Thermal behavior of the β-blocker propranolol

The thermal behavior of the beta-blocker anti-hypertensive drug propranolol was investigated using thermoanalytical techniques TG-DTA, DSC and the evolved gas analysis by TG-FTIR, providing information regarding thermal stability, decomposition steps, melting point and heat of fusion of the compound. The results pointed for the decomposition in a single mass loss step, after melting. DSC data revealed that cold crystallization occurred in heat-cool-heat cycles, around 165 A degrees C. TG-FTIR presented 1-naphthol, isopropylamine and HCl as principal decomposition products. A tentative mechanism for the thermal behavior of propranolol is presented.