Nitric reaction scheme

Another redox reaction leading to arenediazonium salts was described by Morkov-nik et al. (1988). They showed that the perchlorates of the cation-radicals of 4-A,A-dimethylamino- and 4-morpholinoaniline (2.63) react with gaseous nitric oxide in acetone in a closed vessel. The characteristic red coloration of these cation-radical salts (Michaelis and Granick, 1943) disappears within 20 min., and after addition of ether the diazonium perchlorate is obtained in 84% and 92% yields, respectively. This reaction (Scheme 2-39) is important in the context of the mechanism of diazotization by the classical method (see Sec. 3.1). 

Very interesting transformations were reported in terminal alkynes RC=CH (R = alkyl, aryl, alkoxy, carboxylate, etc.). They react readily with nitric acid, in aqueous nitromethane (1 1) and in the presence of catalytic amounts of tetra-butylammonium tetrachloroaurate to give 3,5-disubstituted isoxazoles 15 in 35% to 50% isolable yield (92). The reaction might proceed via a nitrile oxide intermediate by attack of an electrophile (AuCh or H+) and of a nucleophile (N02 ) on the triple bond to form a vinyl nitrite, which is converted to a nitrile oxide by the action of gold(III) or of nitric acid (Scheme 1.8). 

Condensation between the 4-amino group of the oxadiazole moiety of the triazolooxadiazolium inner salt 133 and formaldehyde furnished the methanediamino linked bis(inner salt) 92 from which the methanedinitroamine analogue 137 could be obtained on reaction with nitric acid (Scheme 20) <1995JHC1405>. 

The above reaction scheme between nitric esters and hydrazine or its derivatives is confirmed by the reaction of methylhydrazine and ethyl nitrate which yield methane (not ethane) and nitrogen. This indicates that the unstable monomethyl-di-imid should have been an intermediate product ... 

Brown63 found that nitric oxide would react with liquid isobutene at room temperatures if trace amounts of N02 were present initially. Because N02 was needed and the reaction was self-sustaining, it was necessary that NOa be regenerated. Therefore, he proposed the reaction scheme... 

The reaction of Co(tc-Cp)(CO)2 and of [Co(7t-Cp)NO]2 with nitric oxide in the presence of norbornene has been reported. In both cases the species shown in Figure 14 may be isolated in high yield.125 The mechanism of these three component syntheses could well be related to that of the NO insertion reactions (Scheme 2) in that here NO insertion might occur into the metal-carbon tt-bond of a cobalt-norbornene intermediate. 

The reason why SIA is higher in urban areas is less obvious as these are secondary aerosols. The observed increment is predominantly caused by more nitrate and sulphate. The reaction of nitric acid and sulphuric acid with the sea-salt aerosol in a marine urbanised environment follows an irreversible reaction scheme. In essence, the chloride depletion stabilises part of the nitrate and sulphate in the coarse mode and may partly explain part of the observed increment. However, it also raises the question how to assign the coarse mode nitrate in the mass closure. The sea salt and nitrate contributions cannot simply be added any more as nitrate replaces chloride. Reduction of NOx emissions may cause a reduction of coarse mode nitrate, which is partly compensated by the fact that chloride is not lost anymore. A reduction would yield a net result of ((N03-C1)/N03 = (62-35)/62=) 27/62 times the nitrate reduction (where the numbers are molar weights of the respective components), and this factor could be used to scale back the coarse nitrate fraction in the chemical mass balance. A similar reasoning may be valid for the anthropogenic sulphate in the coarse fraction. Corrections like these are uncommon in current mass closure studies, and consequences will have to be explored in more detail. 

Cellulose nitrate can be prepared by treating highly purified cellulose with a mixture of nitric and sulfuric acid (6). The reaction scheme may be represented as shown in Scheme 2. 

Alternatively, the reaction may proceed through nitrosation by the nitrosonium ion, NO", and subsequent oxidation of the nitroso compound by nitric acid (Scheme 7.3). There is only a small concentration of NO" in dilute nitric acid and so catalytic amounts of sodium nitrite are sometimes added to increase the quantity. This technique is a useful means of effecting smooth, low-temperature nitrations. 

Figure 2 Nitric oxide synthase, (a). Domain architecture of NOS. The heme domain binds Zn + (gray box), heme (gray parallelogram), and H4B (white box). The reductase domain binds FMN, FAD, and NADPH (white boxes). CaM (white box) is between the heme domain and the reductase domain, (b). Two-step reaction scheme for NO synthesis by NOS.

Alkyl-2-imidazolines 544 are in equilibrium with the enediamine tautomers 545 through which carbon-bound diazenium diolates 546 are formed upon reaction with nitric oxide (Scheme 125) <2005JOC7647>. 

The main products of the gas-phase photolysis at 300 °K, with nitric oxide added, are hydrogen, propene, ethylene and pentenes. Other important products are ethane, butenes, methane, propane, butane and acetylene. A reaction scheme that accounts for most of the products of the nitric oxide-inhibited photolysis is as follows... 

Econazole nitrate may be synthesised by the reaction pathway shown in Figure 12. This reaction scheme, taken from Godefroi et al, has optional pathways at each stage. Imidazole is coupled with brominated 2,4-dichloroaceto -phenone and the resultant ketone is oxidized with sodium borohydride to the corresponding alcohol. This product is coupled with 2,4-dichlorotoluene by means of sodium hydride in hexamethylphosphoramide (an aprotic solvent) before being extracted with nitric acid to give econazole nitrate. 

Reaction Scheme 1 shows that during preparation of cellulose plastics, the hydroxyl groups on each cellulose monomer ring are replaced by other substituent groups. To prepare cellulose nitrate, pre-dried cotton linters are treated with concentrated nitric and sulfuric acids. Water tends to slow the reaction, so its presence is limited. Sulfuric acid catalyses the reaction, so it can occur without heating and under ambient conditions. The product is washed with water to remove the residual acids if residues of sulfuric acid are allowed to remain, an explosive reaction can occur. Remaining water in the cellulose nitrate is displaced by alcohol. 

The 3-hydroxy-K end group is characteristic of capsorubin (28), and other carotenoids isolated from paprika (Capsicum annuum). All syntheses are based on the Cio + C2o + Cio = C4o strategy, and use crocetindialdehyde (27) as central building block and the aldol condensation as the coupling reaction Scheme 6). The synthesis of optically active capsorubin (28), reported in 1973, was the first synthesis of an enantiomerically pure xanthophyll [11]. For the optically active form of the key building block, the frans-Cio-hydroxyketone 26, two approaches have been reported. In the first reaction sequence, (+)-camphor (143) was converted into camphoric acid (144) by treatment with nitric acid. Camphoric acid (144) was then esterified with dimethyl sulphate... 

The nitration of pyrene by N(IV) (N02, N204) in methylene chloride at 25 °C under conditions in which the N(IV)is primarily the tetroxide demonstrates first-order product formation both in pyrene and N(IV). The order in N(IV) shifts to second order when the starting N(IV) concentration is increased. N(IV) nitrates pyrene directly nitric acid, that is, N(V), does not. Under first-order conditions, the addition of NO [NO] [N(7Vj] shifts the product formation to second order and substantially accelerates the reaction. The reaction scheme involves the initial formation of a pyrene-N204 complex, followed by (1) the unimolecular collapse of the complex to product and (2) the addition of a second N204 to the pyrene in the complex. The second path leads directly to polynitropyrenes when the concentration of N(IV) is sufficiently high. 

Additional experiments in our laboratory utilizing a superoxidegenerating system support the reductive release of nitric oxide. Under conditions in which no nitric oxide could be detected from SNAP, the addition of xanthine oxidase plus pterin as substrate resulted in a sustained linear oxidation of dihydrorhodamine that was inhibitable by SOD (Crow and Beckman, unpublished observations). We have shown previously that dihydrorhodamine is oxidized by ONOO but not by nitric oxide or superoxide (Kooy et al., 1994). These results are consistent with the reaction scheme shown below, whereby the first superoxide reduces the nitrosothiol, resulting in nitric oxide release, which in turn, reacts with a second superoxide to produce ONOO. ... 

It should be possible to apply quantitative tests of the branched-chain reaction scheme and to decide the part played by NO3, when we have collected more detailed evidence about the relationships between P and Po at both limits of ignition, and investigated the effects of nitric oxide and nitrogen dioxide on the fast reactions just outside the limits of ignition. 

Figure 1 schematically represents an oxidizer-absorption tower used in nitric acid production. In this tower the nitric oxides generated by high-temperature air oxidation of ammonia on platinum gauze are oxidized and absorbed to yield nitric acid. Koukolik and Marek [49] simulated the behavior of the tower on a digital computer. The following reaction scheme was used ... 

Amino[2.2]paracyclophane and diamino[2.2]paracyclophane can be accessed by the nitration with trifluoromethanesulfonic acid/nitric acid and reduction of the nitro group with strategy incorporating triiron dodecacarb-onyl. F33(CO)i2 is a powerful reductant even under mild reaction conditions. Crown ethers are used as a phase transfer catalyst. The reaction scheme is shown in Figure 2.2. 

A high yield synthesis of 5-amino-tetrazolium nitrate (48) is obtained from the reaction of 5-amino-tetrazole with nitric acid (Scheme 12) [57]. Its characterization was accomplished through IR, Raman, and multinuclear ( H, N) NMR spectroscopy, and DSC. Bomb calorimetry, sensitivity measurements, and ab initio calculations were also performed. From the combined... 

Figure S. Reaction scheme for formation of nitric oxide radicals via oxidation of arginine side chains on proteins.

Figure 6.4.1 Reaction scheme of nitric acid process based on NH3. Adapted from Uhde (2005).

The overall reaction of nitric acid production reads (see also the reaction scheme and the block diagram of the process in the Figures 6.4.1 and 6.4.2) ... 

Since these early studies on nitrite photolysis, a number of extensive synthetic and physicochemical studies on the photodissociation of steroidal alcohol nitrite esters and simple alkyl nitrites, such as t-butyl nitrite (as summarized by Calvert and Pitts, Ir. ), estabhshed that the primary reaction of the photolysis of nitrite esters in solution is the homolysis of the ONO bond of their nitrosoxy groups to give alkoxyl radicals and nitric oxide (Scheme 3). 

The use of glucose instead of benzene allows the substitution of organic solvents by water. The standard process for the production of adipic acid is based on the nitric acid oxidation of a cyclohexanol/cyclohexanone mixture derived from cyclohexane, which is in turn derived from benzene. Note that this process produces N2O as a by-product of the reaction (Scheme 8.1). 

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