Hexanitrohexaazaisowurtzitane, also called HNIW and CL-20, is a
polycyclic nitroamine
Nitroamines are organic compounds containing a nitro group bonded to an amine. The parent inorganic compound, where R1 = R2 = H, is nitramide
Nitramide is a chemical compound with the molecular formula H2NNO2. Organyl derivatives of nitramide, ...
explosive with the formula C
6H
6N
12O
12. In the 1980s, CL-20 was developed by the
China Lake Naval Air Weapons Station China Lake is a United States military facility in California.
China Lake may also refer to:
Places in the United States
*China Lake, Kern County, California, an unincorporated community named for a nearby dry lake
*Chi ...
facility, primarily to be used in
propellant
A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the e ...
s. It has a better
oxidizer
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxid ...
-to-
fuel
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...
ratio than conventional
HMX or
RDX
RDX (abbreviation of "Research Department eXplosive") or hexogen, among other names, is an organic compound with the formula (O2N2CH2)3. It is a white solid without smell or taste, widely used as an explosive. Chemically, it is classified as a ...
. It releases 20% more energy than traditional HMX-based propellants, and is widely superior to conventional high-energy propellants and explosives.
While most development of CL-20 has been fielded by the
Thiokol Corporation
Thiokol (variously Thiokol Chemical Corporation(/Company), Morton Thiokol Inc., Cordant Technologies Inc., Thiokol Propulsion, AIC Group, ATK Thiokol, ATK Launch Systems Group; finally Orbital ATK before becoming part of Northrop Grumman) was an ...
, the
US Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage of ...
(through
ONR) has also been interested in CL-20 for use in
rocket propellant
Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propuls ...
s, such as for
missiles
In military terminology, a missile is a guided airborne ranged weapon capable of self-propelled flight usually by a jet engine or rocket motor. Missiles are thus also called guided missiles or guided rockets (when a previously unguided rocket i ...
, as it has lower observability characteristics such as less visible smoke.
CL-20 has not yet been fielded in any production weapons system, but is undergoing testing for stability, production capabilities, and other weapons characteristics.
Synthesis
![Synthesis CL20](https://upload.wikimedia.org/wikipedia/commons/7/7f/Synthesis_CL20.svg)
First,
benzylamine
Benzylamine is an organic chemical compound with the condensed structural formula C6H5CH2NH2 (sometimes abbreviated as PhCH2NH2 or BnNH2). It consists of a benzyl group, C6H5CH2, attached to an amine functional group, NH2. This colorless water ...
(1) is condensed with
glyoxal
Glyoxal is an organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of ...
(2) under acidic and dehydrating conditions to yield the first intermediate compound.(3). Four benzyl groups selectively undergo
hydrogenolysis
Hydrogenolysis is a chemical reaction whereby a carbon–carbon or carbon–heteroatom single bond is cleaved or undergoes lysis (breakdown) by hydrogen.Ralph Connor, Homer Adkins. Hydrogenolysis Of Oxygenated Organic Compounds. J. Am. Chem. Soc. ...
using
palladium on carbon
Palladium on carbon, often referred to as Pd/C, is a form of palladium used as a catalyst. The metal is supported on activated carbon to maximize its surface area and activity.
Uses Hydrogenation
Palladium on carbon is used for catalytic hydrog ...
and hydrogen. The amino groups are then acetylated during the same step using
acetic anhydride
Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH3CO)2O. Commonly abbreviated Ac2O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis. It is a col ...
as the solvent. (4). Finally, compound 4 is reacted with
nitronium tetrafluoroborate
Nitronium tetrafluoroborate is an inorganic compound with formula NO2BF4. It is a salt of nitronium cation and tetrafluoroborate anion. It is a colorless crystalline solid, which reacts with water to form the corrosive acids HF and HNO3. As suc ...
and
nitrosonium tetrafluoroborate
Nitrosonium tetrafluoroborate, also called nitrosyl tetrafluoroborate, is a chemical compound with the chemical formula NOBF4. This colourless solid is used in organic synthesis as a nitrosating agent.
NOBF4 is the nitrosonium salt of fluorobo ...
, resulting in HNIW.
Cocrystal product with HMX
In August 2012,
Onas Bolton
The Selk'nam, also known as the Onawo or Ona people, are an indigenous people in the Patagonian region of southern Argentina and Chile, including the Tierra del Fuego islands. They were one of the last native groups in South America to be enc ...
et al. published results showing that a
cocrystal
Cocrystals are "solids that are crystalline single phase materials composed of two or more different molecular or ionic compounds generally in a stoichiometric ratio which are neither solvates nor simple salts." A broader definition is that cocryst ...
of 2 parts CL-20 and 1 part
HMX had similar safety properties to HMX, but with a greater firing power closer to CL-20.
Cocrystal product with TNT
In August 2011,
Adam Matzger
Adam J. Matzger, a researcher in polymers and crystals, is the Charles G. Overberger Collegiate Professor of Chemistry at the University of Michigan, and an associate editor for the American Chemical Society's journal '' Crystal Growth & Design'' ...
and
Onas Bolton
The Selk'nam, also known as the Onawo or Ona people, are an indigenous people in the Patagonian region of southern Argentina and Chile, including the Tierra del Fuego islands. They were one of the last native groups in South America to be enc ...
published results showing that a
cocrystal
Cocrystals are "solids that are crystalline single phase materials composed of two or more different molecular or ionic compounds generally in a stoichiometric ratio which are neither solvates nor simple salts." A broader definition is that cocryst ...
of CL-20 and
TNT
Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...
had twice the stability of CL-20—safe enough to transport, but when heated to the cocrystal may separate into liquid TNT and a crystal form of CL-20 with structural defects that is somewhat less stable than CL-20.
CL-20 covalent chains and networks
In 2017, K.P. Katin and M.M. Maslov designed one-dimensional covalent chains based on the CL-20 molecules.
Such chains were constructed using CH
2 molecular bridges for the covalent bonding between the isolated CL-20 fragments. It was theoretically predicted that their stability increased with efficient length growth. A year later, M.A. Gimaldinova and colleagues demonstrated the versatility of CH
2 molecular bridges.
It is shown that the use of CH
2 bridges is the universal technique to connect both CL-20 fragments in the chain and the chains together to make a network (linear or zigzag). It is confirmed that the increase of the effective sizes and dimensionality of the CL-20 covalent systems leads to their thermodynamic stability growth. Therefore, the formation of CL-20 crystalline covalent solids seems to be energetically favorable, and CL-20 molecules are capable of forming not only molecular crystals but bulk covalent structures as well. Numerical calculations of CL-20 chains and networks' electronic characteristics revealed that they were wide-bandgap semiconductors.
See also
*
2,4,6-Tris(trinitromethyl)-1,3,5-triazine
*
4,4’-Dinitro-3,3’-diazenofuroxan (DDF)
*
Heptanitrocubane
Heptanitrocubane is an experimental high explosive based on the cubic eight-carbon cubane molecule and closely related to octanitrocubane. Seven of the eight hydrogen atoms at the corners of the cubane molecule are replaced by nitro groups, g ...
(HNC)
*
HHTDD
HHTDD (hexanitrohexaazatricyclododecanedione) is a powerful but moisture sensitive explosive compound. It is essentially an open analogue of the cyclic nitroamine cage compounds such as CL-20. While it is highly explosive, with a velocity of deto ...
*
Iceane
Iceane is a saturated polycyclic hydrocarbon with formula C12H18. It has a cage-like molecular structure, whose carbon skeleton can be viewed as three fused cyclohexane rings in the boat conformation; or as two such rings in the chair conform ...
(Wurtzitane)
*
Octanitrocubane
Octanitrocubane (molecular formula: C8(NO2)8) is a high explosive that, like Trinitrotoluene, TNT, is shock-insensitive (not readily detonated by shock). The octanitrocubane molecule has the same chemical structure as cubane (C8H8) except that ea ...
(ONC)
*
RE factor
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a m ...
*
TEX (explosive)
TEX (chemical name 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo .5.0.05,9.03,11dodecane) is a dense (ρ = 1.985 g cm−3) nitramine high explosive, that derives from the very powerful and sensitive high explosive CL-20. Though related to CL ...
References
Further reading
* {{cite journal , title=Improved Stability and Smart-Material Functionality Realized in an Energetic Cocrystal , last=Bolton , first=Onas , author2=Adam J. Matzger , journal=
Angewandte Chemie
''Angewandte Chemie'' (, meaning "Applied Chemistry") is a weekly peer-reviewed scientific journal that is published by Wiley-VCH on behalf of the German Chemical Society (Gesellschaft Deutscher Chemiker). Publishing formats include feature-length ...
, volume=123 , issue=38 , pages=9122–9125 , date=September 12, 2011 , doi=10.1002/ange.201104164, pmid=21901797 , bibcode=2011AngCh.123.9122B , hdl=2027.42/86799 , hdl-access=free
* Lowe, Derek (11 November 2011
"Things I won't work with: Hexanitrohexaazaisowurtzitane"
Explosive chemicals
Nitroamines
Rocket fuels