Enthalpies of formation of cyclopentylamine and cyclobutylamine; vapor pressure of cyclopentylamine

• Published in: The Journal of chemical thermodynamics 1975-01, Vol.7 (3), p.285-291
• Main Authors: Good, W.D., Messerly, J.F., Osborn, A.G., Doublin, D.R.
• Format: Article
• Language: English
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/0021-9614(75)90067-1

The enthalpies of combustion of cyclobutylamine and cyclopentylamine were measured by precision oxygen-bomb combustion calorimetry. The following values are reported for the standard enthalpy of combustion, ΔH c o(298.15 K)/kcal th mol −1, of these compounds in the liquid state: cyclobutylamine, −(684.96±0.13); cyclopentylamine, −(823.25±0.19). The enthalpy of vaporization of cyclopentylamine, ΔH v(298.15 K) = (9.60 6 ± 0.10 0) kcal th mol −1, was obtained from ebulliometric vapor-pressure measurements; the enthalpy of vaporization of cyclobutylamine was estimated. Values of the enthalpy of formation in the liquid and gaseous states were derived for both compounds. Gaseous cyclobutylamine appears to be about 2 kcal th mol −1 more thermochemically stable than would be predicted from thermodynamic data for other secondary amines such as isopropylamine, sec-butylamine, cyclopropylamine, and cyclopentylamine and their parent hydrocarbons. Values of the thermochemical bond energy, E( rm( C N), were estimated.