Hydrazine
Encyclopedia : H : HY : HYD : Hydrazine
   |
|
| General | |
|---|---|
| Name | Hydrazine |
| Chemical formula | N2H4 |
| Appearance | Colourless liquid |
| Physical | |
| Formula weight | 32.0 amu |
| Melting point | 274 K (1 °C) |
| Boiling point | 387 K (114 °C) |
| Density | 1.01g/ml |
| Solubility | very soluble |
| Thermochemistry | |
| ΔfH0gas | 95.35 kJ/mol |
| ΔfH0liquid | 50.63 kJ/mol |
| ΔfH0solid | 37.63 kJ/mol |
| S0gas, 1 bar | 238.66 J/mol·K |
| S0liquid, 1 bar | 121.52 J/mol·K |
| S0solid | ? J/mol·K |
| Safety | |
| Ingestion | Extremely Toxic, possibly carcinogenic |
| Inhalation | Very dangerous—extremely destructive to the upper respiratory tract |
| Skin | Can cause severe burns, can be absorbed into bloodstream |
| Eyes | Can cause permanent damage |
| More info | [Hazardous Chemical Database] |
| LD50 | as low as 25mg/kg |
|
SI units were used where possible. Unless otherwise stated, standard conditions were used.
Disclaimer and references | |
Hydrazine is a chemical compound with formula N2H4 used as a rocket fuel.
Hydrazine is a liquid with weak basic properties similar to ammonia. Due to the alpha effect the nucleophilicity is much stronger than that of ammonia, which makes it more reactive. It can be made by oxidizing ammonia with sodium hypochlorite (the Raschig process). It is a monopropellant rocket fuel. It is also pyrophoric, i.e. it can ignite spontaneously.
Health effects
Breathing hydrazines may cause coughing and irritation of the throat and lungs, tremors, or seizures. Breathing hydrazines for long periods may cause liver and kidney damage, as well as serious effects on reproductive organs.
Eating or drinking small amounts of hydrazines may cause nausea, vomiting, uncontrolled shaking, inflammation of the nerves, drowsiness, or coma. Hydrazine is found in chewing tobacco and cigarettes.
Tumors have been seen in many organs of animals that were exposed to hydrazines by ingestion or breathing, but most tumors have been found in the lungs, blood vessels, or colon. 1,2-Dimethylhydrazine has caused colon cancer in laboratory animals following a single exposure.
The Department of Health and Human Services (DHHS) has determined that hydrazine and 1,1-dimethylhydrazine are known carcinogens. The International Agency for Research on Cancer (IARC) has determined that hydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine are possible human carcinogens. The Environmental Protection Agency (EPA) has determined that hydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine are probable human carcinogens.[link]
The American Conference of Governmental Industrial Hygienists (ACGIH) currently lists hydrazine and 1,1-dimethylhydrazine as suspected carcinogens, but has recently recommended that the listing of hydrazine be changed to that of animal carcinogen, not likely to cause cancer to people under normal exposure conditions.
The False Morel contains the chemical gyromitrin, which is metabolized into monomethyl hydrazine inside the body. Consequently, the toxic effects of this mushroom are the same as with hydrazine poisoning.
Use
Hydrazine is used primarily as a chemical intermediate to produce agricultural chemicals, spandex fibers, and antioxidants. Hydrazine is also used as rocket fuel (starting in World War II for the Messerschmitt Me 163, under name B-Stoff (hydrazine hydrate) and in a mixture with methanol (M-Stoff) as C-Stoff), an oxygen scavenger (corrosion inhibitor) in water boilers and heating systems, a polymerization catalyst, a blowing agent, and as a scavenger for gases. Additionally, it is used for plating metals on glass and plastics and in fuel cells, solder fluxes, and photographic developers. Hydrazine is used as a reactant in fuel cells in the military, as a reducing agent in electrodeless nickel plating, as a chain extender in urethane polymerizations, as a reducing agent in plutonium extraction from nuclear reactor waste, and as a water treatment chemical. Hydrazine is also used as a chemical intermediate for blowing agents, photography chemicals, pharmaceuticals, antituberculants, textile dyes, heat stabilizers, explosives, and to make hydrazine sulfate. In addition, a semiconductor deposition technique involving the use of hydrazine has recently been demonstrated, with possible application to the manufacture of thin-film transistors used in liquid crystal displays. Hydrazine in a 70% solution is used to power the EPU (emergency power unit) on the F-16 fighter plane. Hydrazine is also used as low-power propellant for Space Shuttle maneuvers in orbit in its Reaction Control System and Orbital Maneuvering System, using hypergolic 1,1-dimethylhydrazine with nitrogen tetroxide oxidizer.[link] The explosive Astrolite is made by combining hydrazine with ammonium nitrate.
Molecular structure
Hydrazine prefers a gauche conformation. The rotational barrier is twice that of ethane.Industrial production
Hydrazine is produced in the Olin Raschig process from sodium hypochlorite and ammonia, a process developed in 1907 . In the Atofina-PCUK cycle hydrazine is produced in several steps. Acetone and ammonia first react to the imine followed by oxidation with hydrogen peroxide to the oxiziridine (three-membered ring containing oxygen and nitrogen) followed by conversion to the hydrazone. This hydrazone reacts with one more equivalent of acetone and after hydrolysis the product hydrazine is liberated together with recreated acetone. Unlike the Raschig process, this process does not produce waste material. In addition, hydrazine can be produced in the ketazine process or the peroxide process.Hydrazines
Hydrazine derivatives 1,1-dimethylhydrazine and 1,2-dimethylhydrazine, in which two of the hydrogen atoms are substituted with methyl groups, are also described as hydrazines. 1,1-Dimethylhydrazine (also known as UDMH) is used to make hypergolic (self-igniting) bipropellant rocket fuels. Another hydrazine derivative, 2,4-Dinitrophenylhydrazine (2,4-DNP), is commonly used as a test for ketones and aldehydes in organic chemistry.The first discovered hydrazine is phenylhydrazine C6H5NHNH2 by Emil Fischer in 1875 by reduction of a phenyl diazonium salt by sulfite salts Fischer, E. Ber. Dtsch. Chem. Ges., 1875, 8, 589.. Fischer prepared many other hydrazines before another chemist Theodor Curtius was able to synthesize free hydrazine for the first time in 1889.
Several naturally occurring hydrazines exist such as gyromitrin and agaritine, a phenylhydrazine found in the commercially produced mushroom species agaricus bisporus. Iproniazid and Hydralazine are hydrazine medications.
Organic reactions
Hydrazines are part of many organic reactions:- direct alkylation of hydrazines with alkyl halides and base to more alkylated hydrazines is not efficient due to poor control on level of substitution (same as in ordinary amines)
- organic reduction of hydrazones to hydrazines present a clean way to produce 1,1-dialkylated hydrazines
- Brady's reagent (2,4-Dinitrophenylhydrazine) reacts with carbonyl groups in ketones and aldehydes to form a hydrazone compound.
- Hydrazine is used in the Wolff-Kishner reduction, which transforms the carbonyl group of a ketone or aldehyde to a methylene (or methyl) group via a hydrazone intermediate; production of the highly stable dinitrogen from the hydrazine derivative helps to drive the reaction forward.
- in the Einhorn-Brunner reaction hydrazines react with amides to triazoles.
References
See also
External links
- The Late Show with Rob! Tonight’s Special Guest: Hydrazine [PDF] Robert Matunas
- For a full list of external links to MSDSs, spectroscopic data, commercial chemicals suppliers etc. for this compound, see [Chemical sources].
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.