Density functional studies of the heats of formation of several nitroester compounds

The heats of formation of several nitroester compounds have been calculated at the levels of B3LYP, B3PW91 and B3P86 theories in conjunction with the 6-31g∗, 6-31g∗∗, 6-311g∗ and 6-311g∗∗ basis sets. Isodesmic reactions of seven nitroester compounds were selected in order to study their heats of formation at 298.15 K. The heats of formation obtained from the isodesmic reaction at the B3P86/6-31g∗∗ level are in reasonable agreement with the experimental results. But the heats of formation obtained from the atomization reaction at these levels are much too lower. Using B3P86/6-31g∗∗ method, the heats of formation of other five nitroesters are computed. In addition, it is noted that the computed heat of formation increases when the number of methylene group increases for normal chain alkyl nitrate and nitrite and the average increment of heat of formation is about 3.7 kcal/mol.