Vapour Pressure Study of Deuterium Exchange Reactions in Water-Ethanol Systems: Equilibrium Constant Determination

1979 ◽  
Vol 32 (11) ◽  
pp. 2353 ◽  
Author(s):  
RC Phutela ◽  
ZS Kooner ◽  
DV Fenby
Keyword(s):  
Liquid Phase ◽  
Equilibrium Constant ◽  
Vapour Pressure ◽  
Equilibrium Constants ◽  
Deuterium Exchange ◽  
Pressure Measurements ◽  
Exchange Reactions ◽  
Molar Excess ◽  
Constant Determination

A method is proposed for the determination of the equilibrium constants of liquid-phase deuterium exchange reactions from vapour pressure measurements. It is applied to water-ethanol systems to give the equilibrium constant of the reaction 2C2H5OH(l) + D2(l) → 2C2H5OD(l) + H2O(l) The value obtained, 1.05+0.02 at 298 K, is significantly greater than the 'random' value and is more precise and reasonable than a recent calorimetric estimate. Vapour pressures at 298.14 K are reported for the systems H2O+C2H5OH, H2O+C2H5OD, D2O + C2H5OH and D2O + C2H5OD. Molar excess Gibbs functions are obtained from these vapour pressure measurements.

Determination of the equilibrium constants of water-methanol deuterium exchange reactions from vapour pressure measurements

1980 ◽  
Vol 33 (1) ◽  
pp. 9 ◽  
Author(s):  
ZS Koner ◽  
RC Phutela ◽  
DV Fenby
Keyword(s):  
Equilibrium Constant ◽  
Satisfactory Agreement ◽  
Vapour Pressure ◽  
Equilibrium Constants ◽  
Deuterium Exchange ◽  
Pressure Measurements ◽  
Exchange Reactions ◽  
Molar Excess

The equilibrium constant of the reaction2CH3OH(l) + D2O(l) → 2CH3OD(l) + H2O(l) is obtained from vapour pressure measurements. The value, 1.09k0.02 at 298 K, is in satisfactory agreement with calculated values and with calorimetric estimates. Vapour pressures at 298.14 K are reported for the systems H2O + CH3OH, H2O+CH3OD, D2O + CH3OH and D2O+ CH3OD. Molar excess Gibbs functions are obtained from these vapour pressures.

Vapour pressure study of the deuterium exchange reaction in methanol-ethanol systems: equilibrium constant determination

1980 ◽  
Vol 33 (9) ◽  
pp. 1943 ◽  
Author(s):  
ZS Kooner ◽  
DV Fenby
Keyword(s):  
Equilibrium Constant ◽  
Exchange Reaction ◽  
Vapour Pressure ◽  
Deuterium Exchange ◽  
Pressure Measurements ◽  
Molar Excess ◽  
Constant Determination ◽  
Good Agreement

The equilibrium constant of the reaction ���������������������� CH3OH(1)+C2H5OD(1) → CH3OD(1)+C2H5OH(1) is obtained from vapour pressure measurements on methanol+ethanol systems. The value obtained, 1.03�0.01 at 298 K, is in good agreement with that calculated independently from previously reported vapour pressure studies of water+methanol and water+ethanol systems. Vapour pressures at 298.15 K are reported for the systems CH3OH+C2H5OH, CH3OH+C2H5OD, CH3OD+C2H5OH and CH3OD+C2H5OD. Molar excess Gibbs functions are obtained from these vapour pressures.

Thermodynamics of deuterium exchange reactions in water-amine and alcohol-amine systems

1981 ◽  
Vol 34 (9) ◽  
pp. 1801
Author(s):  
ZS Kooner ◽  
DV Fenby
Keyword(s):  
Thermodynamic Properties ◽  
Equilibrium Constant ◽  
Deuterium Exchange ◽  
Excess Enthalpies ◽  
Exchange Reactions ◽  
Molar Excess ◽  
Harmonic Frequencies ◽  
Statistical Mechanical

Vapour pressures and molar excess enthalpies at 298.15 K are reported for the systems H2O+(C2H5)2NH and D2O+(C2H5)2NH. They are analysed to give the equilibrium constant and enthalpy of the reaction ����������������� 2(C2H5)2NH(1)+D2O(1)→2(C2H5)2ND(1)+H2O(1) Molar excess enthalpies at 298.15 K of the systems CH3OH+(C2H5)2NH, CH3OD+(C2H5)2NH, C2H5OH+(C2H5)2NH and C2H5OD+(C2H5)2NH are used to obtain enthalpies of the reactions ���������� (C2H5)2NH(1)+ROD(1)→(C2H5)2ND(1)+ROH(1)� (R = CH3, C2H5)Thermodynamic properties of various NH/OD exchange reactions are calculated from statistical mechanical equations by use of harmonic frequencies.

Thermodynamics of Deuterium Exchange Reactions in Water-Thiol and Alcohol-Thiol Systems

1979 ◽  
Vol 32 (4) ◽  
pp. 755 ◽  
Author(s):  
JR Khurma ◽  
DV Fenby
Keyword(s):  
Thermodynamic Properties ◽  
Gas Phase ◽  
Equilibrium Constants ◽  
Deuterium Exchange ◽  
Excess Enthalpies ◽  
Exchange Reactions ◽  
Gas Phase Reactions ◽  
Molar Excess ◽  
Harmonic Frequencies ◽  
Statistical Mechanical

Thermodynamic properties at 298 K are obtained for the deuterium exchange reactions RSH + SHD → O + RSD + H2O RSH + DO2 → O + RSD + HDO RSH + R?OD → O + RSD + R?OH Equilibrium constants and enthalpies of the gas phase reactions with R = R' = CH3 are calculated from statistical mechanical equations using recently published harmonic frequencies. Experimental properties, including the molar excess enthalpies of C2H5SH + CH3OH, C2H5SH + CH3OD, C2H5SH + C2H5OH and C2H5SH + C2H5OD reported in this paper, are used to obtain the equilibrium constants and enthalpies of the liquid and gas phase reactions with R = C2H5, R' = CH3 and C2H5.

Deuterium exchange in water-methanol systems: Calculation of equilibrium constants

1977 ◽  
Vol 30 (11) ◽  
pp. 2371 ◽  
Author(s):  
DV Fenby
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Isotope Effects ◽  
Equilibrium Constants ◽  
Deuterium Exchange ◽  
Exchange Reactions ◽  
Infrared Studies ◽  
Experimental Values ◽  
Calculated Equilibrium ◽  
Water Alcohol

Equilibrium constants for a number of water-alcohol deuterium exchange reactions in the gas phase are calculated from harmonic frequencies of CH3OH, CH3OD, CD3OH and CD3OD obtained from recent infrared studies. These are combined with vapour-pressure isotope effects to give equilibrium constants for the same reactions in the liquid phase. Calculated equilibrium constants agree well with most published experimental values.

Statistical mechanics of deuterium exchange reactions : relationships between equilibrium constants and enthalpies of reaction

1982 ◽  
Vol 35 (2) ◽  
pp. 237 ◽  
Author(s):  
DV Fenby ◽  
GL Bertrand
Keyword(s):  
Statistical Mechanics ◽  
Equilibrium Constant ◽  
Isotopic Exchange ◽  
Equilibrium Constants ◽  
Mechanical Analysis ◽  
Deuterium Exchange ◽  
Exchange Reactions ◽  
Statistical Mechanical

Bertrand and Burchfield proposed that the equilibrium constants K and the (standard) enthalpies ΔH of isotopic exchange reactions are related by the equation K = Kstatexp(-ΔH/RT) in which Kstat is the statistical (random) equilibrium constant. The application of this equation to deuterium exchange reactions for which experimental K and ΔH values are available suggests that it is a good approximation at 298 K. In this paper we present a statistical mechanical analysis to account for the success of the equation and to point out its limitations.

Fundamentals of Electrochemistry

2021 ◽  
pp. 389-411
Author(s):  
Christopher O. Oriakhi
Keyword(s):  
Free Energy ◽  
Equilibrium Constant ◽  
Electrode Potential ◽  
Electrolytic Cell ◽  
Electrochemical Cells ◽  
Standard Electrode Potential ◽  
Cell Potential ◽  
Oxidation Reduction ◽  
Constant Determination

Fundamentals of Electrochemistry build on basic oxidation-reduction reactions and present an overview of their use in electrochemical cells. The construction and operation of a galvanic cell is described with cell diagrams including the function of the electrodes (cathode and anode). Also covered are the standard electrode potential and its applications, including calculations involving the standard electrode potential, the Gibbs free energy and the equilibrium constant, determination of the spontaneity in redox reactions and the dependence of cell potential on concentration (the Nernst equation). Finally a qualitative and quantitative overview of electrolysis is presented with a focus on predicting the products of electrolysis and the stoichiometry of electrolysis, which relates the charge flowing through an electrolytic cell to the amount of products formed at the electrodes.

Deuterium isotope effects in liquid-liquid phase diagrams: Water + phenol and water + 2-methylpropanoic acid systems

1983 ◽  
Vol 36 (2) ◽  
pp. 215 ◽  
Author(s):  
DV Fenby ◽  
JR Khurma ◽  
ZS Kooner ◽  
RF Smith
Keyword(s):  
Liquid Phase ◽  
Phase Diagrams ◽  
Isotope Effects ◽  
Dispersion Interactions ◽  
Exchange Reactions ◽  
Molar Excess ◽  
Deuterium Isotope Effects ◽  
London Dispersion ◽  
Molar Excess Volumes ◽  
System Water

Phase-separation temperatures Tp have been measured for the systems H2O+C6H5OH, H2O+ C6H5OD, H20+ CsD5OD, D20+ C6H50H, D2O+ C6H5OD, D2O+ C6DsOD, H2O+ (CH3)2CHCO2H and D2O+ (CH3)2CHCO2H. For water+ 2-methylpropanoic acid, the differences in the Tp-x curves for the exchange and no-exchange systems are striking. For water + phenol, on the other hand, the effect of deuterium-exchange reactions on the Tp-x curves is very small. The results for all systems are in accord with the qualitative predictions of the Rabinovich theory, which accounts for deuterium isotope effects in liquid-liquid phase diagrams in terms of hydrogen bond and London dispersion interactions. Molar excess enthalpies and molar excess volumes at 300.15 K are reported for the system water + 2-methylpropanoic acid. The results are compared with those for water + acetic acid.

The retroaldol reaction of 3-methyl-2-butenal

1983 ◽  
Vol 61 (1) ◽  
pp. 171-178 ◽  
Author(s):  
J. Peter Guthrie ◽  
Brian A. Dawson
Keyword(s):  
Sodium Hydroxide ◽  
Equilibrium Constant ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Aqueous Sodium Hydroxide ◽  
Initial Increase ◽  
Aqueous Sodium ◽  
Rate Determining Step ◽  
Kinetics Of

In aqueous sodium hydroxide solutions at 25 °C, 3-methyl-2-butenal, 1c, undergoes retroaldol cleavage to acetone and acetaldehyde. The kinetics of the retroaldol reaction were followed spectrophotometrically at 242 nm and showed simple first order behavior. When 3-methyl-3-hydroxybutanal, 2c, was added to aqueous sodium hydroxide solutions at 25 °C, there was an initial increase in absorbance at 242 nm, attributed to formation of 1c, followed by a 20-fold slower decrease; the rate of the slow decrease matches the rate of disappearance of 1c under the same conditions. Analysis of the kinetics allows determination of the three rate constants needed to describe the system: khyd = 0.00342; kdehyd = 0.00832; kretro = 0.0564; all M−1 s−1. The equilibrium constant for enone hydration is 0.41. Rate constants for the analogous reactions for acrolein and crotonaldehyde could be obtained from the literature. There is a reasonable rate–equilibrium correlation for the retroaldol step. For the enone hydration step, rate and equilibrium constants respond differently to replacement of hydrogen by methyl. It is proposed that this results from release of strain after the rate-determining step by rotation about a single bond; this decrease in strain is reflected in the equilibrium constant but not in the rate constant.

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