Thermal decomposition mechanism of tert-butyl peroxybenzoate: insights from calorimetry, GC/MS, and quantum chemical calculation

The thermal decomposition mechanism of tert-butyl peroxybenzoate (TBPB) was investigated by experiment and molecular simulation in consideration of the instability of O–O bond. A single exothermic peak during the decomposition of TBPB was found in the range of 348.17–475.26 K with 70.50–131.91 kJ mol −1 activation energy, releasing 1201.30 ± 124.18 J g −1 heat. The effect of temperature on the decomposition pathways of TBPB was studied by gas chromatography/mass spectrometry and Gaussian. The cleavage of the O–O bond represented the initial and most critical rate-determining step in the thermal decomposition of TBPB. This process required endothermic energy to overcome the energy barrier of 108.3 kJ mol −1 , yielding two core intermediates: C 6 H 5 COO· and (CH 3 ) 3 CO·. These radical species subsequently underwent a series of spontaneous radical chain reactions driven by thermal effects. The final products, (CH 3 ) 2 CO, was firstly detected at 377.15 K due to the decomposition of (CH 3 ) 3 CO·. At 384.15 K, C 6 H 5 COO· broke to form C 6 H 5 ·, which reacted with ·H/·CH 3 to generate C 6 H 6 and C 6 H 5 CH 3 . The other C 6 H 5 COO· reacted with ·H/·CH 3 to form C 6 H 5 COOH and C 6 H 5 COOCH 3 overcoming 33.3 and 73.2 kJ mol −1 energy barriers, which broke up above 398.15 K to produce large amounts of C 6 H 6 and CH 3 C 6 H 5 . The results provide a detailed depiction of the complete, continuous thermal decomposition network of TBPB from initiation to final products, particularly concerning secondary decomposition of intermediates. This lays the foundation for developing targeted strategies, such as radical inhibition at critical stages, to enhance the safety of TBPB storage and transportation.