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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
In contemporary usage, the terms “hypergolic” or “hypergolic propellant” usually mean the most common such propellant combination, dinitrogen tetroxide plus hydrazine and/or its relatives monomethylhydrazine and unsymmetrical dimethylhydrazine.
Catalytic Oxidations
Published in Martyn V. Twigg, Catalyst Handbook, 2018
An important aspect of these reactions is that dinitrogen tetroxide (N2O4) is quite reactive towards water while nitrogen dioxide (NO2) is not. The dissociation reaction of N2O4 shown in equation (9) is endothermic and is favoured by high temperature and low pressure (Figure 10.3), but because absorption is dependent on the concentration of N2O4 and since overall reaction (8) is exothermic, most plant designs incorporate good heat removal and are operated at pressure to enhance absorption. An added bonus is that for a given daily tonnage of nitric acid produced, higher pressure plants have a smaller absorption section, a significantly higher absorption efficiency and are capable of yielding higher acid strengths.
Air Pollution
Published in Takashiro Akitsu, Environmental Science, 2018
“Nitrogen oxides” is a generic term for oxides of nitrogen such as nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (dinitrogen monoxide, N2O), dinitrogen trioxide (N2O3), dinitrogen tetroxide (N2O4), and dinitrogen tetraoxide (N2O5). The chemical formula is NOx.
Ground solid permanganate oxidative coupling of thiols into symmetrical/unsymmetrical disulfides: selective and improved process
Published in Journal of Sulfur Chemistry, 2022
Ngan-Giang Thi Nguyen, Xuan-Triet Nguyen, Ngoc-Huy Nguyen, Thi Xuan Thi Luu, Xuan-Tien Dao
Among synthetic methods available to make disulfides, transformation of thiols to disulfides is the most common method owing to a large number of commercially available thiols and easy interconversion between thiols and disulfides [13]. The oxidative couplings of thiols have been carried out by utilizing various oxidizing agents, e.g. molecular oxygen or air [14–22], metal oxide [23], ferric ion [24,25], nitric oxide, nitrogen dioxide or dinitrogen tetroxide [26], sodium nitrite [27,28], sodium perborate [29], sodium periodate [30], bromine or iodine [31–33], borohydride exchange resin (BER)-transition metal (CuSO4) [34], dimethylsulfoxide [35–37], hydrogen peroxide [38–41], calcium hypochlorite [42], manganese dioxide on molecular sieves [43], permanganate ion [44–51], tributylammonium/triethylammonium halochromate [52–54], N-bromosuccinimide [55], and other organic oxidative reagents, e.g N-phenyltriazolinedione [56], N-t-butyl-N-chlorocyanamide [57], 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) [58], 1,3,5-triazo-2,4,6-triphosphorine-2,2,4,4,6,6-hexachloride [59], and 4,4′-azopyridine [60].
A Numerical Study on Hypergolic Combustion of Hydrazine Sprays in Nitrogen Tetroxide Streams
Published in Combustion Science and Technology, 2018
Hiroumi Tani, Hiroshi Terashima, Yu Daimon, Mitsuo Koshi, Ryoichi Kurose
Miyajima and Sakamoto (1973) proved that gaseous N2H4–NTO coaxial jets auto-ignite even in low-temperature (300–400 K) and low-pressure (0.005–0.01 MPa) environments. Although there was no chemical kinetic mechanism for sufficient prediction of low-temperature ignition for a N2H4–NTO gas mixture, Daimon et al. (2014) recently developed a detailed chemical kinetic mechanism for hypergolic ignition of a N2H4–NTO gas mixture using quantum chemical calculations and the transition state theory. They revealed that low-temperature ignition is initiated by the following sequence of hydrogen abstraction reactions from N2H4 by NO2, which is the main component of NTO in a gas phase because NTO is an equilibrium mixture of nitrogen dioxide (NO2) and dinitrogen tetroxide (N2O4):