Thermochemistry of 2-amino-3-quinoxalinecarbonitrile-1,4-dioxide. Evaluation of the mean dissociation enthalpy of the (N-O) bond.
The standard enthalpy of formation of the 2-amino-3-quinoxalinecarbonitrile-1,4-dioxide compound in the gas-phase was derived from the enthalpies of combustion of the crystalline solid measured by static bomb combustion calorimetry and its enthalpy of sublimation determined by Knudsen mass-loss effusion at T= 298.15 K. This value is (383.8 +/- 5.4) kJ mol(-1) and was subsequently combined with the experimental gas-phase enthalpy of formation of atomic oxygen and with the computed gas-phase enthalpy of formation of 2-amino-3-quinoxalinecarbonitrile, (382.0 +/- 6.3) kJ mol(-1), in order to estimate the mean (N-O) bond dissociation enthalpy in the gas-phase of 2-amino-3-quinoxalinecarbonitrile-1,4-dioxide. The result obtained is (248.3 +/- 8.3) kJ mol(-1), which is in excellent agreement with the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G(d) computed value.
Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007, Porto, Portugal. mdsilva@fc.up.pt
Maria D M C
MD
Ribeiro da Silva
Jose R B
JR
Gomes
Jorge M
JM
Goncalves
Emanuel A
EA
Sousa
Siddharth
S
Pandey
William E
WE
Acree
D002151:Calorimetry; D003198:Computer Simulation; D003497:Cyclic N-Oxides / Q000737:chemistry*; D015394:Molecular Structure; D011804:Quinolines / Q000737:chemistry*; D013816:Thermodynamics
C501552:2-amino-3-quinoxalinecarbonitrile-1,4-dioxide; D003497:Cyclic N-Oxides; D011804:Quinolines