DT A and IR Studies on Cellobiose Treated with Phosphorus Oxychloride­ N, N-Dimethylformamide Mixture

Phosphorylation of cellobiose, a basic unit of cellulose, was carried out in a mixture of N,N-dimethylformamide and phosphorus oxychloride at different temperatures in the range 4O-80°Cand the products of the reaction were subjected to DT A studies. The thermograrns show an endothermic activity in the region 170-230°C in air. The single endotherm at 200°C in air has been found to be shifted to 180°C in nitrogen atmosphere. This lowering of the peak temperature is attributed to the effect . of synergism of nitrogen gas in combination with phosphorus present in the phosphorylated products of cellobiose. The IR spectra of the residues, obtained after partial or complete charring of the phosphorylated products in the vicinity of 180°C, together with elemental analyses provide evidence of dehydration attributable to 0- Hand C - H stretching in the region 3400-288o.cm-I. The study of a thermally induced chemical reaction for a cellulose substrate is difficult because of (i) the existence of a large portion of the substrate as crystalline material which is not easily accessible to the reagent being studied, and (ii) secondary reactions which may occur with primary degradation products or with intermediates resulting from disintegration of the gross polymeric structure. It was, therefore, advantageous to select a model system such as cellobiose, a basic unit of cellulose, for understanding the reaction process. In continuation of our earlier work 1, cellobiose was phosphorylated and chlorinated with a mixture of phosphorus oxychloride (POCI3) and N,N-dimethylformamide(DMF) at different tempera­ tures in the range 40-80°C for I hr. The samples obtained were subjected to DTA studies for evaluating the effectiveness of organo-phosphorus compounds as flame retardants. IR spectra of the partially I completely charred samples, near DTA peak temperatures, were taken to study the char patterns of these samples. Materials and Methods