IUPAC name: Hydrazine
CAS Number: 302-01-2
Chemical formula: N2H4
Molar mass: 32
Hydrazine Hydrate is an inorganic compound with the chemical formula N2H4.
Hydrazine Hydrate is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour.
Hydrazine Hydrate is mainly used as a foaming agent in preparing polymer foams, but applications also include its uses as a precursor to polymerization catalysts, pharmaceuticals, and agrochemicals, as well as a long-term storable propellant for in-space spacecraft propulsion.
Hydrazine hydrate has been used for the deproteination of the enamel samples in a study.
Hydrazine hydrate may be used as a reducing agent in the following:
-Preparation of silver nanoparticles.
-Transformation of monosubstituted nitrobenzene derivatives to the corresponding anilines.
-Along with graphite for the conversion of nitro compounds (aromatic and aliphatic) to the amino compounds.
About two million tons of hydrazine hydrate were used in foam blowing agents in 2015.
Additionally, hydrazine hydrate is used in various rocket fuels and to prepare the gas precursors used in air bags.
Hydrazine Hydrate is used within both nuclear and conventional electrical power plant steam cycles as an oxygen scavenger to control concentrations of dissolved oxygen in an effort to reduce corrosion.
Hydrazines refer to a class of organic substances derived by replacing one or more hydrogen atoms in hydrazine by an organic group.
Uses of Hydrazine Hydrate:
Gas producers and propellants
The majority use of hydrazine hydrate is as a precursor to blowing agents.
Specific compounds include azodicarbonamide and azobisisobutyronitrile, which produce 100–200 mL of gas per gram of precursor.
In a related application of Hydrazine Hydrate, sodium azide, the gas-forming agent in air bags, is produced from hydrazine by reaction with sodium nitrite.
Chemical Properties of Hydrazine Hydrate:
-colourless fuming liquid
Physical properties of Hydrazine Hydrate:
-Colorless fuming liquid; faint odor; refractive index 1.4284; density 1.032g/mL; boils at 119°C; solidifies at -51.7°C; miscible with water and alcohol;insoluble in chloroform, methylene chloride, and ether.
Applications of Hydrazine Hydrate:
-Manufacturing of herbicides
-Manufacturing of pharmaceutical agents
-Pharmaceutical industry / Biotechnology
-Plastic- and Rubberpolymers
-Purification of chemical solutions
Uses of Hydrazine Hydrate:
Hydrazine hydrate is used as a reducing agent in synthetic and analytical reactions and as a solvent for many inorganic compounds.
Hydrazine hydrate also is used with methanol as a propellant for rocket engines.
Another application of Hydrazine Hydrate is catalytic decomposition of hydrogen peroxide.
Preparation of Hydrazine Hydrate:
Hydrazine hydrate is prepared by treating hydrazine sulfate, N2H4•H2SO4 with sodium hydroxide.
The product is collected by distillation under nitrogen.
Hydrazine Hydrate is also used as a long-term storable propellant on board space vehicles, such as the Dawn mission to Ceres and Vesta, and to both reduce the concentration of dissolved oxygen in and control pH of water used in large industrial boilers.
The F-16 fighter jet, Eurofighter Typhoon, Space Shuttle, and U-2 spy plane use hydrazine to fuel their auxiliary power units.
Precursor to pesticides and pharmaceuticals of Hydrazine Hydrate:
Fluconazole, synthesized using hydrazine, is an antifungal medication.
Hydrazine is a precursor to several pharmaceuticals and pesticides. Often these applications involve conversion of hydrazine to heterocyclic rings such as pyrazoles and pyridazines.
Examples of commercialized bioactive hydrazine derivatives include cefazolin, rizatriptan, anastrozole, fluconazole, metazachlor, metamitron, metribuzin, paclobutrazol, diclobutrazole, propiconazole, hydrazine sulfate, diimide, triadimefon, and dibenzoylhydrazine.
Hydrazine Hydrate compounds can be effective as active ingredients in admixture with or in combination with other agricultural chemicals such as insecticides, miticides, nematicides, fungicides, antiviral agents, attractants, herbicides or plant growth regulators.
Hydrazine Hydrate is used as an alternative to hydrogen in fuel cells.
The chief benefit of using hydrazine hydrate is that it can produce over 200 mW/cm2 more than a similar hydrogen cell without the need to use expensive platinum catalysts.
As the fuel is liquid at room temperature, it can be handled and stored more easily than hydrogen.
By storing the hydrazine hydrate in a tank full of a double-bonded carbon-oxygen carbonyl, the fuel reacts and forms a safe solid called hydrazone.
By then flushing the tank with warm water, the liquid hydrazine hydrate is released.
Hydrazine hydrate has a higher electromotive force of 1.56 V compared to 1.23 V for hydrogen.
Hydrazine hydrate breaks down in the cell to form nitrogen and hydrogen which bonds with oxygen, releasing water.
Hydrazine hydrate was used in fuel cells including some that provided electric power in space satellites in the 1960s.
A mixture of 63% hydrazine hydrate, 32% hydrazine nitrate and 5% water is a standard propellant for experimental bulk-loaded liquid propellant artillery.
The propellant mixture above is one of the most predictable and stable, with a flat pressure profile during firing.
Misfires are usually caused by inadequate ignition.
The movement of the shell after a mis-ignition causes a large bubble with a larger ignition surface area, and the greater rate of gas production causes very high pressure, sometimes including catastrophic tube failures (i.e. explosions).
Hydrazine Hydrate is widely used as a reducing agent or an intermediate of synthesis in various industrial sectors like:
- water treatment (effluents, industrial boilers)
- chemical treatment process (metals, mine extraction)
- active ingredients synthesis (pharmaceutcials and agrochemicals).
The United States Air Force (USAF) regularly uses H-70, a 70% hydrazine hydrate 30% water mixture, in operations employing the General Dynamics F-16 “Fighting Falcon” fighter aircraft and the Lockheed U-2 “Dragon Lady” reconnaissance aircraft.
The single jet engine F-16 utilizes hydrazine hydrate to power its Emergency Power Unit (EPU), which provides emergency electrical and hydraulic power in the event of an engine flame out.
The EPU activates automatically, or manually by pilot control, in the event of loss of hydraulic pressure or electrical power in order to provide emergency flight controls.
The single jet engine U-2 utilizes hydrazine hydrate to power its Emergency Starting System (ESS), which provides a highly reliable method to restart the engine in flight in the event of a stall.
Hydrazine Hydrate as Rocket fuel:
Anhydrous (pure, not in solution) hydrazine hydrate being loaded into the MESSENGER space probe.
The technician is wearing a safety suit.
Hydrazine was first used as a component in rocket fuels during World War II.
A 30% mix by weight with 57% methanol (named M-Stoff in the German Luftwaffe) and 13% water was called C-Stoff by the Germans.
The mixture was used to power the Messerschmitt Me 163B rocket-powered fighter plane, in which the German high test peroxide T-Stoff was used as an oxidizer.
Unmixed hydrazine was referred to as B-Stoff by the Germans, a designation also used later for the ethanol/water fuel for the V-2 missile.
Hydrazine hydrate is used as a low-power monopropellant for the maneuvering thrusters of spacecraft, and was used to power the Space Shuttle's auxiliary power units (APUs).
In addition, mono-propellant hydrazine-fueled rocket engines are often used in terminal descent of spacecraft.
Such engines were used on the Viking program landers in the 1970s as well as the Mars landers Phoenix (May 2008), Curiosity (August 2012) and Perseverance (February 2021).
A mixture of hydrazine and red fuming nitric acid was used in the Soviet space program where it was known as devil's venom due to its dangerous nature.
In all hydrazine mono-propellant engines, the hydrazine is passed over a catalyst such as iridium metal supported by high-surface-area alumina (aluminium oxide), which causes it to decompose into ammonia, nitrogen gas, and hydrogen gas according to the following reactions:
N2H4 -> N2 + 2H2
3N2H4 -> 4 NH3 + N2
4NH3 + N2H4 -> 3 N2 + 8 H2
The first two reactions are extremely exothermic (the catalyst chamber can reach 800 °C in a matter of milliseconds,) and they produce large volumes of hot gas from a small volume of liquid, making hydrazine a fairly efficient thruster propellant with a vacuum specific impulse of about 220 seconds.
Reaction 2 is the most exothermic, but produces a smaller number of molecules than that of reaction 1.
Reaction 3 is endothermic and reverts the effect of reaction 2 back to the same effect as reaction 1 alone (lower temperature, greater number of molecules).
The catalyst structure affects the proportion of the NH3 that is dissociated in reaction 3; a higher temperature is desirable for rocket thrusters, while more molecules are desirable when the reactions are intended to produce greater quantities of gas.
Since hydrazine hydrate is a solid below 2 °C, it is not suitable as a general purpose rocket propellant for military applications.
Other variants of hydrazine that are used as rocket fuel are monomethylhydrazine, (CH3)NH(NH2), also known as MMH (mp: -52 °C), and unsymmetrical dimethylhydrazine, (CH3)2N(NH2), also known as UDMH (mp: -57 °C).
These derivatives are used in two-component rocket fuels, often together with dinitrogen tetroxide, N2O4.
A 50:50 mixture by weight of hydrazine hydrate and UDMH was used in the Titan II ICBMs and is known as Aerozine 50.
These reactions are extremely exothermic, and the burning is also hypergolic (it starts burning without any external ignition).
There are ongoing efforts in the aerospace industry to replace hydrazine and other highly toxic substances.
Promising alternatives include hydroxylammonium nitrate, 2-dimethylaminoethylazide (DMAZ) and energetic ionic liquids.
Each H2N−N subunit is pyramidal.
The N−N single bond distance is 1.45 Å (145 pm), and the molecule adopts a gauche conformation.
The rotational barrier is twice that of ethane.
These structural properties resemble those of gaseous hydrogen peroxide, which adopts a "skewed" anticlinal conformation, and also experiences a strong rotational barrier.
Synthesis and production of Hydrazine Hydrate:
Diverse routes have been developed.
The key step is the creation of the nitrogen–nitrogen single bond.
The many routes can be divided into those that use chlorine oxidants (and generate salt) and those that do not.
Oxidation of ammonia via oxaziridines from peroxide
Hydrazine hydrate can be synthesized from ammonia and hydrogen peroxide with a ketone catalyst, in a procedure called the Peroxide process (sometimes called Pechiney-Ugine-Kuhlmann process, the Atofina–PCUK cycle, or ketazine process).
The net reaction follows:
2NH3 + H2O2 -> H2NNH2 + 2H2O
In this route, the ketone and ammonia first condense to give the imine, which is oxidised by hydrogen peroxide to the oxaziridine, a three-membered ring containing carbon, oxygen, and nitrogen.
Next, the oxaziridine gives the hydrazone by treatment with ammonia, which process creates the nitrogen-nitrogen single bond.
This hydrazone condenses with one more equivalent of ketone.
Hydrazine hydrate as an important fine chemical raw materials, mainly used for the synthesis foaming agent; also used as boiler cleaning treatment agent; for the production of anti-pharmaceutical industry tuberculosis, anti-diabetic drugs; for herbicides used in the production in the pesticide industry, plant growth reconcile agents and sterilization, insecticide.
The Olin Raschig process, first announced in 1907, produces hydrazine from sodium hypochlorite (the active ingredient in many bleaches) and ammonia without the use of a ketone catalyst.
This method relies on the reaction of monochloramine with ammonia to create the nitrogen–nitrogen single bond as well as a hydrogen chloride byproduct: NH2Cl + NH3 -> H2NNH2 + HCl
Related to the Raschig process, urea can be oxidized instead of ammonia. Again sodium hypochlorite serves as the oxidant.
The net reaction is shown: (H2N)2CO + NaOCl + 2 NaOH -> N2H4 + H2O + NaCl + Na2CO3}
The process generates significant by-products and is mainly practised in Asia.
The Bayer Ketazine Process is the predecessor to the peroxide process.
It employs sodium hypochlorite as oxidant instead of hydrogen peroxide.
Like all hypochlorite-based routes, this method produces an equivalent of salt for each equivalent of hydrazine.
Redox reactions of Hydrazine Hydrate:
The heat of combustion of hydrazine in oxygen (air) is 1.941 × 107 J/kg (8345 BTU/lb).
Hydrazine is a convenient reductant because the by-products are typically nitrogen gas and water.
Thus, Hydrazine Hydrate is used as an antioxidant, an oxygen scavenger, and a corrosion inhibitor in water boilers and heating systems.
Hydrazine is also used to reduce metal salts and oxides to the pure metals in electroless nickel plating and plutonium extraction from nuclear reactor waste.
Some colour photographic processes also use a weak solution of hydrazine as a stabilising wash, as it scavenges dye coupler and unreacted silver halides. Hydrazine is the most common and effective reducing agent used to convert graphene oxide (GO) to reduced graphene oxide (rGO) via hydrothermal treatment.
Hydrazine can be monoprotonated to form various solid salts of the hydrazinium cation (N2H5+) by treatment with mineral acids.
A common salt is hydrazinium sulfate, [N2H5]HSO4, also called hydrazine sulfate.
Hydrazine sulfate was investigated as a treatment of cancer-induced cachexia, but proved ineffective.
Double protonation gives the hydrazinium dication (H3NNH32+), of which various salts are known.
As of 2015, the world hydrazine hydrate market amounted to $350 million.
Hydrazines are part of many organic syntheses, often those of practical significance in pharmaceuticals (see applications section), as well as in textile dyes and in photography.
Hydrazine is used in the Wolff-Kishner reduction, a reaction that transforms the carbonyl group of a ketone into a methylene bridge (or an aldehyde into a methyl group) via a hydrazone intermediate.
The production of the highly stable dinitrogen from the hydrazine derivative helps to drive the reaction.
Being bifunctional, with two amines, hydrazine is a key building block for the preparation of many heterocyclic compounds via condensation with a range of difunctional electrophiles. With 2,4-pentanedione, it condenses to give the 3,5-dimethylpyrazole.
In the Einhorn-Brunner reaction hydrazines react with imides to give triazoles.
Being a good nucleophile, N2H4 can attack sulfonyl halides and acyl halides.
The tosylhydrazine also forms hydrazones upon treatment with carbonyls.
Hydrazine hydrate is used to cleave N-alkylated phthalimide derivatives.
This scission reaction allows phthalimide anion to be used as amine precursor in the Gabriel synthesis.
Hydrazine hydrate formation:
Illustrative of the condensation of hydrazine hydrate with a simple carbonyl is its reaction with propanone to give the diisopropylidene hydrazine (acetone azine).
The latter reacts further with hydrazine to yield the hydrazone:
2(CH3)2CO + N2H4 -> 2 H2O + [(CH3)2C=N]2
(CH3)2C=N]2 + N2H4 -> 2 (CH3)2C=NNH2
The propanone azine is an intermediate in the Atofina-PCUK process.
Direct alkylation of hydrazines with alkyl halides in the presence of base yields alkyl-substituted hydrazines, but the reaction is typically inefficient due to poor control on level of substitution (same as in ordinary amines).
The reduction of hydrazones to hydrazines present a clean way to produce 1,1-dialkylated hydrazines.
In a related reaction, 2-cyanopyridines react with hydrazine to form amide hydrazides, which can be converted using 1,2-diketones into triazines.
Hydrazine hydrate is the intermediate in the anaerobic oxidation of ammonia (anammox) process.
Hydrazine hydrate is produced by some yeasts and the open ocean bacterium anammox (Brocadia anammoxidans).
The false morel produces the poison gyromitrin which is an organic derivative of hydrazine that is converted to monomethylhydrazine by metabolic processes.
Even the most popular edible "button" mushroom Agaricus bisporus produces organic hydrazine derivatives, including agaritine, a hydrazine derivative of an amino acid, and gyromitrin.
History of Hydrazine Hydrate:
The name "hydrazine" was coined by Emil Fischer in 1875; he was trying to produce organic compounds that consisted of mono-substituted hydrazine.
By 1887, Theodor Curtius had produced hydrazine sulfate by treating organic diazides with dilute sulfuric acid; however, he was unable to obtain pure hydrazine, despite repeated efforts.
Pure anhydrous hydrazine was first prepared by the Dutch chemist Lobry de Bruyn in 1895.
Release to the environment of this substance can occur from industrial use: of articles where the substances are not intended to be released and where the conditions of use do not promote release.
Hydrazine can be found in complex articles, with no release intended: vehicles, machinery, mechanical appliances and electrical/electronic products (e.g. computers, cameras, lamps, refrigerators, washing machines) and vehicles not covered by End of Life Vehicles (ELV) directive (e.g. boats, trains, metro or planes).
Widespread uses of Hydrazine Hydrate by professional workers:
Hydrazine is used in the following products: pH regulators and water treatment products, laboratory chemicals and fuels.
Hydrazine hydrate is used in the following areas: health services and scientific research and development.
Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) and outdoor use in close systems with minimal release (e.g. hydraulic liquids in automotive suspension, lubricants in motor oil and break fluids).
Uses of Hydrazine Hydrate at industrial sites:
Hydrazine hydrate is used in the following products: laboratory chemicals, water treatment chemicals, fuels, pH regulators and water treatment products and polymers.
Hydrazine hydrate has an industrial use resulting in manufacture of another substance (use of intermediates).
Hydrazine hydrate is used in the following areas: municipal supply (e.g. electricity, steam, gas, water) and sewage treatment and scientific research and development.
Hydrazine hydrate is used for the manufacture of: chemicals, metals, machinery and vehicles and plastic products.
Release to the environment of Hydrazine can occur from industrial use: as processing aid, as an intermediate step in further manufacturing of another substance (use of intermediates) and of substances in closed systems with minimal release.
Appearance: Colorless, fuming, oily liquid
Density: 1.021 g·cm−3
Melting point: 2 °C; 35 °F; 275 K
Boiling point: 114 °C; 237 °F; 387 K
Solubility in water: Miscible
log P: 0.67
Vapor pressure: 1 kPa (at 30.7 °C)
Acidity (pKa): 8.10 (N2H5+)
Basicity (pKb): 5.90
Conjugate acid: Hydrazinium
Refractive index (nD): 1.46044 (at 22 °C)
Viscosity: 0.876 cP
Flash point: 52 °C (126 °F; 325 K)
Autoignition temperature: 24 to 270 °C (75 to 518 °F; 297 to 543 K)
Explosive limits: 1.8–99.99%
Hydrogen Bond Donor Count: 2
Hydrogen Bond Acceptor Count: 2
Rotatable Bond Count: 0
Exact Mass: 32.037448136
Monoisotopic Mass: 32.037448136
Topological Polar Surface Area: 52 Å²
Heavy Atom Count: 2
Formal Charge: 0
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes
Hydrazine hydrate (1; 0.1 g, 2 mmol), ethyl acetoacetate (2; 0.26 g, 2 mmol), carbonyl compound (3; 2 mmol) and malononitrile (4; 0.13 g, 2 mmol) were added successively to per-6-ABCD (0.01 g, 0.008 mmol) under solvent-free conditions at room temperature.
The reaction mixture was then ground for 1 minute.
After completion of the reaction, 1 mL of distilled ethanol was added to the reaction mixture.
The precipitated per-6-ABCD was removed by filtration, washed with distilled ethanol (1 mL) for three times, dried in vacuum and reused.
The desired product, dihydropyrano[2,3-c]pyrazole 5 was obtained by evaporating the combined ethanol portions. Each of the products was characterized by 1H NMR, 13C-NMR and mass spectral studies.
Hydrazine hydrate is a highly reactive base and reducing agent used in many industrial and medical applications.
In biological applications, hydrazine hydrate and its derivatives exhibit antidepressant properties by inhibiting monoamine oxidase (MAO), an enzyme that catalyzes the deamination and inactivation of certain stimulatory neurotransmitters such as norepinephrine and dopamine.
In psychiatry, the use of hydrazine derivatives is limited due to the emergence of the tricyclic antidepressants.
RCRA waste number U133
hydrazine solution anhydrous
RCRA waste no. U133
HYDRAZINE (HYDRAZINE SULFATE)
Scav-Ox II (Salt/Mix)
Hydrazine, anhydrous, 98%
Nitrogen hydride, (N2H4)
UN 2029 (Salt/Mix)
UN 2030 (Salt/Mix)
Hydrazine (hydrazine sulphate)
Catalyzed hydrazine (Salt/Mix)
Hydrazine solution, 1.0 M in THF
Hydrazine, standard solution, N2H4
Hydrazine solution, 35 wt. % in H2O
Hydrazine, aqueous solution with not >37% hydrazine, by mass [UN3293] [Poison]
Hydrazine solution, 1 M in acetonitrile
Hydrazine, standard solution , Specpure?, N2H4 100?g/ml
Hydrazine, aqueous solution with not >37% hydrazine, by mass
Hydrazine, anhydrous or hydrazine aqueous solutions with >64% hydrazine, by mass
Hydrazine, anhydrous or hydrazine aqueous solutions with >64% hydrazine, by mass [UN2029] [Corrosive]