Preparation of Tri‐O‐alkylcellulose by the use of a nonaqueous cellulose solvent and their physical characteristics

Tri‐ O ‐methyl‐, ‐ethyl‐, ‐ n ‐propyl‐, ‐ n ‐butyl‐, ‐ n ‐pentyl‐, ‐iso‐amyl‐, ‐ n ‐hexyl‐, ‐ n ‐heptyl‐, ‐ n ‐octyl‐, ‐ n ‐decyl‐, and ‐3‐phenoxypropyl‐celluloses have been prepared with powdered sodium hydroxide and the corresponding alkyl iodides or bromides in one of nonaqueous cellulose solvents, SO 2 ‐diethylamine‐dimethylsulfoxide. These new tri‐ O ‐alkylcelluloses were characterized by infrared spectra, 13 C‐NMR spectra, and optical rotations. The first six tri‐ O ‐alkylcelluloses described above were obtained as white powders and most of them (tri‐ O ‐methyl‐, ‐ethyl‐, ‐ n ‐propyl‐, and ‐ n ‐pentyl‐celluloses) showed thermotropic liquid crystals due to smetic or short pitch cholesteric phases. On the other hand, the latter five derivatives were obtained as gummy solids even at room temperature, and easily showed lyotropic liquid crystals in their concentrated chloroform solutions due to choresteric phases. some of these tri‐ O ‐alkyl‐celluloses (tri‐ O ‐methyl‐, ‐ethyl‐, ‐ n ‐propyl‐, and ‐ n ‐butyl‐celluloses) were characterized by differential scanning calorimetric and X‐ray diffractometric analyses.