Polyglucuronic Acid Research Articles

Polysaccharide conformation: Effect of side-group geometry on four diequatorially (1→4)-linked polysaccharides

A systematic approach to the stereochemical aspect of the conformational analysis of the polysaccharides cellulose, polyglucuronic acid, mannan, and polymannuronic acid has been undertaken. A more-exact treatment was given of the main side-groups, and differences from the previously used approximate method were found. A comparison of the flexibility of the four polysaccharides indicates that the polyuronic acids are more flexible than the corresponding glycans and that the mannopyranoses are more flexible than the glucopyranoses. The freedom of rotation of the main side-groups in the conformation of lowest overall potential energy was investigated and found to be restricted, but not sufficiently to cause localization.

Acid hydrolysis of polyglucuronic acid

Acid hydrolysis of polyglucuronic acid

The kinetics of decarboxylation of uronic acids, polysaccharides, and oxycelluloses

Measurements of the rate of carbon dioxide evolution from sulphuric acid solutions of galacturonic acid have revealed that it follows first-order kinetics, but some carbon dioxide is also formed in a side reaction at a constant rate. Glucuronolactone, polyglucuronic acid, and oxycelluloses decarboxylate in essentially homogeneous sulphuric acid solutions according to a two-step reaction scheme, both steps being kinetically first order. This main reaction is accompanied by side reactions in which carbon dioxide is evolved at an approximately constant rate. Mathematical expressions have been derived and applied to compute the constants of the rate equation for the decarboxylation of materials containing uronic acid.

Some Observations on the Evaporation of Water from Cellulose

The influence of water on the deterioration of cellulose is discussed, with special reference to deterioration at the brown line which forms when water rises in cotton by capillary action. The brown, fluorescent, water-soluble material results from the evaporation of water at the cellulose-water-air interface. Oxycellulose of the mildly reducing acidic type is formed. The oxidation appears to occur in part at the primary hydroxyl group, with the formation of polyglu curonic acid followed by chain scission and formation of soluble, low-molecular-weight frac tions. The deterioration proceeds even at moderate temperatures and in diffused light indoors. The brown-line effect undoubtedly contributes significantly to the degradation of cotton during its production, processing, and use.