Condensed 1,3,5-triazepines—II : The synthesis of 2,3-dihydro-1H-imidazo[1,2-a] [1,3,5]benzotriazepin-5(6H)-ones and -thiones

A method, based on the reaction of 1-(2-aminoaryl)-2-iminoimidazolidines 8 with phosgen, 1,1′-carbonydiimidazole and thiophosgene, carbon disulfide and 1,1′-thiocarbonyldiimidazole, respectively, has been devised for the synthesis of the title compounds. The compounds 8 are rearranged at elevated temperatures into the isomeric 2-amino-1-(2-amino-ethyl) benzimidazoles 11.     

The reaction of α-chloro-α,α-diphenylacetamides with potassium n-cyanoanilide: A novel type of cine substitution

Three types of products are formed in the reactions of α-chloro-α,α-diphenylacetamides (1a–c with potassium N-cyanoanilide: cine substitution products of type 2 as the main products, and two types of normal products (4a and b, and 3, 6 and 7a, respectively) whose formation reflects the ambident reactivity of the N-cyanoanilide anion.     

1,1-Bis(methoxy-<Emphasis Type="Italic">NNO</Emphasis>-azoxy)ethene. Synthesis and X-ray diffraction analysis

A reaction of 2,2-bis(methoxy-NNO-azoxy)ethyl methanesulfonate with ethyl(diisopropyl)amine afforded 1,1-bis(methoxy-NNO-azoxy)ethene (3). Compound 3 was examined by X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 619–624, March, 2008.     

NO PLIF imaging in the CUBRC 48-inch shock tunnel

Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging is demonstrated at a 10-kHz repetition rate in the Calspan University at Buffalo Research Center??s (CUBRC) 48-inch Mach 9 hypervelocity shock tunnel using a pulse burst laser?Cbased high frame rate imaging system. Sequences of up to ten images are obtained internal to a supersonic combustor model, located within the shock tunnel, during a single ~10-millisecond duration run of the ground test facility. Comparison with a CFD simulation shows good overall qualitative agreement in the jet penetration and spreading observed with an average of forty individual PLIF images obtained during several facility runs.     

Features of combustion of gas-generating solid compositions based on high-enthalpy dispersants

Russian Chemical Bulletin - The features governing the high-rate thermal transformation (combustion without air access) of several dispersants (high-enthalpy N-heterocyclic compounds) were...     

Several aspects of intermolecular interactions between the carbonyl and imine groups in the crystals of compounds containing six-membered heterocycles

Three modifier compounds that stabilize the phase state of ammonium nitrate over a wide range of temperatures, 1,3,5-trihydroxyisocyanuric acid dihydrate (1), 4-aminouracil (2), and 4-aminouracil monohydrate (3) were studied by X-ray diffraction. Strong donor-acceptor intermolecular interactions were found for structures 2 and 3. The electronic parameters of the molecules were calculated by quantum-chemical methods, and it was found that additional intermolecular interactions were possible.     

Kinetics of hydrolysis of the geminal alkoxy-NNO-azoxy compounds in sulfuric acid

The kinetics of hydrolysis of two alkoxy-NNO-azoxy compounds with geminal position of N₂O₂ groups, di(methoxy-NNO-azoxy)methane (I) and di(methyl-NON-azoxy)formal (II), as well as isomeric geminal nitramine, 2,4-dinitro-2,4-diazapentane (III) in 64.16% H₂SO₄ were studied by a manometric method. The relative rates of the hydrolysis at 80°C of compounds I?CIII and methoxy-NNO-azoxymethane (IV) were found to be equal to 4.2:77:??50000:1. The limiting stage of hydrolysis of compound I is the attack of the nucleophile on the carbon atom of the MeO group of the protonated molecule I by S _N2 mechanism. According to the parameters of the Arrhenius equation the hydrolysis of compound II proceeds more probably by the S _N1     

A parallel multi-configuration self-consistent field algorithm

A scalable multi-configuration self-consistent field (MCSCF) algorithm is described. The method for optimizing the orbital and configurational parameters is based upon the two-step Newton–Raphson approach with an augmented orbital Hessian matrix. A single copy of the two-electron integrals in the molecular orbital basis is distributed over the memory of all processors. Storage of the augmented Hessian is avoided by re-computing its elements as needed. A replicated data approach is used to parallelize the configuration interaction step. Scalability to 1024 processors is demonstrated.     

Multi-kHz mixture fraction imaging in turbulent jets using planar Rayleigh scattering

In this study, we describe the development of two-dimensional, high repetition-rate (10-kHz) Rayleigh scattering imaging as applied to turbulent flows. In particular, we report what we believe to be the first sets of high-speed 2D Rayleigh scattering images in turbulent non-reacting jets, yielding temporally correlated image sequences of the instantaneous mixture fraction field. Results are presented for turbulent jets of propane issuing into a low-speed co-flow of air at jet-exit Reynolds numbers of 10,000, 15,000, and 30,000 at various axial positions downstream of the jet exit. The quantitative high-speed mixture fraction measurements are facilitated by the use of a calibrated, un-intensified, high-resolution CMOS camera in conjunction with a unique high-energy, high-repetition rate pulse-burst laser system (PBLS) at Ohio State, which yields output energies of ∼200 mJ/pulse at 532 nm with 100-μs laser pulse spacing. The quality, accuracy, and resolution of the imaging system and the resulting image sets are assessed by (1) comparing the mean mixture fraction results to known scaling laws for turbulent jets, (2) comparing instantaneous images/mixture fraction profiles acquired simultaneously with the high-speed CMOS camera and a well-characterized, high-quantum efficiency CCD camera, and (3) comparing statistical quantities such as the probability density function of the mixture fraction results using the high-speed CMOS camera and the CCD camera. Results indicate accurate mixture fraction measurements and a high potential for accurately measuring mixture fraction gradients in both time and space.