Self-decomposition

Guide to the Self-decomposition ofRaidiochemicals, Amersham International pic, Amersham, U.K., 1992. 

The absence of mixing (PFR) leads to an optimal ozone usage. If it is assumed that in the PFR the concentration at the exit approaches 0 (optimal conditions) then the amount of ozone self-decomposition in the PFR can be compared to that in the CFSTR using the third term in the right-hand side of the equations (4) and (8). From this comparison it is clear that in the CFSTR more ozone will be lost due to self-decomposition than in the PFR. 

The sustained decomposition of a substance without introduction of any other apparent ignition source besides thermal energy and without air or other oxidants present. Autodecomposition is the result of a thermal self-decomposition reaction for given initial conditions (temperature, pressure, volume) at which the rate of heat evolution exceeds the rate of heat loss from the reacting system, thus resulting in an increasing reaction temperature and reaction rate. 

The formation of RDX cluster ions in LC/MS and the origin of the clustering agents have been studied in order to determine whether the clustering anions originate from self-decomposition of RDX in the source or from impurities in the mobile phase [19], IsotopicaUy labeled RDX ( C3-RDX and Ng-RDX) were used in order to estabhsh the composition and formation route of RDX adduct ions produced in ESI and APCI sources. Results showed that in ESI, RDX clusters with formate, acetate, hydroxyacetate and chloride anions, present in the mobile phase as impurities at ppm levels. In APCI, part of the RDX molecules decompose, yielding NO2 species, which in turn cluster with a second RDX molecule, producing abundant [M- -N02] cluster ions. 

An extensive kinetic study of the H-abstraction reactivity (A h) from appropriate substrates (RH) has been undertaken by spectrophotometry in MeCN solution at 25 °C, by using CAN for the generation of BTNO from HBT . The rate constants, which are first order in both BTNO and the H-donor, are faster than the self-decomposition of BTNO for the substrates reported in Table 6, but uniformly slower than those determined with PINO (cf. Table 4) for equal substrate by at least one order of magnitude. 

The alpha radiation chemical effects at the curie level are severe, leading to the self-decomposition of most polonium compounds thus solid polonium salts of organic acids char rapidly and polonium iodate evolves free iodine. 

Chemical Stability. Chemical stability as defined by TCC-RMD refers to the ability of a material to be stored for long periods without undergoing self-decomposition or chemical reaction. If this occurs, it can produce gaseous products which can cause a dangerous buildup of pressure within the storage container. 

A number of papers deal with the self-decomposition of radioac-tively labelled carbohydrates.387-371... 

Escher, E.H.F., Robert, H. and Guillemette, G. (1979) Helv. Chim. Acta 62. 1217. Evans, E.A. (1976) Self-Decomposition of Radiochemicals Principles. Control Observations and Effects, The Radiochemical Centre, Amersham, England. 

The polymerization reaction is known to be of the radical type, since it is initiated by suitable compounds ("initiators") that, either by reaction with the monomer or by self-decomposition, give origin to primary radicals in the past, oxygen was used almost exclusively (1), while the modem trend is to use organic initiators such as peroxides, hydroperoxides and so on. 

Nitric acid is subject to self-decomposition, depending on the concentration and temperature. The general rule is the higher the concentration or the temperature, the faster the decomposition rate. Nitric acid must be transported from the manufacturer to the user within the shortest possible time, particularly in the summer months 97... 

In general, an explosion is an exothermic chemical reaction between two components. A well-known example is the reaction between the oxygen content of the atmospheric air and a combustible substance like petrol. As an exception, there are very few substances - such as acetylene - which are thermodynamically unstable and tend to exothermic self-decomposition. An explosion can start only with an ignition source and a volume or mass ratio of the two components in such a manner that the reaction zone is sustained by itself. Typical values of the peak explosion pressure - when starting with components at atmospheric pressure in a constant volume - are 1 MPa (10 bar) and a propagation velocity of the reaction zone up to 102m/ s (as an order of magnitude). 

Burden and Burgoyne [60] measured not only the cool flame and hot ignition limits for mixtures of ethylene oxide with air and oxygen, but also observed blue flames and self-decomposition flames. 

The adiabatic flame temperature calculated from the stoichiometry was 1000 °K, while the measured value was 923 °K the difference being almost certainly due to heat losses from the 0.05 cm diameter thermocouple used. The residence time in the reaction zone under the conditions employed was approximately 3 x 10 sec which was long enoi h for appreciable self-decomposition to have taken place. For a brief discussion of the likely mechanism, see Sect. 4.2... 

Methyl nitrite burns vigorously with oxygen at atmospheric pressure giving a very fast flame. It will also support a very feeble, slow self-decomposition flame [122—124]. The latter is orange-red and the burning velocity [125], relative to the unburnt gas at 18 °C, is about 3.5 cm.sec , while the global activation energy [126] is 37.5 kcal.mole . The final products of the flame are represented by the stoichiometric equation... 

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... 

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