W. Acree, S. Bott, S. Tucker
Jun 1, 1996
Citations
1
Influential Citations
7
Citations
Journal
The Journal of Chemical Thermodynamics
Abstract
Abstract The standard ( p o = 0.1 MPa) enthalpies of formation Δ f H m o (cr) at the temperature T = 298.15 K were determined using static-bomb calorimetry for crystalline 5-methoxybenzofurazan (5MeOBFN), 5-methoxybenzofurazan-1-oxide (5MeOBFNO), 5-methylbenzofurazan-1-oxide (5MeBFNO), and 4-nitrobenzofurazan-1-oxide (4NO 2 BFNO); using rotating-bomb calorimetry for 5-chlorobenzofurazan-1-oxide (5ClBFNO). The standard enthalpies of sublimation Δ cr g H m o at T = 298.15 K were measured by microcalorimetry and, from the enthalpies of formation of the gaseous compounds, the dissociation enthalpies D m o of the (N + −O − ) dative covalent bonds were derived. Δ f H m o (cr)/(kJ·mol −1 ) Δ cr g H m o /(kJ·mol −1 ) D m o (N–O)/(kJ·mol −1 ) 5MeOBFN 57.9±1.7 89.2±0.7 5MeOBFNO 52.3±3.3 96.0±1.6 248.0±3.7 5MeBFNO 175.2±1.8 92.2±1.2 249.8±3.2 5ClBFNO 193.5±1.8 81.2±1.8 244.1±3.5 4NO 2 BFNO 202.6±2.1 97.3±1.6 255.9±6.7 The weighted mean value of D m o (N–O)/(kJ·mol −1 ) in benzofurazan-1-oxide derivatives has been assessed as (249.9±0.6)/(kJ·mol −1 ).