Lactone of aldonic acids

The carbonyl frequency in the infrared spectrum provides a fairly characteristic method for differentiating between 1,4- and 1,5-lactones of aldonic acids. With few exceptions, the absorptions are in the range 1790-1765 and 1760 to 1725 cm-1, respectively.69 Configurational and conformational conclusions have been drawn from H and 13C NMR spectroscopy of aldonic acids and aldonolactones, using different correlation methods, enriched compounds, and shift reagents. For example, the solution conformation of aldono-1,4-lactones enriched with 13C at C-l have been determined on the basis of the coupling constants (homo and heteronuclear). In general, 0-2 is oriented quasi-equatorially due to stereoelectronic factors.36 Similar conclusions were made by Horton and Walaszek, who described the conformation of pentono- 1,4-lactones as an equilibrium between the 3E and forms.70 Conformations of D-hexono-1,4-lactones in solution have also been studied by NMR spectroscopy.70a The solution equilibrium of protected derivatives and their conformations have been described.71... 

Optical rotatory dispersion studies on lactones of aldonic acids and other carbohydrate acids were made by Hirst et al.11 and later by Okuda et al.7S The latter workers related the absolute configuration at C-2 of aldono-1,4-lactones to the sign of the Cotton effect. 

Infrared Spectra of Carbohydrates. Differentiation of y- and 5-Lactones of Aldonic Acids, S. A. Barker, E. J. Bourne, R. M. Pinkard, and D. H. Whiffen, Chem. lnd. 

Types I to IV were 7-lactones of aldonic acids, Types V and VI were uronic acid derivatives with the same basic configuration as Types I and II, respectively. 

W.J. Humphlett, Synthesis of some esters and lactones of aldonic acids,... 

So far only a table of the 13C chemical shifts of aldonic acid salts and aldonolactones has been published in the literature (Table 5.20, [696]). The carbons of the carboxylate ion groups of all D-aldonic acid salts resonate at 180 + 0.7 ppm. Upon /-lactone formation an upfield shift for C-l and a downfield shift for the /-carbon is observed throughout. 

The relationship between structure and paper-chromatographic mobility of aldono-1,4-lactones has been discussed.65 Butanone, saturated with water, is suitable for the preparative separation of lactones on cellulose columns free acids and reducing sugars move very slowly in this system. Separation of aldono-1,4-lactones and of aldonic acids as their O-(trimethylsilyl) derivatives has been accomplished.66 The mass spectra of such derivatives are characteristic, so that it is possible to identify aldonic acids67 and lactones68 by means of combined gas chromatography-mass spectrometry. 

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

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... 

Chloric acid, in conjunction with catalysts (particularly vanadium pentaoxide), is used for the oxidation of aldonic acids or lactones to the 2-glyculosonic acids. Thus, D-glucono-1,4-lactone (9) and potassium D-galactonate in methanol, in the presence of phosphoric acid and vanadium pentaoxide, are oxidized by chloric acid to methyl D-arabino-2-hexulosonate (10) and methyl D-/yxo-2-hexulosonate, respectively.38 At moderate temperatures in the absence of a catalyst, aldoses, ketoses, and sucrose are inert to the action of chlorates over a several weeks time period 39 bromates in alkaline solution also exert no oxidative action (Scheme 5). 

The use of sodium amalgam originates with E. Fischer. The method was a cornerstone of his aldose homologation (cyanohydrin formation, hydrolysis, lactone formation and reduction) which was so important to the development of carbohydrate chemistry. Although the yields obtained by Fischer were moderate ca. 20-50%), more recent work by Sperber et al. has resulted in significant improvements. In particular, they discovered that control of the pH of the reaction mixture was very important. At pH 3-3.5, yields in the range 52-82% were obtained with a variety of aldonolactones. As an example, the preparation of arabinose is shown in equation (4). If the pH was allowed to rise, yields were lower due to overreduction. Methyl esters of aldonic acids could also be used as substrates. 

The various types of carbohydrates considered in this chapter are shown in formulas I-XVIII. The two ring forms (II and III) of the aldoses are shown because careful oxidation can produce the lactones X and XI directly without breaking the oxygen bridge. In most cases, however, the products of oxidation have been isolated as salts of aldonic acids (IX) thus the nature of the initial oxidation product, either a lactone having the same ring structure as the sugar, or possibly the free... 

Anodic oxidation of glucose gives mainly the glucono-(5-lactone (XCI) or gluconic acid (XCII) [Eq. (55)] [133-135]. Formation of aldonic acids from aldoses is the most commonly observed process in other cases [126]. Additional work has been done in the area of indirect anodic oxidation of partially protected carbohydrates at a nickel hydroxide anode [136]. 

Hudson lactone rule. The value of the rotation of aldonic acid lactones is decisively affected by the configuration of that carbon atom whose hydroxyl group is engaged in the cyclization. If, in the normal Fischer projection formula, the lactone ring is written on the right, the lactone is dextrorotatory if it is written on the left, the lactone is levorotatory. 

Isolation of Aldonic Acid Lactones through their Hydrazides, Alva Thompson and M. L. Wolfrom,/. Amer. Chem. Soc., 68, 1509-1510 (1946). 

Mostly, these compounds were synthesized by cyclocondensation of aldonic acid derivatives, such as lactones, imidate esters, or thioimidate esters, with acylhydrazines. Thus, reaction of the 2,5-anhydro-D-allono-l,6-lactone derivative 682 with aminoguanidine gave the 3-amino-5-(j8-D-ribofuranosyl)- ,2,4-triazole 684 (75TL985) (Scheme 182). 

Other articles " dealt with the preparation of aldonic acids, their lactones, and the basic calcium salts of aldonic acids obtained by electro-oxidation. By the procedure proposed, not only calcium, but also... 

Lactones have also been found to be competent substrates for the Schollkopf oxazole synthesis. For example, treatment of aldonic acid lactone 40 with ethyl a-isocyanoacetate (8) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at ambient temperature provided acyclie sugar oxazole 41 in 49% yield. ... 

Trioses and tetroses have been separated as their trimethylsilylated oximes by g.l.c. mass-spectral data for these derivatives were also recorded. Mixtures of xylitol, arabinitol, mannitol, glucitol, and maltitol have been separated efficiently by h.p.l.c. of the corresponding 4-nitrobenzoates. Alditols have been determined in the presence of neutral sugars by oxidation with acidified sodium periodate and colorimetric measurement of the formaldehyde released. G.l.c. retention data have been reported for the TMS derivatives of a large number of aldonic acids and their lactones and aldaric acids. ... 

Thin-layer chromatography of a number of aldonic acids, their lactones and phenylhydrazides on silica gel G with XXI has been reported (Table 204) [16]. The mobilities of the y-lactones have been reported also in the neutral solvent XXII (Table 204) [47]. While the y- and d-lactones and the free acids are well differentiated, the differences in hi /-values between the free acids are slight [16]. 

Methods for lengthening the carbon chains of sugars may involve the formation of aldonic acids as intermediates. The Kiliani cyanohydrin synthesis (see p. 106) creates two new aldonic acids with one more carbon atom than in the original aldose. The configuration of the new asymmetric atom can be assigned by use of the lactone rule discussed below. 

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