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101.
Nidhi Vyas Bhawana Pandey Animesh Ojha Abhinav Grover 《International journal of quantum chemistry》2019,119(24):e26025
Conversion of free nitrogen to ammonia is a required chemical reaction for both biologically and industrially but their mechanism, specifically the attachment of electron and proton transfer during the cycle, is still doubtful. In this view, a thorough knowledge of the mechanism is crucial. In this article, we employ a density functional method on [(TPB)FeN2]−, the iron-dinitrogen complex carrying the tris(phosphine)borone (TPB) ligand, for the ammonia production with the inclusion of electrons and protons. The electronic structures, reactivity, and mechanistic possibilities have been extensively explored using the B3LYP functional. Both asymmetric and symmetric pathways in addition to the possible intermediates species and transition states are considered here. Our results conclude tremendously small energy barrier of 3.5 kJ/mol for the first protonation (S = 1/2) for the N─H bond activation by the [(TPB)FeN2]− species. However, high activation barrier for the third protonation was estimated to be 78.5 kJ/mol, which is explained by the high energy of the unoccupied δx2-y2 orbital in 1ts4 species. The computed spectroscopic parameters such as absorption, electron paramagnetic resonance, and Mössbauer also established the electronic structure details of the species. The calculated parameters are compatible with the experimental results. 相似文献
102.
Hari K. Gakhar Sushma Kiran Sashi Bhushan Gupta 《Monatshefte für Chemie / Chemical Monthly》1982,113(10):1145-1150
4H,6H-[1,3,4]Thiadiazino[2,3-b]quinazolin-6-one with a methyl group in position 3 (6a) has been synthesised by the condensation of 3-amino-2-mercapto-3H-quinazolin-4-one (1) with allyl bromide (2) followed by treatment with bromine and subsequent dehydrohalogenation of the brominated product (4) with ethanolic sodium hydroxide. Its isomeric 3-methyl-2H,6H-[1,3,4]thiadiazino[2,3-b]quinazolin-6-one (6b) has also been obtained by condensation of1 and bromoacetone (7) followed by cyclisation of the intermediates (8 or9) with hydrobromic acid or with concentrated sulphuric acid. The structures have been established on the basis of IR and PMR data.
3-Methyl[1,3,4]thiadiazino[2,3-b]chinazolin-6-one
Zusammenfassung Zur Synthese von 4H,6H-[1,3,4]thiadiazino[2,3-b]chinazolin-6-on (6a) wurde die Kondensation von 3-Amino-2-mercapto-3H-chinazolin-4-on (1) mit Allylbromid mit nachfolgender Behandlung mit Brom und Dehydrohalogenierung des bromierten Produktes4 mit ethanolischer Natronlauge herangezogen. Das zu6a isomere 2H,6H-Produkt6b wurde ebenfalls durch Kondensation von1 mit Bromaceton und nachfolgender Cyclisierung der Zwischenprodukte8 bzw.9 mit HBr oder H2SO4 erhalten. Die Strukturen wurden mittels IR und NMR abgesichert.相似文献
103.
The oxidation of substituted benzyl alcohols by bis(2,2′-bipyridyl) copper(II) permanganate (BBCP), leading to the corresponding benzaldehydes is first-order with respect to BBCP. Michaelis-Menten type kinetics were observed with respect to the alcohols. The oxidation of a,a-dideuteriobenzyl alcohol indicated the presence of a substantial kinetic isotope effect. The rates of oxidation of meta- and para-substituted benzyl alcohols were correlated in terms of Charton's triparametric LDR equation whereas ortho- substituted benzyl alcohols were correlated with a four parametric LDRS equation. The results of correlation analyses point to an electron-deficient reaction center in the transition state. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 9–16, 1997. 相似文献
104.
Urvashi Raina Sushma Bhat P. N. Kotru P. Franzosi F. Licci 《Crystal Research and Technology》1996,31(6):783-788
Results of X-ray diffraction topography, in reflection and transmission scanning geometry, of flux grown single crystals of substituted and unsubstituted hexaferrites bearing composition SrGaxInyFe12-(x+y)O19 (where x = 0, 5, 7, 9; y = 0, 0.8, 1.3, 1.0) are presented. Diffraction topographs reveal defects like misoriented grains, dislocations, cavities, inclusions, and the strain patterns in these crystals. The unsubstituted hexaferrites exhibit better perfection when compared to the substituted ones. The study is reported to support the results obtained by chemical etching and fractography, besides yielding additional information covering defects. 相似文献
105.
Bearing as an important machine element is widely used for industrial and auto-motive applications.At certain operational speed,bearings induce disturbing vibra... 相似文献
106.
P. Sharma S. Vyas S. Sanganeria 《International journal of environmental analytical chemistry》2013,93(3):391-395
Abstract Low levels of mercury have been determined in industrial waste waters by differential pulse anodic stripping voltammetry with a precision of ±3.6 standard deviation. The limit of determination was observed to be 1.0 μg/L. 相似文献
107.
M. K. R. Vyas 《Fiber and Integrated Optics》2013,32(1):69-81
Abstract The tensile testing of packaged optical fibers involves the measurement of elastic strains in the range 2–10%. Under these conditions slippage at the tensile grips can produce erroneous results when a nonextensometric method of measurement (e.g., in positive production testing) is used. Slippage of packaged silica fibers (polypropylene/silicone resin-coated silica fibers) observed when using standard pneumatic parallel-faced jaws has been eliminated by using 50-mm-diameter pulley grips with suitable clamps to hold the fiber ends. With this arrangement clean fiber failures are obtained within the gauge length. A correction factor has been estimated for the measured strain values by a theoretical analysis of the measured tension/extension curves for the composite polypropylene/silicone resin-coated fibers. Statistical data have also been obtained for polypropylene-(PP) coated lead silicate fibers and PP-coated “plastic clad” silica fibers. In the latter case, true failure had been obscured by the onset of fiber slippage within the PP jacket. 相似文献
108.
109.
U. D. Vyas 《General Relativity and Gravitation》2008,40(11):2461-2465
It is shown by Clarke and Felice (J Phys A Math Gen 15:2415–2417, 1982) that under certain conditions a stationary space-time
will produce a closed timelike curve through each point of the space-time. Here a simpler proof and a different version of
their theorem are provided. 相似文献
110.
Electrical and volume measurements to high pressure indicate two phase transitions at 294 K in a natural crystal of chalcopyrite. At 28 kbar there is a semiconductor-semiconductor transition and at 65 kbar a semiconductor-metal transition. 相似文献