Nitromethane explosive properties

The effect of sulphuric acid and oleum on the explosive properties of nitromethane, dinitrotoluene, trinitrobenzene and trinitrotoluene was studied. They are considerably sensitised. 

Nitroparaffins. Nitroparaffins, such as nitromethane and tetranitromethane, may also act as constituents of propergols, although there is obviously an essential difference in employing these two substances, resulting from their chemical and explosive properties. 

Until recently only the higher nitrated paraffins were considered to have explosive properties or to be of use in explosive compositions. It was only quite recently that nitromethane was discovered to possess powerful explosive properties, although it requires a strong initiator. Among other nitro compounds tetranitromethane deserves special attention. Due to its high oxygen content it may be considered as an oxygen carrier. 

Data on the explosive properties of solutions of both substances in nitromethane and nilroethane are given in Table 44. 

Explosion Properties of Nitromethane with Basic Additives... 

A) Explosion properties of nitromethane sensitized by ammonium salts... 

Using ammonium salts as the sensitizer for nitromethane-based explosives appears to be an advantageous approach. First of aU, ammonium salts usually are not very toxic, thus they would not impose toxicity-related health risks on operation staffs. Second, unlike amine sensitizers that often lead to damaged explosive properties, the explosion properties of nitromethane with ammonium salt sensitizers are almost the same as plain nitromethane. Detonation distance of nitromethane with different sensitizers was shown in Table 7.6. 

The best combustible agent is nitromethane for perchloric acid urea liquid explosives as it can be mixed to form solution under any molar ratio. Different liquid explosives become available in terms of the ratio between perchloric acid urea and water and nitromethane. See Table 7.44 for component and explosion properties. 

Trauzl Test. 127% of PA Velocity of Detonation. 6165m/sec as detd in a glass tube 15/16 diam and 1/32 wall thickness vs 621Qm/sec for straight Nitromethane PLX corroded brass, but did not affect stainless steel, mild steel, or duriron Ref Anon, EngrDesHndbk, Explosives Series, Properties of Explosives of Military Interest , AMCP 706-177 (1971), 298... 

The heat of decomposition (238.4 kJ/mol, 3.92 kJ/g) has been calculated to give an adiabatic product temperature of 2150°C accompanied by a 24-fold pressure increase in a closed vessel [9], Dining research into the Friedel-Crafts acylation reaction of aromatic compounds (components unspecified) in nitrobenzene as solvent, it was decided to use nitromethane in place of nitrobenzene because of the lower toxicity of the former. However, because of the lower boiling point of nitromethane (101°C, against 210°C for nitrobenzene), the reactions were run in an autoclave so that the same maximum reaction temperature of 155°C could be used, but at a maximum pressure of 10 bar. The reaction mixture was heated to 150°C and maintained there for 10 minutes, when a rapidly accelerating increase in temperature was noticed, and at 160°C the lid of the autoclave was blown off as decomposition accelerated to explosion [10], Impurities present in the commercial solvent are listed, and a recommended purification procedure is described [11]. The thermal decomposition of nitromethane under supercritical conditions has been studied [12], The effects of very high pressure and of temperature on the physical properties, chemical reactivity and thermal decomposition of nitromethane have been studied, and a mechanism for the bimolecular decomposition (to ammonium formate and water) identified [13], Solid nitromethane apparently has different susceptibility to detonation according to the orientation of the crystal, a theoretical model is advanced [14], Nitromethane actually finds employment as an explosive [15],... 

It is produced by the action of sodium hydroxide on nitromethane at an elevated temperature (Friese [72] Steinkopf and Kirchhoff [73]). Urbanski and Kowalczyk [74] found that some heavy metal salts of this compound have weak initiating properties and that metazonic acid itself is a fairly weak explosive. Its expansion in the lead block is 240 cm3. 

Mixtures of aluminium powder with liquid chlorine, dinitrogen tetraoxide or tetra-nitromethane are detonable explosives, but not as powerful as aluminium—liquid oxygen mixtures, some of which exceed TNT in effect by a factor of 3 to 4 [1], Mixtures of the powdered metal and various bromates may explode on impact, heating or friction. Iodates and chlorates act similarly [2]. Detonation properties of gelled slurries of aluminium powder in aqueous nitrate or perchlorate salt solutions have been studied [3]. Reactions of aluminium powder with potassium chlorate or potassium perchlorate have been studied by thermal analysis [4],... 

Reliable evidence that nitromethane possesses properties characteristic of an explosive has been provided relatively recently. In particular two disastrous railway accidents which occurred in 1958 in the U.S.A. (one at Niagara Junction said the other at Mount Pulaski, HI.) gave decisive proof that nitromethane should be considered as an explosive and classified as such when subjected to transportation. Both accidents occurred with nitromethane in tank cars. Since then nitromethane has been the only nitroparaffin which is not allowed to be shipped in tank cars but only in smaller containers, such as drums. 

Low-carbon nitroalkanes have similar physical properties as nitromethane, but they are comparatively more difficult to detonate, exhibiting inferior detonation properties, therefore, they are mainly used in liquid explosive mixtures to lower the freezing point of nitromethane. Table 7.1 listed the physical properties of four low-carbon nitroalkanes including nitromethane (NM), nitroethane (NE), o-nitropro-pane, and nitropropane. 

Adding dichioromethane to nitromethane can reduce its freezing point. Particularly, adding 2-12 % of diethylenetriamine (NH2C2H4NHC2H4NH2) as a sensitizer can produce liquid explosive mixture suitable to low temperature usage [35]. For example, when 2-12 % diethylenetriamine was added into the mixture of nitromethane and dichioromethane (70/30), the explosive mixture does not freeze at -40 °C and still can transmit detonation in a stable manner. When 10-12 % of diethylenetriamine was employed, the explosive mixture can detonate even at -51.1 °C. Table 7.4 showed the detonation properties of the mixture of nitromethane and dichioromethane (70/30) with 2 % sensitizer. 

Properties Colorless liq. or rhombic crystals, odorless sol. in water, alcohol misc. with many org. soivs. m.w. 97.99 dens. 1.70 (20/4 C) vapor pressure 0.0285 mm (20 C) m.p. 42.4 C b.p. 158 C starts to dec. above 200 C forming polyphosphoric acids Toxicology ACGIH TLV/TWA1 mg/m STEL 3 mg/m LD50 (oral, rat) 1530 mg/kg, (skin, rabbit) 2740 mg/kg mod. toxic by skin contact human poison by ing. corrosive irritant to eyes, skin, mucous membranes systemic irritant by inh. common air contaminant TSCA listed Environmental Environmentally hazardous Precaution DOT Corrosive material strong acid mixts. with nitromethane are explosive incompat. with alkalis corrosive to many metals violent reaction possible with sodium tetrahydroborate Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of PO,... 

Properties Wh. flakes, lumps or pellets sol. in water, alcohol, glycerol si. sol. in ether m.w. 56.11 dens. 2.044 m.p. 405 C b.p. 1320 C Toxicology ACGIH TLV/CL 2 mg/m LD50 (oral, rat) 365 mg/kg toxic by ing., inh. strong caustic eye and severe human skin irritant ing. may cause violent throat pain and stricture of esophagus mutagenic data TSCA listed Precaution DOT Corrosive material releases heat in contact with water and acids corrodes many metals when wet violent exothermic reactions with water potentially explosive reactions with chlorine dioxide, nitrobenzene, nitromethane... 

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