Modeling Protic to Dipolar Aprotic Solvent Rate Acceleration and Leaving Group Effects in SN2 Reactions:  A Theoretical Study of the Reaction of Acetate Ion with Ethyl Halides in Aqueous and Dimethyl Sulfoxide Solutions

2005 ◽  
Vol 109 (3) ◽  
pp. 507-511 ◽  
Author(s):  
Daniel W. Tondo ◽  
Josefredo R. Pliego
Keyword(s):  
Dimethyl Sulfoxide ◽  
Theoretical Study ◽  
Aprotic Solvent ◽  
Dipolar Aprotic Solvent ◽  
Sn2 Reactions ◽  
Rate Acceleration ◽  
Leaving Group ◽  
Group Effects

Solvation of Ions. V. Rates of SN2 Reactions in Mixtures of Protic and Dipolar Aprotic Solvents

1963 ◽  
Vol 16 (4) ◽  
pp. 585 ◽  
Author(s):  
AJ Parker
Keyword(s):  
Aprotic Solvent ◽  
Chloride Ion ◽  
Solvent Mixtures ◽  
Protic Solvent ◽  
Dipolar Aprotic Solvent ◽  
Sn2 Reactions ◽  
Protic Solvents ◽  
Bonding Interaction ◽  
Solvation Of Ions ◽  
Dipolar Aprotic Solvents

The rates of reaction of methyl iodide with chloride ion in some protic-dipolar aprotic solvent mixtures have been measured. The rate-retarding effect of protic solvents at M concentration in dimethylacetamide is in the order p-NO2C6H4OH > C6H5OH > C6H5SH > C6H5CO2H ≈ CH3OH > C6H5NH2 >H2O ≈ D2O. Protic solvents slow the reaction by a general rather than a specific hydrogen bonding interaction with the anion. Both the dipolar aprotic solvent and the protic solvent, as well as the anion, accept hydrogen bonds, and this influences the interaction between protic solvent and anion.

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

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

scholarly journals Butadiene sulfone as ‘volatile’, recyclable dipolar, aprotic solvent for conducting substitution and cycloaddition reactions

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Yong Huang ◽  
Esteban E. Ureña-Benavides ◽  
Afrah J. Boigny ◽  
Zachary S. Campbell ◽  
Fiaz S. Mohammed ◽  
...  
Keyword(s):  
Aprotic Solvent ◽  
Cycloaddition Reactions ◽  
Dipolar Aprotic Solvent

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.

DENSITY FUNCTIONAL STUDY OF SELECTED MONO-ZINC AND GEM-DIZINC RADICAL CARBENOID CYCLOPROPANATION REACTIONS: OBSERVATION OF AN EFFICIENT RADICAL ZINC CARBENOID CYCLOPROPANATION REACTION AND THE INFLUENCE OF THE LEAVING GROUP ON RING CLOSURE

2003 ◽  
Vol 02 (03) ◽  
pp. 357-369 ◽  
Author(s):  
CUNYUAN ZHAO ◽  
DONG-QI WANG ◽  
DAVID LEE PHILLIPS
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Radical Reaction ◽  
Ring Closure ◽  
Functional Study ◽  
Reaction Step ◽  
Leaving Group ◽  
Reaction Barriers ◽  
Leaving Groups ◽  
Zinc Carbenoid

We report a theoretical study of the cyclopropanation reactions of EtZnCHI, (EtZn)2CH EtZnCHZnI, and EtZnCIZnI radicals with ethylene. The mono-zinc and gem-dizinc radical carbenoids can undergo cyclopropanation reactions with ethylene via a two-step reaction mechanism similar to that previously reported for the CH2I and IZnCH2 radicals. The barrier for the second reaction step (ring closure) was found to be highly dependent on the leaving group of the cyclopropanation reaction. In some cases, the (di)zinc carbenoid radical undergoes cyclopropanation via a low barrier of about 5–7 kcal/mol on the second reaction step and this is lower than the CH2I radical reaction which has a barrier of about 13.5 kcal/mol for the second reaction step. Our results suggest that in some cases, zinc radical carbenoid species have cyclopropanation reaction barriers that can be competitive with their related molecular Simmons-Smith carbenoid species reactions and produce somewhat different cyclopropanated products and leaving groups.

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