Sucrose mono , preparation

We have noted that this derivative is readily oxidized (either by air or iodine) to disulfide 36 which can be converted back to 35 by reduction with LiAlH4. Sucrose mono-thiol 37, prepared from the monosilylated at the C6 ( fructose end ) derivative 24, was used for construction of C2-symmetrical disulfide 38. It could be readily oxidized to di-sulfide 38 (Scheme 8). °... 

Using sucrose mono-esters of fatty acids prepared according to Osipow et al. [173], Mima [174] solubilized vitamins A, D2, and vitamin E acetate. The sucrose esters were employed in an attempt to overcome the problems encountered when polyoxyethylene glycol ethers are used, such as the sensitivity... 

Gupta, R. K., K. James, F. J. Smith, Sucrose mono- and diesters prepared from triglycerides containing C]2-Cig fatty acids,/. Am. Oil Chem. Soc., 1983,60, 1908-1913. 

These emulsifiers are prepared from sucrose and edible fatty acids. The primary hydroxyl groups of the sucrose are esterified by the fatty acid. In Figure 2, R is the alkyl group of the fatty acid. Fatty acids can be reacted with one, two or three primary hydroxyl groups to yield mono, di or triesters, respectively. 

Finally, an elegant example of a product derived from renewable raw materials is the bioemulsifier, marketed by Mitsubishi, which consists of a mixture of sucrose fatty acid esters. The product is prepared from two renewable raw materials - sucrose and a fatty acid - and is biodegradable. In the current process the reaction is catalysed by a mineral acid, which leads to a rather complex mixture of mono- and di-esters. Hence, a more selective enzymatic esterification (Fig. 1.43) would have obvious benefits. Lipase-catalysed acylation is possible [126] but reaction rates are very low. This is mainly owing to the fact that the reaction, for thermodynamic reasons, cannot be performed in water. On the other hand, sucrose is sparingly soluble in most organic solvents, thus necessitating a slurry process. 

Niosomes are non-ionic surfactant vesicles. They have been used to develop a vaccine-delivery system by peroral and oral routes. Ovalbumin was encapsulated in various lyophilized niosome preparations consisting of sucrose esters, cholesterol, and dicetyl phosphate. Encapsulation of ovalbumin into niosomes consisting of 70% stearate sucrose ester and 30% pal-mitate sucrose ester (40%i mono-, 60% di/triester) resulted in a significant increase in antibody titers in serum, saliva, and intestinal washings. ... 

With few exceptions, enzymatic processes in carbohydrates cause degradation. Enzymes are used in the form of pure or semipure preparations or together with their producers, i.e., microorganisms. Currently, semisynthetic enzymes are also in use. Alcoholic fermentation is the most common method of utilization of monosaccharides, sucrose, and some polysaccharides, e.g., starch. Lactic acid fermentation is another important enzymatic process. Lactic acid bacteria metabolize mono- and disaccharides into lactic acid. This acid has a chiral center thus either D(-), L(+), or racemic products can be formed. In the human organism, only the L(+) enantiomer is metabolized, whereas the D(-) enantiomer is concentrated in blood and excreted with urine. Among lactic acid bacteria, only Streptococcus shows specificity in the formation of particular enantiomers, and only the L(+) enantiomer is produced. 

Titanium-based catalysts, would seem particularly attractive candidates, but the pore size of e.g. TS-1, is much too small to admit even a monosaccharide. Recently a number of synthetic approaches towards mesoporous titanium containing catalysts of the MCM-41 type have appeared in the literature . In the present paper we will deseribe the use of Ti-MCM-41 materials in the oxidation of the model mono- and disaccharides methyl a-D-glucopyranoside, sucrose and a,a-trehalose, and we will discuss the effect of the zeolite synthesis on the effectiveness in these reactions. Several preparative approaches of Ti-MCM-41 have been compared in the oxidation of these model carbohydrates. 

The chelates are prepared in anhydrous DMF or DMSO by ionization of the desired number of hydroxyl groups of the sucrose molecule with stoichiometric cunounts of sodium hydride to form alcoholates which, with metal salts, give the chelates. The etherification of sucrose with alkyl halides or esterification with organic acids caus is hydrolysis. The hydrolysis or diether formation is avoided if sucrose chelate is etherified at moderate temperatures and with only a small excess of allyl halide or sodium bromoacetate, giving 55-69% mono- and 0-2% diallyl ethers respectively, 41-48% mono- and 4-7% dicarboxymethyl ethers of sucrose. 

A characteristic difference from the preparation of sucrose esters, is that sugar alcohols are much more stable than sucrose, so that they can withstand the relatively long reaction times needed for direct esterification by fatty acids. The method is very satisfactory for preparing fatty acid esters of sugar alcohols of mono- and disaccharides. 

Sugar alcohols can be prepared by hydrogenation of reducing mono-, di- and oligosaccharides. Sorbitol and mannitol are obtained from sucrose, maltitol from maltose and lactitol from lactose. Maltose is more expensive than sucrose while lactose, obtained from whey, potentially is an inexpensive raw material. 

Synthesis from sucrose ester, aluminium diiso-propoxide monoacetylacetonate and diisocyanate. In pre-liminary experiments, sucrose "penta"soyate or sucrose "penta" dehydrated castor ester reacted in toluene at IIQOC with an equimolar proportion of aluminium diiso-propoxide monoacetylacetonate. (The latter was prepared separately by reaction of equimolar proportions of aluminium isopropoxide and acetylacetone in refluxing toluene with elimination of 1 mole 2-propanol). The modified sucrose ester reacted with 1.1 mole toluene diisocyanate (the maximum without gelation) and dibutyl tin dilaurate as catalyst. The performance of air-dried or stoved coatings was similar to material derived by the mono-/diisocyanate route in terms of alkali resistance, but they were more brittle. 

The initial steps of solubilization, DEAE chromatography and gel filtration were slight modifications of reported procedures [19]. The pooled fractions from a Sephacryl S-200 (Pharmacia) column were applied to a Mono Q HR5/5 FPLC column (Pharmacia) and eluted in a 20 ml gradient from 0-350 mM NaCl in 0.25 M sucrose-20 mM Tris-HCl pH 7.3. Fractions of 1 ml were collected and assayed for binding of NAA-1-[ C] (61 mCi/mmol, Amersham) by one of three methods [20]. The most active fractions were pooled, desalted and lyophilized. This preparation (approx. 50% receptor) was used either for monoclonal antibody production or was fully purified by native PAGE in a neutral pH discontinuous system [3]. The gel was briefly electroblotted (5 min, 10 mA) to nitrocellulose and the small fraction of transferred proteins visualized by rapid staining [8]. This blot was then used to locate precisely the bulk protein bands remaining in the gel. 

D-Glucose reacted with dodecyl chloroformate in DMF in the presence of sodium carbonate to produce a mixture of carbonates which was separated into mono-, di-, and tri-carbonates by t.l.c. on silica gel. Sucrose monoesters have been prepared in 44—85% yield from sucrose and 1-alkoxyethyl isocyanates in DMF containing triethylamine. The syntheses and properties of sucrose A (aryloxyalkaneacyl)-carbamates from sucrose and the corresponding isocyanate have been reported. As part of a study of the behaviour of the... 

---