Nitration chemistry

Another aspect of my early research in Budapest was in nitration chemistry, specifically the preparation of nitronium tetrafluoroborate, a stable nitronium salt. 1 was able to prepare the salt in a simple and efficient way from nitric acid, hydrogen fluoride, and boron trifluoride. 

Although anhydrous nitrates of the alkali and alkaline earth metals have been known and widely used for a long time, the anhydrous nitrates of many other metals have been prepared only relatively recently. (See Figure 5.2.) The existence of some is still in doubt. Methods for preparing these nitrates have been described by Addison and Logan.6 These authors, as well as Hardy and Field,8 have also written extensive reviews of nitrate chemistry. Since not much has changed since they were written, only a brief summary of factors relevant to thermal decomposition is provided here. 

In France as well, some companies that had been traditionally involved in fine chemicals through their specific expertise engaged in similar activities. The state-owned Societe Nationale des Poudres et Explosifs decided to make use of its skills in phosgene and nitration chemistry by buying Isochem from the... 

It is noted [321] that alkylated 5-nitroimidazoles show more distinct maxima in a field of 220-260 nm than the corresponding 4-nitroisomers. This band is also slightly displaced to the long-wave area (7-13 nm) for 5-nitrosubstituted compounds in comparison with 4-nitroimidazoles. Thus, statistical analysis of the absorption spectra of 1-alkylnitroimidazoles allows establishing the nitro group position in the ring that is extremely valuable in the nitration chemistry of imidazoles. The absorption bands of... 

Several publications on anhydrous metal nitrate chemistry describe the properties and reactions of these and related compounds. ... 

Evidence to support this "counterion modified" model comes from the investigation of hydrated Ln(NC>3)Cl2 prepared in the usual way in water (LnCl3, AgN03). The lanthanide(III) chlorides themselves show little or no catalytic activity for nitrations. A possible rationale for this is obtained by noting that HC1 is a poor activator of nitric acid in nitration chemistry since it is not sufficiently acidic to protonate nitric acid. However, the IR spectra of the Ln(NC>3)Cl2 salts are essentially identical to those of Ln(N03)(0Tf)2 indicating that the chloride ions are outer sphere in these complexes. Additionally the nitrate bands show the same trend as demonstrated for the triflate series (e.g., for La(N03)Cl2 the characteristic nitrate stretch is observed at 1459 cm1 and for Yb(NC>3)Cl2 the band appears at 1497 cm-1)- This indicates that the lanthanide chlorides are capable of activating nitric acid (via metal-nitrate interactions) but critically, the counterion (i.e. chloride) is incapable of fulfilling its role (in whatever capacity that may be) and hence no nitration occurs. 

APPENDIX 7.3 AQUEOUS-PHASE NITRITE AND NITRATE CHEMISTRY 7.A.4 NO Oxidation... 

Chapters 17—24 consider various aspects of plant operation. Process improvements, safety features, and new processes are discussed in several cases nitration chemistry is also presented. 

CHEMISTRY OF THE ATMOSPHERIC AQUEOUS PHASE TABLE 6.A.5 Nitrite and Nitrate Chemistry... 

Varied nitrocompounds ranging from such Onitrocompounds as TNT to N-nitrocompounds such as RDX and HMX to 0-nitrocompounds such as trinitroglycerol play a most significant role in energetic compounds. Their preparation is thus of substantial importance. This chapter reviews the most frequently used electrophilic nitration chemistry with particular emphasis on the use of superacidic systems, nitronium salts, and related complexes on which my research group for 30 years has continued to cairv out intensive research. 

The scope of nitrating agents, however, by now is much wider (Table I) 13). The discussion in this chapter will primarily emphasize reagents and methods developed by the Olah group in its study of nitration chemistry. 

The very fast reaction (5.211) is dominant in the presence of low SO2 concentrations and has not been considered until now to budget for the NO2 transfer to HONO. In Fig. 5.24, the nitrate chemistry is included however, it is likely that we can neglect this and conclude the following main pathway ... 

One should not be misled from what appears above into thinking that any chemical reaction of some complexity will oscillate when run in a CSTR if only one is patient and careful enough. We have spent considerable time trying to design new oscillators based on the bistable Fe(II)-HN0o reaction [49]. While we have learned a great deal about nitrate chemistry and now believe we understand the problem, we have not been able to produce a genuine nitrate... 

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