Additive substituent effects on the ionization of meta-substituted phenols

1968 ◽  
Vol 21 (6) ◽  
pp. 1541 ◽  
Author(s):  
PD Bolton ◽  
FM Hall ◽  
J Kudrynski
Keyword(s):  
Thermodynamic Functions ◽  
Substituent Effects ◽  
Ionization Constants ◽  
Free Energies ◽  
Reaction Series ◽  
Substituted Phenols ◽  
Temperature Range

Thermodynamic ionization constants of 3-ethoxyphenol; 3,5-diethoxyphenol, 3,5-dichlorophenol, 3,5-dibromophenol, 3,5-diiodophenol, and 3,5-dinitrophenol have been measured spectrophotometrically within the temperature range 5-60�, and the thermodynamic functions of ionization ΔG25, ΔH25, ΔS25, and ΔCp.25 calculated. These results, in conjunction with others measured previously, indicate that, for this reaction series, substituent effects on the free energies of ionization are precisely additive, and on the entropies of ionization closely additive. An assessment of the results in terms of Hepler's internal/external enthalpy theory is made.

Substituent effects on the thermodynamic functions of ionization of metasubstituted anilinium ions

1968 ◽  
Vol 21 (4) ◽  
pp. 939 ◽  
Author(s):  
PD Bolton ◽  
FM Hall
Keyword(s):  
Linear Function ◽  
Thermodynamic Functions ◽  
Substituent Effects ◽  
Negative Slope ◽  
Hammett Equation ◽  
Reaction Parameter ◽  
Reaction Series ◽  
Acidity Constants ◽  
Temperature Range ◽  
Relationship Of

Thermodynamic acidity constants of the meta-methoxyanilinium, meta- chloroanilinium, meta-bromoanilinium, and meta-iodoanilinium ions have been measured spectrophotometrically over the temperature range 5-50� and those of the meta-nitroanilinium ion over the temperature range 5-60�. The thermodynamic functions of ionization, ΔG25, ΔH25, ΔS25, and ΔCp,25, have also been calculated for each ion. For a series of seven meta-substituted anilinium ions the acidity constants show close obedience to the Hammett equation over the temperature range 10-50� with the reaction parameter p being a precise linear function of 1/T. The same reaction series also shows a well-defined isoequilibrium relationship of negative slope.

Thermodynamic functions of ionization of t-butyl-substituted and methoxysubstituted phenols

1972 ◽  
Vol 25 (1) ◽  
pp. 75 ◽  
Author(s):  
PD Bolton ◽  
FM Hall ◽  
J Kudrynski
Keyword(s):  
Aqueous Solution ◽  
Thermodynamic Functions ◽  
Spectrophotometric Method ◽  
Substituent Effects ◽  
Steric Effects ◽  
Ionization Process ◽  
Ionization Constants ◽  
Temperature Range

Thermodynamic ionization constants of 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 3,5-di-t-butylphenol, and 3,5-dimethoxyphenol have been measured in aqueous solution by an e.m.f./spectrophotometric method within the temperature range 5-60�C and the thermodynamic functions of ionization ΔG25, ΔH25, ΔS25, and ΔCp25 calculated. These results confirm the additivity of substituent effects noted previously for the ionization of 3,5-disubstituted phenols and indicate that this ionization process is relatively insensitive to steric effects.

Revision of the Dual-Substituent-Parameter Treatment; Reaction Series with a Donor Reaction Centre

2007 ◽  
Vol 72 (8) ◽  
pp. 1158-1176 ◽  
Author(s):  
Stanislav Böhm ◽  
Otto Exner
Keyword(s):  
Substituent Effects ◽  
Protonated Form ◽  
Isodesmic Reaction ◽  
Reaction Centre ◽  
Reaction Series ◽  
Substituted Phenols ◽  
Substituted Anilines ◽  
The Common ◽  
Substituted Benzoic Acids ◽  
Isolated Molecules

The dual-substituent-parameter (DSP) treatment was challenged previously as not generally valid. Just in the fundamental reaction, dissociation of 4-substituted benzoic acids and in similar reactions, DPS does not hold for acceptor substituents because the constant reaction centre is itself an acceptor. In this communication, the reverse case was examined, i.e., a reaction series with a donor reaction centre: basicity and acidity of 4-substituted anilines, and acidity of 4-substituted phenols. The reaction energies were calculated for 19 common substituents at the level B3LYP/6-311+G(d,p)//B3LYP/6-311+G(d,p); the substituents effects were also estimated separately in uncharged molecules and in the ions in terms of isodesmic reaction. DSP is valid and its resonance term is highly significant for molecules with acceptor substituents; donor substituents behave differently and cannot be described by simple resonance constants. Basicity of substituted anilines is more complex since the substituent effects are quite different in the free base and in the protonated form: basicity is controlled by a combination of various effects. It is recommended to use DSP only for acceptor substituents with a donor reaction centre or vice versa; otherwise the accuracy is decreased. All results were obtained with isolated molecules and with resonance constants derived on isolated molecules; however, they retain their validity even with the common constants σR determined from the reactions in solution.

Thermodynamics of Sr2NiMoO6 and Sr2CoMoO6 and their stability under reducing conditions

2018 ◽  
Vol 20 (30) ◽  
pp. 20108-20116 ◽  
Author(s):  
V. V. Sereda ◽  
D. S. Tsvetkov ◽  
A. L. Sednev ◽  
A. I. Druzhinina ◽  
D. A. Malyshkin ◽  
...  
Keyword(s):  
Thermodynamic Functions ◽  
Broad Temperature Range ◽  
Temperature Range ◽  
Reducing Conditions

Essential thermodynamic functions, obtained for Sr2NiMoO6 and Sr2CoMoO6 in broad temperature range, allowed to evaluate their stability in reducing conditions.

scholarly journals Activity measurement of solid Cu-In alloys by EMF method with solid electrolyte

2002 ◽  
Vol 38 (1-2) ◽  
pp. 23-31 ◽  
Author(s):  
I. Katayama ◽  
K. Miyakusu ◽  
T. Iida
Keyword(s):  
Solid Electrolyte ◽  
Thermodynamic Activity ◽  
Activity Measurement ◽  
Published Data ◽  
Emf Method ◽  
Free Energies ◽  
Temperature Range

The thermodynamic activity of indium in the solid Cu-In alloys was obtained from the EMF measurement of cell: In,In2O3, ZrO2(+11mol%CaO), Cu-In,In2O3 for 16 alloys in the temperature range 773 to 900K. Activity changes with composition at 823K are very large in the and - phase regions. Activity and free energies of formation are derived and compared with the published data.

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