Thermochemische untersuchungen an nitraminen

Heats of combustion of seven nitramines were determined by calorimetric measurement from which standard enthalpies of formation could be derived. By means of differential scanning calorimetry (DSC) heats of fusion were measured of those substances which have a fusion point below their decomposition temperature (tetryl, methyltetryl, ethyltetryl). Heats of transformation of the four known polymorphic forms of octogen were ascertained. Specific heats (C_p) of the seven compounds are indicated for the temperature region from ?7O°C up to beginning decomposition.     

Heats of hydrogenation and formation of some 5-membered ring compounds by molecular mechanics calculations and direct measurements

Molecular mechanics calculations (MM2) have been carried out on twenty hydrocarbons, all of which are either cyclopentenes or alkylidenecyclopentanes. The heats of hydrogenation of eight of these compounds were measured in hexane solution at room temperature. These calculated and experimental results are compared with available heats of formation, determined primarily from combustion data. The agreement between the hydrogeneration values and the molecular mechanics values is in general quite good, the agreement with the combustion data somewhat less so.     

Synthesis,thermal stability,heats of formation,and explosive properties of cyano-substituted di-, tri-, and tetraazidopyridines

A method of synthesis of 2,6-diazido-3,5-dicyanopyridine, 2,4,6-triazido-3,5-dicyanopyridine, and 2,3,4,5-tetraazido-6-cyanopyridine was developed. The heats of formation and explosive properties of compounds obtained were determined; kinetics and the composition of the gaseous thermolysis products were studied. The replacement of endocyclic nitrogen atoms by C-CN fragments in the aromatic ring of polyazides strongly reduces the explosive risk of these compounds with retention of the energetic properties of the molecules.     

Thermochemical Characteristics of a Series of Terpenoids,Alkaloids, and Flavonoids

The heats of combustion and melting of a series of natural terpenoids, alkaloids, and flavonoids were estimated by approximate thermochemical methods. From these quantities, the standard heats of formation of the compounds in the liquid (molten) and solid states were calculated.     

Formation and nitration heats for 3-nitro-4-chloro- and 3,5-dinitro-4-chloro-benzotrifluoride. Dinitration reaction investigation

Although various authors have determined the heats of combustion of many halogen derivatives we still do not have at our disposal data concerning the 3-nitro-4-chlorobenzotrifluoride and the 3,5-dinitro-4-chlorobenzotrifluoride.The object of this study has been that of determining the thermochemical constants for the above mentioned compounds. The values of the heats of combustion and of formation have been determined experimentally and from them the heats of nitration. These data and those determined with Handrick's method (group's energy contribution) have been compared with the heats of reaction carrying the nitration into an adiabatic system.Afterwards it has been investigated how to get the maximum output for the dinitro production. Data and considerations are reported.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Thermochemische Untersuchungen an cyclischen Ketonen

The enthalpies of formation of the nine cyclic ketones C_nH_2n?2O (n = 4–12) were determined by combustion calorimetry. The heats of vaporization were determined by measuring the vapor pressure as a function of temperature and the heats of fusion of the three compounds with n = 8, 9, 12 which are solids at room temperature, by DSC.     

Density function theory study on energetic nitro-triaziridine derivatives

The series of nitro-triaziridines had been studied as high-energy density compounds at B3LYP/6-311G** and MP2/6-311G** levels by means of density functional theory. The heats of formation (HOFs), bond dissociation energies, and detonation performance had been calculated in detail. It was found that all nitro-triaziridines have high position HOFs, and electron-withdrawing of nitro, the steric hindrance, and abundant N–N bond had positive effect with increasing values of HOFs. The thermodynamic stability is estimated by bond dissociation energy and available free space per molecule in unit cell. The detonation performance had been estimated via Kamlet–Jacobs equation and relative specific, However, two different consequences were obtained for detonation performance. Hence, for nitro-triaziridines derivatives, we assumed that a large number of extra oxygen was produced in combustion reaction or explosive reaction, which was negative for the energy released. Therefore, the oxygen balance must be considered for designing high-energy compounds. We also assumed that the Kamlet–Jacobs equation may not be applicable for the compounds, which was constituted of only oxygen, hydrogen, and nitrogen elements.     

Contemplation on the heats of combustion of isomeric hydrocarbons

Within the Hückel molecular orbital theory, the heats of combustion of isomeric hydrocarbons are related to some topological factors. The standard heats of combustion values of alternant hydrocarbons, expressed as kcal/g, seem to be related to a₄ coefficient of their secular polynomials.     

New approaches to the development of high-performance hydrocarbon propellants

An approach to express screening of promising hydrocarbon propellants, based on the calculation of the specific impulse of an engine from the results of quantum-chemical calculation of their heats of combustion, was suggested. The approach ensures high accuracy irrespective of the composition and structure of the compounds under consideration. Polycyclic and framework hydrocarbons with small rings were suggested as promising propellants.     

The standard enthalpies of formation of some dibenzoannelated cycloalkanols

The heats of combustion of trans-9,10-bis-hydroxymethyl-9,10-dihydrophenanthrene, trans-5-hydroxymethyl-5,6-dihydro-7H-dibenzo[a,c]cyclohepten-6-ol, 5-hydroxymethyl-5,6-dihydro-7H-di-benzo[a,c]cycloheptene, 6-hydroxymethyl-5,6-dihydro-7H-dibenzo[a,c]cycloheptene, 5H-dibenzo-[a,d]cyclohepten-5-ol and 5H-10,11-dihydrodibenzo[a,d]cyclohepten-5-ol were measured by means of a Gallenkamp adiabatic bomb calorimeter. Uncertainties in the determination of the heats of combustion ranged between 0.2 and 0.3%. The enthalpies of formation and atomization for the six compounds were derived. The experimental values of the heats of atomization were compared with those calculated using the Allen–Skinner bond energy scheme. Conclusions about energetic contributions which stabilize the structure of the investigated compounds were drawn.     

Modernization and validation of an isoperibol rotating bomb calorimeter for the measurement of energies of combustion of sulphur compounds

A rotating bomb calorimeter belonging to the Laboratory of Chemistry and Process Engineering (UCP) at ENSTA ParisTech since the 1960s was modernized and re-set in order of service for the measurement of heats of combustion of sulphur-containing compounds. The parts of the calorimeter that were replaced concerned essentially the thermal regulation, firing system and data acquisition, while most of the mechanical organs were found to work perfectly. The apparatus was tested extensively and calibrated using standard benzoic acid. The standard energy of combustion of thianthrene was measured to validate the operating protocol for sulphur compounds.     

Thermodynamic properties of cytisine dithiocarbamate derivatives

The heat of solution in water and the heat capacity in the range 173 K-T _m of triethylammonium, sodium, and potassium dithiocarbamates derived from cytisine were studied by calorimetry. The heats of combustion and melting and the standard enthalpies of formation of the compounds were calculated.     

1,2,4‐Triazole Links and N‐Azo Bridges Yield Energetic Compounds

Triazole links and polynitropyrazole rings give rise to compounds with energetic properties. These materials were fully characterized by NMR and infrared spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). In addition, the structures of compounds 5 and 8 were confirmed by single‐crystal X‐ray diffraction analysis. Detonation properties, calculated from heats of formation and experimental densities, thermal stabilities, and impact and friction sensitivities support the potential use of these materials for explosive applications.     

Synthesis and promising properties of a new family of high-density energetic salts of 5-nitro-3-trinitromethyl-1H-1,2,4-triazole and 5,5'-bis(trinitromethyl)-3,3'-azo-1H-1,2,4-triazole

Salts of trinitromethyl-substituted triazoles, 5-nitro-3-trinitromethyl-1H-1,2,4-triazole and 5,5'-bis(trinitromethyl)-3,3'-azo-1H-1,2,4-triazole (5), form a new class of highly dense energetic materials. Single-crystal X-ray structuring supports the formation of the cocrystal of 5 with 3,5-diamino-1,2,4-triazole, which was found to be remarkably less impact-sensitive than the azo precursor. The compounds were fully characterized using IR and multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry. Based on heats of formation calculated with Gaussian 03 and combined with experimentally determined densities, detonation properties of the energetic materials obtained with the EXPLO5 program identify them as potentially explosive compounds. They exhibit high density, moderate to good thermal stability, acceptable oxygen balance, reasonable heat of formation, and excellent detonation properties, which in some cases are superior to those of 1,3,5,-trinitrotriazacyclohexane (RDX).     

Heat of combustion of biofuels mixed with fossil diesel oil

The Brazilian government has presented a biofuel program, which aims the addition of 2% of biofuel in fossil diesel in 2008 and 5% up to 2013. Thus, the knowledge of heat of combustion of biofuel/diesel blends is necessary. The biodiesel was produced by transesterification of soybean oil with a yield of 87%. The diesel-like was obtained by pyrolysis of soybean oil. This biofuel presented all parameters according to ANP. The obtained heats of combustion were 41.36 ± 0.17; 38.70 ± 0.16; and 36.71 ± 0.17 MJ/kg for diesel, diesel-like and biodiesel, respectively. The results show that the heats of combustion of biofuels are approximately 17% smaller than fossil diesel. The obtained data also show that the heats of combustion depend on the methodology used for the biofuel production. Addition of biofuels to traditional diesel fuel results in a linear decreasing of the heat of combustion with the amount of the alternative fuel added to the diesel.     

A Study of 5‐(1,2,4‐Triazol‐C‐yl)tetrazol‐1‐ols: Combining the Benefits of Different Heterocycles for the Design of Energetic Materials

The synthesis and full structural and spectroscopic characterization of three 5‐(1,2,4‐triazol‐C‐yl)tetrazol‐1‐ol compounds with selected energetic moieties including nitrimino ( 5 ), nitro ( 6 ) and azido ( 7 ) groups are reported. The influence of those energetic moieties as well as the C? C connection of a tetrazol‐1‐ol and a 1,2,4‐triazole on structural and energetic properties has been investigated. All compounds were well characterized by various means, including IR and multinuclear NMR spectroscopy, mass spectrometry, and DSC. The molecular structures of 5 – 8 were determined in the solid state by single‐crystal X‐ray diffraction. The standard heats of formation were calculated on the CBS‐4M level of theory utilizing the atomization energy method, revealing highly positive values for all compounds. The detonation parameters were calculated with the EXPLO5 program and compared to the common secondary explosive RDX. Additionally, sensitivities towards impact, friction and electrostatic discharge were determined.     

Heats of combustion for L-α-amino acids

The heats of combustion for series of L-α-amino acids of different composition were analyzed using an additivity scheme. Group contributions were calculated, and these data were used to calculate the heats of combustion for 50 L-α-amino acids.     

Density functional calculation on a high energy density compound having the formula C2OH4?n (NO2) n

A series of ethylene oxide derivations, C₂OH_4?Cn (NO2) _n (x?=?1?C4), has been designed computationally. We calculated the heats of formation (HOFs), bond dissociation energy (BDE), and explosive performances (detonation velocity and detonation pressure) of the title compounds by using density functional theory with 6-311G** basis set. The results show that most of ethylene oxide derivations have positive HOFs values except I. All the calculated BDE and the bond dissociation energies without zero-point energy corrections (BDE⁰) are larger than 200?kJ?mol^?1, which indicate that all the ethylene oxide derivations have good thermal stabilities. The explosive performances of most of ethylene oxide derivations would rank up with cyclotrimethylenetrinitramine (RDX). The results have not only shown that these compounds may be used as high energy density compounds, but also provide some useful information for further syntheses.     

Thermodynamics of a series of harmine alkaloid derivatives

The enthalpies of solution in water and ethanol of a series of harmine alkaloid derivatives, harminium di(o-carborano-1,2-dimethyl)borate, harminium tosylate, harminium thiocyanate, N(2)-hydroxyharminium hydrogen sulfate, and adduct of harmine N-oxide with phthalic anhydride, were determined by isothermal calorimetry. The standard heats of combustion, melting, and formation of these compounds were calculated by approximate methods.