Nucleophilic substitution at a benzylic carbon by an ambident nucleophile—A linear free energy relationship

1979 ◽  
Vol 88 (5) ◽  
pp. 329-335
Author(s):  
K. Madhavan ◽  
V. S. Srinivasan ◽  
N. Venkatasubramanian
Keyword(s):  
Free Energy ◽  
Nucleophilic Substitution ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Benzylic Carbon ◽  
Ambident Nucleophile

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
Keyword(s):  
Free Energy ◽  
Nucleophilic Substitution ◽  
Deep Understanding ◽  
Quantum Mechanical ◽  
Linear Free Energy Relationship ◽  
Substitution Reactions ◽  
Linear Free Energy ◽  
Free Energy Of Activation ◽  
Mechanical Study ◽  
Quantum Mechanical Study

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.

scholarly journals Dynamic Effects May Affect Hammett Linear Free Energy Relationship

2019 ◽  
Author(s):  
Xinyu Xu ◽  
Zongchang Han
Keyword(s):  
Free Energy ◽  
Nucleophilic Substitution ◽  
Substitution Reaction ◽  
Dynamic Effect ◽  
Nucleophilic Substitution Reaction ◽  
Linear Free Energy Relationship ◽  
Aromatic Nucleophilic Substitution ◽  
Linear Free Energy ◽  
Rearrangement Reaction ◽  
Aromatic Nucleophilic Substitution Reaction

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.

scholarly journals Dynamic Effects May Affect Hammett Linear Free Energy Relationship

2019 ◽  
Author(s):  
Xinyu Xu ◽  
Zongchang Han
Keyword(s):  
Free Energy ◽  
Nucleophilic Substitution ◽  
Substitution Reaction ◽  
Dynamic Effect ◽  
Nucleophilic Substitution Reaction ◽  
Linear Free Energy Relationship ◽  
Aromatic Nucleophilic Substitution ◽  
Linear Free Energy ◽  
Rearrangement Reaction ◽  
Aromatic Nucleophilic Substitution Reaction

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.

Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

2004 ◽  
Vol 82 (8) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vanessa Renée Little ◽  
Keith Vaughan
Keyword(s):  
Free Energy ◽  
Chemical Shifts ◽  
Linear Free Energy Relationship ◽  
Piperazine Ring ◽  
Linear Free Energy ◽  
In Series ◽  
Methylene Groups ◽  
Diazonium Coupling ◽  
The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

Absorption Spectra of Substituted 2-Phenylindan-1,3-Dion-2-YL Radicals in Solution

1983 ◽  
Vol 38 (12) ◽  
pp. 1337-1341
Author(s):  
J. Zechner ◽  
N. Getoff ◽  
I. Timtcheva ◽  
F. Fratev ◽  
St. Minchef
Keyword(s):  
Free Energy ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Bathochromic Shift ◽  
Substitution Effects ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy

Abstract Flash photolysis of a series of 2-phenylindandione-1,3 derivatives substituted in the 4′ position results in both the formation of stable benzylidenephthalides and of phenylindan-1,3-dion-2-yl radicals. The u. v. absorption maxima of these radicals are dependent on the solvent and show a bathochromic shift upon substitution. These substitution effects were correlated by means of a linear free energy relationship. Attempts were made to draw conclusions concerning the changes in the gap of the states involved and their curvature due to substitution.

Correlation of Human and Animal Air-to-Blood Partition Coefficients With a Single Linear Free Energy Relationship Model

2008 ◽  
Vol 27 (9) ◽  
pp. 1130-1139 ◽  
Author(s):  
Laura M. Sprunger ◽  
Jennifer Gibbs ◽  
William E. Acree ◽  
Michael H. Abraham
Keyword(s):  
Free Energy ◽  
Partition Coefficients ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Relationship Model

Linear free energy relationship rate constants and basicities of N-substituted phenyl glycines in positronium-glycine complex formation

1987 ◽  
Vol 137 (5) ◽  
pp. 471-474 ◽  
Author(s):  
Rongti Chen (Y.T. Chen) ◽  
Jiachang Liang ◽  
Youming Du ◽  
Chun Cao ◽  
Dinzhen Yin ◽  
...  
Keyword(s):  
Free Energy ◽  
Complex Formation ◽  
Rate Constants ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy
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