The Enthalpies of Formation of Ethylenediamine, 1,2-Propanediamine, 1,2-Butanediamine, 2-Methyl-1,2-propanediamine, and Isobutylamine. the C--n and N--f Thermochemical Bond Energies.
The enthalpies of combustion of ethylenediamine, 1,2-propanediamine, 1,2-butanediamine, 2-methyl-1,2-propanediamine, and isobutylamine, as determined by oxygen-bomb combustion calorimetry, were used to derive the following values, in kcal per mole, for the enthalpies of formation of the liquid, ahf deg 298.15, From graphite and gaseous hydrogen and nitrogen: ethylenediamine, -15.06 +/- 0.13; 1,2- Propanediamine, -23.38 +/- 0.10; 1,2-Butanediamine, -28.74 +/- 0.19; 2-Methyl-1,2-propanediamine, -32.00 +/- 0.16; and isobutylamine, - 31.68 +/- 0.12. These values were combined with enthalpies of vaporization derived from vapor pressure measurements to obtain values of the enthalpies of formation in the gaseous state. For these molecules, the c--n thermochemical bond energy was derived and compared to that in the simple alkyl amines. The n--h thermochemical bond energy in a 1,2-diamine was compared to the n--f thermochemical bond energy in a 1,2-bis(difluoroamino)-alkane.
J. Chem. and Eng. Data, V. 15, No. 1, January 1970, PP. 150-154