Polysaccharides esters

Della Valle, F. and Romeo, A. New Polysaccharide Esters and Their Salts. Italy FIDIA SpA, 1987. 

Roussel [3] prepared chiral polysaccharide esters by grafting a-phenylpro-pionic acid, (R)-, (IV), and (S)-ibuprofen, or (R)- and (S)-naproxen onto cellulose. These agents were then used for isolating optically active acids. 

The thickness of the membranes could be controlled in a range of 20 to 500 nm. Optical interference colors of the ultrathin membrane served as a guide for estimating thickness actual measurements were made by interferometric or gravimetric methods. Ultrathin films could be cast on a water surface from many other commercial polymers for preparation of composite membranes. However, only those formed from cellulosic or related polysaccharide esters exhibited adequate flux for use in reverse osmosis. 

Ralph, J., Grabber, J. H., and Hatfield, R. D. (1995) Lignin-ferulate crosslinks in grasses Active incorporation of ferulate polysaccharide esters into ryegrass lignins. Carbohydr. Res. 275(1), 167-178. 

Reaction of dextran with acetylsalicyloyl chloride gives the polysaccharide ester in which, presumably, the 2- and 4-hydroxyl groups of the D-glucose residues are esterified. p-Nitrobenzoic esters of polysaccharides may be prepared by treating the carbohydrates with p-nitrobenzoyl chlo-ride and 0-(p-aminobenzoyl)cellulose, produced by the reduction of 0-( p-nitrobenzoyl )cellulose, is used as a matrix for the covalent attachment of macromolecules. 

Of the attempted replacements of various ester groups of polysaccharide esters by halide, the displacement of the p-tolylsulfonyloxy group has been the most successful, although nitric esters undergo the reaction to some extent. The reactions reported have been performed on polysaccharides selectively sulfonylated at 0-6, namely, 2,3-di-O-acetyl-6-O-p-tolylsulfonylcellulose, 6-O-p-tolylsulfonylamylose, 6-O-p-tolylsulfonylstarch, 6-O-p-tolylsulfonylcellulose, and 2,3-di-O-benzyl-6-0-p-tolylsulfonylamylose, to give the 6-deoxy-6-iodo derivatives. 

R. Dicke, A straight way to regioselectively functionalized polysaccharide esters. Cellulose, 11 (2004) 255-263. 

Abstract New acylation techniques were developed for the fabrication of fatty estos of cellulose and starch. They exclude the use of organic solvents and are readily achieved. Emulsification of the fatty acid in water allowed die intimate contact between the tty recent and die polysaccharide. Fatty acid salts (soap) were used as both catalyst and emulsifying agent. Reaction conditions were optimized using an experimental design. Starch and cellulose octanoates were obtained having a DS of 0.52 and 0.23 with a recuperation yield of 70 and 85 %, respectively. Both polysaccharide esters showed a marked hydrophobic character. 

The acylation of cellulose with acid chlorides in DMA/LiCl is most suitable for the homogeneous synthesis of readily soluble partially functionalized long-chain aliphatic esters and substituted acetic acid esters (Table 16.3). In contrast to the anhydrides, the fatty acid chlorides are soluble in the reaction mixture and soluble polysaccharide esters may be formed with a very high efficiency. Even in the case of stearoyl chloride, 79 per cent of the reagent is consumed for the esterification of cellulose. 

Using ab initio LCAO-MO calculations on alkyl formates as a basis, the electronic structures and conformations of polysaccharide esters have been interpreted. Acetate units were calculated to be 30° to the eclipsed position due to non-bonded interactions. ... 

It is possible to react almost any acid with a polysaccharide to produce an ester, and a great variety of polysaccharide esters have been produced. Polysaccharide esters of aliphatic acids are readily prepared by reacting the free acid with the polysaccharide in the presence of an impelling agent consisting of a mixture of chloroacetic anhydride, chloroacetic acid, and magnesium perchlorate Mixed esters, especially the acetate-propio-... 

Ethers can be formed with the alcohol groups of polysaccharides by reacting an alkaline solution or suspension of the polysaccharide with alkyl halides or epoxides [8]. The ethers produce polysaccharide derivatives that are usually soluble in water. This is in contrast to polysaccharide esters, which are usually insoluble in water and soluble in organic solvents. 

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