Preparation of 6-O-alkylcelluloses

Cellulose derivatives specifically substituted at the primary hydroxyl groups, 6-O-alkylcelluloses, were prepared from 6-O-tritylcellulose (trityl = triphenylmethyl). In the preferred procedure, the 6-O-tritylcellulose was first completely allylated in dimethyl sulfoxide (Me₂SO), and subsequently detritylated with hydrogen chloride to yield 2,3-di-O-allylcellulose. This product was isomerized into 2,3-di-O-(1-propenyl)cellulose with potassium tert-butoxide in Me₂SO. The polymer thus prepared was then alkylated completely with methyl or ethyl iodide in Me₂SO containing a trace of water. The alkylated polymer was finally treated with 0.1 M HCl in aqueous 90% methanol at room temperature to remove the 1-propenyl groups. The products were shown by Fourier-transform infrared spectroscopy, ¹³C nuclear magnetic resonance spectroscopy, and gas-liquid chromatographic analysis to be uniformly substituted at the 6 position.