D -Sorbitol

D[Pg.367]

Isomalt, a mixture of a-D-glucopyranosyl-l,l-D-mannitol dibydrate and a-D-glucopyranosyl-l,6-D-sorbitol, is obtained by hydrogenating isomaltulose which is en2ymatically derived from sucrose (102). 

Most current industrial vitamin C production is based on the efficient second synthesis developed by Reichstein and Grbssner in 1934 (15). Various attempts to develop a superior, more economical L-ascorbic acid process have been reported since 1934. These approaches, which have met with htde success, ate summarized in Crawford s comprehensive review (46). Currently, all chemical syntheses of vitamin C involve modifications of the Reichstein and Grbssner approach (Fig. 5). In the first step, D-glucose (4) is catalytically (Ni-catalyst) hydrogenated to D-sorbitol (20). Oxidation to L-sotbose (21) occurs microhiologicaRy with The isolated L-sotbose is reacted with acetone and sulfuric acid to yield 2,3 4,6 diacetone-L-sorbose,... 

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). 

Sterile aqueous D-sorbitol solutions are fermented with y cetobacter subo >gichns in the presence of large amounts of air to complete the microbiological oxidation. The L-sorbose is isolated by crystallisation, filtration, and drying. Various methods for the fermentation of D-sorbitol have been reviewed (60). A.cetobacter suboyydans is the organism of choice as it gives L-sorbose in >90% yield (61). Large-scale fermentations can be carried out in either batch or continuous modes. In either case, stefihty is important to prevent contamination, with subsequent loss of product. 

D-Glucitol, the alditol produced by reduction of D-glucose, is itself a naturally occurring substance present in many fruits and berries. It is used under its alternative name, D-sorbitol, as a sweetener and sugar substitute in foods. 

Anhydro-d-Sorbitol (3,4,5,1-Tetraoxy-l-methyl-pyrantetrahydride, Polygalitol or Poly-... 

In an earlier study the authors proposed a [3.2.0] bicyclic sulfonium salt 8 as the reactive intermediate in the trimethylsilyl iodide mediated ring contraction of 4-methoxythiephane <1996T5989>. Enantiomerically pure thio-lane derivatives were synthesized via a ring contraction of a seven-membered sulfur heterocycle by nucleophilic transannular substitution <2000TA1389>. The thiepane derivative 15, derived from d-sorbitol, was converted into the dimesyl derivative 16 following deprotection under acidic conditions. Treatment of 16 with sodium azide in DMSO at 120°C yielded the corresponding thiolane as a mixture of two diastereoisomers, 17a and 17b, in a 5 1 ratio (see Scheme 1). 

Michel P.E., Gautier S.M., Blum L.J., A high-performance bioluminescent trienzymatic sensor for D-sorbitol based on a novel approach of the sensing layer design". Enzyme Microb. Technol. 1997 21(2) 108-116. 

FIGURE 1.1 Structures of organic compounds referred to in the text (a) sucrose (also known as saccharose), (b) dimethyl sulfoxide (DMSO), (c) dimethylformamide (DMF), (d) sorbitol, (e) mannitol, (f) nitrilotriacetic acid (NTA), (g) citric acid, (h) N,N,N, N -fran,s-1,2-diaminocyclohexane-tetraacetic acid (CyTA), (i) saccharic acid, (j) glutamic acid. 

Other analytes recently determined by means of immobilized biolumines-cent enzymes are europium(III) [232], d- and L-lactate in beer [233], and d-sorbitol [234], A novel approach of the sensing layer design was reported for... 

Stereospecific contraction of the seven-membered nucleus was observed on treatment of the dimesylated thiepanetetrol derivatives 67 (obtained in turn from d-sorbitol) with sodium azide to give a 5 1 mixture of the bis(azido)tetrahydrothiophenes 68 and 69. Intramolecular nucleophilic displacement of either mesylate group initiates this ring contraction <00TA1389>. 

D-isoascorbic acid D-mannitol D-mannose D-quinic acid D-ribolactone D-ribose D-saccharic acid D-sorbitol L-sorbose D-xylose (—)-a-Pinene (+)-a-Pinene (—)-/ -Pinene (i )-(+)-pulegone... 

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