Investigations on the Chemical Constitution of Cotton Cross-Linked With Formaldehyde

Abstract

Cotton was cross-linked with formaldehyde by various methods (Form D, W, and V processes). The cellulose formals containing 1-4% formaldehyde were permeth ylated by a series of dimethylsulfate/dimethylsulfoxide treatments followed by exchange methylations of sodium cellulosate with methyl iodide in n-butanol. The permethylated cellulose formals were hydrolyzed in sulfuric acid and the methyl glucoses thus formed were reduced to the respective sorbitols. The mixture of these sorbitols, after suitable blocking of the free hydroxyl groups, was separated and quantitatively analyzed by gas-liquid phase chromatography. The results indicate a decreasing reactivity of the hydroxyl groups in the sequence C(6)>C(2)>C(3), the occurrence of 2,3-methylene linkages, and an average length of the oxymethylene cross links of between 1,3 and 2,0. The constitution of these cellulose formals is influenced by the type of formaldehyde application. Discrepancies between our results and those of other investigators are explained by their incomplete methylation, substitution of methylene cross links by methyl groups in permethylations, and incomplete separation of the degradation products.