The tetrahedral intermediate from the hydration of N-methylformanilide

1993 ◽  
Vol 71 (12) ◽  
pp. 2109-2122 ◽  
Author(s):  
J. Peter Guthrie ◽  
Jonathan Barker ◽  
Patricia A. Cullimore ◽  
Jinqiao Lu ◽  
David C. Pike
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Dimethyl Acetal ◽  
Heat Of Formation ◽  
Basic Solution ◽  
Tetrahedral Intermediate ◽  
Rate Determining Step ◽  
Free Energy Of Formation ◽  
Hydrolysis Of ◽  
Energy Of Formation

Heats of hydrolysis of N-methylformanilide dimethyl acetal have been measured in basic solution. The heat of formation of N-methylformanilide was obtained by determining the equilibrium constant in aqueous solution for its formation from formic acid and N-methylaniline as a function of temperature:[Formula: see text]. These data permit the calculation of the heat of formation of N-methylformanilide dimethyl acetal, [Formula: see text]. The free energy of formation of the tetrahedral intermediate in the hydrolysis of N-methylformanilide was calculated by methods we have previously reported. Consideration of the energetics of the intermediates and the known rates of reaction leads to the conclusion that the rate-determining step for alkaline hydrolysis is cleavage of the C—N bond.

The enol content of simple carbonyl compounds: a thermochemical approach

1979 ◽  
Vol 57 (2) ◽  
pp. 240-248 ◽  
Author(s):  
J. Peter Guthrie ◽  
Patricia A. Cullimore
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Carbonyl Compounds ◽  
Free Energy Change ◽  
Energy Change ◽  
Free Energies ◽  
Enol Ethers ◽  
Free Energy Of Formation ◽  
Hydrolysis Of ◽  
Energy Of Formation

From the heats of hydrolysis of enol ethers, the heats of formation of the enol ethers, and thence the free energies of formation of the enol ethers in aqueous solution can be calculated. For this calculation it was necessary to determine the free energies of transfer from the gas phase to aqueous solution. By methods previously published it was possible to estimate the free energy change for the hypothetical hydrolysis reaction leading from the enol ether to the enol, which in turn made possible calculation of the free energy of formation of the enol. Finally the free energy change for enolization in aqueous solution could be calculated using the known free energy of formation of the corresponding keto tautomer. In this way the following were determined: carbonyl compound, pKenol = −log ([enol]/[keto]): acetaldehyde, 5.3; propionaldehyde, 3.9; isobutyraldehyde, 2.8; acetone, 7.2; 2-butanone, 8.3; 3-pentanone, 7.8; cyclopentanone, 7.2; cyclohexanone, 5.7; acetophenone, 6.7.

Energetics of acetic acid enol in aqueous solution. A new method for thermodynamic estimation

1993 ◽  
Vol 71 (12) ◽  
pp. 2123-2128 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Acetic Acid ◽  
Satisfactory Agreement ◽  
Marcus Theory ◽  
New Method ◽  
Free Energy Of Formation ◽  
Independent Estimate ◽  
Energy Of Formation

A new disproportionation calculation allows the estimation of the free energy of formation of the enol of acetic acid as 65 ± 2 kcal/mol. The value of pKE derived from this free energy, pKE = 21 ± 2, is in satisfactory agreement with information from the literature about rates of exchange. Analysis of the data on rates of exchange of the C-H protons of acetic acid using Marcus theory allows an independent estimate of the enol content. Exchange in acid and in base lead to internally consistent estimates, pKE = 19.3 ± 2.2, which are within the combined uncertainties of the values from the thermodynamic estimate.

Tautomeric equilibria and pKa values for 'sulfurous acid' in aqueous solution: a thermodynamic analysis

1979 ◽  
Vol 57 (4) ◽  
pp. 454-457 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Aqueous Solutions ◽  
Equilibrium Constants ◽  
Acid Solutions ◽  
Sulfurous Acid ◽  
Free Energy Of Formation ◽  
Dilute Aqueous Solutions ◽  
Sulfite Ion ◽  
Energy Of Formation

The free energy of formation of dimethyl sulfite in aqueous solution can be calculated as −91.45 ± 0.79 kcal/mol; this calculation required measurement of the solubility of dimethyl sulfite. From this value and the pKa of SO(OH)2, using previously reported methods, the free energy of formation of SO(OH)2 can be calculated to be −129.26 ± 0.89 kcal/mol. Comparison of this value with the value obtained from the free energy of formation of 'sulfurous acid' solutions, calculated from the free energy of formation of sulfite ion and the apparent pKa, values, permits evaluation of the free energy of covalent hydration of SO2 as 1.6 + 1.0 kcal/mol, in agreement with earlier qualitative spectroscopic observations. From the apparent pKa and the anticipated pKa values for the tautomers (SO(OH)2, pK1 = 2.3; HSO2(OH), pK1 = −2.6) it is possible to calculate the free energy change for tautomerization of SO(OH)2 to H—SO2(OH) as +4.5 ± 1.2 kcal/mol. All equilibrium constants required for Scheme 1, describing the species present in dilute aqueous solutions of SO2, have been calculated. In agreement with previous Raman studies the major tautomer of 'bisulfite ion' is calculated to be H—SO3−.

THERMODYNAMIC PROPERTIES OF SYNTHETIC BASIC ALUMINITE [Al4(OH)10SO4∙5H2O] FROM SOLUBILITY DATA

1980 ◽  
Vol 60 (2) ◽  
pp. 381-384 ◽  
Author(s):  
S. SHAH SINGH
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Entropy Change ◽  
Heat Of Formation ◽  
Standard Free Energy Change ◽  
Kcal Mole ◽  
Free Energy Of Formation ◽  
Equilibrium Data ◽  
Solubility Equilibrium ◽  
Energy Of Formation

From the solubility equilibrium data of basic aluminite at three temperatures, the standard free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were determined as 160.02 kcal∙mole−1, 65.48 kcal∙mole−1 and 317.1 cal∙deg−1]mole−1, respectively. From these values the free energy of formation (ΔGf°) and the heat of formation (ΔHf°) of basic aluminite was also computed and was 1465.25 kcal∙mole−1 and 1682.08 kcal∙mole−1, respectively.

scholarly journals Isomers of (L)-Diiodotyrosine - A DFT Treatise

2021 ◽  
pp. 347-361
Author(s):  
Lemi Türker
Keyword(s):  
Density Functional Theory ◽  
Free Energy ◽  
Hydrogen Bonding ◽  
Quantum Chemical ◽  
Density Functional ◽  
Heat Of Formation ◽  
Functional Theory ◽  
Free Energy Of Formation ◽  
Ionic Forms ◽  
Energy Of Formation

(L)-Diiodotyrosine isomers are considered within the realm of density functional theory at the level of B3LYP/6-311+G(d,p). Their zwitter ionic forms are considered as well. All the structures are electronically stable, have exothermic heat of formation and favorable Gibbs free energy of formation values. Within the limitations of the method the zwitter ionic forms are not different from the corresponding parent structures in the vacuum conditions and no hydrogen bonding seems to exist between the NH2 and COOH groups. Some structural, quantum chemical and spectral data have been collected and discussed.

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