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1. The interaction of 2,2,6,6-tetramethylpiperidin-1-oxyl with xenon difluoride leads to the formation of oxopiperidinium cations through oxidation of the\(\begin{array}{*{20}c} {\backslash \backslash } \\ {//} \\ \end{array} N\mathop - \limits^ \cdot 0\) group, nitroso compounds, through detachment ofβ-hydrogen atoms from the piperidinoxyl radicals by monofluoroxenon radicals, and products resulting from nitroso-compounds oxidation. 2. The interaction of piperidinoxyl with xenon difluoride follows a second-order rate equation. Kinetic parameters have been estimated for this process, and a mechanism developed for it.

Oxoammonium fluorides have been prepared for the first time by oxidizing nitroxyl radicals with xenon fluoride. Nitroso compounds are formed in the oxidation of piperidinoxyl radicals.

1. The enthalpies of combustion, vaporization, and formation of N-nitro- and N-nitrosomorpholine have been determined calorimetrically. 2. Based on the kinetic data for the decomposition of N-nitro- and N-nitrosomorpholine in the gas phase it is concluded that the primary and rate-limiting step in these reactions is homolytic N-N bond cleavage. 3. By comparing the thermochemical and kinetic data we have been able to determine the N-N bond dissociation energies in N-nitro- and N-nitrosomorpholine, as well as the N-O bond energy in N-nitromorpholine and the N-H bond dissociation energy in morpholine; these values were found to agree with literature data for the thermochemical parameters in related compounds.

1. A study has been made of the kinetics of thermal decomposition of N,N′-dinitropiperazine and 1,3-dinitro-1,3-diazacyclopentane, in melts and in solution. Energies of N-NO2 bond dissociation in these compounds have been calculated. 2. The activation parameters for the thermal decomposition of the cyclic nitroamines are only weakly dependent on the number of nitroamine groups in the molecule, and the size of the ring. 3. The enthalpy of formation of the N-nitropiperazyl radical has been determined.

1. The thermal decomposition of N,N-dinitroamines is homogeneous and unimolecular in the gas phase. The limiting step of the process is the rupture of the N-NO2 bond. 2. The activation parameters of the process imply that the dinitroamine group is more reactive than the mononitroamine group in thermal decomposition. The energy of dissociation of the N-NO2 bond in dinitroamines is ∼42 kJ/mole less than in mononitroamines. 3. Nitrogen dioxide and acetaldehyde do not influence the kinetics of thermal decomposition of dinitroamines due to their high reactivity.

1. The kinetics of the thermal decomposition of bis-(2,2-dinitropropyl)-N-nitrosoamine, bis-(2,2-dinitro-2-fluoroethyl)-N-nitrosoamine, and bis-(2,2,2-trinitroethyl)-N-nitrosoamine was studied. 2. The reactions are described by a first-order equation. The activation energies and preexponential factors were determined. 3. The reaction center in the bis-(2,2,2-trinitroethyl)-N-nitrosoamine molecule is the trinitromethyl group, while in the other two compounds it is the nitrosoamine group. The mechanism of the decomposition is discussed. 4. The enthalpy of formation of the (NO2)2CCH2N(NO)CH2C(NO2)3 radical was calculated.

1. The decomposition of xenon trioxide in aqueous solution proceeds via a chain mechanism over the range 1 < pH < 10 with the formation of hydrogen peroxide and XeO2 (XeO) as intermediate substances. 2. Over the range pH >10 the chain mechanism changes to an ionic mechanism involving the di-sproportionation of Xe(VI) with the formation of Xe(VIII) perxenates.

Results primarily on nitramines are summarised. Analysis of modern views indicates that a non-chain radical mechanism with rupture of the N?NO2 bond in the rate-determining stage is the most soundly based. Kinetic parameters of the thermal decomposition of N-nitro-compounds are systematised. The kinetic role of phase constitution is discussed, and prospects for future research are considered. A list of 108 references is included.

1. High-purity lithium perxenonate Li4XeO8· 2H2O was synthesized. 2. The thermal stability of lithium perxenonate was studied by the methods of weight loss of the sample under isothermal conditions, differential thermal and gravimetric analyses. 3. The temperatures of the decomposition of lithium perxenonate depend substantially on the conditions of production and preliminary drying of the preparation. 4. The kinetics of the thermal decomposition of lithium perxenonate were studied, and the activation energy, equal to 55.7 kcal/mole, was determined.

1. The kinetics of heat evolution for tetryl decomposition were measured over the temperature range 130–155°. The mean heat of reaction in this temperature range was 341 cal/g. 2. The kinetics of tetryl decomposition could be expressed by the equation for an autocatalytic reaction of the first order, with a correction for the change in volume during the reaction. 3. The calculated kinetic constants, pre-exponential factors, and activation energies for tetryl decomposition, over the temperature range studied, were the same, using data obtained by the heat evolution and loss in weight methods.

CONTENTS I. Introduction 278 II. Generalisation and development of the classical theory of thermal explosions 278 III. Thermal explosion regimes not described by the classical theory 285 IV. Methods of experimental investigation and tests of the theory 288 V. Mechanism of thermal explosion in condensed media 289

Literature data on the thermal decomposition reactions of aliphatic nitro-compounds are surveyed and described systematically. Information concerning the influence of molecular structure on the rates and mechanisms of the gas-phase reactions is presented and the structures of the transition states in the C-N dissociation and HNO2 elimination processes are examined. The characteristic features of the decomposition of nitro-compounds in the condensed phase are desctibed. Data are presented on the C-N bond dissociation energy and the influence on the latter of electronic, steric, and conformational effects. The bibliography includes 86 references.

1. The composition of the decomposition products of tetranitromethane, 1,1,1-trinitroethane, chloro-, bromo-, and iodonitroforms in the gas phase was determined by mass spectrometric and chromatographic methods. 2. The data obtained confirm a radical nonchain mechanism of the decomposition, the first step of which is cleavage of the C-N bond. A detailed scheme of the decomposition has been proposed, considering the reactions of nitroalkyl radicals in systems containing NO and NO2.

1. In the decomposition of vapors of nitroform, fluoro- and chlorodinitromethane under static conditions, a significant influence on the rate is exerted by a reaction proceeding on the surface of the reaction vessel. A consideration of this reaction permits a determination of the characteristics of homogeneous decomposition, which in the case of nitroform and fluorodinitromethane, agree with the radical mechanism of decomposition. 2. The thesis that H and F atoms have the same effect on the energy of cleavage of the C-N bond in the nitro-compounds studied was confirmed.

1. The kinetics of the thermal decomposition of solid xenon trioxide was studied at 51–106°. The reaction is described by a first-order equation with activation energy 31.4 kcal/mole and preexponential factor 1014.8 sec−1. The thermal stability of solid XeO3 is low. 2. The kinetic parameters of the decomposition of xenon trioxide in the solid phase and in neutral solution are close (solid xenon trioxide is somewhat more stable). This is evidence that in both cases the particles that undergo decomposition are XeO3 molecules.

1. The thermal decomposition of N-nitrosopiperidine in the interval 265–312° proceeds homogeneously and monomolecularly with an activation energy of 42.4±4.1 kcal/mole and a preexponential factor 1015.5±sec−1. The limiting step of the process is cleavage of the N-NO bond. 2. As a result of an Investigation of N-nitrosopiperidine, its standard enthalpy of combustion, standard enthalpy of formation, heat of evaporation, enthalpy of formation in the gas phase, and energy of dissociation of the N-NO bond were determined. 3. The strength of the N-NO bond in N-nitrosopiperidine is significantly lower than in N,N-dimethyl-nitrosoamine.

1. The effect of high pressures on the burning of secondary high explosives has been investigated. 2. An empirical equation for the relation between the burning velocity and pressure over the range from 1–900 cm2 has been obtained. 3. Burning in the gas evidently proceeds over the burning surface and in the pores of the charge with different velocities, the difference depending on the external pressure.

1. A study has been made of the gas-phase thermal decomposition of RC(NO2)3 compounds, where R=CH3, C2H5, C3H7. The reactions are unimolecular and are characterized by high preexponential factors. The activation energy is determined by the strength of the C-N bond. 2. Consideration has been given to the question of the effect of substituents and molecular structure on the Arrhenius parameters for the radical decomposition of nitro compounds.

1. A procedure was developed for studying the thermal explosion of liquid and molten explosives with purely convective heat transfer.

We have studied the kinetics of gas-phase decomposition of 1,1-dinitroalkanes in a static system. The results agree with a radical decomposition mechanism. The dissociation energy of the C-N bond in 1,1-dinitroalkanes is 47–48 kcal/mole.

Thermal decomposition ofα-fluoropolynitro compounds in the gas phase takes place by a radical mechanism. The effect of fluorine on the strength of the C-N bond in theα-position is equivalent to that of the hydrogen atom or methyl group.

1. The thermal decomposition of N,N-diethylamine and N-nitropiperidine in the gas phase was studied within the temperature interval 180–240°. 2. The reaction kinetics is complex. Thermal decomposition is accelerated by nitrogen dioxide. 3. Formaldehyde accelerates the decomposition. In the presence of excess formaldehyde the reaction is first order. Beginning with some formaldehyde concentration, further additions of it have no effect upon the kinetics of the process. 4. The mechanism of the decomposition of diethylnitroamine and nitropiperidine is analogous to the mechanism of the decomposition of dimethylnitroamine. 5. The heat of formation of the diethylnitrogen radical was calculated, ΔHf=19.8 kcal/mole.

1. The kinetic parameters and composition of the decomposition products of 1-chloro-1, 1-dinitro-, 1-bromo-1, 1-dinitro-, 1, 1-dichloro-1-nitroethane, and 1, 1-dichloro-1-nitropropane are evidence of a radical mechanism of the decomposition of these compounds with primary cleavage of the C-N bond. 2. When an NO2 group in the compound RC(NO2)3 is replaced by Cl or Br atoms, the activation energy is practically unchanged, but the preexponential factor is significantly reduced.

Ammonium perxenonate (NH4)4XeO6 was synthesized and some of its physieochemical properties were studied.

1. The thermal decomposition of fluorochloro-, fluorobromo-, and fluoroiododinitromethane in the gas phase was studied. 2. The results obtained are in accord with the previously established principles of the effect of halogen substituents on the dissociation energy of the C-N bond and the rate of decomposition of aliphatic nitro compounds.

The manometric method was used to study the kinetics of the reaction of phenylacetylene with the complex of decaborane and diethyl sulfide, with the formation of 1-phenyl-o-carborane. The reaction is described by a second order equation.