RESUMEN
In this work, we have investigated the mechanism, thermochemistry and kinetics of the reaction of syn-cis-CH2îRzCRyCîO+O- (where Rz, Ry = H, CH3-) unsaturated Criegee intermediates (CIs) with CF3COOH using quantum chemical methods. The rate coefficients for the barrierless reactions were calculated using variable reaction coordinate variational transition state theory (VRC-VTST). For the syn-cis-CH2îRzCRyCîO+O- conformation in which conjugated CîC and CîO double bonds are aligned with each other, we propose a new pathway for the unidirectional addition of an OîC-OH molecule (CF3COOH) to the CîC double bond of syn-cis-CH2îRzCRyCîO+O-. The rate coefficient for the 1,4-CîC addition reaction at 298 K is â¼10-10 to 10-11 cm3 s-1, resulting in the formation of CF3C(O)OCH2CRzîRyCOOH trifluoroacetate alkyl allyl hydroperoxide (TFAAAH) as a new transitory adduct. It can act as a precursor for the formation of secondary organic aerosols (SOAs). This novel TFAAAH hydroperoxide was identified through a detailed quantum chemical study of the 1,4-addition mechanism and will provide new insights into the significance of the 1,4-addition reaction of unsaturated Cls with trace tropospheric gases on -CRzîCH2 vinyl carbon atoms.