ChemInform Abstract: SOLVOLYTIC REACTIVITY OF 1-TRIFLUOROMETHYL-1-PHENYLETHYL TOSYLATE. CORRELATION OF SUBSTITUENT EFFECTS IN THE FORMATION OF HIGHLY DESTABILIZED CARBONIUM IONS

1982 ◽  
Vol 13 (16) ◽  
Author(s):  
A. D. ALLEN ◽  
M. P. JANSEN ◽  
K. M. KOSHY ◽  
N. N. MANGRU ◽  
T. T. TIDWELL
Keyword(s):  
Substituent Effects ◽  
Carbonium Ions

Stabilities of Carbonium-Ions. IV. Steric Effects in the Solvolysis of Substituted Diphenylmethyl Chlorides

1986 ◽  
Vol 39 (4) ◽  
pp. 625 ◽  
Author(s):  
R Bolton ◽  
RE Burley ◽  
NJ Williams
Keyword(s):  
Electronic Effect ◽  
Substituent Effects ◽  
Methyl Chloride ◽  
Steric Effects ◽  
Methyl Groups ◽  
Hydrogen Atoms ◽  
Carbonium Ions ◽  
Rate Of Reaction ◽  
Resonance Stabilization ◽  
Planar Transition

The replacement of ortho-hydrogen atoms by methyl groups in diphenylmethyl chloride has three distinguishable results upon the rate of solvolysis . Firstly, the alkyl groupactivates by its electronic effect; secondly, steric interactions diminish all observed substituent effects regardless of the position of the substituent in the aryl system; and thirdly, steric acceleration of the solvolysis can be seen in the rate of reaction of bis (2,6-dimethylphenyl)methyl chloride. The ortho-methyl substituents inhibit the formation of the planar transition state necessary to allow the greatest resonance stabilization by the aryl substituents of the incipient carbocation. Greater degrees of twist are reflected both in the variations in the rates of solvolysis of the poly(orthomethyl ) diphenylmethyl chlorides and in the consistent fall in the value of p+ with successive ortho-substitution.

A MNDO study of planar thioacyl-substituted carbocations

1992 ◽  
Vol 70 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Jack Leon Ginsburg ◽  
Richard Francis Langler ◽  
Raj Kumar Raheja ◽  
Laura Precedo
Keyword(s):  
Gas Phase ◽  
Substituent Effects ◽  
Mndo Method ◽  
Saturation Effect ◽  
Semiempirical Calculations ◽  
Isodesmic Reactions ◽  
Electron Population ◽  
Resonance Saturation ◽  
Carbonium Ions

Relative gas phase stabilities of pairs of planar regioisomeric thioacyl-substituted carbocations have been calculated using the MNDO method. These systems are stabilized by good π donors. The role of S π-electron population as a gauge of substituent effects is examined. Similar results were obtained using isodesmic reactions to gauge substituent effects. Results of this and earlier studies are consistent with the resonance saturation effect. Keywords: semiempirical calculations, carbonium ions.

Solvolytic reactivity of 1-trifluoromethyl-1-phenylethyl tosylate. Correlation of substituent effects in the formation of highly destabilized carbonium ions

1982 ◽  
Vol 104 (1) ◽  
pp. 207-211 ◽  
Author(s):  
Annette D. Allen ◽  
Michael P. Jansen ◽  
Kalavelil M. Koshy ◽  
Nevindra N. Mangru ◽  
Thomas T. Tidwell
Keyword(s):  
Substituent Effects ◽  
Carbonium Ions
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