Selective Preparation of 3,4,5-Trinitro-1H-Pyrazole: A Stable All-Carbon-Nitrated Arene

✍ Scribed by Grégoire Hervé; Christian Roussel; Hervé Graindorge

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 424 KB
• Volume: 49
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.201000764

✦ Synopsis

The all-carbon-nitrated azoles, such as 1,2,3,4-tetranitropyrrole (1), 2,4,5-trinitroimidazole (2), 3,5-dinitro-1,2,4-triazole (3), 3,4-dinitro-1,2,3-triazole (4), and5-nitrotetrazole (5) are known (Figure 1). They suffer from several prohibitive drawbacks in terms of stability and water sensitivity (hygroscopic) due to their very high acidity (pK a < 0). [1] Compound 1 is unstable at ambient temperature upon storage, [2] and 3 is deliquescent. [2] As a light yellow instable oil, 4 begins to decompose at 100 8C and must be stored in a diethyl ether solution, [2] and 5 decomposes at low temperature after melting (m.p. 101 8C, dec. 115-120 8C). [2] For all these reasons, they cannot be used in any suitable applications as energetic materials unless the corresponding conjugated bases are used. [2] Surprisingly, 3,4,5-trinitro-1H-pyrazole (6; TNP) is the only all-carbon nitrated azole missing in the series (Figure 1). The synthesis of TNP has probably been attempted numerous times in several specialized laboratories. The diazotization of 4-amino-3,5-dinitropyrazole (7; see Scheme 1) has been reported in the literature, [3] therefore diazotization of 7

[*] Dr.