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Thermochemical properties for n ‐propyl, iso ‐propyl, and tert ‐butyl nitroalkanes, alkyl nitrites, and their carbon‐centered radicals
Author(s) -
Snitsiriwat Suarwee,
Asatryan Rubik,
Bozzelli Joseph W.
Publication year - 2010
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20479
Subject(s) - chemistry , isodesmic reaction , nitroethane , standard enthalpy of formation , nitromethane , nitro , heat capacity , propane , conformational isomerism , radical , thermochemistry , alkyl , density functional theory , medicinal chemistry , computational chemistry , thermodynamics , organic chemistry , molecule , physics
Density functional theory (DFT) based calculations are performedon a series of alkyl nitrites and nitroalkanes representinglarge‐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 C° p (T) (10 K ⩽ T ⩽ 5000 K)] are calculated at the B3LYP/6‐31G(d,p) DFT level. Δ f H° 298 values are from B3LYP/6‐31G(d,p), B3LYP/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. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 181–199, 2010