Thermal studies on cellobiose and cellobiose halobenzoates

Abstract

Cellobiose 2-chlorobenzoate, 2-bromobenzoate and 2-iodobenzoate samples with different degrees of substitution (DS) were prepared. The DS in each sample was determined from the respective halogen content. The samples were subjected to DTA, TG and DTG studies in air from ambient temperature to 800°C. The decomposition temperatures for cellobiose halobenzoate samples are found to decrease with increasing DS and size of the halogen atom. Various kinetic parameters for the different stages of the thermal degradation of the treated cellobiose samples were calculated from the TG thermograms using Broido's method. The energies of activation for the decomposition of cellobiose and its halobenzoate samples were found to be in the range 120–194 kJ mol −1. Further, with increasing DS and the size of the halogen atom. the activation energies were found to decrease. The IR spectra of the partially charred residues of cellobiose 2-chlorobenzoate indicated elimination of the acid and formation of compounds containing carbonyl groups. A mechanism for thermal degradation of cellobiose halobenzoates has been proposed.