Esters aldonates

Aldonic Acids, Their Derivatives and Nitric Esters. Aldonic Acids are hydroxy-... 

Aldonic Acids, Their Derivatives and Nitric Esters. Aldonic Acids are hydroxy-aciu of aldoses, which arc carbohydrates contg aldehyde gtoups (pentose, hexose, etc). The acids can be obtained by mild... 

Much of the chemistry of monosaccharides is the familiar chemistry of alcohols and aldehydes/ketones. Thus, the hydroxyl groups of carbohydrates form esters and ethers. The carbonyl group of a monosaccharide can be reduced with NaBH4 to form an alditol, oxidized with aqueous Br2 to form an aldonic acid, oxidized with HNO3 to form an aldaric acid, oxidized enzymatically to form a uronic acid, or treated with an alcohol in the presence of acid to form a glycoside. Monosaccharides can also be chain-lengthened by the multistep Kiliani-Fischer synthesis and can be chain-shortened by the Wohl degradation. 

Esters derived from the acid function are also named using the ending -onate . The name of the alkyl (aryl, etc.) group is given before the aldonate name. Alternative periphrase names like aldonic acid alkyl (aryl, etc.) ester may be suitable for an index. 

Esters, lactones, lactams, acyl halides etc. are named by modifying the ending -ic acid as described for aldonic acids (2-Carb-20.2). 

Aldono-1,5-lactones and free aldonic acids react with alcohols in the presence of hydrogen chloride to give the corresponding alkyl aldonates (84). The reaction is slower with 1,4-lactones. Because esterification takes place very slowly in the absence of an acidic catalyst, aldonic acids and their lactones may be recrystallized from boiling alcohols without appreciable esterification (85). However, in some instances, alkyl esters are formed under these conditions. For example, essentially pure ethyl L-mannonate was isolated (6.4% yield) from the mother liquors of crystallization L-man-nono-1,4-lactone, obtained by Kiliani synthesis from L-arabinose (86). Similarly, repeated recrystallization from ethanol of crude 2,3,4,6-tetra-O-acetyl-D-glucono- 1,5-lactone afforded the corresponding ethyl gluconate derivative (87). 

In the carbohydrate series, the acids encountered are aldonic, aldaric, uronic, or saccharinic acids. Often, these acids are readily transformed into their lactones or methyl esters, and it is as derivatives of these that they are commonly studied. Table VIII (see p. 136) records examples in which derivatives of such acids and lactones have been subjected to gas-liquid chromatography. 

Aldonic acids, their derivs and nitric esters 1 A122 A123... 

A number of such compds were prepd and then converted to the corresponding nitric esters by Wolfram et al of Ohio State Univ while working under a US Ordnance Corps contract(Ref 5 6). They found that all the pentanitrates prepd by them could be detonated by gentle heat or by a hammer blow on steel. Thermal stability tests have shown that the aldonamide pentanitrates are more stable than aldonic acid pentanitrates or their methyl esters and that the esters were less stable than the corresponding acids. All of their purified nitrates underwent rapid decompn at their mp s, accompanied by violent bubbling and evolution of nitrogen oxides. No residue was visible after decompn... 

Under dehydrating conditions, it is probable that, in addition to lactonization, intermolecular esterification also occurs, yielding esters of aldonic acids and polymers. 

Aldonic acids form crystalline esters, amides, hydrazides, and benzimidazoles. Many of these derivatives, as well as the lactones, have been valuable... 

Esters are prepared by reaction of aldonic acids or lactones with an alcohol in the presence of hydrogen chloride 80 the reaction is slower with 1,4-lactones. Amides are readily formed from lactones by reaction with liquid ammonia followed by evaporation of the solvent.81 D-Gluconamide has also been prepared by treatment of D-glucono-1,5-lactone with concentrated ammonium hydroxide and subsequent precipitation with ethanol.82 A-Substituted aldonamides may be obtained by reaction of the aldono-lactones with ethanolamine, diethanolamine, and related species.83... 

Kochetkov and Dmitriev have reported66,79 an investigation on the hydroxylation of certain a,)3-unsaturated aldonic esters. The hydrox-ylation was performed by treatment of these compounds with chloric or iodic acid (or their salts) and a catalytic amount of osmium tetra-oxide in a suitable solvent. The resulting diastereoisomers were then separated as their cadmium salts. 

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