2-Dimethylaminoethylazide (DMAZ) is a liquid

rocket fuel Rocket propellant is used as reaction mass ejected from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines. Overvi ...

being investigated for use as a spacecraft propellent to replace the toxic, carcinogenic

monomethylhydrazine Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide () ...

. It is a member of the competitive impulse non-carcinogenic hypergol (CINCH) family which were assessed as a replacement for

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...

-derived propellants. DMAZ was also found to be sensitive to impact, direct flame, shock wave, heat in confined space, and electrostatic discharge.

Formation and reactions

DMAZ is an organic azide, which is prepared by reacting the chloride of the corresponding alkyl-amine (in this case dimethyl ethylamine) with

sodium azide Sodium azide is an inorganic compound with the formula . This colorless salt is the gas-forming component in some car airbag systems. It is used for the preparation of other azide compounds. It is highly soluble in water and is acutely poisonou ...

: : Ideally, the complete combustion of DMAZ produces carbon dioxide, water, and nitrogen: :

Ignition delays

During their inquiry into finding alternative hypergolic fuel, a joint effort by the

Aviation and Missile Research, Development, and Engineering Center The U.S. Army Combat Capabilities Development Command Aviation & Missile Center (AvMC), formerly known as the U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC), a part of the U.S. Army Research, Development, and ...

(AMRDEC), the U.S. Army Research Laboratory (ARL), and the

National Aeronautics and Space Administration The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the United States's civil space program, aeronautics research and space research. Established in 1958, it su ...

(NASA) determined that DMAZ could perform competitively with

Aerozine-50 __NOTOC__ Aerozine 50 is a 50:50 mix by weight of hydrazine and unsymmetrical dimethylhydrazine (UDMH), developed in the late 1950s by Aerojet General Corporation as a storable, high-energy, hypergolic fuel for the Titan II ICBM rocket engines. Aer ...

and is less toxic than hydrazine-based fuels. However, DMAZ-

inhibited red fuming nitric acid Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of nitric acid (), dinitrogen tetroxide () and a small amount of water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which br ...

(IRFNA) systems have demonstrated longer ignition delays than

-IRFNA systems. In an effort to address this issue, researchers synthesized the related compounds 2-azidoethanamines – 2-azido-''N''-methylethanamine (MMAZ) and 2-azido-''N''-cyclopropylethanamine (CPAZ) in hopes of enhancing the reactivity of DMAZ's amine nitrogen to reduce ignition delays. MMAZ is not hypergolic, while CPAZ is

hypergolic A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other. The two propellant components usually consist of a fuel and an oxidizer. The ...

. According to research conducted by Army Research Laboratory, the azido group in DMAZ's lowest energy structure will prevent the transfer of protons from nitric acid to the amine lone pair acid, a chemical reaction that may be associated with a

rate-limiting step In chemical kinetics, the overall rate of a reaction is often approximately determined by the slowest step, known as the rate-determining step (RDS or RD-step or r/d step) or rate-limiting step. For a given reaction mechanism, the prediction of the ...

in DMAZ-IRFNA ignition. However, according to a 2014 ARL report, a correlation between compound basicities and ignition delays was not observed, which indicates that the proton transfer from nitric acid to DMAZ's amine may not be a rate-controlling step in the ignition process of DMAZ-IRFNA systems.

Formation and reactions

Ignition delays

References

Further reading