Estimation of heats of vaporization for non associating organic liquids from the boiling points at various pressures

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. Can. J. Chem. 71, 2109Chem. 71, (1993.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: m : (~) = -33.78 * 1.85 kcal/mol. These data permit the calculation of the heat of formation of N-methylfonnanilide dimethyl acetal, AH;(l) = -72.95 * 1.85 kcal/mol. 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. Operant en solution basique, on a mesurC les chaleurs d'hydrolyse l'acktal dimkthylique de la N-mCthylformanilide. On a obtenu la chaleur de formation de la N-mCthylformanilide en determinant la constante d'kquilibre en fonction de la temperature (en solution aqueuse) pour sa formation 2 partir de l'acide formique et la N-methylaniline: m;(1) = -33,78 * 1,85 kcal/mol. Ces donnCes permettent de calculer la chaleur de formation de I'acCtal dimkthylique de la N-mCthylformanilide, mY(1) = -72,95 * 1,85 kcal/mol. Utilisant des methodes dkcrites anterieurement, on a calculC 1'Cnergie libre de formation de I'intermCdiaire tCtraCdrique implique dans l'hydrolyse de la N-mCthylformanilide. Une considCration des energies des intermediaires et des constantes de vitesse connues mkne i la conclusion que 1'Ctape qui dktermine la vitesse de la reaction de l'hydrolyse alcaline est le clivage de la liaison C-N.[Traduit par la redaction]

“…This was done by van't Hoff analysis of the equilibrium constants at 25,35, and 45°C for processes [5] and 161.…”

Section: = X[hcon(me)ph (1) + 2meoh (L)]mentioning

confidence: 99%

Section: = X[hcon(me)ph (1) + 2meoh (L)]mentioning

confidence: 99%

Section: = X[hcon(me)ph (1) + 2meoh (L)]mentioning

confidence: 99%

See 1 more Smart Citation

The tetrahedral intermediate from the hydration of N-methylformanilide

Guthrie¹,

Barker²,

Cullimore³

et al. 1993

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“…[8]. Then, by methods we used before, we could calculate the heats of formation for the liquids, heats of vaporization (125), entropies, free energies of transfer (126), and thus free energies of formation in aqueous solution. Then we could calculate the (small) free energy changes for the hypothetical hydrolysis reactions replacing 0CH3 by OH (29), eq.…”

Section: Conjecture 2: Multidimensional Marcusmentioning

confidence: 99%

1995 Syntex Award Lecture Correlation and prediction of rate constants for organic reactions

Guthrie¹

1996

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Abstract:Marcus theory provides a framework for correlating rate and equilibrium constants, and thus the possibility of predicting rate from structure. This had been successful for a number of simple reactions, including the addition of hydroxide to carbonyl compounds, enolate formation from carbonyl compounds, and aldol addition and elimination reactions. The theory can be extended, as Multidimensional Marcus Theory, to cover concerted reactions such as E2 eliminations, the water-mediated proton switch, or the breakdown of the tetrahedral intermediate in amide hydrolysis. We have now found that Marcus theory can be applied not only to inter-molecular reactions but also to intra-molecular reactions. This is illustrated for aldol condensation and esterllactone formation.Key words: Marcus theory, concerted reactions, intramolecular reactions, aldol condensation, ester formation, proton transfer.Resume : La thCorie de Marcus offre un s y s t h e pour Ctablir des corrClations entre les constantes de vitesse et dlCquilibre et, de ce fait, la possibilitC de faire des pridictions relatives aux vitesses ii partir des structures. Cette approche a Ct C couronnke de succks pour un certain nombre de rCactions simples, y compris l'addition de l'ion hydroxyde ii des composks carbonylks, la formation d'Cnolates 5 partir de composCs carbonylks et les rkactions d'addition et d'klimination aldoliques. On a ktendue la thiorie, sous la forme de la thCorie multidimensionnelle de Marcus, pour couvrir les rCactions concertkes, comme les Climinations E2, 1'Cchange de protons avec l'eau comme mCdiateur ou 1adCpyramidalisation de l'intermkdiaire tCtraCdrique lors de l'hydrolyse des amides. On a trouvC que la thCorie de Marcus peut &tre appliquCe, non seulement aux rCactions inter~nolCculaires mais aussi aux rCactions intramolCculaires. On illustre ce point par la condensation aldolique et le formation d'esterllactone.

“…For the cases where atmospheric pressure boiling points were available the agreement is good. Estimation of heats of vaporization We estimated heats of vaporization from the boiling p i n t data, using a method that we had previously devised to use boiling points at various pressures (12). The boiling points and derived heats of vaporization are found in Table 3.…”

Section: Heats Of Formationmentioning

confidence: 99%

Equilibrium constants and heats of formation of methyl esters and N,N-dimethyl amides of substituted benzoic acids

Guthrie¹,

Pike²,

Lee³

1992

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.Heats of methanolysis and dimethylaminolysis of substituted benzoyl chlorides (4-X-C6H4-COC1, X = H, CH,, 0CH3, C1, NO,) have been measured, as have the heats of hydrolysis of the esters, permitting the calculation of the heats of formation of the benzoyl chlorides (4-X-C6H4-COCl, X, DHf: CH30, -80. 29 of transfer from methanol to water and from gas to water were determined for the esters and amides. Free energies of formation in aqueous solution were calculated for the acids, esters and amides, making use of thermodynamic estimation procedures where necessary. Equilibrium constants were measured for ester formation in water (X, K (M-I): CH30, 0.14; CH,, 0.14; H, 0.12; C1, 0.15; NO,, 0.13) and N,N-dimethylaminolysis in methanol (X, K (M-I): CH30, 8.16; CH,, 17.5; H, 26.5; C1, 22.6; NO,, 41.0). Partition constants for esters and amides were measured for methanol/dodecane and dodecane/water, permitting calculation of the free energy of transfer from methanol to water (4-X-C6H4-COOCH,, X, DG,,: CH30, 3.12; CH,, 3.17; H, 3.01; C1, 3.43; NO,, 2.89; 4-X-C6H4-CON(CH,),, X, DG,,: CH30, 0.96; CH,, 1.48; H, 0.92; Cl, 1.77; NO2, 0.99). These data permit calculation of the equilibrium constants for dimethylaminolysis of substituted methyl benzoates in water, and for amide formation in water (4-X-C6H4-CON(CH,),, X, K(M-', reactants and products as neutral molecules): CH30, 767; CH,, 752; H, 2050; C1, 1020; NO,, 2350). In the course of our calorimetric measurements we derived an improved value for the heat of solution of HC1 in methanol.