Gas-phase aromatic substitution by positive bromine ions from 80mBr(IT)80Br: a study of linear free energy relation

1977 ◽  
Vol 99 (9) ◽  
pp. 3037-3041 ◽  
Author(s):  
E. J. Knust
Keyword(s):  
Free Energy ◽  
Gas Phase ◽  
Energy Relation ◽  
Aromatic Substitution ◽  
Linear Free Energy ◽  
Free Energy Relation

Linear free energy relation involving ortho substituents in gas phase reactions. XVII

1969 ◽  
Vol 34 (7) ◽  
pp. 2090-2095 ◽  
Author(s):  
Grant G. Smith ◽  
Kin K. Lum ◽  
J. A. Kirby ◽  
J. Posposil
Keyword(s):  
Free Energy ◽  
Gas Phase ◽  
Energy Relation ◽  
Gas Phase Reactions ◽  
Linear Free Energy ◽  
Free Energy Relation

The Excited Singlet State of Chloropentafluoroacetone; Quenching by Unsaturated Hydrocarbons

1971 ◽  
Vol 49 (12) ◽  
pp. 2053-2058 ◽  
Author(s):  
H. S. Samant ◽  
A. J. Yarwood
Keyword(s):  
Gas Phase ◽  
Singlet State ◽  
Excited Singlet State ◽  
Energy Relation ◽  
Excited Singlet ◽  
Quenching Rate ◽  
Unsaturated Hydrocarbons ◽  
Linear Free Energy ◽  
Free Energy Relation ◽  
A Charge

The fluorescence of chloropentafluoroacetone in the gas phase at 23 °C is quenched by the addition of certain olefins. The quenching rate constants of 17 unsaturated hydrocarbons for the first excited singlet state of chloropentafluoroacetone are reported. The molecules are divided into two classes on the basis of their quenching abilities, (a) olefins with only electron-withdrawing substituents and (b) olefins with electron-donating substituents. It is shown that the quenching by molecules in the latter group can be quantitatively correlated with the ionization potential (i.p.) of the quenching molecule. The relation is log k = 18.0 − 0.79 (i.p.), i.e. a type of linear free energy relation is obeyed. This implies that the quenching by molecules containing only electron-donating substituents involves a charge-transfer complex.

The transmission of polar effects. Part VI. The ionization of ortho-substituted benzoic acids

1968 ◽  
Vol 46 (18) ◽  
pp. 2941-2944 ◽  
Author(s):  
Keith Bowden ◽  
G. E. Manser
Keyword(s):  
Free Energy ◽  
Benzoic Acid ◽  
Field Effect ◽  
Energy Relation ◽  
Benzoic Acids ◽  
Linear Free Energy ◽  
Free Energy Relation ◽  
Substituted Benzoic Acids ◽  
Reaction Constants

The pKa values of a series of ortho-substituted benzoic acids in 50% ethanol–water have been determined. The effect of ortho-substitution on the ionization of benzoic acid in this and other solvents has been correlated by a linear free energy relation. The reaction constants found are compared with those for the meta/para-substituted benzoic acids. While those for the former system are insensitive to changes in the medium, the latter vary considerably. It is suggested that this is due to transmission by the field effect passing almost entirely through the molecular cavity for ortho-substituents.

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