Mechanism Study On Pd-Catalyzed Coupling Reaction Of3-methoxyacetanilide With N-butyl Acrylate

Acetyl aniline is an important chemical raw material, used for thesynthesis of various acetyl aniline compounds, and widely used invarious areas of chemical industry, medicine, daily necessities, etc.However, it is not an easy thing to produce some desired products bythe C C coupling of acetyl aniline. After decades of research, it isfound that transition metal (Pd, Cu, Ni, Rh, etc.) can activate the C Hbonds in aromatic ring to obtain an intermediate containing transitionmetal, this would help to occur electrophilic addition or nucleophilicaddition reactions with other substances, achieving C C couplingproducts. Recently, researchers have begun to focus on thedevelopment of new catalysts which are both economic and green.A green transition metal palladium complex catalyst with goodcatalytic performance is chosen in this paper. The purpose of thiswork is to clarify the detailed mechanism of C C coupling reaction of3-methoxyacetanilide with n-butyl acrylate at the B3LYP level ofdensity functional theory, the main contents are as follows:In the first part, we introduce the background of the Pd-catalyzedcoupling reaction, the background and research significance of the C H activation reaction.In the second part, we give a brief introduction of the theoryfoundation involved in this paper, such as quantum chemistryoverview, ab initio method, density functional theory, transition statetheory and solvent effect.In the third part, we study the detailed mechanism of the reaction,it is showed that the catalyst cycle is divided into three steps: C Hactivation, alkene insertion, and β-H elimination. In C H activation,there are two possible pathways to obtain8, that is the four-memberring pathway through transition state TS(2/3) and the six-member ringpathway through transition state TS(2/6). The results indicate that thesix-member ring pathway is more favorable than four-member ringpathway both thermodynamically and kinetically, and it is partlyattributed to the fact that the ring strain in six-member-ring structureis smaller than that in four-member-ring structure. In alkene insertionand β-H elimination, the comparison of the absence and presence ofHF mechanisms are discussed and the calculation results reveal thepresence of HF mechanism is more favorable, getting theortho-positioned coupling product through the coupling of theterminal carbon of n-butyl acrylate with the ortho-carbon of3-methoxyacetanilide. This is consistent with the experiment findings.In addition, the role of benzoquinone is two-fold, one is to assist HF inparticipating the alkene insertion and β-H elimination processes, theother is to play the role of oxidation. For comparison, the effect ofsolvent have also been studied, it can be concluded that water assolvent does not change the general trends of the reaction potentialenergy surfaces.