Computational Study of Chemical Reactivity Using Information-Theoretic Quantities from Density Functional Reactivity Theory for Electrophilic Aromatic Substitution Reactions

Abstract

The electrophilic aromatic substitution for nitration, halogenation, sulfonation, and acylation is a vastly important category of chemical transformation. Its reactivity and regioselectivity is predominantly determined by nucleophilicity of carbon atoms on the aromatic ring, which in return is immensely influenced by the group that is attached to the aromatic ring a priori. In this work, taking advantage of recent developments in quantifying nucleophilicity (electrophilicity) with descriptors from the information-theoretic approach in density functional reactivity theory, we examine the reactivity properties of this reaction system from three perspectives. These include scaling patterns of information-theoretic quantities such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy and information gain at both molecular and atomic levels, quantitative predictions of the barrier height with both Hirshfeld charge and information gain, and energetic decomposition analyses of the barrier height for the reactions. To that end, we focused in this work on the identity reaction of the monosubstituted-benzene molecule reacting with hydrogen fluoride using boron trifluoride as the catalyst in the gas phase. We also considered 19 substituting groups, 9 of which are ortho/para directing and the other 9 meta directing, besides the case of R = -H. Similar scaling patterns for these information-theoretic quantities found for stable species elsewhere were disclosed for these reactions systems. We also unveiled novel scaling patterns for information gain at the atomic level. The barrier height of the reactions can reliably be predicted by using both the Hirshfeld charge and information gain at the regioselective carbon atom. The energy decomposition analysis ensued yields an unambiguous picture about the origin of the barrier height, where we showed that it is the electrostatic interaction that plays the dominant role, while the roles played by exchange-correlation and steric effects are minor but indispensable. Results obtained in this work should shed new light for better understanding of the factors governing the reactivity for this class of reactions and assisting ongoing efforts for the design of new and more efficient catalysts for such kind of transformations.

Information‐theoretic approach in density functional theory and its recent applications to chemical problems

“…The validity and effectiveness of our proposal to employ information gain as well as the Hirshfeld charge to quantify electrophilic and nucleophilic regioselectivity have been demonstrated by a number of applications . Schemes and , respectively, shows the 21 electrophilic systems and 22 nucleophilic molecules that we investigated earlier as illustrative examples with known experimental electrophilicity and nucleophilicity scales and compared with our theoretical results from information gain and Hirshfeld charge.…”

Evaluation of the molecular inclusion process of β-hexachlorocyclohexane in cyclodextrins

“…65 This method is based on deformation density partition and provides results that are qualitatively consistent with general chemical concepts such as atomic and group electrophilicity. 66,67 Although calculating Hirshfeld charges requires integration in real space, due to the smooth integrand, sophisticated DFT grid-based integration schemes can be directly used; thus, Hirshfeld population is a highly efficient method and has a wide application eld. 68 For the analysis of the local charge transfer tendencies, the dual descriptor 69 (Df(r)) was calculated.…”

Information theoretic approach provides a reliable description for kinetic component of correlation energy density functional

“…As a branch of applied mathematics and computer science, information theory deals with the quantification of information for a quantum system. Immense efforts have been made to comprehend physical and chemical processes from the perspective of information theory . Considering atomic and molecular species as information systems with the electron density as the basic variable, there are various quantities in information theory to appreciate and predict their properties.…”