Theoretical studies on kinetics, mechanism and thermochemistry of gas-phase reactions of CF3CHFCF2OCF3 with OH radicals and Cl atoms and fate of alkoxy radical at 298K

A theoretical study on gas-phase reactions of acrylic acid with chlorine atoms: mechanism, kinetics, and insights

Chlorine atoms initiated oxidation reactions are significant for the removal of typical volatile organic compounds (VOCs) in the atmosphere. The intrinsic mechanisms of CH₂=CHCOOH + Cl reaction have been carried out at the CCSD(T)/cc-pVTZ//M06-2X/6-311++G(d,p) level. There are hydrogen abstraction and C-addition pathways on potential energy surfaces. By analyses, the addition intermediates of IM1(ClCH₂CHCOOH) and IM2(CH₂CHClCOOH) are found to be dominant. The secondary reactions of IM1 and IM2 have been discussed in the presence of O₃, O₂, NO, and NO₂. And we have also investigated the degradation mechanisms of ClCH₂CHO₂COOH with NO, NO₂, and self-reaction. Moreover, the atmospheric kinetics has been calculated by the variable reaction coordinate transition-state theory (VRC-TST). As a result, the rate constants show negative temperature and positive pressure dependence. The atmospheric lifetime and global warming potentials of acrylic acid have been calculated. Overall, the current study elucidates a new mechanism for the atmospheric reaction of chlorine atoms with acrylic acid.

The reaction pathway analysis of phosphoric acid with the active radicals: a new insight of the fire-extinguishing mechanism of ABC dry powder

Dry powder fire-extinguishing agent is one of Halon substitutes due to its superior fire-extinguishing performance, non-toxicity, and environmental friendliness. As one of the most widely used dry powders, ABC dry powder has attracted wide attention. Understanding its reaction mechanism is important to the design of more efficient compound dry powder based on it. When ABC dry powder was applied to the flame, ammonium dihydrogen phosphate (the main fire-extinguishing component of ABC dry powder) would rapidly decompose into phosphoric acid (H₃PO₄) and ammonia. Therefore, in order to figure out the chemical reaction mechanism of ABC dry powder and active radicals, the main focus of this paper is on the H₃PO₄. Analysis of the electrostatic potential on van der Waals surface of H₃PO₄ was carried out. Besides, detailed theoretical investigation has been performed on the mechanism, kinetics, and thermochemistry of the reactions of H₃PO₄ with H, OH, and CH₃ radicals and further decomposition of H₃PO₄ using M06-2X/6-311G(d,p)//CCSD(T)/cc-pVTZ level of theory. Mayer bond order for all intrinsic reaction coordinate points was also calculated. Finally, it is theoretically proved that ABC dry powder extinguishes the fire mainly by chemical inhibition on H and OH radicals. Grapical Abstract .