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This paper gives the results of temperature measurements at the beginning of fast decomposition of nine commercial azo dyes under heating. The enthalpies of formation of three azo dyes are measured, and the parameters of their explosive transformation are calculated. It is shown that for the flash temperatures obtained using the kinetic parameters of decomposition reactions and calculated heats of explosion of azo dyes, the average deviation from experimental values is 4.5%. [ABSTRACT FROM AUTHOR]

Abstract  Conformational analysis of cumene hydroperoxide PhCMe2OOH (1) has been carried out using the density functional methods B3LYP/6-31G(d,p) and B3LYP/6-311+G(3df,2p). Ignoring rotation of methyl groups, molecule 1 has seven conformers differing in orientation of the — CMe2OOH fragment relative to the benzene ring and in mutual position of atoms in this fragment. The molecular structures, relative energies, and statistical distribution of the conformers were determined, and intramolecular rotational barriers were estimated. The enthalpies of formation of all conformers of molecule 1 were calculated using two approximations with inclusion of zero-point vibrational energy and temperature correction. Calculations using the isodesmic reaction (IDR) scheme made it possible to reduce the systematic error of the determination of the enthalpy of reactions. The total enthalpy of formation of compound 1 calculated with inclusion of statistical distribution of rotamers equals −19.7±3.6 kcal mol−1. The combination of the B3LYP/6-31G(d,p) approximation and the IDR scheme gives fairly accurate results (relative error is ±0.4 kcal mol−1) as compared to those obtained with the extended basis set 6-311+G(3df,2p). [ABSTRACT FROM AUTHOR]