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.

Legate Ions. The Use of the Oxibase Scale to Predict Leaving Group Orders from Carbon in SN2 Reactions

1965 ◽  
Vol 87 (13) ◽  
pp. 3010-3011 ◽  
Author(s):  
Robert Earl Davis
Keyword(s):  
Sn2 Reactions ◽  
Leaving Group

Elimination reactions. Leaving group tendencies in E2C, E2H and SN2 reactions

1968 ◽  
Vol 9 (50) ◽  
pp. 5183-5188 ◽  
Author(s):  
D.J. Lloyd ◽  
A.J. Parker
Keyword(s):  
Sn2 Reactions ◽  
Leaving Group ◽  
Elimination Reactions

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

Effects of Substituent and Leaving Group on the Gas-Phase SN2 Reactions of Phenoxides with Halomethanes: A DFT Investigation

2009 ◽  
Vol 113 (38) ◽  
pp. 10359-10366 ◽  
Author(s):  
Qiang-gen Li ◽  
Ying Xue
Keyword(s):  
Gas Phase ◽  
Sn2 Reactions ◽  
Leaving Group

Brønsted βNuValues and Leaving Group Effects in SN2 Reactions. Tests of the Reactivity-Selectivity Postulate

1985 ◽  
Vol 26 (4) ◽  
pp. 357-366 ◽  
Author(s):  
Frederick G. Bordwell ◽  
John C. Branca ◽  
Thomas A. Cripe
Keyword(s):  
Sn2 Reactions ◽  
Leaving Group ◽  
Group Effects

Neutral Metal Atoms Acting as a Leaving Group in Gas-Phase SN2 Reactions: M(CH3)++ NH3→ CH3NH3++ M (M = Zn, Cd, Hg)

2012 ◽  
Vol 31 (10) ◽  
pp. 3816-3824 ◽  
Author(s):  
Robert Kretschmer ◽  
Maria Schlangen ◽  
Martin Kaupp ◽  
Helmut Schwarz
Keyword(s):  
Gas Phase ◽  
Sn2 Reactions ◽  
Metal Atoms ◽  
Leaving Group ◽  
Neutral Metal
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