Mechanisms Of Aromatic Amines Alkylation And [4+4] Cycloaddition Reaction Investigated By Density Functional Reactivity Theory

Density Functional Reactivity Theory is widely applied to computational chemistry, which excellently explains the mechanisms of chemical reactions and helps people better understand the experimental phenomena. The main content of this thesis is to investigate the mechanisms of aromatic amines alkylation reaction and [4+4] cycloaddition reaction using M06-2X method of Density Functional Theory(DFT) and the related functionals like Fukui functions and dual descriptor in the framework of Density Functional Reactivity Theory, which can analyze and discuss the configuration and reaction mechanism involved in the reaction processes. This thesis mainly contains two parts:1. The theoretical investigation on the mechanism of aromatic amines alkylation reaction. All the work in this part was calculated at the M06-2X/6-311++G(d,p) level of DFT. The monoalkylation of anilines can be readily realized by employing trichloroacetimidates as alkylating agents and a Br?nsted acid like(±)-camphorsulfonic acid(CSA) as catalyst. Four possible reaction pathways(I, II, III and IV) resulting in the same product have been illustrated. The calculated results reveal that pathway I is more favorable, in which CSA is more likely to initiate the reaction by transferring a proton to aniline and then to trichloroacetimidate. The protonated trichloroacetimidate is converted to carbocation by stripping off trichloroacetamide. Finally, the carbocation interacts with aniline and gives a proton back to aniline, leading to the product. Meanwhile, the mechanism of side reaction and the substituent effect were also explored to explain the experimental observations.2. The theoretical investigation on the mechanism of [4+4] cycloaddition reaction. All the work in this part was calculated at the M06-2X/6-31+G(d,p) level of DFT. Firstly, the reactants alkynones and α-cyano-α, β-unsaturated ketones go through a series of reactions to produce the final product of eight-membered cyclic ethers under the effect of moderator triethylene-diamine(DABCO) via four possible pathways(a, b, c and d). The calculated results showed that the pathway(a) is the most favorable, and revealed the function of moderator DABCO in the reaction process. In addition, we analyzed and discussed the electron transfer participated in the bonding atomic orbital of the reactants with Natural Orbital Fukui Function(NOFF), which not only reveals the reaction mechanism to deepen the understanding about this reaction, but also provides theoretical insights into the design of subsequent reactions.