Alkali, action sugars

The results of further investigations strongly support this formation of a-diketones and aldehydes. Before this work is considered, it is pertinent to discuss the action of alkali on sugars. As has already... 

This benzilic acid type of rearrangement is the result of the action of alkali on the dicarbonyl compound, and is accelerated by calcium ions. The formation of saccharinic acids by the action of aqueous alkali on sugars is very well known 82,84,92 however, if ammonia is present, very little8 or no production of saccharinic acid has been reported. The reaction of the intermediate carbonyl compounds with ammonia is faster than the benzilic acid type of rearrangement to give saccharinic acid, and, hence, substituted imidazoles are formed, as illustrated in Scheme 9. 

Regarding the amine component, ammonia is a special case because it is a nucleophile and also a strong base. A survey of the reactions of free sugars with aqueous ammonia was provided by Kort in 1970 [80]. A large number of products can be found in such reaction mixtures, depending on the conditions employed. Short reaction times, low temperature, and the absence of catalyst arrest the reaction before heterocyclic compounds can be formed. The products obtained are the same as those formed by action of alkali on sugars, whereby a Lobry de Bruyn - Alberda van Ekenstein (LdB-AvE) rearrangement (see An-... 

Amino-sugars and Related Compounds. VI. The Action of Alkali on Some Benzyloxycarbonyl-amino Derivatives, A. B. Foster, M. Stacey, and S. V. Vardheim, Acta Chem. Scand., 13 (1959) 281-288. 

Studies in the Amino-Sugars. Part II. The Action of Dilute Alkali... 

Most investigations of the mechanism of ring scission have been made by studying the action of alkali on ethylene oxide anhydro sugars. These investigations will now be reviewed. 

The action of alkaline reagents on sugars has been the subject of much study since Lobry de Bruyn s researches in 1896. Many complex changes are induced in the sugar molecule by alkaline reagents, as is exemplified by the researches of Evans.Here, however, mention will be made only of the production of lactic acid by the action of alkali on sucrose. 

The products obtained by the reaction of sugars with aqueous ammonia for a short time at low temperature, in the absence of catalysts (see Table I) are simply those obtained by the action of alkali on the sugars. The reaction is known as the Lobry de Bruyn-Alberda van Ekenstein transformation87 after the chemists who dis-... 

Another important carbohydrate group of cane final molasses, and one which has been little studied, consists of the products formed by the action of heat, alkali and amino acids upon the reducing sugars. This is sometimes termed the non-fermentable fraction as it remains after yeast fermentation although it is thereby badly contaminated with metabolic products from the yeast. 

R. J. Ferrier, W. G. Overend, and A. E. Ryan, Structure and reactivity of anhydro-sugars. 4. The action of alkali on 2-deoxy-D-glucose structure of isoglucal, J. Chem. Soc., (1962) 1488-1490. 

The proposed intermediate, 2-0-(/3-D-glucopyranosyl)-D-erythrose (XC), hydrolyzes, supposedly via the enediol, to D-glucose and D-erythrose (XCI). This D-glucose, under the action of alkali, then produces lactic acid. The other products shown above (formaldehyde, glycolaldehyde) are known to be formed by alkaline fragmentation of the carbon chain, and are ordinarily present when alkali acts on a reducing sugar.68... 

The powdered-cellulose column has performed valuable service in the study of sugar synthesis. DL-Xylose was resolved from the products of the action of heat and alkali on paraformaldehyde DL-xylose and DL-arabinose were isolated after the action of alkali at 20° on a mixture of glyceraldehyde and glycolaldehyde subsequently, DL-ribose (identified as the p-tolyl-sulfonylhydrazone ) was obtained using a column operating at 60 . 

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