Ammonium thermal stability

When potassium fluoride is combined with a variety of quaternary ammonium salts its reaction rate is accelerated and the overall yields of a vanety of halogen displacements are improved [57, p 112ff. Variables like catalyst type and moisture content of the alkali metal fluoride need to be optimized. In addition, the maximum yield is a function of two parallel reactions direct fluorination and catalyst decomposition due to its low thermal stability in the presence of fluoride ion [5,8, 59, 60] One example is trimethylsilyl fluoride, which can be prepared from the chloride by using either 18-crown-6 (Procedure 3, p 192) or Aliquot 336 in wet chlorobenzene, as illustrated in equation 35 [61],... 

Simultaneous fluorination of niobium oxide and oxides of trivalent metals using an ammonium hydrofluoride melt leads only to oxide-type compounds, MinNbC>4 due to low thermal stability of fluoride or oxyfluoride compounds that contain both niobium and trivalent metals. 

Trimerization to isocyanurates (Scheme 4.14) is commonly used as a method for modifying the physical properties of both raw materials and polymeric products. For example, trimerization of aliphatic isocyanates is used to increase monomer functionality and reduce volatility (Section 4.2.2). This is especially important in raw materials for coatings applications where higher functionality is needed for crosslinking and decreased volatility is essential to reduce VOCs. Another application is rigid isocyanurate foams for insulation and structural support (Section 4.1.1) where trimerization is utilized to increase thermal stability and reduce combustibility and smoke formation. Effective trimer catalysts include potassium salts of carboxylic acids and quaternary ammonium salts for aliphatic isocyanates and Mannich bases for aromatic isocyanates. 

In some cases, the Q ions have such a low solubility in water that virtually all remain in the organic phase. ° In such cases, the exchange of ions (equilibrium 3) takes place across the interface. Still another mechanism the interfacial mechanism) can operate where OH extracts a proton from an organic substrate. In this mechanism, the OH ions remain in the aqueous phase and the substrate in the organic phase the deprotonation takes place at the interface. Thermal stability of the quaternary ammonium salt is a problem, limiting the use of some catalysts. The trialkylacyl ammonium halide 95 is thermally stable, however, even at high reaction temperatures." The use of molten quaternary ammonium salts as ionic reaction media for substitution reactions has also been reported. " " ... 

The ammonium salt is an explosive comparable to RDX but of higher thermal stability. 

The fe-ester derivatives of trithiophosphinic acids, RP(S)(SR )2, have also been studied and, similar to the metal and ammonium salts, show enhanced thermal stability compared to their parent acids. Trithiophosphonic acid Zj zA (tr im e t lr y 1 s i 1 y 1) esters have been synthesised from organo-/u.v(trim-ethylsilyl)phosphanes with elemental sulfur in toluene (Equation 40).53 These 6z,s(silyl esters) can be readily converted into the parent trithiophosphinic acid by a very slow, controlled reaction with water or methanol.53... 

The thermal stability, structures and physical properties of various non-metal perchlorates (nitrosyl, nitronium, hydrazinium, ammonium, etc.) have been reviewed [1], Many organic perchlorates were examined for sensitivity to impact. The salts of cations containing only C, H and S exploded quite consistently, while those with C, H, and N, or C, H, N, and S did not explode, except 1,2-bis(ethylammonio)ethane diperchlorate [2],... 

Treatment of the ammonium salt of 3,5-dinitro-1,2,4-triazole (113) with hydrazine hydrate leads to selective reduction of one of the nitro groups to yield 3-amino-5-nitro-1,2,4-triazole (ANTA) (114), a high performance explosive (calculated VOD 8460 m/s) possessing thermal stability (m.p. 238 °C) and an extremely low sensitivity to impact. ANTA (114) is also synthesized from the nitration of 3-acetyl-l,2,4-triazole with anhydrous nitric acid in acetic anhydride at subambient temperature followed by hydrolysis of the acetyl functionality. The ammonium salt of 3,5-dinitro-l,2,4-triazole (113) is itself a useful explosive which forms a eutectic with ammonium nitrate. ... 

Heretofore, ionic liquids incorporating the 1,3-dialkylimidazolium cation have been preferred as they interact weakly with the anions and are more thermally stable than the quaternary ammonium cations. Recently, the physical properties of 1,2,3,4-tetraalkylimidazolium- and 1,3-dialkylimidazolium-containing ionic liquids in combination with various hydrophobic and hydrophilic anions have been systematically investigated (36,41). The melting point, thermal stability, density, viscosity, and other physical properties have been correlated with alkyl chain length of the imidazolium cation and the nature of the anion. The anion mainly determines water miscibility and has the most dramatic effect on the properties. An increase in the alkyl chain length of the cations from butyl to octyl, for example, increases the hydrophobicity and viscosity of the ionic liquid, whereas densities and surface tension values decrease, as expected. 

They generally have reasonable thermal stability. While tetra-alkyl-ammonium salts have limited thermal stability, owing to decomposition via the Hoffmann elimination, [emim][BF4] is reportedly stable up to 300 °C and emim-(CF3S02)2N up to 400 °C. In other words many ionic liquids have liquid ranges of more than 300 °C, compared to the 100 °C liquid range of water. 

Tetradecyl trimethyl ammonium bromide (TTAB)/heptane/octanol Thermal stability [62]... 

The long-term operation of a continuous reaction process with catalyst recovery requires a catalyst with very good thermal stability. Unfortunately the tetra(n-alkyl) ammonium iodides which have good solubility properties also have poor thermal stability due to breakdown by dealkylation. This was observed during operation of the continuous process and in thermal analysis. Thermogravimetric... 

Three expls were used in experiments by Stresau et al RDX, TNT and Ammonium Pic-rate. In their previous experiments it had been shown that the energy required to initiate RDX by EBW can be substantially reduced by the judicious use of confinement. Data given in their report demonstrated the applicability of this principle to less sensitive expls such as TNT Ammonium Picrate. Practical implications of these results include 1) the possibility of eliminating PETN (which is undesirable because of its sensitivity and relatively poor thermal stability) from EBW systems ... 

The most important attributes of this invention are high impulse performance coupled with high exit temperature on primary combustion and favorable boron species in the primary motor exhaust. The system is also insensitive to impact and possesses excellent thermal stability at elevated temperatures. Additionally, the system is readily castable since the addition of solid oxidizers is not required. Further, high flexibility in the ballistic properties of the gas generator can be achieved by the addition of solid oxidizers such as ammonium nitrate, ammonium perchlorate, hydroxylammonium perchlorate, potassium perchlorate, lithium perchlorate, calcium nitrate, barium perchlorate, RDX, HMX etc. The oxidizers are preferably powdered to a particle size of about 10 to 350 microns [13]. 

N-guanylurea dinitramide (commonly known as FOX-12) has low sensitivity and is an excellent candidate for insensitive munitions [72]. It is neither hygroscopic nor soluble in water. Its thermal stability is comparable to RDX and superior to that of ADN. The substitution of ammonium in dinitramide by an organic cation results in the change of combustion temperature and reactivity of the fuel. 

Additional information <1> (<1> 35% ammonium sulfate, AMP or other substrates enhance thermal stability [1]) [1]... 

The first polymer prepared was from the ammonium salt of the maleamic acid 106. Acid 106 was reacted with ammonium hydroxide to form the water soluble ammonium maleamate salt which was in turn cast as a film upon glass [6]. Evaporation of the water followed by thermal curing of the salt at 175 °C provided a pale yellow coating which adhered quite well to the glass and was not affected by a variety of organic solvents. It also showed thermal stability up to... 

Incompatibility of the second type appears as an unexpected increase in sensi-tivenes or decrease in thermal stability, and may be caused by any of the foregoing phenomena. Rogers found that zinc reacts readily with ammonium nitrate. He also found that adding 20% urea to RDX reduces the thermal stability of the latter. 

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