Pressure and temperature dependent kinetics and the reaction mechanism of Criegee intermediates with vinyl alcohol: a theoretical study.

Criegee intermediates (CIs), the key intermediates in the ozonolysis of olefins in atmosphere, have received much attention due to their high activity. The reaction mechanism of the most simple Criegee intermediate CHOO with vinyl alcohol (VA) was investigated by using the HL//M06-2X/def2TZVP method. The temperature and pressure dependent rate constant and product branching ratio were calculated using the master equation method. For CHOO + -VA, 1,4-insertion is the main reaction channel while for the CHOO + -VA, cycloaddition and 1,2-insertion into the O-H bond are more favorable than the 1,4-insertion reaction. The 1,4-insertion or cycloaddition intermediates are stabilized collisionally at 300 K and 760 torr, and the dissociation products involving OH are formed at higher temperature and lower pressure. The rate constants of the CHOO reaction with -VA and -VA both show negative temperature effects, and they are 2.95 × 10 and 2.07 × 10 cm molecule s at 300 K, respectively, and the former is agreement with the prediction in the literature.