4-Dimethylaminophenylpentazole Explained

4-Dimethylaminophenylpentazole is an unstable, explosive compound that contains the rare pentazole ring, which is composed of five nitrogen atoms. The electron donating effect of the 4-dimethylamino substituent on the phenyl ring makes this compound one of the more stable of the phenylpentazoles. At room temperature, its chemical half-life is only a few hours, although storage is possible at cryogenic temperatures. The compound was first prepared in 1956^{[1] [2] [3]} along with other substituted phenylpentazoles. Studies have been conducted on various other derivatives, though necessarily limited by the instability of these compounds.^{[4] [5] [6] [7] [8]} Some more highly substituted derivatives, such as 2,6-dihydroxy-4-dimethylaminophenylpentazole, are slightly more stable but conversely, more difficult to make.^{[9] [10]} Current research has focused on forming transition metal complexes of these pentazole derivatives, as the pentazole ring should be stabilised by bonding to the metal centre.^{[11] [12] [13]}

Notes and References

1. Huisgen R, I. Ugi. Zur Losung eines klassichen Problems der organischen Stickstoff-Chemie. Angewandte Chemie. 1956; 68:705-706.
2. Ugi I, R. Huisgen. Pentazole II. Die Zerfallsgeschwindigkeit der Arylpentazole. Chemische Berichte. 1958; 91:531-537.
3. Ugi I, Perlinger H, Perlinger L. Pentazole III. Kristallisierte Aryl-pentazole. Chemische Berichte 1958; 98:2324-2329,
4. John D. Wallis and Jack D. Dunitz. An all-nitrogen aromatic ring system: structural study of 4-dimethyl-aminophenylpentazole. Journal of the Chemical Society. Chemical Communications. 1983: 910-911.
5. 10.1039/P29960000801 . Butler . R. N. . Collier . S. . Fleming . A. F. M. . Pentazoles: proton and carbon-13 NMR spectra of some 1-arylpentazoles: kinetics and mechanism of degradation of the arylpentazole system . Journal of the Chemical Society, Perkin Transactions 2 . 5 . 801 . 1996.
6. 10.1039/A804040K . Butler . R. N. . Fox . A. . Collier . S. . Burke . L. A. . Pentazole chemistry: the mechanism of the reaction of aryldiazonium chlorides with azide ion at −80 °C: concerted versus stepwise formation of arylpentazoles, detection of a pentazene intermediate, a combined 1H and 15N NMR experimental and ab initio theoretical study . Journal of the Chemical Society, Perkin Transactions 2 . 10 . 2243–2248 . 1998.
7. Benin V, Kaszynski P, Radziszewski JG . Arylpentazoles revisited: experimental and theoretical studies of 4-hydroxyphenylpentazole and 4-oxophenylpentazole anion . The Journal of Organic Chemistry . 67 . 4 . 1354–8 . February 2002 . 11846686 . 10.1021/jo0110754 .
8. 10.1021/jp0484480 . Carlqvist . P. . Östmark . H. . Brinck . T. . The Stability of Arylpentazoles . The Journal of Physical Chemistry A . 108 . 36 . 7463 . 2004. 2004JPCA..108.7463C .
9. https://www.foi.se/rest-api/report/FOI-R--1602--SE Efforts to synthesize the pentazolate anion
10. David Adam. The synthesis and characterisation of halogen and nitro phenyl azide derivatives as highly energetic materials. PhD dissertation, Ludwig-Maximilans-Universität München, 2001 http://edoc.ub.uni-muenchen.de/184/1/Adam_David.pdf
11. Tsipis AC, Chaviara AT . Structure, energetics, and bonding of first row transition metal pentazolato complexes: a DFT study . Inorganic Chemistry . 43 . 4 . 1273–86 . February 2004 . 14966962 . 10.1021/ic035112g .
12. Burke. 2004 . L. A. . Fazen . P. J.. Electronic Supplementary Information for Chemical Communications. Chemical Communications. 9 . 1082–3 . 10.1039/B315812H . 15116195 .
13. Burke . L. A. . Fazen . P. J. . 2009 . Correlation analysis of the interconversion and nitrogen loss reactions of aryl pentazenes and pentazoles derived from aryl diazonium and azide ions . International Journal of Quantum Chemistry . 109 . 15 . 3613 . 2009IJQC..109.3613B . 10.1002/qua.22408.