Decomposition flames, unimolecular

The Unimolecular Decomposition Flame with Lewis Number of Unity... 

THE UNIMOLECULAR DECOMPOSITION FLAME WITH LEWIS NUMBER OF UNITY... 

This ester resembles its methyl homologue in possessing three modes of decomposition [131]. It also supports a self-decomposition flame, the multiple reaction zones of which are clearly separated at low pressures [122, 123, 125]. Temperature and composition profiles in the low-pressure decomposition flame have been measured [133]. The products include formaldehyde, acetaldehyde and ethanol with smaller amounts of methane and nitromethane. The activation energy derived from the variation of flame speed with final flame temperature was 38 kcal. mole", close to the dissociation energy of the RO—NO2 bond. The controlling reaction is believed to be unimolecular in its low pressure regime, and the rate coefficient calculated from the heat-release profile is... 

The slow, thermal decomposition of hydrazoic acid in a static system has been studied by Meyer and Schumacher58. It turned out to be completely governed by heterogeneous catalysis. There are no studies on the kinetics of the homogeneous decomposition of this substance save for the investigation of its decomposition flame59. From the variation of flame properties with pressure it can be deduced that second-order reactions control the over-all rate. The unimolecular reaction... 

The slow combustion reactions of acetone, methyl ethyl ketone, and diethyl ketone possess most of the features of hydrocarbon oxidation, but their mechanisms are simpler since the confusing effects of olefin formation are unimportant. Specifically, the low temperature combustion of acetone is simpler than that of propane, and the intermediate responsible for degenerate chain branching is methyl hydroperoxide. The Arrhenius parameters for its unimolecular decomposition can be derived by the theory previously developed by Knox. Analytical studies of the slow combustion of methyl ethyl ketone and diethyl ketone show many similarities to that of acetone. The reactions of methyl radicals with oxygen are considered in relation to their thermochemistry. Competition between them provides a simple explanation of the negative temperature coefficient and of cool flames. 

Above 250°C. we approach, in the gas phase, what is known as the cool flame regime. This is characterized by induction periods and by the appearance of pressure peaks and luminescent phenomena in the oxygen-hydrocarbon system. The consensus of present data seems to support the contention that these cool flames arise from the secondary decomposition of the hydroperoxides produced by the low temperature chain. The unimolecular decomposition of the hydroperoxide yields active alkoxy and hydroxyl radicals ... 

Most of the ethyl nitrate decomposes in the high temperature region (740—800 °K) of the flame where it is believed that unimolecular thermal decomposition [129] is the rate controlling process. The rate equation given above corresponds to a unimolecular reaction in its low-pressure region and the pre-exponential term suggests that the activation energy is distributed over about 10 square terms. 

Inagaku N., Sakm-ai S., and Katsuru a K., Affeet tris(2,3-bromo-propyl) phosphate with flame retardant of polystyrene , J. Appl. Polym. Sci., 1979, vol. 23, pp. 2023 - 2030. Brown C., Wilkie C., Smukalla J., and Cody B., Inhibition by red phosphorus of unimolecular thermal chain scission in poly(methyl methacrylate) investigation by NMR, FT-IR and laser decomposition/ Fourier transform mass spectroscopy, J. Polym. Sci. Polym. Chem. Ed., 1986, vol. 24, pp. 1297 - 1311. 

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