Hydroxylammonium nitrate

The use of aqueous mixtures of hydroxylammonium nitrate with various butylam-monium nitrates as gun propellants is reviewed. 

A recently published new synthesis of dinitrosomethanides salts (DNM = rfinitroso-methanide) starts from formamidinium nitrate (8), which represents an easily accessible source for an NC(H)N unit . Treating a methanolic solution of 8 and hydroxylammonium nitrate (two equivalents) with a methanolic solution of KOBu-t (two equivalents) results in the formation of the labile intermediate Af,Af -dihydroxyformamidinium nitrate (9) (Scheme 8). The reaction of 9 with MOBu-t (two equivalents, M = alkali metal) in the presence of oxygen yields the deep blue alkali DNM salt (7), which can easily be purified by recrystaUization from methanol (yield 60-70%) . 

Considerable research and development has been undertaken in this area and it is estimated that a liquid gun propellant will probably come into service in the 21st century. Liquid gun propellants that are undergoing development are compositions which contain an aqueous ( 63%) solution of the crystalline salt hydroxylammonium nitrate (HAN) and a 50 50 mixture of nitromethane and isopropyl nitrate. 

Klein, N., Progr. Astronaut. Aeronaut., 1988, 109(Gun Propell. Technol.), 473—497 The use of aqueous mixtures of hydroxylammonium nitrate with various butylammo-nium nitrates as gun propellants is reviewed. 

Each of the ammonium salts, and even hydroxylammonium nitrate, initiate decomposition in the same fashion—loss of amine. Indeed, ammonium nitrate, perchlorate, and dinitramidate all sublime. 

A new composition involving a solution of ADN in a mixture of glycerol and water has been presented as a new non-toxic monopropellant with a better specific impulse (Isp) than hydrazine [25], Below is a table of performance, Isp at an expansion ratio of 50 and toxicity as LD5o orally, compared with hydrazine and hydroxylammonium nitrate (HAN).2 HAN has over the past seven years emerged as a Green... 

A number of other materials have received attention as potential oxidizers for propellant use, but to date have found little actual use. They include hydroxylammonium nitrate (HAN), hydroxylammonium perchlorate (HAP), hydrazinium nitrate (HN), hydra-zinium perchlorate (HP), and hexanitroiso-wurtzitane (CL-20). 

Ionic liquids should also be very suitable for use as monopropellants, but the salts used must contain either the oxidizer and fuel combined, or salt mixtures which contain both oxidizing and reducing salts. Since these mixtures are homogeneous systems which contain both the oxidizer and fuel, they can be labeled as monopropellants, just as hydrazine is. Particularly interesting are salt mixtures which are less toxic and have a lower vapor pressure than hydrazine. Such mixtures are also known as green propellants . Suitable anions are the nitrate or dinitramide ions [58], A combination which has already been studied intensively as an oxidizer is the HAN, hydroxylammonium nitrate system. ADN, ammonium nitrate (AN) and hydrazinium nitrate (HN) have also been investigated. As fuels, hydroxylammonium azide (HAA), ammonium azide (AA) or hydrazinium azide (HA) may be appropriate. As a rule, these salt mixtures are not used as pure substances on safety grounds, but with 20 or 40% water added they then decompose catalytically in an exothermic reaction. Table 9.7 shows the dependence of the calculated specific impulses on the water content for such salt mixtures. 

Monopropellants have been made from solutions containing water, Itydrogen peroxide, and either hydroxylammonium nitrate or l drazinium mononitrate. The fuel used was a hydrocarbon that could be a short-chain alkylanunonium nitrate or alkanolammonium nitrate. 

Liquid monopropellants incorporating the PIL into the solution have so been produced, consisting of water, ammonium nitrate, and all l-, dialkyl-, or trialkyl ammoniitm nitrate or alkanol-, dialkmol-, or trialkanolammorrirrm rri-trate,236 These materials were easy to handle, were nonftam-mable, had zero organic vapor emission, were less corrosive than conventional monopropellants, and did not contain hydrazine or hydroxylammonium nitrate. In addition, the costs were expected to be about one-third compared to conventionally used monopropellants. ... 

Several ammonium nitrate salts without alkyl groups have been studied by fast thermolysis. These are ammonium nitrate [77], triaminoguanidinium nitrate (TAGN) [78], hydroxylammonium nitrate (HAN) [79], and hydrazinium nitrate [77]. HNO3 is the initially detected gas product in all cases. All but HAN produce NH3. HAN is conspicuous and unusual because of the... 

Chemical oscillations may or may not be a factor in combustion instability. There is little evidence of oscillations in the product concentrations in any of the energetic materials that we have studied by fast thermolysis. However, in the case of hydroxylammonium nitrate under certain conditions of pressure and heating rate, the relative product composition reproducibly changes in an oscillating manner [79]. Figure 13 shows this behavior for... 

Cronin, J.T. and Brill, T.B. (1986) Thermal Decomposition of Energetic Materials 8. Evidence of an Oscillating Process during the High-Rate Thermolysis of Hydroxylammonium Nitrate, and Comments on the Ionic Interactions Journal of Physical Chemistry 90, 178-181. 

To improve the performances of a monopropellant engine and reduce the risk linked to the simultaneous presence of an oxidizer and a fuel for the long term storage, the oxidizer can be use alone and after decomposition, the hot gaseous oxygen can burn a solid fuel grain in a hybrid solid/liquid engine (Fig. 13). The proposed IL oxidizers can be concentrated aqueous solution of HAN (hydroxylammonium nitrate) or HAN plus AN (ammonium nitrate) and the fuel polyethylene or HTPB (hydroxy-terminated polybutadiene) (Biddle Sutton, 1985 Ramohalli Dowler, 1995). 

Chang, Y.-P. Kuo, K K (2002). Assessment of combustion characteristics and mechanism of hydroxylammonium nitrate-based liquid monoptrofjellant, J. Propul. Power, Vol. 18, No. 5, pp. 1076-1085, ISSN 0748 658... 

Combustion characteristics of hydroxylammonium nitrate aqueous solutions. Int J. Energetic Materials Chem. Prop., Vol.9, No.3, pp. 219-231, ISSN 2150-766X... 

Reactive groups. Some compounds have components that are self-reactive and are composed of an oxidative group together with a reductive group. These are called redox compounds (hydrazine, hydroxylamine, hydroxylammonium nitrate), and are unstable. 

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