Thermochemical properties for n‐propyl, iso‐propyl, and tert‐butyl nitroalkanes, alkyl nitrites, and their carbon‐centered radicals

Abstract

Density functional theory (DFT) based calculations are performed on a series of alkyl nitrites and nitroalkanes representing large-scale primary, secondary, and tertiary nitro compounds and their radicals resulting from the loss of their skeletal hydrogen atoms. Geometries, vibration frequencies, and thermochemical properties [S • (T) and /6-31+G(2d,2p), and the composite CBS-QB3 levels. Potential energy barriers for the internal rotations have been computed at the B3LYP/6-31G(d,p) level of theory, and the lower barrier contributions are incorporated into entropy and heat capacity data. The standard enthalpies of formation at 298 K are evaluated using isodesmic reaction schemes with several work reactions for each species. Recommended values derived from the most stable conformers of respective nitro-and nitrite isomers include −30.57 and −28.44 kcal mol −1 for n-propane-, −33.89 and −32.32 kcal mol −1 for iso-propane-, −42.78 and −41.36 kcal mol −1 for tert-butane-nitro compounds and nitrites, respectively. Entropy and heat capacity values are also reported for the lower homologues: nitromethane, nitroethane, and corresponding nitrites. C

Thermochemical Properties of exo-Tricyclo[5.2.1.02,6]decane (JP-10 Jet Fuel) and Derived Tricyclodecyl Radicals

“…Higher level ab initio and DFT-based composite methods G3MP2B3 , and CBS-QB3 are also utilized in work reaction calculations which are more reliable in predicting accurate energies as shown in our previous studies. , G3MP2B3 is a modified version of the G3MP2 method where the geometries and zero-point vibration energies are from B3LYP/6-31G(d) calculations. CBS-QB3 uses the B3LYP/6-311G(2d,d,p) level to calculate geometries and frequencies followed by several single point energy calculations at the MP2, MP4SDQ, and CCSD(T) levels.…”

Mechanism and Kinetics of the Reaction NO3+ C2H4

“…The magnitude of this adjustment is within the range of error expected for the CBS-QB3 method, especially when the enthalpy of formation of the NO 3 free radical computed using CBS-QB3 is in error by ∼3–4 kcal/mol (see Table S1, Supporting Information). Experience shows that the CBS-QB3 method can predict “chemically accurate” energies (including barrier heights, heats of formation, bond dissociation energies, and others) within 1–2 kcal mol –1 of experimental values. − The empirical adjustment (i.e., reduction of the energy of TS-ar by 1 kcal mol –1 ) was made to obtain better agreement with the rate constants measured by Canosa-Mas, Atkinson et al, Biggs et al, and Boyd et al, as described below.…”

Letter to the editor: Electronic data formats for open storage of published chemical kinetic data

“…This will be published in a future issue and is already available on request to submitting authors. The current issue contains an article with online supplementary material demonstrating our proposed approach for storing species identifiers, 3D molecular structures, and thermodynamic data [8]. We are very grateful to the authors for their help and patience, especially Dr. Joseph Bozzelli.…”