Skip to main content

Hexanitrohexaazaisowurtzitane (CL-20) and CL-20-based formulations (review)

Combustion, Explosion and Shock Waves volume 41, pages 121–132 (2005)Cite this article

Abstract

This paper reviews the research and development work on CL-20, the most powerful high-energy material of today, as well as CL-20-based formulations. Methods of CL-20 synthesis and processes for obtaining a desired particle size are discussed. Particular attention is paid to optimization of conditions for obtaining the most stable high-density polymorph. The Fourier Transform Infrared spectroscopy and X-ray diffraction appear to be effective means for distinguishing CL-20 polymorphs. The thermal decomposition pattern of CL-20 as well as the proposed decomposition and combustion mechanisms also form part of this manuscript. Investigations performed by various researchers show that its relatively high sensitivity needs special attention from the viewpoint of CL-20 preparation and processing of formulations based on this substance. Salient features of CL-20-based explosives and gun/rocket propellants studied are included into this review. CL-20 may be ranked as the most attractive compound for futuristic explosive and propellant formulations. The research activities performed by the authors on synthesis and characterization of CL-20 are briefly described.

This is a preview of subscription content, access via your institution.

Access options

Buy single article

Instant access to the full article PDF.

39,95 €

Price includes VAT (Finland)

REFERENCES

  1. M. Golfier, H. Graindorge, Y. Longevialle, and H. Mace, “New energetic molecules and their applications in the energetic materials,” in: Proc. 29th Int. Annual Conf. of ICT, Karlsruhe, June 30–July 3 (1998), pp. 3/1–3/17.

  2. R. L. Simpson, P. A. Urtiev, D. L. Ornellas, et al., “CL-20 performance exceeds that of HMX and its sensitivity is moderate,” Propellant, Explosives, and Pyrotechnics, 22, No.5, 249–255 (1997).

    Google Scholar 

  3. A. T. Nielsen, R. A. Nissan, A. P. Chaffin, et al., “Polyazapolycyclics by condensation of aldehydes with amines. 3. Formation of 2,4,6,8-tetrabenzyl-2,4,6,8-tetraaza bicyclo [3.3.0]octanes from formaldehyde, glyoxal, and benzyl amine,” J. Org. Chem., 57, 6756–6759 (1992).

    Article  CAS  Google Scholar 

  4. Y. Ou, Y. Xu, L. Liu, et al., “Comparison of acetonitrile process with ethanol process for synthesis of hexabenzyl-hexaazaisowurtzitane,” Jiang-tao Hanneng Cailiao, 7, No.4, 152–155 (1999); Chem. Abst. No. 132:154038.

    CAS  Google Scholar 

  5. A. T. Nielsen, “Caged polynitramine compound,” US 5693794 A, December 2 (1997).

  6. A. J. Bellamy, “Reductive debenzylation of hexabenzyl hexaazaisowurtzitane,” Tetrahedron Lett., 51, No.6, 4711–4722 (1995).

    CAS  Google Scholar 

  7. A. T. Nielsen, “Syntesis of caged nitramine explosives,” Presented at Joint Army, Navy, NASA Airforce (JAN-NAF) Propulsion Meeting, San Diego, CA17, December (1987).

  8. T. Kodama, “Preparation of hexakis (trimethylsilylethylcarbamyl) hexaazaisowurtzitane,” Jpn. Kokai Tokkyo Koho JP 06321962 A2, Heisei, November 22 (1994); Chem. Abst. No. 122:265409.

  9. T. Kodama, N. Ishihara, H. Minoura, et al., “Method for acylating hexakis (arylmethyl) hexaazaisowurtzitane,” PCT Int. Appl. WO 99191, 328 (CI CO 77487122), April 22 (1999).

  10. R. B. Wardle and W. W. Edwards, “Hydrogenolysis of 2,4,6,8,10,12-hexabenzyl-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.05.9.03.11] dodecane for explosives and propellants,” PCT Int. Appl. WO 9720,785 (CI CO 61325134), June 12 (1995).

    Google Scholar 

  11. R. B. Wardle and J. C. Hinshaw, “Multi step synthesis of polycyclic polyamides as precursors for polycyclic polynitramine oxidizers in propellants and explosives,” Brit. UK Pat. Appl. GB 2333292 Al, July 21 (1999).

  12. R. B. Wardle and J. C. Hinshaw, “Synthesis and reactions of hexaaza isowurtzitane type compounds in synthesis of hexanitro hexaaza isowurtzitane (HNIW) explosive,” US 6147209 A, November 14 (2000).

  13. Y. Ou, Y. Xu, B. Chen, et al., “Synthesis of hexanitrohexaazaisowurtzitane from tetraacetyldiformylhexaazaisowurtzitane,” Youji Huaxue, 20, No.4, 556–559 (2000); Chem. Abst. No. 133:269072.

    CAS  Google Scholar 

  14. A. T. Nielson, A. P. Chafin, S. L. Christian, et al., “Synthesis of polyazapolycyclic caged polynitramines,” Tetrahedron, 54, No.39, 11793–11812 (1998).

    Google Scholar 

  15. N. V. Latypov, U. Wellmar, P. Goede, and A. J. Bellamy, “Synthesis and scale-up of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane from 2,6,8,12tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW, CL-20),” J. Org. Process Res. Dev., 4, No.3, 156–158 (2000).

    Article  CAS  Google Scholar 

  16. R. S. Hamilton, A. J. Sanderson, R. B. Wardle, and K. F. Warner, “Studies of the synthesis and crystallization of CL-20,” in: Proc. 31st Int. Annual Conf. of ICT, Karlsruhe, June 27–30 (2000), pp. 21/1–21/8.

  17. A. J. Bellamy, “Polynitro hexaaza isowurtzitane derivatives related to hexanitrohexaaza isowurtzitane (HNIW) WN6,” ibid., pp. 109/1–109/14.

  18. C. Wang, Y. Ou, and B. Chen, “One-pot synthesis of hexanitrohexaazaisowurtzitane,” Beijing Ligong Daxue Xuebao, 20, No.4, 521–523 (2000); Chem. Abst. No. 133:298398.

    CAS  Google Scholar 

  19. S. Kawabe, H. Miya, T. Kodama, and N. Miyake, “Process for the preparation of hexanitrohexaazaisowurtzitanes,” PCT Int. Appl. WO 9805666 A1, February 12 (1998).

  20. A. J. Sanderson, K. F. Warner, and R. B. Wardle, “HNIW manufacture by mixed-acid nitration of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo [5.5.0.05.9.03.11]-dodecane,” PCT Int. Appl. WO 2000052011 A2, September 8 (2000).

  21. S. Rao, D. Reddy, D. Rajagopal, et al., “Process improvements in CL-20 manufacture,” in: 31st Int. Annual Conf. of ICT, Karlrushe, June 27–30 (2000), pp. 108/1–108/4.

  22. H. Y. Chung, H. S. Kil, I. Choi, et al., “New precursors for hexanitrohexaazaisowurtzitane (HNIW, CL-20),” J. Heterocyclic Chem., 37, No.6, 1647–1649 (2000); Chem. Abst. No. 134:149661.

    CAS  Google Scholar 

  23. M. Geetha, U. R. Nair, D. B. Sarwade, et al., “Thermal studies on CL-20: The most powerful high energy material,” J. Therm. Anal. and Calorimetry, 71, 913–922 (2003).

    Article  Google Scholar 

  24. A. K. Sikder, N. Sikder, B. R. Gandhe, et al., “Hexanitrohexaazaisowurtzitane, or CL-20 in India: Synthesis and characterization,” Defence Sci. J., 52, No.2, 135–146 (2002).

    CAS  Google Scholar 

  25. X. Zhao, Z. Feng, J. Liu, et al., “Preparation of high purity and high yield of CL-20 from tetraacetyl hexaazaisowurtzitane,” in: Proc. 33rd Int. Annual Conf. of ICT, Karlsruhe (2002), pp. 149/1.

  26. T. P. Russel, P. J. Miller, G. J. Piermarini, and S. Black, “High pressure phase transition in γ-hexanitrohexaazaisowurtzitane,” J. Phys. Chem., 96, No.13, 5509–5512 (1992).

    Article  Google Scholar 

  27. M. F. Foltz, C. L. Coon, F. Garcia, and A. L. Nichols, III, “The thermal stability of the polymorphs of hexanitrohexaazaisowurtzitane, Part II,” Propel., Explos., Pyrotech., 19, 133–144 (1994).

    Google Scholar 

  28. V. Thome, P. B. Kempa, and M. Herrman, “Solvent effects on the morphology of ε-CL-20 crystals,” in: Proc. 32nd Int. Annual Conf. of ICT, Karlsruhe (2001), pp. 157/1–157/7.

  29. E. H. Johnston and R. W. Eugene, “Use of chlorine-free non-solvents in solvent crystallization of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12,-hexaazatetracyclo [5.5.0.05.9.03.11]-dodecane (CL-20) explosive,” US 5874574 A, February 23 (1999).

  30. T. P. Russel, P. J. Miller, G. J. Piermarini, and S. Black, “Pressure/temperature phase diagram of hexanitrohexaazaisowurtzitane,” J. Phys. Chem., 97, No.9 (1993).

    Google Scholar 

  31. S. Jin, Z. Yu, Q. Song, and Y. Ou, “The role of properties of solvents in the properties of HNIW,” in: Proc. 34th Int. Annual Conf. of ICT, Karlsruhe (2003), pp. 57/1–57/4.

  32. R. B. Wardle, J. C. Hinshaw, P. Braithwaite, et al., “Synthesis of the caged nitramine HNIW (CL-20),” in: Proc. 27th Int. Annual Conf. of ICT, Karlsruhe, June 25–28 (1996), pp. 27/1–27/10.

  33. E. Marioth, S. Lobbecke, and H. Krause, “Screening units for particle formations of explosives using supercritical uids,” in: Proc. 31st Int. Annual. Conf. of ICT, Karlsruhe, June 27–30 (2000), pp. 119/1–119/3.

  34. R. H. B. Bouma, W. Duvalois, A. E. D. M. van der Heijden, et al., “Characterization of commercial grade CL-20: Morphology, crystal shape, sensitivity and shock initiation testing by Flyer Impact,” ibid., pp. 105/1–105/9.

  35. J. Kim and Y. Yim, “Effect of particle size on the thermal decomposition of ε-hexanitrohexaazaisowurtzitane,” Chem. Eng. Jpn. J., 32, No.2, 237–241 (1999).

    Article  CAS  Google Scholar 

  36. P. V. Prabhakaran, B. K. George, P. V. Ravindran, et al., “NMR characterization of hexaazahexabenzylisowurtzitane (HBIW),” in: Proc. 33rd Int. Annual Conf. of ICT, Karlsruhe (2002), pp. 66/1–66/9.

  37. M. Kaiser and B. Ditz, “Characterization of impurities in CL-20 by NMR spectroscopy,” in: Proc. 30th Int. Annual Conf. of ICT, Karlsruhe, June 29–July 3 (1999), pp. 94/1–94/16.

  38. D. C. Sorescu, B. M. Rice, and D. L. Thompson, “Molecular packing and NPT-molecular dynamics investigation of the transferability of the RDX intermolecular potential to 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane,” J. Phys. Chem. B, 102, No.6, 948–952 (1998).

    Article  CAS  Google Scholar 

  39. J. Liu, X. Zhao, M. Lu, and J. Pan, “Complete NMR spectral assignment of monoacetylpentanitrohexaazaisowurtzitane,” Huozhayao Huebao, 20, No.4, 26–28 (1997); Chem. Abst. No. 128:50387.

    CAS  Google Scholar 

  40. M. D. Pace, “EPR spectra of photochemical nitrogen dioxide formation in monocyclic nitramines and hexanitrohexaazaisowurtzitane,” J. Phys. Chem., 95, No.15, 5858–5864 (1991).

    Article  CAS  Google Scholar 

  41. W. Qiu, S. Chen, and Y. Yu, “Structure of 2,4,8,10-tetrabenzyl-6,12-dibenzoyl-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.05.9.03.11]dodecane,” Huozhayao Xuebao, 24, No.3, 62–63 (2001); Chem. Abst. No. 135:359832.

    CAS  Google Scholar 

  42. V. N. Chukanov, N. I. Golovina, V. V. Nedelko, et al., “Phase transformations in hexanitrohexaazaisowurtzitane,” in: Proc. 32nd Int. Annual Conf. of ICT, Karlsruhe (2001), pp. 101/1–101/9.

  43. Z. Feng, C. Liu, T. Fang, and Zhao, “Molecular and crystal structure of diacetyltetranitrohexaazaisowurtzitane (DATN),” Xinqi Huozhayao Xuebao, 24, No.1, 38–40 (2001); Chem. Abst. No. 134:282871.

    CAS  Google Scholar 

  44. G. Jacob, G. Lacroix, and V. Destombes, “Identification and analysis of impirities of HNIW,” in: Proc. 31st Int. Annual Conf. of ICT, Karlsruhe, June 27–30 (2000), pp. 106/1–106/12.

  45. M. F. Foltz, “Thermal stability of ε-hexanitro hexaaza isowurtzitane in an estane formulation,” Propell., Explos., Pyrotech., 19, 63–69 (1994).

    Google Scholar 

  46. L. Tian, “Determination of purity of CL-20 explosive by high-performance liquid chromatography,” Huozhayao Xuebao, 22, No.1, 31–32 (1999); Chem. Abst. No. 131:7243.

    CAS  Google Scholar 

  47. L. Tian, “Analysis of CL-20 by high performance liquid chromatography,” Beijing Ligong Daxue Xuebao (Chinese), 18, No.4, 520–522 (1998); Chem. Abst. No. 130:141342.

    CAS  Google Scholar 

  48. Y. Liu, S. Chen, S. H. Luo, and Y. Yanjiu, “HPLC method for analysis of CL-20 in explosive mixture,” Huaxue Yanjiu Yu Yingyong, 12, No.4, 446–448 (2000); Chem. Abst. No. 134:44138.

    CAS  Google Scholar 

  49. A. J. Bellamy, “A simple method for the purification of crude hexanitrohexaazaisowurtzitane (HNIW or CL-20),” Propell., Explos., Pyrotech., 28, No.3, 145–152 (2003).

    Google Scholar 

  50. B. Korsounskii, V. V. Nedelko, N. V. Chukanov, et al., “Kinetics of thermal decomposition of hexanitro hexaaza isowurtzitane,” in: Proc. 30th Int. Annual Conf. of ICT, Karlsruhe, June 29–July 2 (1999), pp. 64/1–64/20.

  51. V. V. Nedelko, N. V. Chukanov, A. V. Raevski, et al., “Comparative investigation of thermal decomposition of various modifications of hexanitrohexaazaisowurtzitane (CL-20),” Propell., Explos., Pyrotech., 25, No.5, 255–259 (2000).

    Google Scholar 

  52. V. V. Nedelko, N. V. Chukanov, B. L. Korsounskii, et al., “Comparative investigating of the thermal decomposition of various modifications of hexanitrohexaazaisowurtzitane,” in: Proc. 31st Int. Annual Conf. of ICT, Karlsruhe, June 27–30 (2000), pp. 9/1–9/9.

  53. M. A. Bohn, “Kinetic description of mass loss data for the assessment of stability, compatibility and aging of energetic components and formulations exemplified with ε CL-20,” Propell., Explos., Pyrotech., 27, 125–135 (2002).

    Google Scholar 

  54. B. Brill and D. G. Patil, “Thermal decomposition of energetic materials 53, kinetics and mecanisms of thermolysis of hexanitrohexaazaisowurtzitane,” Combust. Flame, 87, 145–151 (1991).

    Article  Google Scholar 

  55. W. Xinhzhong, Y. Ou, B. Chen, and C. Feng, “Determination of thermal stabilities of CL-20 and HMX using accelerating rate calorimeter (ARC),” in: Proc. 3rd Beijing Int. Symp. on Pyrotechnics and Explosives, November 6–9 (1995), pp. 520–525.

  56. S. Lobbecke, M. A. Bohn, A. Pfeil, and A. Krause, “Thermal behaviour and stability of HNIW (CL-20),” in: Proc. 29th Int. Annual Conf. of ICT, Karlsruhe, June 30–July 3 (1998), pp. 145/1–145/5.

  57. D. G. Patil and T. B. Brill, “Thermal decomposition of energetic materials. Characterization of the residue of hexanitrohexaazaisowurtzitane,” Combust. Flame, 92, No.4, 456–458 (1993).

    Article  CAS  Google Scholar 

  58. J. K. Rice and T. P. Russel, “High pressure matrix isolation of heterogeneous condensed phase chemical reactions under extreme conditions,” Chem. Phys. Lett., 234(1,2,3), 195–202 (1995).

    Article  CAS  Google Scholar 

  59. M. J. Mezger, S. M. Nicholich, D. A. Geiss, et al., “Performance and hazard characterzation of CL-20 formulations,” in: Proc. 30th Int. Annual Conf. of ICT, Karlsruhe, June 29–July 2 (1999), pp. 4/1–4/14.

  60. K. Dudek, P. Marecek, and P. Vavra, “Laboratory testing of HNIW mixtures,” in: Proc. 31st Int. Conf. of ICT, Karlsruhe, June 27–30 (2000), pp. 110/1–110/6.

  61. D. Mueller, “New gun propellant with CL-20,” Propell., Explos., Pyrotech., 24, 176–181 (1999).

    Google Scholar 

  62. W. H. Veltmans and F. J. Wierckx, “Crystallization of explosives and high-energy oxidizers in presence of ultrasound,” Eur. Pat. Appl. EP 1033357 A, September 16 (2000).

  63. T. G. Manning and B. Strauss, “Reduction of energetic filler sensitivity in propellants through coating,” US 6524706 B1, February 25 (2003).

  64. S. Eiselle and K. Menke, “About the burning behaviour and other properties of smoke reduced composite propellants based on AP/CL-20/GAP,” in: Proc. 32nd Int. Annual Conf. of ICT, Karlsruhe (2001), pp. 149/1–149/18.

  65. L. E. Harris, T. Manning, K. Klingaman, et al., “Thermoplastic elastomer (TPE) gun propellant,” CPIA Publ., Vol. 680 (1998), pp. 1–14. (JANNAF 35th Combustion Subcommittee Meeting, Vol. 1.)

    CAS  Google Scholar 

  66. D. J. Lewis, D. E. Olander, and M. C. Magenot, “Gas generating device,” PCT Int. Appl. WO 2002022214 A2, March 21 (2002).

  67. S. Sato and T. Kodama, “Composition of detonator for initiating booster,” Jpn. Kokai Tokkyo Koho JP 11060372 A2, Heisei, March 2 (1999); Chem. Abst. No. 130:239638.

  68. S. Sato and T. Kodama, “Composition of detonation cords,” ibid., JP 11060371 A2; Chem. Abst. No. 130:239637.

  69. R. L. Simpson, R. S. Lee, T. M. Tillotson, et al., “Energetic formulations prepared by sol-gel processing and polymerization methods,” PCT Int. Appl. WO 9912870 A1, March 18 (1999).

  70. T. Heintz and U. Teipel, “Coating of particulate energetic materials,” in: Proc. 31st Int. Annual Conf. of ICT, Karlsruhe, June 27–30 (2000), pp. 120/1–120/12.

  71. B. C. Tappan and T. B. Brill, “Thermal decomposition of energetic materials 86. Cryogel synthesis of nanocrystalline CL-20 coated with cured nitrocellulose,” Propell., Explos., Pyrotech., 28, No.5, 223–230 (2003).

    Google Scholar 

  72. C. M. Tarver, R. L. Simpson, and P. A. Urtiew, “Shock initiation of an ε-CL-20-estane formulation,” in: AIP Conf. Proc., Vol. 370 (Part 2, Shock Compression of Condensed Matter-1995) (1996), pp. 891–894.

    CAS  Google Scholar 

  73. Y. Tian, R. Xu, Y. Zhou, and F. Nie, “Study on formulation of CL-20,” in: Proc. 4th Proc. of the Int. Autumn Seminar on Propell., Explos., Pyrotech., Shaoxing, China, October 25–28 (2001), pp. 43–47.

  74. D. C. Wagstaff, “Desensitization of energetic materials by energetic plasticizer,” Brit. UK Pat. Appl. GB 2374867 A1, October 30 (2002).

  75. R. B. Wardle, P. C. Braithwaite, A. C. Halaand, et al., “High energy oxitane/HNIW gun propellant,” in: Proc. 27th Int. Annual Conf. of ICT, Karlsruhe, June 25–28 (1996), pp. 52/1–52/7.

  76. I. A. Wallace, P. C. Braithwaite, A. C. Haaland, et al., “Evaluation of a homologous series of high energy oxetane thermoplastic elastomer gun propellants,” in: Proc. 29th Int. Annual Conf. of ICT, Karlsruhe, June 30–July 3 (1998), pp. 87/1–87/7.

Download references

Author information

Authors and Affiliations

  1. High Energy Materials Research Laboratory, Pune, 411021, India

    U. R. Nair, R. Sivabalan, G. M. Gore, M. Geetha, S. N. Asthana & H. Singh

Authors
  1. U. R. Nair
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. R. Sivabalan
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. G. M. Gore
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. M. Geetha
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. S. N. Asthana
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. H. Singh
    View author publications

    You can also search for this author in PubMed Google Scholar

Additional information

__________

Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 2, pp. 3–16, March–April, 2005.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Nair, U.R., Sivabalan, R., Gore, G.M. et al. Hexanitrohexaazaisowurtzitane (CL-20) and CL-20-based formulations (review). Combust Explos Shock Waves 41, 121–132 (2005). https://doi.org/10.1007/s10573-005-0014-2

Download citation

  • Received:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10573-005-0014-2

Key words

  • HNIW
  • CL-20
  • formulations
  • rocket propellants
  • sensitivity
  • explosives