Carbanilation of cellulose in the paraformaldehyde–dimethyl sulfoxide solvent system

Methylol cellulos carbanilate (methylol cellulose phenylcarbamate) was prepared under homogeneous conditions with phenylisocyanate following the dissolution of cellulose into the paraformaldehyde–dimethyl sulfoxide system. Previously reported procedures were utilized to control the oligo‐oxymethylene side chain length of the dissolved cellulose. Methylol cellulose carbanilates with different side chain lengths were characterized by infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The homogeneous carbanilation reaction was found to be completed with a degree of substitution of around 2.4 within 3 h at room temperature, which is substantially faster than heterogeneous carbanilation. Methylol cellulose carbanilates were found to have lower heats of decomposition (23.5–32.2 kcal/mol, depending upon the side chain length) and lower heats of decomposition temperatures (236°C) under air compared with conventional cellulose carbanilate. This suggests that the decomposition mechanism of the methylol cellulose carbanilate is through decomposition of the oligo‐oxymethylene side chains, while cellulose carbanilate decomposes by rupture of the cellulose carbamate linkage.