An ab initio study of electrophilic aromatic substitution

Wang, Daniel Zerong; Streitwieser, Andrew

doi:10.1007/s002140050475

Cited by 37 publications

(12 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…the protonated regioisomer with the lowest free energy) corresponds to the most probable site for EAS, as was demonstrated by Wang and Streitwieser for several polycyclic aromatic hydrocarbons. 10 This approach is in line with the commonly accepted EAS reaction mechanism when considering the protonated species as a "surrogate" for the arenium ion (Scheme 1). The rationalization of the regioselectivities in the benzene series based on the relative stabilities of the possible sigma complexes is textbook knowledge and Galabov and co-workers 11,12 electrophile have shown that the computed binding energy of the Bromine cation is correlated with the experimentally measured partial rate factors.…”

Section: Introductionsupporting

confidence: 59%

Fast and Accurate Prediction of the Regioselectivity of Electrophilic Aromatic Substitution Reactions

Jimmy¹,

Jensen²,

Monika³

et al. 2017

Preprint

View full text Add to dashboard Cite

While computational prediction of chemical reactivity is possible it usually requires expert knowledge and there are relatively few computational tools that can be used by a bench chemist to help guide synthesis. The RegioSQM method for predicting the regioselectivity of electrophilic aromatic substitution reactions of heteroaromatic systems is presented in this paper. RegioSQM protonates all aromatic C-H carbon atoms and identifies those with the lowest free energies in chloroform using the PM3 semiempirical method as the most nucleophilic center. These positions are found to correlate qualitatively with the regiochemical outcome in a retrospective analysis of 96% of more than 525 literature examples of electrophilic aromatic halogenation reactions. The method is automated and requires only a SMILES string of the molecule of interest, which can easily be generated using chemical drawing programs such as ChemDraw. The computational cost is 1-10 minutes per molecule depending on size, using relatively modest computational resources and the method is freely available via a web server at regiosqm.org. RegioSQM should therefore be of practical use in the planning of organic synthesis.

show abstract

Section: Introductionsupporting

confidence: 59%

Fast and Accurate Prediction of the Regioselectivity of Electrophilic Aromatic Substitution Reactions

Jimmy¹,

Jensen²,

Monika³

et al. 2017

Preprint

View full text Add to dashboard Cite

show abstract

“…To test the reliability of eq as a proposed definition of Δ – h ( k ), positional selectivity and relative rates (compared to that of benzene) of nitration, benzylation, and chlorination on halobenzenes and alkylbenzenes are studied here. There are a number of earlier attempts where electrophilic substitutions on arenes are studied using reactivity indices based on density functional reactivity theory (DFRT) and other theoretical approaches. ,,,,− …”

Section: Results and Discussionmentioning

confidence: 99%

Relative Contribution of Combined Kinetic and Exchange Energy Terms vs the Electronic Component of Molecular Electrostatic Potential in Hardness Potential Derivatives

Bhattacharjee

Roy

2013

J. Phys. Chem. A

View full text Add to dashboard Cite

The relative contribution of the sum of kinetic [(10/9)CFρ(r)2/3] and exchange energy [(4/9)CXρ(r)1/3] terms to that of the electronic part of the molecular electrostatic potential [Vel(r)] in the variants of hardness potential is investigated to assess the proposed definition of Δ+h(k) = −[VelN+1(k) – VelN(k)] and Δ–h(k) = −[VelN(k) – VelN–1(k)] (Saha; et al. J. Comput. Chem. 2013, 34, 662). Some substituted benzenes and polycyclic aromatic hydrocarbons (PAHs) (undergoing electrophilic aromatic substitution), carboxylic acids, and their derivatives are chosen to carry out the theoretical investigation as stated above. Intra- and intermolecular reactivity trends generated by Δ+h(k) and Δ–h(k) are found to be satisfactory and are correlated reasonably well with experimental results.

show abstract

“…Nucleus-independent chemical shifts [1] (NICS) show that the induced magnetic field is strongest at the center of the middle ring, which has led some to claim that this ring is the "most aromatic". [2,3] However, it is known that the middle ring of anthracene is the most reactive in reactions such as protonation, [4] Diels-Alder reactions, [5] bromination, and so on. These observations are usually rationalized by considering that the 9,10-addition product (the result of a reaction upon the middle ring) is more aromatic, and thus, more stable, than the 1,4-addition product (resulting from a reaction upon either of the side rings).…”

Section: Introductionmentioning

confidence: 99%

The NICS‐XY‐Scan: Identification of Local and Global Ring Currents in Multi‐Ring Systems

Gershoni‐Poranne

Stanger

2014

Chemistry A European J

303

288

View full text Add to dashboard Cite

Nucleus-independent chemical shift (NICS)-based methods are very popular for the determination of the induced magnetic field under an external magnetic field. These methods are used mostly (but not only) for the determination of the aromaticity and antiaromaticity of molecules and ions, both qualitatively and quantitatively. The ghost atom that serves as the NICS probe senses the induced magnetic field and reports it in the form of an NMR chemical shift. However, the source of the field cannot be determined by NICS. Thus, in a multi-ring system that may contain more than one induced current circuit (and therefore more than one source of the induced magnetic field) the NICS value may represent the sum of many induced magnetic fields. This may lead to wrong assignments of the aromaticity (and antiaromaticity) of the systems under study. In this paper, we present a NICS-based method for the determination of local and global ring currents in conjugated multi-ring systems. The method involves placing the NICS probes along the X axis, and if needed, along the Y axis, at a constant height above the system under study. Following the change in the induced field along these axes allows the identification of global and local induced currents. The best NICS type to use for these scans is NICSπZZ , but it is shown that at a height of 1.7 Å above the molecular plane, NICSZZ provides the same qualitative picture. This method, namely the NICS-XY-scan, gives information equivalent to that obtained through current density analysis methods, and in some cases, provides even more details.

show abstract

An ab initio study of electrophilic aromatic substitution

Cited by 37 publications

References 14 publications

Fast and Accurate Prediction of the Regioselectivity of Electrophilic Aromatic Substitution Reactions

Fast and Accurate Prediction of the Regioselectivity of Electrophilic Aromatic Substitution Reactions

Relative Contribution of Combined Kinetic and Exchange Energy Terms vs the Electronic Component of Molecular Electrostatic Potential in Hardness Potential Derivatives

The NICS‐XY‐Scan: Identification of Local and Global Ring Currents in Multi‐Ring Systems

Contact Info

Product

Resources

About