Theoretical study on reaction mechanism of thermal decomposition of dialkyl peroxides

Dialkyl peroxides are hazardous chemicals that can easily decompose, potentially causing fire or explosion. The thermal decomposition process of dialkyl peroxides were studied in this study. The initial decomposition steps of ten different dialkyl peroxides were investigated by using density functional theory. It is observed that there are similar structures in the transient state of decomposition reactions, indicating that the decomposition mechanisms are similar. A comprehensive decomposition mechanism was proposed, which could be reasonably employed to explain the transformation of dialkyl peroxides in the decomposition. Reduced density gradient (RDG), electron density (ρ), and the sign of the second Hessian eigenvalue (Sign(λ₂)) were used to visualize the weak interaction in peroxide molecules, respectively. The results showed that the weak interaction would affect the decomposition pathways of peroxides. Laplacian bond orders (LBO) in the structure of the intrinsic reaction coordinate points were calculated to reflect the variation of bond strength in two initial decomposition pathways. The results showed that the weak O–O bond smoothly breaks during the two essential pathways. This study could provide some guidance for understanding the incident-causing process of the thermal decomposition of dialkyl peroxides.