Experimental and Quantum Mechanical Study of Nucleophilic Substitution Reactions of meta- and para-Substituted Benzyl Bromides with Benzylamine in Methanol: Synergy Between Experiment and Theory

2017 ◽  
Vol 70 (1) ◽  
pp. 90 ◽  
Author(s):  
Rachuru Sanjeev ◽  
Ramavath Ravi ◽  
Vandanapu Jagannadham ◽  
Adam A. Skelton

This work involves the experimental and theoretical study of the nucleophilic substitution of meta- and para-substituted benzyl bromides with benzylamine. Conductometric rate experiments confirm the applicability of the Hammett linear free-energy relationship to this system. To gain a deep understanding of the physical chemistry at play, a quantum mechanical study of the reaction is also conducted. The quantum mechanical calculations not only reproduce the experimental free energy of activation, but also provide greater insights at the molecular and atomic level. Isolation of the calculated transition state structure and application of the Hammett equation to its electronic, structural, and energetic properties are studied.

2003 ◽  
Vol 17 (4) ◽  
pp. 753-762
Author(s):  
Christopher J. Rhodes ◽  
Thuy T. Tran ◽  
Philip Denton ◽  
Harry Morris

Using Transition-State Theory, experimental rate constants, determined over a range of temperatures, for reactions of vitamin E type antioxidants are analysed in terms of their enthalpies and entropies of activation. It is further shown that computational methods may be employed to calculate enthalpies and entropies, and hence Gibbs Free Energies, for the overall reactions. Within the Linear Free Energy Relationship (LFER) assumption, that the Gibbs Free Energy of activation is proportional to the overall Gibbs Free Energy change for the reaction, it is possible to rationalise, and even to predict, the relative contributions of enthalpy and entropy for reactions of interest, involving potential antioxidants.


2019 ◽  
Author(s):  
Xinyu Xu ◽  
Zongchang Han

The aromatic nucleophilic substitution reaction in the Clayden rearrangement reaction has an abnormal Hammett linear free energy relationship1. Inspired by the concertedstepwise variation of the aromatic nucleophilic substitution reaction in 20182, we determined the mechanism of Clayden rearrangement reaction under several conditions by DFT calculation then explained the mechanism diversity. We also found that there is a significant dynamic effect in the system due to the emergence of dynamic intermediates, which may be one of the reasons for the Hammett linear free energy relationship.


RSC Advances ◽  
2015 ◽  
Vol 5 (4) ◽  
pp. 2669-2676 ◽  
Author(s):  
Binh Khanh Mai ◽  
Yongho Kim

The long-range proton transfer dependence on the pKa of hydroxyl molecules in hydrogen (H)-bonded wires was investigated using quantum mechanical calculations.


2019 ◽  
Author(s):  
Xinyu Xu ◽  
Zongchang Han

The aromatic nucleophilic substitution reaction in the Clayden rearrangement reaction has an abnormal Hammett linear free energy relationship1. Inspired by the concertedstepwise variation of the aromatic nucleophilic substitution reaction in 20182, we determined the mechanism of Clayden rearrangement reaction under several conditions by DFT calculation then explained the mechanism diversity. We also found that there is a significant dynamic effect in the system due to the emergence of dynamic intermediates, which may be one of the reasons for the Hammett linear free energy relationship.


2014 ◽  
Vol 28 (4) ◽  
pp. 375-400 ◽  
Author(s):  
Paulius Mikulskis ◽  
Daniela Cioloboc ◽  
Milica Andrejić ◽  
Sakshi Khare ◽  
Joakim Brorsson ◽  
...  

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