trehalose), and polyhydric alcohols (inositol, mannitol, and sorbitol) are examples of commonly used lyo-additives in parenterals. These excipients may also affect photochemical stability of the products after reconstitution. 

Tin(II) triflate has been used to catalyse the condensation between tetra-O-acetyl-a-D-glucopyranosyl bromide and primary and secondary alcohol groups on other monosaccharide derivatives. The products had the 3-configuration exclusively but the yields were modest (30-65%). In a related study the influences of catalyst, solvent, and temperature on the reaction of 0-(tetra-O-benzyl-a-D-glucopyranosyDtrichloroacetimidate with primary and secondary sugar alcohols were examined. With boron trifluoride in dichloro-methane at -I8—good yields (e.g. 80 for a secondary alcohol) and anomeric ratios (a,3, ca. 1 4) were obtained. 

The reactions of monosaccharides in aqueous alkaline solution is the subject of a review covering initial transformations, alkaline degradation and the Influence of reaction variables on product for-1... 

Intramolecular Diels-Alder (IMDA) reactions of 1,6,8-nonatrienes and 1,7,9-decatrienes have been used frequently for the construction of chiral ring systems of complex natural products (18-20), Although saccharide derivatives have been employed many times in intermolecular Diels-Alder reactions (21-28) their IMDA reaction appears not to have been studied so far. The diastereoselectivity of IMDA reactions can be influenced, among other factors, by the size of substituents, and by the chirality of carbons of the connecting chain. Our aim was to study the possibilities of the application of single monosaccharides as tether chains in IMDA reactions. The influence of the presence of three or four chiral... 

This chapter on saccharides is divided into two main parts. The first part describes major monosaccharides, and their functional derivatives, oligosaccharides and polysaccharides. Their structure and nomenclature, occurrence in major food commodities, properties and importance in human physiology and nutrition, recommended intake and use in food technology are all described. The second part is devoted to reactions of saccharides that lead to the formation of products that influence odour, taste and colour of foods, and to reactions taking place during storage and thermal processing of food raw materials and foods. 

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