Polysaccharide homogeneous solution reactions

Homogeneous Solution Reactions of Cellulose, Chitin, and Other Polysaccharides... 

McCormick, C.L. and D.K. Lichatowich, "Homogeneous Solution Reactions of Cellulose, Chitin, and Other Polysaccharides to Produce Controlled Activity Pesticide Systems," submitted... 

McCormick, C.L. and Lichatowhich, D.K. (1979) Homogeneous solution reactions of cellulose, chitin and other polysaccharides to produce controlled... 

For the total hydrolysis of polysaccharides, trifluoroacetic acid (TFA) has important advantages over sulfuric acid. The reaction time is short and there is no need for conventional neutralization, as TFA is volatile and can be removed by evaporation. Several methods have been developed, depending on the substance to be hydrolyzed. Soluble saccharides (e.g., polyoses) can be hydrolyzed with diluted TFA, while cellulose, pulp, and wood need treatments with concentrated TFA in homogeneous solution. The presence of lignin impedes the hydrolysis of polysaccharides thus, especially for wood samples, an intensive treatment with TFA is necessary, and correction values have to be considered. Several application examples show that the hydrolysis with TFA enables a rapid quantitative determination of the composition of polysaccharides, pulps, and woods. 

Chitinase from Bacillus sp. was added to a solution of Xyl (l— 4)GlcNAc oxazoline 13 dissolved into a phosphate buffer. The consumption rate of 13 was accelerated by the enzyme addition and chitin-xylan hybrid polysaccharide 14 was produced. During the polymerization, the reaction proceeded homogenously throughout the reaction. The yield was 76% and its average molecular weight value of 14 was M = 1500 with MJMa = 1.76, determined by GPC. Furthermore, MALDI-TOF mass spectrum of 14 indicated the peaks at every m/z 335, which corresponds to the molecular mass of the repeating disaccharide unit. 

DMSO/TBAF is highly efficient as a reaction medium for the homogeneous esterification of cellulose by transesterification and after the in situ activation (see below) of complex carboxylic acids. The acylation using acid chlorides and anhydrides is limited because the solution contains a certain amount of water caused by the use of the commercially available TBAF trihydrate and the residual moisture in the air-dried polysaccharides. Nevertheless, this system has shown a remarkable capacity for the esterification of lignocellulosic mataials, for example, sisal fibres, which contain about 14 per cent hemicellulose [28]. The DS values of cellulose acetate prepared from these fibres with acetic anhydride in mixtures of DMSO/TBAF were found to decrease with increasing TBAF concentration from 6 to 11 per cent (Table 16.4), due to the increased rate of hydrolysis both of the anhydride and the ester moieties. 

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