Studies in the Reaction of Formaldehyde with Unmodified, Modified, and Dyed Celluloses

Abstract

The equilibrium reaction between formaldehyde and cotton cellulose has been studied at 30° ± 1° C using the technique described in Part I [4]. The reaction reaches equi librium within the reaction period (96 hr). The equilibrium reaction depends on the concentration of formaldehyde and calcium chloride and seems to be independent of the concentration of hydrogen chloride. The combined formaldehyde ( CF) value for cotton cellulose at saturation has been calculated, and corresponds to ca. 20% accessibility. It is found that the saturation CF value is the same, within experimental limits, as the saturation value of sorbed formaldehyde calculated from published data. It is concluded that the reaction is limited to the accessible fraction of the fiher substance and proceeds at the reactive secondary hydroxyl groups, with the initial formation of the methylol ether of cellulose, which then condenses with the less reactive secondary hydroxyl groups. water molecules being eliminated to form methylene ether. It appears that all the methylene ether linkages are only between the 2 and 3 carbon atoms of anhydroglucose units and are monomeric under the present reaction conditions. The results of acid hydrolysis of cellulose by hydrogen chloride are included in support of the explanation put forward for some of the observations.