Synthesis and Comparison of the Reactivity of 3,4,5-1H-Trinitropyrazole and ItsN-Methyl Derivative

Abstract

3,4,5‐Trinitro‐1H‐pyrazole (1) has been obtained via nitration of 3,5‐dinitropyrazole with mixture of sulfuric and nitric acids. Compound 1 reacts with excess ammonia and aliphatic amines, in the presence of bases with NH‐azoles, phenols, thiols, and triflouroethanol at mild conditions in water. All these reactions occur as the nucleophilic substitution of the nitro‐group at position 4 in 1 affording 4‐R‐3,5‐dinitropyrazoles. The product of methylation of 1, N‐methyl‐3,4,5‐trinitropyrazole (4), also reacts with thiols, phenols, oximes, ammonia, amines, and NH‐azoles. The reactions proceed with high yields but nucleophilic substitutions in these cases occur regioselectively at position 5 in 4 to afford 5‐R‐3,4‐dinitropyrazoles.

Lithium Nitropyrazolates as Potential Red Pyrotechnic Colorants

“…There are three different possibilities to stabilize the nitropyrazole backbone: N-functionalization, amination or salt formation. While deprotonation by a base partially lowers the sensitivities toward ignition stimuli, [8] hydrogen bonding between proton-donating amino groups and neighboring proton-accepting nitro functionalities [9] additionally raises the density [10] (4-amino-3,5-dinitro-1H-pyrazole (8): pK a = 3.42, [11] 1 = 1.90 g cm À 3 at 294 K, [12] T dec (onset) = 176 °C, [12] FS > 360 N, [13] IS = 12 J [13] ). The same effect is expected for hydroxylation of nitropyrazoles since the hydroxyl group also acts as proton donor (4-hydroxy-3,5-dinitro-1H-pyrazole (10) • 2/3 H 2 O: [6] 1 = 1.81 g cm À 3 at 293 K, T dec (peak) = 194 °C).…”

Recent Advances in Synthesis and Properties of Nitrated-Pyrazoles Based Energetic Compounds

“…There were also many routes to synthesize MTNP. Dalinger et al [105,106] dissolved TNP in NaHCO 3 aqueous solution with Me 2 SO 4 as methylation reagent to acquire MTNP ( Figure 22, Scheme B). Guo et al [107] synthesized MTNP from 1-methyl-pyrazole by one-step method with nitric acid and fuming sulfuric acid (Figure 22, Scheme C).…”

5‐Amino‐3,4‐dinitropyrazole as a Promising Energetic Material

“…The main problemi nd evelopingn ew energetic materials is to combine various( in particular cases, mutually exclusive) properties in as ame moiety.F or example, guanidinium 4-amino-3,5-dinitropyrazolate, being highly insensitive and remarkably thermalstabile (up to 303 8C), has an unsatisfactory detonation velocity of 7.7 km s À1 becauseo fi ts low density (1.63 gcm À3 ) [ 3].O ther promisingp yrazole species with fully-nitrated Ca toms, viz. 3,4,5-trinitropyrazole, combines high performance and thermal stability [ 7,8] with strong acidity [9],w hich prevents itsp racticala pplication.I t is worthn oting that compatibility issuesw ith othere nergetic components are among the major concerns, since many N-unsubstituted polynitropyrazolese xhibit acidic nature (pK a 0.05 [10,11]).…”

“…Other promising pyrazole species with fully‐nitrated C atoms, viz. 3,4,5‐trinitropyrazole, combines high performance and thermal stability with strong acidity , which prevents its practical application. It is worth noting that compatibility issues with other energetic components are among the major concerns, since many N‐unsubstituted polynitropyrazoles exhibit acidic nature (p K a 0.05 ).…”