Reactivity–selectivity relationships. Part 11. Effect of leaving group on selectivity in SN2 reactions. A frontier orbital analysis

1979 ◽  
pp. 857-861 ◽  
Author(s):  
Yishai Karton ◽  
Addy Pross
Keyword(s):  
Frontier Orbital ◽  
Sn2 Reactions ◽  
Leaving Group ◽  
Orbital Analysis

Effect of the Leaving Group on the Rates of SN2 and SN2' Reactions in Allylic Systems

1960 ◽  
Vol 82 (11) ◽  
pp. 2881-2888 ◽  
Author(s):  
F. G. Bordwell ◽  
Phillip E. Sokol ◽  
James D. Spainhour
Keyword(s):  
Sn2 Reactions ◽  
Leaving Group

Mechanisms of aromatic nucleophilic substitution by the ambident thiocyanate ion

1973 ◽  
Vol 26 (2) ◽  
pp. 273 ◽  
Author(s):  
DE Giles ◽  
AJ Parker
Keyword(s):  
Nucleophilic Substitution ◽  
Transition States ◽  
Reactivity Ratio ◽  
Substitution Reactions ◽  
Aromatic Nucleophilic Substitution ◽  
Thiocyanate Ion ◽  
Sn2 Reactions ◽  
Leaving Group ◽  
Electrophilic Reactivity ◽  
Saturated Carbon Atom

Sulphur/nitrogen reactivity ratios in a series of aromatic nucleophilic substitution reactions of ambident thiocyanate ion have been determined. There are profound differences from the pattern found in SN2 reactions at a saturated carbon atom. Abnormal transition states, involving interactions between entering and leaving group, are likely in the bond-breaking step of the intermediate complex in reactions of thiocyanate ion with 1-fluoro-2,4-dinitrobenzene and with 2,4- dinitrophenyl 4-toluenesulphonate. The nitro-substituted aryl thiocyanates are shown to be tri-functional electrophiles, with reactive centres at aromatic carbon, at cyanide carbon, and at sulphur. Aryl 4-toluenesulphonates are bifunctional electrophiles with reactive centres at aryl carbon and sulphonyl sulphur. The site of attack by nucleophiles depends on the nature of the nucleophile. The sulphur/nitrogen reactivity ratio of ambident SCN-, and the electrophilic reactivity of tri- and bi-functional substrates, are in most instances consistent with the Hard and Soft Acids and Bases principle. Exceptions to the principle in some instances reveal differences between the SNAr and SN2 mechanisms, and in others indicate abnormal transition states.

Properties of the [M(dppm)2M′]2+Building Blocks (M, M′ = Pd or Pt): Site Selectivity, Emission Features, and Frontier Orbital Analysis

2009 ◽  
Vol 48 (9) ◽  
pp. 4118-4133 ◽  
Author(s):  
Sébastien Clément ◽  
Shawkat M. Aly ◽  
Diana Bellows ◽  
Daniel Fortin ◽  
Carsten Strohmann ◽  
...  
Keyword(s):  
Building Blocks ◽  
Frontier Orbital ◽  
Site Selectivity ◽  
Orbital Analysis

Biodegradation Mechanism of Anionic Polyacrylamide in Coal Preparation Using Molecular Simulation

2021 ◽  
Author(s):  
Fanglue Wang ◽  
Dongchen Zhang ◽  
Xuefeng Wu ◽  
Shengsong Deng
Keyword(s):  
Hydrophobic Interactions ◽  
Interaction Mechanism ◽  
Docking Study ◽  
Binding Modes ◽  
Frontier Orbital ◽  
Orbital Theory ◽  
Orbital Analysis ◽  
Insight Into ◽  
Anionic Polyacrylamide ◽  
Rhodococcus Sp

Abstract Biodegradation of anionic polyacrylamide (HPAM) and polyacrylate (PAA) by key enzymes, such as amidase and bacterial laccase, have been reported. However, the interaction mechanism between HPAM or PAA and enzymes is still poorly unclear. Here, docking study was undertook to demonstrate the binding modes and interaction details for degradation of HPAM or PAA. Then, bioactivities between PAA and HPAM were compared with frontier orbital theory. The docking results showed that HPAM completely buried in pocket of Rhodococcus sp. N-771 amidase (Rh Amidase), while most of PAA molecule exposed outside pocket of Bacillus subtilis laccase ( B. subtilis laccase ), further suggesting PAA was much more difficult to degrade than HPAM. Hydrophobic interactions and hydrogen bonds were necessary for stabilizing HPAM-Rh Amidase or PAA- B. subtilis laccase complex. The frontier orbital analysis indicated that bioactivity of PAA was higher than that of PAA. These findings provide an insight into enzyme-catalyzed degradation of HPAM. It is helpful in designing highly efficient enzymes against HPAM or PAA to protect environment.

SN2 Substitution Reactions at the Amide Nitrogen in the Anomeric Mutagens, N-Acyloxy-N-alkoxyamides

2009 ◽  
Vol 62 (7) ◽  
pp. 700 ◽  
Author(s):  
Katie L. Cavanagh ◽  
Stephen A. Glover ◽  
Helen L. Price ◽  
Rhiannon R. Schumacher
Keyword(s):  
Kinetic Studies ◽  
Model Reaction ◽  
Side Chain ◽  
Carboxylate Group ◽  
Amide Nitrogen ◽  
Substitution Reactions ◽  
Sn2 Reactions ◽  
Leaving Group ◽  
Rate Of Substitution

N-Acyloxy-N-alkoxyamides 1a are unusual anomeric amides that are pyramidal at the nitrogen because of bis oxyl substitution. Through this configuration, they lose most of their amide character and resemble α-haloketones in reactivity. They are susceptible to SN2 reactions at nitrogen, a process that is responsible for their mutagenic behaviour. Kinetic studies have been carried out with the nucleophile N-methylaniline that show that, like SN2 reactions at carbon centres, the rate constant for SN2 displacement of carboxylate is lowered by branching β to the nitrogen centre, or bulky groups on the alkoxyl side chain. Branching or bulky groups on the carboxylate leaving group, however, do not impact on the rate of substitution, which is mostly controlled by the pKA of the departing carboxylate group. These results are in line with computed properties for the model reaction of ammonia with N-acetoxy-N-methoxyacetamide but are in contrast to the role of steric effects on their mutagenicity.

Absence of steric effects on the leaving group in SN2 reactions

1961 ◽  
Vol 2 (14) ◽  
pp. 473-476
Author(s):  
Ernest L. Eliel ◽  
Rico P. Gerber
Keyword(s):  
Steric Effects ◽  
Sn2 Reactions ◽  
Leaving Group
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