Evaluation of the Correlation between the Onset Temperature and the Elongation of Bond Length by Temperature Rise

Teruhito OTSUKA

Chemical Safety Research Group, National Institute of Occupational Safety and Health, Japan
1-4-6 Umezono, Kiyose-shi, Tokyo, 204-0024, Japan

(Received: August 4, 2009; Accepted for publication: September 15, 2009)

Dedicated to the late Prof. Kazuhide MORI.

The correlation between the elongation of the bond length and the onset temperature of the self-decomposing reaction was evaluated. The substitution products of nitrobenzene were chosen as the samples. The dispersion of the bond length calculated by quantum-chemistry theory with the harmonic oscillator approximation was used for evaluating the elongation. They were used for the calculation of the vibration frequencies and the unitary conversion coefficients which convert Cartesian coordinates to the standard vibration coordinates. Temperature influence was included in the partition function. The influence of the quantum-chemical calculation method was checked by the partition function. Even with the PM3 method of the semi-empirical molecular orbital theory, the partition function was agreed well with the experimental results. The results of the PM3 calculation of the non-conjugative substituent showed that the elongation was longer when the substance had a lower onset temperature.

Keywords: Onset temperature, Nitrobenzene, Differential scanning calorimetry, Bond length, Partition function, MOPAC

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