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- Author or Editor: K. Wojciechowski x
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Thermal analysis was performed on amide derivatives ofN,N-dialkylaminoazobenzene. A correlation was found between the stability of the investigated dyes and the nature of the amide residue. The intermolecular interaction and the mechanism of thermal decomposition are discussed.
Abstract
The kinetic data on the molecular oxygen activity of CH3CH·, CH3CF2 · and CF3CHF· radicals are reported. In laboratory, these radicals were generated by pulsed (12 ns) electron beam interaction with the gaseous RHF-O2-CO2 mixtures containing large excess of carbon dioxide (RHF = CH3CH2F, CH3CHF2 or CH2FCF3). The transient product (O3 or RFO2 ·) formation was monitored by the UV absorptions at 250 nm and the rate constants of Reactions (4) and (9) were obtained. The values of k 9 diminished with increasing number of fluorine atoms in RHF molecule. For CH3CH2F and CH3CHF2 the k 9’s were equal to (8.8–10.2)·10−14cm3 ·s−1 and (7.3–8.4)·10−14cm3 ·s−1, respectively, and seem to be determined for the first time. In the case of CH2FCF3 the obtained value of k CF3CHF+O2 = 5.20±0.76·10−14cm3 ·s−1 is much higher than the value published in the literature.4 The other determined rate constant data are comparable to the literature values.
Abstract
The kinetics of the peroxy radicals RHFO2 reactions with NO has been studied by using pulse radiolysis and UV absorption spectroscopy. The rate constants of interaction of oxygen atoms with NO − k 2 = 2.2±0.2·10−12 cm3·s−1 and NO2 − k 3 = 2.1±0.2·10−11 cm3·s−1 were found in agreement with the literature values. The bath gases (SF6 or CO2) have got minor effect on the rate constants of RHFO2+NO→NO2+prod. reactions; RHFO2 = CH3CH2O2, CH3CHFO2, CH3CF2O2, CF3CH2O2, CF3CHFO2. The obtained rate coefficients are in the scope of the literature values, although they are lower than those recommended in NIST database. The reasons are discussed.
Abstract
Abstract
A detailed analysis is presented of the applicability of several dependences commonly used for the determination of activation energies from non-isothermal measurements. Reactions proceeding according to different kinetic equations are simulated and the validity of the activation energy values obtained is discussed. The general conclusion is drawn that none of the examined dependences should be used to determine the activation energy. For a rough estimation of activation energy, the Kissinger equation can be applied according to Ockham's razor.
Abstract
A series of six nitrates(V) hydrates of 4d-metals as well as mercury and cadmium thermal decomposition was examined by DTA, TG and EGA techniques. It was found that thermal decomposition of d-metals nitrate(V) hydrates proceeds in three stages: partial dehydration, oxo-nitrates and hydroxide nitrates formation and metal oxides formation. General chemical equations for all decomposition stages were proposed. It was found that dehydration of hydrated salts is accompanied by partial decomposition of nitrate(V) groups.
