A study was made of the alcoholysis of cotton linters using methanol, n-butanol, n-hexanol, and n -octanol acidified with hydrogen chloride. All traces of water could not be removed from this system, and further water was formed during the degradations by a reaction between the alcohol and the hydrogen chloride. The linters were degraded in all of the alcohols studied. The amount of linters solubilized during the degradations tended to increase as the molecular weight of the alcohol used increased. It appeared that, in the study made, the cellulose was being degraded by hydrolysis caused by the traces of water present. The acidified alcohols combined with the reducing groups formed to give a degraded cellulose with a low reducing value. The residual reducing power was lowest when methanol was used.I'1 MEASURE of the availability of portions of cellulose to other molecules is defined as the accessibility of cellulose. Previous workers have shown evidence that the accessibility of cellulose in heterogeneous reaction is partly a function of the size of the molecules penetrating the cellulose.
Molecular-Size Effects in HeterogeneousReactions Davis, Barry, Peterson, and King [5] found that methyl, ethyl, and propylamine would swell cellulose directly. Only after preswelling with either liquid ammonia or ethylamine could straight-chain amines as large as heptylamine swell cellulose.Assaf, Haas, and Purves [1] studied the variation of the accessible portion of cellulose with the molecular weight of the solvent used to carry a reacting molecule into the cellulose. Thallous ethylate, the reacting molecule, formed a thallium alcoholate compound with the accessible cellulose. The alcoholate was then decomposed with methyl iodide replacing the thallium atom with a methoxyl group, and the methoxyl content of the cellulose gave a measure of the accessibility of the cellulose to the solvent used. Complete methylation (45.59% ) was considered to represent complete accessibility. The results were plotted as the percentage of methoxyl introduced vs. the molecular volume of the solvent (molecular weight divided by density). An alkali-swollen cotton sample was about 7% accessible to ethyl ether and only about 2% accessible to amyl ether. The same sample was about 5 % accessible to ethanol and only about 1 /o accessible to n-heptanol. The curves for ethers and alcohols extrapolated to the same value of methoxyl content at zero molecular volume.Walseth [19] found that enzyme-catalyzed hydrolysis was characterized by a smaller drop in the average D.P. of the residue compared to an acidcatalyzed hydrolysis of the same cellulose. Walseth believed that enzyme hydrolysis attacked only a small portion of the noncrystalline cellulose but broke the portion attacked into soluble fragments. He contrasted this behavior to that in acid-catalyzed hydrolysis in which the hydrolysis proceeded throughout the entire noncrystalline region, producing insoluble low molecular-weight fragments. Blum and Stahl [ 3 ] , using a different enzyme, also found t...
