Thermal degradation of two liquid fuels and detonation tests for pulse detonation engine studies

The use of liquid fuels such as kerosene is of interest for the pulse detonation engine (PDE). Within this context, the aim of this work, which is a preliminary study, was to show the feasibility to initiate a detonation in air with liquid-fuel pyrolysis products, using energies and dimensions of test facility similars to those of PDEs. Therefore, two liquids fuels have been compared, JP10, which is a synthesis fuel generally used in the field of missile applications, and decane, which is one of the major components of standard kerosenes (F-34, Jet A1, ...). The thermal degradation of these fuels was studied with two pyrolysis processes, a batch reactor and a flow reactor. The temperatures varied from 600°C to 1,000°C and residence times for the batch reactor and the flow reactor were, respectively, between 10–30 s and 0.1–2 s. Subsequently, the detonability of synthetic gaseous mixtures, which was a schematisation of the decomposition state after the pyrolysis process, has been studied. The detonability study, regarding nitrogen dilution and equivalence ratio, was investigated in a 50 mm-diameter, 2.5 m-long detonation tube. These dimensions are compatible with applications in the aircraft industry and, more particularly, in PDEs. Therefore, JP10 and decane were compared to choose the best candidate for liquid-fuel PDE studies. This paper was based on work that was presented at the 20th International Colloquium on the Dynamics of Explosions and Reactive Systems, Montreal, Canada, July 31 – August 5, 2005.     

Equilibria in complexes of N-heterocyclic molecules,part XII. The reaction of hydroxide and alkoxide Ions with platinum(II) complexes of 5-nitro-1,10-phenanthroline and 2,2′-bipyridyl

Summary Bis-(5-nitro-1,10-phenanthroline)platinum(II) dichloride and diperchlorate have been prepared. The reaction between the parent cation and hydroxide ion has been studied using 1 FI n.m.r. spectroscopy and found to involve attack at the ligand. The bis-(2,2-bipyridyl)platinum(II) ion has been shown to be highly reactive towards methoxide ion. The dissociation of a 2,2-bipyridyl ligand is preceded by attack at the ligand.Part XI: R. D. Gillard, t.. A. P. Kane-Maguire and P. A. Williams,Transition Met. Chem., 2, 47 (1977).On leave from the University of Baghdad, Iraq.     

Equilibria in complexes ofN-heterocyclic molecules,part XXXI. an explanation for rates of dissociation of iron(II) complexes of diimine ligands

Summary [Fe(3,3'-bipyridazine)₃]²⁺ has a negligible rate of dissociation in water at pH 7, and in 0.05 mol dm^–3 HO^– at ionic strength 1.00 mol dm^–3 (NaNO₃) at 298.2 K, the second-order rate constant involving HO_– is only 3.3 x 10^–5 dm³ mol^–1 s^–1. Examination of kinetic and other data and results for it wide variety oftris-diimine complexes of Fe^II related compounds, indicates that dissociation takes placevia attack at the ligand. The significance of the various possible intermediates is assessed and it is evident that a previously postulated intramolecular transfer of HO^– from the ligand to the metal atom, with associated metal-nitrogen bond fission, is important in the reaction. A general scheme for dissociation of these kinds of compounds is set out.Part XXX: R. D. Gillard, R. P. Houghton and J. N. Tucker,J. Chem. Soc., Dalton Trans., submitted for publication.Present address: Department of Chemistry. University of Nottingham, University Park, Nottingham NG7 2RD U.K.     

Addition of hydroxide to an isoelectronic series of bis-diazineplatinum(II) complex ions

Base hydrolysis of bis-bipyridylplatinum(II) occurs via a 1:1 intermediate adduct with hydroxide ion. The equilibrium constants for this 1:1 addition of hydroxide inwater to complex ions [PtL2]2+, where L=one of theisoelectronic set 2,2-bipyridyl (bpy); 2,2- bipyrazine (bpz); 3,3-bipyridazine (bpdz) and 2,2- bipyrimidine (bpym) are respectively (as log10K at 25°C): 4.23; 4.59; 3.82; 6.14. This result is rationalized in terms of addition at the 6–position of the ligand.     

Separation des alcalino-terreux par l'edta sur resine echangeuse d'ions

The quantitative separation of a few mg of strontium and barium from several g of calcium is described. The alkaline earth carbonates are dissolved in 0.1 M EDTA, fixed at pH 4.8 on an ammoniacal Dowex column, and eluted, also with 0.1 M EDTA, calcium at pH 5.25, strontium at pH 6.0, barium at pH 9.0. The end of the calcium elution can be followed accurately by a sudden pH increase in the eluate(from 4.8 upto 5.25).     

Equilibria in complexes ofN-heterocyclic molecules,Part XXIV. The reaction of nucleophiles with tris-(2,2′-bipyrimidine)iron(II) ion and its ruthenium(II) analogue

Summary The reactions of [Fe(bipym)₃]²⁺ and [Ru(bipym)₃]²⁺ with hydroxide ion in aqueous solution have been followed. The [Ru(bipym)₃]²⁺ species undergoes nucleophilic attack at the ligand to yield [Ru(bipym)₂(pyrimidine)(OH)]⁺ and [HCO₂]^– ion, involving cleavage of one pyrimidyl ring. Intermediates can be observed in the reaction of [Fe(bipym)₃]²⁺ with HO^–, N₃ ^– and SCN^–. The kinetics of the first reaction have been followed and the results are compared with those known for the reactions of [Fe(bipy)₃]²⁺, [Fe(phen)₃]²⁺ and similar compounds.Part XXIII: P. A. Williams,Transition Met. Chem., 78/84.     

Real-time method for the identification and quantification of hydrocarbon pyrolysis products: Part II. Application to transient pyrolysis and validation by numerical simulation

A real-time quantification infra red method has been developed with a gas cell to determine the composition of hydrocarbon pyrolysis products. The aim is to chemically characterise the fuel decomposition in case of regenerative cooling. The method can be extended to a large variety of applications. A transient analysis of the method behaviour is conducted to estimate its capacity to be applied to unsteady conditions (one measure per second), which can be encountered in cooling activity and unsteady processes. A numerical tool called RESPIRE (French acronym for Supersonic Combustion Ramjet Cooling with Endothermic Fuel, Transient Reactor Programming) is used to help in understanding the complex phenomena involved in such a chemical reactor. The validation of transient behaviour with respect to the computations shows negligible time delay (lower than few seconds with gasification rate higher than 60 wt.%) due to residence time in the experimental setup. The quantification accuracy is confirmed to be around 2 mol%. The agreement obtained on gas cell measurements is found to be correct over 10-20 wt.% of gasification rate and very satisfactory over 60 wt.% but this depends on the species. An extension of the method has been developed with a dedicated online cell to be specifically applied to supercritical and multiphase flows. The quantification of the gas phase in the pyrolysis mixture in case of biphasic flow is proposed and validated with an uncertainty around 3 wt.%. The coke formation is monitored as a function of time and its quantification is even tested with 50% of uncertainty after a numerical calibration with respect to simulation.     

Electrophilic substitution in phenanthroline coordinated to transition metal ions. Rates of nitration of some rhodium(III) and cobalt(III) complexes

Summary The rates of nitration in sulphuric acid of 1,10-phenanthroline coordinated to rhodium(III) and cobalt(Ill) in a number of complexes have been measured and found to be much greater in these complexes than in free phenanthroline under the same conditions. Relative rates are generally higher in those complexes which bear the smaller overall positive charges, but these charges may be modified by protonation of the other ligands in the complexes.Contrary to earlier reports, some other electrophilic substitutions do not occur in a variety of phenanthroline complexes.     

Dearomatization of 3-Nitroindoles with Highly γ-Functionalized Allenoates in Formal (3+2) Cycloadditions

3-Nitroindoles are easily reacted with highly substituted γ-allenoates in the presence of a commercially available phosphine catalyst. For instance, allenoates derived from biomolecules such as amino and deoxycholic acids are combined for the first time with 3-nitroindole. The corresponding dearomatized (3+2) tricyclic cycloadducts are obtained as α-regioisomers exclusively. DFT computations shed light on this multi-step reaction mechanism and on the selectivities observed in the sequence.