The effect of N‐methyl‐2‐(3‐nitrophenyl)pyrrolidino[3′,4′:1,2]fullerene (mNPF) on the decomposition characteristics of hexogen (RDX) was investigated using differential scanning calorimetry (DSC). The results show that mNPF can accelerate the decomposition of RDX, the peak temperature (Tp) of the exothermal decomposition is reduced by 6.4 K, and the corresponding apparent activation energy (Ea) is decreased by 8.7 kJ mol−1. N‐methyl‐2‐(3‐nitrophenyl)pyrrolidino[3′,4′:1,2]fullerene (mNPF), carbon black (CB), and C60 were used as combustion catalysts to improve the combustion performance of a composite modified double‐base propellant containing RDX (RDX‐CMDB). The burning rate experimental results show that mNPF has a stronger catalytic effect than C60 and CB. The magnitude of the effect of the three carbon substances on the enhancement of the burning rate is as follows: mNPF>C60>CB. The catalytic effects of different contents of mNPF on the burning rates of RDX‐CMDB propellants were also studied, and the results show that the burning rates of RDX‐CMDB propellants are improved with increasing mNPF content. The plateau burning rate of a RDX‐CMDB propellant can be increased to 19.6 mm s−1 when 1.0 % mNPF is added, and the corresponding plateau combustion region occurs at 8–22 MPa. 相似文献
Symmetrical internal alkynes can be prepared either by diarylation of mono‐ and bis(trimethylsilyl)acetylene (TMSA and BTMSA) catalyzed by ligand‐less palladium(II) chloride or by a di(2‐pyridyl)methylamine‐derived palladium(II ) chloride complex 1 (typical 0.1–1 mol % of Pd loading) in water using pyrrolidine as base and tetra‐n‐butylammonium bromide as additive. Alternatively, this same process is performed in NMP in the presence of tetra‐n‐butylammonium acetate (TBAA) as base with even lower Pd loadings (0.001–1 mol % Pd). The same reaction conditions are applied to the synthesis of unsymmetrical internal alkynes by monoarylation of silylated terminal alkynes. Aryl iodides can be coupled with TMSA, BTMSA and silylated terminal alkynes under heating or at room temperature, whereas for aryl bromides couplings are performed under water reflux or at 110 °C in the case of NMP. Complex 1 can be reused during several cycles either in water or in NMP without loss of catalytic activity. These simple reaction conditions allow the preparation of internal alkynes without secondary products, most probably by succesive protiodesilylation‐Sonogashira coupling. 相似文献
The RDX burning rates and temperature profiles in the combustion wave are measured with the pressure and initial temperature
varied within wide limits. Parameters of combustion waves are found. The gas phase of RDX is demonstrated to have a single-zone
structure. Two regimes of RDX combustion are found: a basic regime at p > 0.1 MPa and a special regime at p ≤ 0.1 MPa. The main characteristics of these regimes are obtained, and the wave regions responsible for the burning rate
are determined. Both regimes are characterized by wide reaction zones in the gas phase. The processes of vaporization and
decomposition of the condensed phase proceed simultaneously on the burning surface. The fraction of thermal expansion in the
reaction layer of this phase is estimated. Laws of RDX gasiffication (pyrolysis) in the combustion wave are found, which turn
out to be the same as those for HMX. Distributions of the heat-release rate in the combustion wave (in the reaction layer
of the condensed phase and in the gas phase) are obtained. Sensitivity of the burning rate to the initial temperature is measured.
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Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 32–45, September–October, 2006. 相似文献
The thermal decomposition of poly(3‐difluoroaminomethyl‐3‐methyloxetane) (PDFAMO) with an average molecular weight of about 6000 was investigated using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The kinetics of thermolysis were studied by a model‐free method. The thermal decomposition of PDFAMO occurred in a two‐stage process. The first stage was mainly due to elimination of HF and had an activation energy of 110–120 kJ mol−1. The second stage was due to degradation of the polymer chain. The Fourier transform infrared (FTIR) spectra of the degradation residues showed that the difluoroamino groups decomposed in a two‐step HF loss at different temperatures. The remaining monofluoroimino groups produced by the incomplete elimination of HF were responsible for the two‐stage thermolysis process. The compatibility of PDFAMO with some energetic components and inert materials used in polymer‐bonded explosives (PBXs) and solid propellants was studied by DSC. It was concluded that the binary systems of PDFAMO with cyclotrimethylenetrinitramine (RDX), 2,4,6‐trinitrotoluene (TNT), 2,4‐dinitroanisole (DNAN), pentaerythritol tetranitrate (PETN), ammonium perchlorate (AP), aluminum powder (Al), aluminum oxide (Al2O3) and 1,3‐diethyl‐1,3‐diphenyl urea (C1) were compatible, whereas the systems of PDFAMO with lead carbonate (PbCO3) and 2‐nitrodiphenylamine (NDPA) were slightly sensitized. The systems with cyclotetramethylenetetranitroamine (HMX), hexanitrohexaazaisowurtzitane (CL‐20), 3‐nitro‐1,2,4‐triazol‐5‐one (NTO), ammonium nitrate (AN), magnesium powder (Mg), boron powder (B), carbon black (C. B.), diphenylamine (DPA), and p‐nitro‐N‐methylamine (PNMA) were incompatible. The results of compatibility studies fully supported the suggested thermal decomposition mechanism of PDFAMO. 相似文献
A new catalyst separation and recycling protocol combining magnetic nanoparticles and host‐guest assembly was developed. The catalyst, (η6‐arene)[N‐(para‐toluenesulfonyl)‐1,2‐diphenylethylenediamine]ruthenium trifluoromethanesulfonate [Ru(OTf)(TsDPEN)(η6‐arene)] bearing a dialkylammonium salt tag, was easily separated from the reaction mixtures by magnet‐assisted decantation, on basis of the formation of a pseudorotaxane complex by using dibenzo[24]crown‐8‐modified Fe3O4 nanoparticles. The ruthenium catalyst has been successfully reused at least 5 times with the retention of enantioselectivity but at the expense of relatively low catalytic activities in the asymmetric hydrogenation of 2‐methylquinoline. 相似文献
New 3rd generation designer ansa‐ruthenium(II) complexes featuring N,C‐alkylene‐tethered N,N‐dialkylsulfamoyl‐DPEN/η6‐arene ligands, exhibited good catalytic performance in the asymmetric transfer hydrogenation (ATH) of various classes of (het)aryl ketones in formic acid/triethylamine mixture. In particular, benzo‐fused cyclic ketones furnished 98 to >99.9% ee using a low catalyst loading.
The ultraviolet absorption properties of a series of ferrocene‐modified hyper‐branched polyesters (HBPE‐Fcs) were analyzed by Ultraviolet/visible spectrometry. HBPE‐Fcs were used as burning rate catalyst components added into hydroxyl‐terminated polybutadiene (HTPB) based elastomers to investigate their migration behavior. Migration inhibition effects of HBPE‐Fcs in different aging conditions were analyzed. The diffusion coefficients (D) of the migration components were calculated according to Fick’s law of diffusion. The catalytic performances of HBPE‐Fcs for the thermal decomposition of cyclotrimethylenetrinitramine (RDX) were also investigated by non isothermal measurements using Kissinger method. The incorporation of ferrocenes into hyper‐branched polyesters (HBPEs) endows HBPEs with new ultraviolet absorption properties. The migration of HBPE‐Fc was minimized by grafting ferrocene on the hyper‐branched structures compared to that of simple ferrocene derivatives. HBPE‐Fcs present efficient catalytic effects on the thermal degradation of RDX; and, the catalytic reactions were characterized by decreased activation energies and increased rate constants. 相似文献
Regioselective Markovnikov‐type addition of PhSH to alkynes (HC≡C‐R) has been performed using easily available nickel complexes. The non‐catalytic side reaction leading to anti‐Markovnikov products was suppressed by addition of γ‐terpinene to the catalytic system. The other side reaction leading to the bis(phenylthio)alkene was avoided by excluding phosphine and phosphite ligands from the catalytic system. It was found that catalytic amounts of Et3N significantly increased the yield and selectivity of the catalytic reaction. Under optimized conditions high product yields of 60–85% were obtained for various alkynes [R=n‐C5H11, CH2NMe2, CH2OMe, CH2SPh, C6H11(OH), (CH2)3CN]. The X‐ray structure of one of the synthesized products is reported. 相似文献
The thermal stability and decomposition characteristic of nitramine modified double‐base propellant (RDX‐CMDB propellant) with high solid content and its components were investigated under dynamic and isothermal conditions by differential scanning calorimetry (DSC). It was found that the mixture of nitrocellulose (NC) and nitroglycerin (NG) had a promote effect on the decomposition of RDX. The activation energy (E ) and the pre‐exponential factor (A ) of two obviously exothermic processes were obtained by Friedman iso‐conversional method. The screening method suggested by ICTAC was used to determine the most probable mechanism functions and kinetic parameters of the two processes which are corresponding to the deceleration model and the autocatalytic model. The theoretical value was consistent with the experiment result. 相似文献
A series of (η6‐arene)ruthenium complexes have been tested in the arylation of arylpyridines. One (η6‐p‐cymene)ruthenium(N‐heterocyclic carbene) complex (labelled as 1 in the text) was found to be the most effective, being capable of arylating a wide set of substantially different arylpyridines. Complex 1 is also able to promote the regioselective deuteration of a series of arylated N‐heterocycles, via a nitrogen‐directed mechanism. Two of the deuterated amines were used to measure the kinetic isotope effect (KIE) in the arylation process. The detection of an inverse KIE, together with the observation that the C H activation process does not require the addition of a base, suggest that the rate‐limiting step in the arylation process may be different to that of previously reported studies. 相似文献