Nickel Carbonylation Free Energies and Equilibrium Constants

2011 ◽  
pp. 583-586
Keyword(s):  
Equilibrium Constants ◽  
Free Energies

scholarly journals Binding of coenzymes to yeast alcohol dehydrogenase

2010 ◽  
Vol 75 (2) ◽  
pp. 185-194 ◽  
Author(s):  
Vladimir Leskovac ◽  
Svetlana Trivic ◽  
Draginja Pericin ◽  
Mira Popovic ◽  
Julijan Kandrac
Keyword(s):  
Alcohol Dehydrogenase ◽  
Equilibrium Constants ◽  
Point Mutations ◽  
Free Energies ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Mutant Type ◽  
Yeast Alcohol Dehydrogenase ◽  
Internal Equilibrium ◽  
Individual Reaction

In this work, the binding of coenzymes to yeast alcohol dehydrogenase (EC 1.1.1.1) were investigated. The main criterions were the change in the standard free energies for individual reaction steps, the internal equilibrium constants and the overall changes in the reaction free energies. The calculations were performed for the wild type enzyme at pH 6-9 and for 15 different mutant type enzymes, with single or double point mutations, at pH 7.3. The abundance of theoretical and experimental data enabled the binding of coenzymes to enzyme to be assessed in depth.

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 934-942
Author(s):  
J Peter Guthrie
Keyword(s):  
Carbon Dioxide ◽  
Free Energy ◽  
Equilibrium Constants ◽  
Marcus Theory ◽  
Energy Of Activation ◽  
Free Energies ◽  
Orbital Theory ◽  
Activation Free Energy ◽  
Free Energy Of Activation ◽  
Rms Error

Rate constants for hydration of carbon dioxide and ketene can be calculated by applying No Barrier Theory, which needs only equilibrium constants and distortion energies, the latter calculated using molecular orbital theory. The calculated free energies of activation are in satisfactory agreement with experiment: the rms error in free energy of activation is 2.38 kcal/mol. These compounds can also be described using Marcus Theory or Multidimensional Marcus Theory using the transferable intrinsic barrier appropriate to simple carbonyl compounds; in this case the rms error in free energy of activation is 2.19 kcal/mol. The two methods agree on preferred mechanistic path except for uncatalyzed hydration of ketene where Multidimensional Marcus Theory leads to a lower activation free energy for addition to the C=O, while No Barrier Theory leads to a lower free energy of activation for addition to the C=CH2. A rate constant for hydroxide ion catalyzed hydration of ketene can be calculated and is in accord with preliminary experimental results.Key words: ketene, carbon dioxide, hydration, Marcus Theory, No Barrier Theory.

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.

Acid Ionizations of Nitroalkanes in Aqueous Solution

1973 ◽  
Vol 51 (12) ◽  
pp. 1941-1944 ◽  
Author(s):  
Takeki Matsui ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solution ◽  
Carboxylic Acids ◽  
Equilibrium Constants ◽  
Free Energies ◽  
Methyl Substitution ◽  
Calorimetric Measurements ◽  
Acid Ionizations

Calorimetric measurements have led to ΔH0 values for ionization of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane in aqueous solution at 298°K. Combinations of these enthalpies with free energies from equilibrium constants for ionization have led to ΔS0 values for the ionization reactions. It is noted that the trend toward decreasing pK with methyl substitution in nitroalkanes is unusual compared to phenols and carboxylic acids. Similarly, correlations of ΔS0 with ΔG0 and ΔH0 are different for nitroalkanes than for other acids.

Sorption in decationated zeolites. I. Gases in hydrogen-chabazite

1970 ◽  
Vol 320 (1542) ◽  
pp. 289-308 ◽  
Keyword(s):  
Gas Phase ◽  
Equilibrium Constants ◽  
Virial Coefficients ◽  
Sorption Isotherms ◽  
Quadrupole Moments ◽  
Free Energies ◽  
Guest Molecules ◽  
Isotherm Equation ◽  
Guest Species ◽  
Sorbed Phase

Decationated (hydrogen) chabazites have been prepared and their stability examined. Reversible sorption isotherms have been measured in the crystals at a considerable number of temperatures for Ne, Ar, Xe, H 2 , O 2 , N 2 and CO 2 . The isotherms have been analysed in terms of an isotherm equation based upon an equation of virial form relating concentration and pressure in the sorbed phase. The empirical virial coefficients were functions of temperature and of the particular gas-zeolite system considered. Based upon this isotherm equilibrium constants for the distribution of sorbate between crystals and gas phase, standard heats, entropies and free energies of transfer, and activity coefficients of the sorbed gases were determined. Differential and integral heats of sorption have been derived as functions of amount sorbed for all the guest species. These heats did not vary much with uptake unless the guest molecules had permanent quadrupole moments (N 2 , CO 2 ). The energetic basis of this behaviour is discussed and interpreted. Entropies of the sorbed gases have also been found as functions of amount taken up. Near saturation of the crystals the integral entropy was intermediate between that of the liquid and solid sorbate, in accordance with a fluid mobility limited by the rigid cavity walls and by neighbouring guest molecules.

scholarly journals Heats, equilibrium constants, and free energies of formation of cyclopentene and cyclohexene

1949 ◽  
Vol 42 (4) ◽  
pp. 379 ◽  
Author(s):  
Morton B. Epstein ◽  
Kenneth S. Pitzer ◽  
Frederick D. Rossini
Keyword(s):  
Equilibrium Constants ◽  
Free Energies

scholarly journals Heats, equilibrium constants, and free energies of formation of the alkylbenzenes

1946 ◽  
Vol 37 (2) ◽  
pp. 95 ◽  
Author(s):  
W.J. Taylor ◽  
D.D. Wagman ◽  
M.G. Williams ◽  
K.S. Pitzer ◽  
F.D. Rossini
Keyword(s):  
Equilibrium Constants ◽  
Free Energies

Solvation of Cl− and O2− with H2O, CH3OH, and CH3CN in the gas phase

1973 ◽  
Vol 51 (15) ◽  
pp. 2507-2511 ◽  
Author(s):  
R. Yamdagni ◽  
J. D. Payzant ◽  
P. Kebarle
Keyword(s):  
High Pressure ◽  
Temperature Dependence ◽  
Gas Phase ◽  
Experimental Technique ◽  
Equilibrium Constants ◽  
Ion Source ◽  
Mass Spectrometric ◽  
Mass Spectrometric Detection ◽  
Free Energies

Determination of the temperature dependence of the equilibrium constants Kn,n−1 for the reactions A −Bn = A −Bn−1 + B where A− equals Cl− and O2− and B is HOH, CH3OH, or CH3CN leads to the corresponding ΔH0n−1, ΔG0n−1,n, and ΔS0n−1,n values. The experimental technique is based on mass spectrometric detection of ions escaping from a high pressure ion source. At n = 1, Cl− is solvated most strongly by methanol, then CH3CN and HOH. At higher n a cross over is observed with water becoming the best solvent. These results are in agreement with the positive transfer enthalpies and free energies for Cl− from the liquid solvents HOH → CH3OH and HOH → CH3CN reported in the literature.O2− is solvated more strongly than Cl− appearing thus as an ion of "size" intermediate between Cl− and F− Again CH3OH gives the highest interaction for n = 1, however for n > 1 water gives stronger interactions.

Sign in / Sign up

Export Citation Format

Share Document