18 Mitteilung uber textilchemische Untersuchungen [I] Summary.(1) A method is described which allows the elucidation of the structure of cotton cross-linked with formaldehyde. I t consists of a pcrmethylation process (5 methylations with dimethyl sulphate and sodium hydroxide in dimethyl sulphoxide, followed by two exchange methylations of the formalised sodium cellulosate with methyl iodide in z-butanol), hydrolysis of the product in 72% sulphuric acid to the respective methylated glucoses, reduction of the mixture of glucoses to the respective sorbitols, blocking of all free hydroxyl groups by acetylation, trifluoroacetylation or formation of trimethylsilyl ethers, and vapour phase chromatographic separation of the derivatives.(2) It is shown that after permethylation practically no free hydroxyl groups can be detectcd and that scarcely any replacement of methylene or oxyniethylene cross-links by methyl groups has taken place. With the exception of losses in filtration of the permethylation product, all stages of the process proceed on an almost quantitative basis.

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Cotton was cross-linked with formaldehyde by various methods (Form D, W, and V processes). The cellulose formals containing 1-4% formaldehyde were permethylated 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.

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