Competitive and Cooperative Torquoselectivity in the thermal ring opening of cyclobutene: A density functional insight

Akilandeswari, Lakshminarayanan; Prathipa, Chandrasekaran

doi:10.1007/s12039-015-0936-5

Cited by 11 publications

(2 citation statements)

References 34 publications

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“…Torquoselectivity is defined to be the preference for either the transition state (TS) inward conrotatory reaction pathway (TSIC) or the transition state outward conrotatory (TSOC) reaction pathway . Rondan and Houk first postulated the mechanism of torquoselectivity using orbital symmetry to understand electrocyclic reactions but only for reactions where a high degree of symmetry was present . Realistic conrotatory ring‐opening reactions are not highly symmetrical and, therefore, only reaction measures that possess directional character can correctly predict the TSIC or TSOC pathways consequently, that is, only vector‐based and not scalar measures can be used.…”

Section: Introductionmentioning

confidence: 99%

A vector‐based representation of the chemical bond for predicting competitive and noncompetitive torquoselectivity of thermal ring‐opening reactions

Azizi

Momen

Morales-Bayuelo

et al. 2018

Int J of Quantum Chemistry

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We present a new vector-based representation of the chemical bond referred to as the bondpath frame-work set B = {p, q, r}, where p, q, and r represent three paths with corresponding eigenvector-following paths with lengths H*, H, and the bond-path length from the quantum theory of atoms in molecules (QTAIM). We find that longer path lengths H of the ring-opening bonds predict the preference for the transition state inward (TSIC) or transition state outward (TSOC) of thermal ring opening reactions in agreement with experiment for all five reactions R1-R5. Competitiveness and noncompetitiveness have traditionally been considered using activation energies within transition state theory that is known to fail for thermal ring-opening reactions. Consequently, we find that the activation energy for R3 does not satisfactorily determine competitiveness or provide consistent agreement with experimental yields. We choose a selection of five competitive and noncompetitive reactions; methyl-cyclobutene (R1), ethyl-methylcyclobutene (R2), iso-propyl-methyl-cyclobutene (R3), ter-butyl-methyl-cyclobutene (R4), and phenyl-methyl-cyclobutene (R5). Therefore, in this investigation we provide a new criterion, within the QTAIM framework, to determine whether the reactions R1-R5 are competitive or noncompetitive. We that find R2, R3, and R5 are competitive and R1 and R4 are noncompetitive reactions in contrast to the results from the activation energies, calling into question the reliability of activation energies.

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Section: Introductionmentioning

confidence: 99%

A vector‐based representation of the chemical bond for predicting competitive and noncompetitive torquoselectivity of thermal ring‐opening reactions

Azizi

Momen

Morales-Bayuelo

et al. 2018

Int J of Quantum Chemistry

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“…4C. According to ΔTS < 1.0 kcal/mol shown in this table results that Reaction 1 is competitive while the other three reactions, Reactions(2)(3)(4), are non-competitive. As mentioned earlier, some plots such as, metallicity ξ(r b ), stress tensor polarizability P σ , ellipticity ε, total local energy density H(r b ), and stress tensor λ 3σ have been considered in which contain chemical topological properties of reactions.…”

mentioning

confidence: 84%

Discerning torquoselectivity in a series of cyclobutene ring‐opening reactions using quantum theory of atoms in molecules and stress tensor

Momen

Azizi

Morales-Bayuelo

et al. 2021

Int J of Quantum Chemistry

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This study aims to investigate the phenomenon of torquoselectivity through four thermal cyclobutenes ring-opening reactions including 1-chlorocyclobut-1-ene (Reaction 1), 3-chloro-4-methylcyclobut-1-ene (Reaction 2), 3-methoxy-4-methylcyclobut-1-ene (Reaction 3), and finally 3-chloro-4-methoxycyclobut-1-ene (Reaction 4). Despite the limitation of conventional methods in which just considers activation energies within transition state theory, this research focuses on the nature of the chemical bond, electronic reorganization, and predicting either non-competitive or competitive reactions within quantum theory of atoms in molecules (QTAIM) and stress tensor frameworks. Various theoretical analyses for these reactions such as metallicity ξ(r b ), ellipticity ε, total local energy density H(r b ), stress tensor polarizability P σ , stress tensor eigenvalue λ 3σ , bond-path length, and path lengths H display differently for noncompetitive and competitive reactions as well as for the conrotatory preferences either it is the transition state outward conrotatory (TSOC) or transition state inward conrotatory (TSIC) directions by presenting degeneracy or non-degeneracy in their results.Results illustrate that the preference of TSOC or TSIC of these thermal ring-opening reactions could obtain from path lengths H of the ring-opening bonds, where the longer one apparently predicts the preference. In addition, examinations indicate that Reaction 1 is competitive and Reactions (2-4) are non-competitive reactions with TSOC, TSOC, and TSIC preference directions respectively. The concordant results of stress tensor and QTAIM scalar and vectors with experimental results provide a better understanding of all reactions mechanism.

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Determining the Factors Accounting for Reaction Selectivity: A Relative Energy Gradient – Interacting Quantum Atoms and Natural Bonding Orbitals Study

Cador,

Morell,

Tognetti

et al. 2024

ChemPhysChem

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Identifying the main physicochemical properties accounting for the course of a reaction is of utmost importance to rationalize chemical syntheses. To this aim, the relative energy gradient (REG) method is an appealing approach because it is an unbiased and automatic process to extract the most relevant pieces of energy information. Initially formulated within the interacting quantum atoms (IQA) framework for a single reaction, here we extend the REG method to natural bond orbitals (NBO) analysis and to the case of two competitive processes. This development enables the determination of the driving forces of any chemical selectivity. We illustrate the extended REG method on the case study of ring opening in cyclobutenes, which is an important instance of the so‐called torquoselectivity.

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Competitive and Cooperative Torquoselectivity in the thermal ring opening of cyclobutene: A density functional insight

Cited by 11 publications

References 34 publications

A vector‐based representation of the chemical bond for predicting competitive and noncompetitive torquoselectivity of thermal ring‐opening reactions

A vector‐based representation of the chemical bond for predicting competitive and noncompetitive torquoselectivity of thermal ring‐opening reactions

Discerning torquoselectivity in a series of cyclobutene ring‐opening reactions using quantum theory of atoms in molecules and stress tensor

Determining the Factors Accounting for Reaction Selectivity: A Relative Energy Gradient – Interacting Quantum Atoms and Natural Bonding Orbitals Study

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