Comparative Computational Study of Hydrogen Abstraction Reactions of CY₃H + XO⁻ (X, Y = F, Cl, and Br)

Abstract

The effects of halogen substituents on the reactivity are characterized by the hybrid B3LYP and BHandHLYP functionals of density functional theory using the aug-cc-pVDZ basis set. The species XO − and CY 3 H, where X, Y = F, Cl, and Br, have been chosen as model reactants in this work. Also, the mechanism of the hydrogen abstraction (HAT) reaction has been used to study the chemical reactivity of these anionic reactions. Our theoretical findings suggest that the relative reactivity of the CY 3 H + XO − reactions increases as Y goes from F to Br and decreases as X goes from F to Br. Moreover, among all reactions investigated in this study, the special role of the Y has very dominant effect on activation of the C-H bond in CY 3 H when XO − attacks the CY 3 H. Again, through the transition state theory the rate constants at 298-1000 K are also evaluated for the HAT reactions, indicating the lower the temperature the faster is the chemical reaction. FIGURE 1 Optimized geometries for the H-abstraction reactions of CF 3 H + XO − (X = F, Cl, and Br), with bond distances in A and angles in degrees. (B3LYP/aug-cc-pVDZ are shown in black and BHandHLYP/aug-cc-pVDZ in red for the purpose of comparison; The symbol "-" denotes nonexistent.)Heteroatom Chemistry

Benchmark ab initio characterization of the complex potential energy surfaces of the HOO− + CH3Y [Y = F, Cl, Br, I] reactions

“…participating in S N 2 reactions. 8,9,[64][65][66][67][68][69][70][71] In the case of these a-nucleophiles, one or more lone-pair electrons are located on the atom adjacent to the nucleophilic center, inducing enhanced reactivity compared to that expected from the Brønsted-type correlation. 72 This phenomenon is known as the a-effect.…”

Theoretical study of the possible mechanisms for the synthesis of dialkyl thiourea from dithiocarbamate

“…However, according to the previous studies, any approved full mechanistic details for the synthesis of thiourea derivatives from dithiocarbamate and amines has not been reported. While, because of the highly importance of these synthetic methods, finding the clear details related to their mechanism has high scientific value . Therefore, in the continuation of our previous studies related to the mechanistic studies of chemical phenomena, we wish to report a full theoretical study for all possible mechanisms of this reaction.…”