Oxonium nitrates

Oxonium nitrates have been known since 1835 [72]. They were originally described as addition compounds of aldehydes and ketones with nitric acid [72, 73], Reddelien [74], who carried out particularly extensive studies, represented the 

Hofman, Stefaniak and T. Urbanski [75] produced evidence of the oxonium structure of the additive compounds, on the basis of infra-red absorption spectra  

The products of addition of nitric acid to ethers also possess the same oxonium structure  

Taylor and G. P. Sillitto, Third Symposium on Combustion and Flame, Wisconsin, 1948, p. 572, William Wilkins, Baltimore, 1949 Trans. Inst. Min. Engrs. (London) 109, 991 (1949-50). 

Berthelot, Sur la force des matiires explosives, Gauthier-Villars, Paris, 1883. 

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Oxonium nitrates have been known since 1835 (Ref 1). They were originally described as... 

Hydrazine nitrate Fluorine nitrate Mcthylaminc nitrate Tetramethylammonium nitrate Guanidine nitrate Properties Manufacture Urea nitrate Thiourea nitrate Ethylene diamine dinitrite Hexamethylenetetramine diniiraie Nitrates of cthanolamine nitric esters Ethanolaminc nitric ester nitrate (ethanolamine dimtratc) Diethanolamine dinitric ester nitrate (diethanolamine trinitrate I Triethanolamine irimtnc ester nitrate (triethanolamine tctranitraie) Oxonium nitrate Literature... 

Energetic Materials 41. Fast Thermolysis of Cyclic and Acyclic Ethanediammonium Dinitrate Salts and their Oxonium Nitrate Double Salts, and the Crystal Structure of Piperazinium Dinitrate Propellants, Explosives and Pyrotechnics, in press. 

That some modification to the position so far described might be necessary was indicated by some experiments of Nesmeyanov and his co-workers. Amongst other compounds they nitrated phenyl trimethyl ammonium and triphenyloxonium tetrafluoroborates with mixed acid the former gave 96 % of m- and 4 % of -nitro compound (88 % total yield), whilst the latter gave 80% of the tri-(p-nitrophenyl)oxonium salt. Ridd and his co-workers have made a quantitative study of the phenyl trimethyl ammonium ion. Their results, and those of other recent workers on the nitration of several cations, are collected in table 9.3. 

Nitrating cellulose with pure HNO is the simplest method of obtaining CN. In practice, nitration does not occur with acid concentrations below 75%. At acid concentrations <75%, an unstable compound (so called Knecht compound) is formed which has been described as a molecular complex or an oxonium salt of the nitric acid (72). HNO concentrations of 75—85% yield CN with 5—8% N, which dissolve in excess acid. CN with % N of 8—10% are formed at acid concentrations of 85—89%. Above 89%, a heterogeneous nitration occurs without apparent swelling of the cellulose fibers. CN with 13.3% N can be obtained with 100% HNO. Addition of inorganic salts to 100% HNO can raise the % N to 13.9. 

Oxidation of either alkyl or aryl sulphoxides to sulphones in 65-90% yields may be accomplished by treatment with a nitronium salt15. In the case of aryl sulphoxides no nitration is observed (which is in contrast to the results of nitric acid oxidation). The reaction was shown to proceed through intermediate nitratosulphonium and nitritosulph-oxonium ions, as depicted in equation (7), which were studied by nmr spectroscopy. 

It Appears that dinitrogen tetroxide functions as rutrosyl nitrate, in analogy with nitrosyl chloride, forming an oxonium-typo intermediate (Eq. 042). Attack by nitrate ion upon the latter gives rise to the observed product, which in turn reacts further by the same process. 

The cyclohexadiene complex 29 has been further elaborated to afford either the cydo-hexenone 34 or the cyclohexene 36 in moderate yields (Scheme 1) [21]. The addition of HOTf to 29 generates the oxonium species 33, which can be hydrolyzed and treated with cerium(IV) ammonium nitrate (CAN) to release the cyclohexanone 34 in 43 % yield from 29. Alternatively, hydride reduction of 33 followed by treatment with acid eliminates methanol to generate the r 3-allyl complex 35. This species can be trapped by the conjugate base of dimethyl malonate to afford a cyclohexene complex. Oxidative decomplexation of this species using silver trifluoromethanesulfonate liberates the cyclohexene 36 in 57 % overall yield (based on 29). 

This was based on infra-red absorption spectra which show frequencies of the oxonium ion bond (0+-H, ca. 2600 cm 1) and of the nitrate ion. 

Transient oxonium ions could be generated from 2-tetrahydrofuranylsilanes <1996TL9119> and 2-tetrahydrofur-anylstannanes <2006TL3607> by oxidation with cerium ammonium nitrate. Intramolecular capture of the cations by the hydroxyl group provided furo[2,3-3]pyrans, as depicted in Equation (145). 

Spontaneous decomposition of C,H5N2l IgBrj was also a source of diphenylbromonium salts 4). Diphenylbromonium and, especially, triphenyloxonium salts prov ed surprisingly stable towards electrophiles, and could be nitrated under drastic conditions to give the meta-substituted halogenonium and para-substituted oxonium cations 37). On the other hand, they arylated nucleophiles readily 38). 

The acidic hydrogen of phenol may participate in the formation of a phenolacetyl nitrate-silica complex, in which the nitro group is well positioned in a six-membered transition state, for the ortlio-attack. In other words, the initially formed oxonium ion is... 

Although the oxide dissolves in adds, it is only weakly basic. In aqueous solution, Hg(II) salts that are ionized (e.g. Hg(N03)2 and HgS04) are hydrolysed to a considerable extent and many basic salts are formed, e.g. HgO HgCl2 and [0(HgCl)3]Cl (a substituted oxonium salt). Solid Hg(OH)2 is unknown. However, [Hg(0H)][N03] H2O (hydrated basic mercury(II) nitrate ) can be isolated. In the solid state, this contains zigzag chains (23.90) to which H2O molecules are loosely connected. 

Excluding the oxonium dihydrate nitrate salt (mpt. -18.5°C) [60], the lowest-melting wholly inorganic material, with a mpt. of 18-23°C [617], is hydro g iammonium dinitramide [80] though (as discussed in Section 11.6.11 in the crystal, in addition to the two eponymous ions, neutral hydroxylamine and its zwitterionic [ NH30 ] isomer are seen. Interestingly, the crystal structure of the monopropellant [NH30H][N03] is reported [629], and while no reliable... 

For example, in the dissociation or ionization of nitric acid, the nitrate(v) ion, N03"(aq), is the conjugate base of nitric acid, while the oxonium ion, H30 , is the conjugate acid of water which acts as the base. Nitric(v) acid and nitrate(v) ions are a conjugate acid-base pair and water and oxonium ions form another conjugate acid-base pair (Figure 8.4). 

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