Substituent effects on the binding of phenols to cyclodextrins in aqueous solution

1989 ◽  
Vol 93 (18) ◽  
pp. 6863-6867 ◽  
Author(s):  
Gary L. Bertrand ◽  
James R. Faulkner ◽  
Soon M. Han ◽  
Daniel W. Armstrong
Keyword(s):  
Aqueous Solution ◽  
Substituent Effects

scholarly journals Carbonyl Addition Reactions: Factors Affecting the Hydrate–Hemiacetal and Hemiacetal–Acetal Equilibrium Constants

1975 ◽  
Vol 53 (6) ◽  
pp. 898-906 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Carbonyl Compounds ◽  
Equilibrium Constants ◽  
Substituent Effects ◽  
Steric Effects ◽  
Addition Reactions ◽  
Free Energies ◽  
Electronic Effects ◽  
Factors Affecting ◽  
Analogous Formula

Equilibrium constants for hydrate–hemiacetal interconversion in aqueous solution at 25° have been measured for four fluorinated carbonyl compounds: compound, alcohol, K4 (M−1): CF3CHO, C2H5OH, 2.3; CF3COCH3, CH3OH, 1.0; CF3COPh, CH3OH, 3.5; CF3COCF3, CH3OH, 0.14. These values, combined with values from the literature, permit an examination of substituent effects upon the equilibrium constant for[Formula: see text]The free energy change for this process, corrected for symmetry and steric effects, follows the equation[Formula: see text]Thus electronic effects upon this equilibrium are generally small and in fact are often smaller than steric effects.This analysis permits and justifies the calculation of free energies of formation of [Formula: see text] compounds from the (more generally measurable) free energies of formation of the analogous [Formula: see text] compounds.

A Comparison of Substituent Effects on the Stability of .alpha.,.alpha.-Dimethylbenzyl Carbocations in Aqueous Solution and in the Gas Phase: How Significant is Nucleophilic Solvation?

1994 ◽  
Vol 116 (15) ◽  
pp. 6706-6712 ◽  
Author(s):  
John P. Richard ◽  
Vandannapu Jagannadham ◽  
Tina L. Amyes ◽  
Masaaki Mishima ◽  
Yuho Tsuno
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Substituent Effects ◽  
The Stability ◽  
Nucleophilic Solvation

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.

scholarly journals Substituent Effects on Carbon Acidity in Aqueous Solution and at Enzyme Active Sites

Synlett ◽  
2017 ◽  
Vol 28 (12) ◽  
pp. 1407-1421 ◽  
Author(s):  
John Richard ◽  
Tina Amyes
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Active Site ◽  
Active Sites ◽  
Substituent Effects ◽  
Imidazolium Cations ◽  
Enzyme Active Sites ◽  
Iminium Cations ◽  
Carbon Acids

Methods are described for the determination of pK as for weak carbon acids in water. The application of these methods to the determination of the pK as for a variety of carbon acids including nitriles, imidazolium cations, amino acids, peptides and their derivatives and, α-iminium cations is presented. The substituent effects on the acidity of these different classes of carbon acids are discussed, and the relevance of these results to catalysis of the deprotonation of amino acids by enzymes and by pyridoxal 5′-phosphate is reviewed. The procedure for estimating the pK a of uridine 5′-phosphate for C-6 deprotonation at the active site of orotidine 5′-phosphate decarboxylase is described, and the effect of a 5-F substituent on carbon acidity of the enzyme-bound substrate is discussed.1 Introduction2 The Carbon Acidity of Ethyl Thioacetate3 The Carbon Acidity of Carboxylic Acid Derivatives4 The Carbon Acidity of Imidazolium Cations5 The α-Carbon Acidity of Amino Acids, Peptides and Their Derivatives6 Electrophilic Catalysis of Deprotonation of Amino Acids: The α-Carbon Acidity of Iminium Cations7 pK as for Carbon Acids at Enzyme Active Sites8 Concluding Remarks

Substituent effects on nitroaromatic radical anions in aqueous solution

1976 ◽  
Vol 80 (5) ◽  
pp. 519-524 ◽  
Author(s):  
P. Neta ◽  
Dan Meisel
Keyword(s):  
Aqueous Solution ◽  
Substituent Effects ◽  
Radical Anions

Hemiacetals of acetophenone. Aromatic substituent effects in the H+- and general-base-catalysed decomposition in aqueous solution

1994 ◽  
pp. 2199-2206 ◽  
Author(s):  
Robert A. McClelland ◽  
Karen M. Engell ◽  
Truels S. Larsen ◽  
Poul E. Sørensen
Keyword(s):  
Aqueous Solution ◽  
Substituent Effects ◽  
Aromatic Substituent ◽  
General Base
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