HEAT-CAPACITY AND THERMAL-DECOMPOSITION OF 1,6-BIS(DIPHENYLPHOSPHINO)HEXANE

A thermochemical study of 1,6-bis(diphenylphosphino)hexane(BDPH) has b een performed using adiabatic calorimetry, differential scanning calor imetry (DSC) and thermogravimetric analysis (TG). The low-temperature heat capacity of BDPH was determined precisely with a small-sample aut omated adiabatic calorimeter in the temperature range from 80 to 350 K . No indication of any phase transition or thermal anomaly was observe d in this temperature range. The high-temperature heat capacity of BDP H was measured with a differential scanning calorimeter in the tempera ture range from 310 to 730 K. From the DSC curve obtained for this com pound, a solid-liquid transition was found at 399.4 K and the enthalpy and entropy of transition were evaluated at 66.8 kJ mol(-1) and 167.2 J K-1 mol(-1), respectively. In addition, an endothermal change was o bserved between 690 and 710 K. The heat of reaction corresponding to t he change was determined to be 81.6 kJ mol(-1). The TG analysis of BDP H was carried out in the temperature range from 300 to 800 K, from whi ch it was found that this compound starts to decompose at 690 K and de composes almost completely at 710 K in a single step. (C) 1998 Elsevie r Science B.V.