Abstract
In this study, a thermal degradation pathway of Triphenyltin (TPT) is proposed. The thermal analyses of TPT were performed using elementary analysis (CHO), X-ray diffraction with differential thermal analysis (DTA), differential scanning calorimetry (DSC) and thermogravimetry (TG) .
It was revealed that TPT experienced internal structural changes at 88°C and melted at 123°C . In addition, two phenyl groups were extruded at 230°C resulting in the formation of mono-n-phenyltin hydroxide. Subsequently, degradation to inorganic tin occurred at 380°C following the extrusion of the residual phenyl group at 280 °C. It was determined that TPT was ultimately oxidized to tin oxide in air from the results of the DTA, TG and CHO analyses
From the results of the DSC analysis, the enthalpy of formation (ΔH°f) of SnO2 was calculated to be 363 KJ/mol, which is lower than the standard value of 580 KJ/mol. The reason for this lower calculated value was thought to be due to the final products being a mixture of SnO and SnO2 as evidenced from the experimental results of X-ray diffraction.
TPT is composed of a tetra-hedral structure with four groups sharing the sp3 hybrid orbital of the tin atom and it has one hydroxyl group and three phenyl groups, so that there is a positional molecular distortion. In addition, the TPT molecule has a localized polarity due to the electro-negativity of the hydroxyl radical.
In conclusion, it was suggested that the extrusions of the phenyl groups of TPT occur stepwise, because of the difference in the degree of bonding between the phenyl groups and the tin atom.
