This is the first comprehensive study on the kinetic modeling of adiabatic decomposition of di-tert-butyl peroxide (DTBP) and its solvent mixtures. The adiabatic thermal decomposition of DTBP and its solvent mixtures was examined using an accelerating rate calorimeter under varying thermal inertia. The decomposition products were characterized using gas chromatography−total inorganic carbon analysis and gas chromatography−mass spectroscopy to elucidate the mechanistic pathways for decomposition under adiabatic conditions. Reaction models (overall stoichiometric equations) for the decomposition of neat DTBP and its mixture in various solvents have been proposed for the first time. A comprehensive kinetic analysis based on simultaneous treatment of mass and energy balances has been done using a software called BatchCAD. The activation energies for the decomposition of DTBP and its mixtures in various solvents were quite consistent. This comprehensive study has answered to many ambiguities and questions on the mechanism of DTBP decomposition and its kinetics.

The purpose of this study is to obtain a better understanding of Michael addition reaction (MAR) which may induce runaway polymerization of acrylic acid. The heat of MAR was measured using a C80 Calvet-type heat flux calorimeter, and products of MAR were revealed by gel permeation chromatography. The reaction rate constant of MAR was obtained from kinetic analysis. In high-sensitivity calorimetry, a low rate of heat release due to MAR was detected. The heat of MAR was 109 J g -1 and conversion of acrylic acid to Michael adducts was 82 mass%. The products of MAR were acrylic acid dimers, trimers and tetramers. The reaction order was 2.5th, and the overall reaction rate constant was k = 3.52 9 10 3 9 exp (-1.18 9 10 5 /T [K]) L 1.5 mol -1.5 s -1 . The activation energy of MAR was 98.0 kJ mol -1 , which was similar in value to that of dimerization in previous studies. This indicated that dimer formation is the dominant reaction in MAR.

No abstract

Dimethyl sulfoxide (DMSO) has been extensively used as a solvent because of its high-performance characteristics. However, there have been accidents when DMSO has been used in some chemical processes (Lam et al. in J Therm Anal Calorim 85:25-30, 2006; http:// riscad.db.aist.go.jp/PHP_EN/index.php). Although the decomposition mechanism of DMSO under acidic conditions is known (Santosusso et al. in Tetrahedron Lett 48:4255-4258, 1974), the number of studies about thermal behavior of DMSO under acidic condition is not large. The purpose of this investigation is to understand the decomposition thermal behavior of DMSO under acidic conditions. Thermal analysis using an accelerating rate calorimeter (ARC) was carried out with acids chosen for their acid dissociation degree constant (pKa), which is a typical parameter of acid strength. ARC data show that the self-heat rate increased and the exothermic onset temperature decreased with decreasing pKa. Additionally, the exothermic onset temperature and pKa had good linear correlation. To verify the initial exothermic reaction, differential scanning calorimetry (DSC) analysis was carried out. DSC results showed that the exothermic onset temperature was due to decomposition of DMSO. The activation energy of the decomposition reaction was calculated from the ARC results (self-heat rate). Our data indicate that the activation energy of the decomposition reaction decreased with decreasing pKa. Therefore, thermal hazards of DMSO increase with the decrease in pKa, with good linear correlation.

No abstract