L-Sorbitol

The catalytic hydrogenation of D-glucose to D-sorbitol is carried out at elevated temperature and pressure with hydrogen ia the preseace of nickel catalysts, in both batch and continuous operations, with >97% yield (56,57). The cathodic reduction of D-glucose to L-sorbitol has been practiced (58). D-Mannitol is a by-product (59). 

N.A. Lonicera caerulea L. L. caprifolium L. Sorbitol, inositol, limonic acid, malic acid, citric acid, tannins, salicylic acid.102 Hypotensive, sedative, antipyretic. 

Maltitol (= 4-0-ot-D-Glc-l)-sorbitol] (disaccharide alcohol) Semi-synthetic Sweet [low cariogenicity]... 

In 1923 the bacterium Acinetobacter suboxydans was isolated and, starting in 1930, was used for the industrial oxidation of L-sorbitol to L-sorbose in the Reichstein-Griissner synthesis of vitamin C[39]. Bayer uses the same type of reaction, but instead of Acinetobacter the bacterium Gluconobacter suboxydans is used in the oxidation of N-protected 6-amino-L-sorbitol to the corresponding 6-amino-L-sorbose, which is an intermediate in miglitol production (Fig. 19-7). 1-Desoxynojirimydn is produced by chemical intramolecular reductive amination of 6-amino-L-sorbose. In contrast, the... 

Liposwb, [L ] SorbitoL sorbitan es-tos, or edioxjdates emulsifier, lubricant antistat diickener. 

From carbohydrates, several diphosphines have been derived and used as ligands in hydroformy-lation reactions (Section D.l. 5.8.). a,a -TREDFP (a,a -40) is prepared from commercially available a, a -trehalose (39) by the reaction sequence outlined42,43 similarly, the / ,/f-anomer is obtained from / ,/ -trehalose44. L-Iditol is commercially available but expensive, but may be prepared by catalytic reduction of L-sorbose and separation from the isomeric L-sorbitol by fractionated crystallization of the hexaacetate45. Conversion to the diphosphine 42 involves a further fractional crystallization for the separation of isomeric ditosylates46. The reactions for the synthesis of the precursors employ techniques described in Section 4.4. for the derivatization of carbohydrates. 

Reflect and Apply The sugar alcohol often used in sugarless gums and candies is L-sorbitol. Much of this alcohol is prepared by reduction of D-glucose. Compare these two structures and explain how this can be. 

L-Sorbitol was named early in biochemical history as a derivative of L-sorbose. Reduction of D-glucose gives a hydroxy sugar that could easily be named D-glucitol, but it was originally named L-sorbitol and the name stuck. 

The boronic acid 20 reported by Shinkai is a rare example of an enantiopme chiral redox-active receptor." It was found to bind linear and cyclic sugars in aqueous solution at neutral pH due to the reversible reaction between the boronic acid moiety of the protonated ferrocene receptor and the sugar to form a boronate ester. Electrochemical studies revealed that complexation imparted cathodic (ca. - 50 mV) shifts in the Fc /Fc redox couple. Interestingly, moderate enantioselectivity was observed in that (+ ) — 1 bound the linear saccharide D-sorbitol more strongly than L-sorbitol (ATd/AIl = 1-4). However, differences in the electrochemical response to the binding of these enantiomers by 20 were not apparent. 

Chiral ferroceneboronic acid derivatives have been synthesized by Ori and tested for chiral electrochemical detection of monosaccharides. The best discrimination was observed for L-sorbitol and L-iditol at pH 7.0 in 0.1 mol dm phosphate buffer solution. Moore and Wayner have explored the redox switching of carbohydrate binding with commercial ferrocene boronic acid. From their detailed investigations, they have determined that binding constants of saccharides with the ferrocenium form are about 2 orders of magnitude greater than those for the ferrocene form. The increased stability is ascribed to the lower pKe of the ferrocenium (5.8) than ferrocene (10.8) boronic acid. 

Fig. 3-154. Separation of various sugar alcohols and saccharides. — Separator column CarboPac PAl eluant 0.15 mol/L NaOH flow rate 1 mL/min detection pulsed amperometry at a Au working electrode injection volume 50 pL solute concentrations 10 mg/L xylitol (1), 5 mg/L sorbitol (2). 20 mg/L each of rhamnose (3). arabinose (4). glucose (5), fructose (6). and lactose (7). 100 mg/L sucrose (8),...

Chiral ferroceneboronic acid derivatives (- or -h)-60 have been synthesized and tested for chiral electrochemical detection of monosaccharides [138], The best discrimination was observed for L-sorbitol and L-iditol at pH 7.0 in 0.1 mol dm phosphate buffer solution. 

Until now, other L-sugars have been available only in small amounts. It is assumed that they are metabolized not at all or only to a small extent by human beings and even in low concentrations, they are capable of inhibiting the glycosidases of the small intestine. Therefore, economic methods of synthesis are of interest. A suitable educt is L-arabinose, which yields a L-glucose/L-mannose mixture by chain extension. This mixture can be oxidized directly to L-fructose or after reduction via L-sorbitol/L-mannitol. The isomerization of L-sorbose to L-idose and L-gulose is also under discussion. 

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