Unsymmetrical dimethylhydrazine

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Unsymmetrical dimethylhydrazine
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Names
Preferred IUPAC name
1,1-Dimethylhydrazine[1]
Other names
Dimazine
1,1-Dimethyldiazane
Identifiers
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3D model (JSmol)
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605261
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MeSH dimazine
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UN number 1163
  • InChI=1S/C2H8N2/c1-4(2)3/h3H2,1-2H3 ☒N
    Key: RHUYHJGZWVXEHW-UHFFFAOYSA-N ☒N
  • CN(C)N
Properties
H2NN(CH3)2
Appearance Colorless liquid
Odor Ammoniacal, fishy
Density 791 kgTemplate:Nnbspm−3 (at 22 °C)
Melting point −57 °C; −71 °F; 216 K
Boiling point 64.0 °C; 147.1 °F; 337.1 K
Miscible[2]
Vapor pressure 13.7 kPa (at 20 °C)
1.4075
Thermochemistry
164.05 JTemplate:NnbspK−1Template:Nnbspmol−1
200.25 JTemplate:NnbspK−1Template:Nnbspmol−1
48.3 kJTemplate:Nnbspmol−1
−1982.3 – −1975.1 kJTemplate:Nnbspmol−1
Hazards
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NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
4
3
1
Flash point −10 °C (14 °F; 263 K)
248 °C (478 °F; 521 K)
Explosive limits 2–95%
Lethal dose or concentration (LD, LC):
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  • 122 mg kg−1 (oral, rat)
  • 1.06 g kg−1 (dermal, rabbit)
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  • 252 ppm (rat, 4 hr)
  • 172 ppm (mouse, 4 hr)
  • 392 ppm (hamster, 4 hr)
  • 3580 ppm (dog, 15 min)
  • 1410 ppm (rat, 1 hr)
  • 981 ppm (dog, 1 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 0.5 ppm (1 mg/m3) [skin][2]
REL (Recommended)
 Ca C 0.06 ppm (0.15 mg/m3) [2 hr][2]
IDLH (Immediate danger)
 Ca [15 ppm][2]
Related compounds
Related compounds
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Unsymmetrical dimethylhydrazine (abbreviated as UDMH; also known as 1,1-dimethylhydrazine, heptyl or Geptil) is a chemical compound with the formula H2NN(CH3)2 that is primarily used as a rocket propellant.[4] At room temperature, UDMH is a colorless liquid, with a sharp, fishy, ammonia-like smell typical of organic amines. Samples turn yellowish on exposure to air and absorb oxygen and carbon dioxide. It is miscible with water, ethanol, and kerosene. At concentrations between 2.5% and 95% in air, its vapors are flammable. It is not sensitive to shock.

Symmetrical dimethylhydrazine (1,2-dimethylhydrazine) also exists, but it is not as useful.[5] UDMH can be oxidized in air to form many different substances, including toxic ones.[6][7][8]

Synthesis

In 1875, UDMH was first prepared by Emil Fischer, who discovered and named the class of hydrazines, by reducing N-Nitrosodimethylamine with zinc in boiling acetic acid.[9][10] Fischer's student Edward Renouf later studied UDMH more extensively as part of his doctoral dissertation. Other historical lab routes include methylation of hydrazine, reduction of nitrodimethylamine and amination of dimethylamine with aminopersulfuric acid.[11]

UDMH is produced industrially by two routes.[5] Based on the Olin Raschig process, one method involves reaction of monochloramine with dimethylamine giving 1,1-dimethylhydrazinium chloride:

(CH3)2NH + NH2Cl → (CH3)2NNH2 ⋅ HCl

In the presence of suitable catalysts, acetylhydrazine can be N-dimethylated using formaldehyde and hydrogen to give the N,N-dimethyl-N'-acetylhydrazine, which can subsequently be hydrolyzed:

CH3C(O)NHNH2 + 2CH2O + 2H2 → CH3C(O)NHN(CH3)2 + 2H2O
CH3C(O)NHN(CH3)2 + H2O → CH3COOH + H2NN(CH3)2

Uses

UDMH is often used in hypergolic rocket fuels as a bipropellant in combination with the oxidizer nitrogen tetroxide and less frequently with IRFNA (inhibited red fuming nitric acid) or liquid oxygen.[12] UDMH is a derivative of hydrazine and is sometimes referred to as a hydrazine. As a fuel, it is described in specification MIL-PRF-25604 in the United States.[13]

UDMH is stable and can be kept loaded in rocket fuel systems for long periods, which makes it appealing for use in many liquid rocket engines, despite its cost. In some applications, such as the OMS in the Space Shuttle or maneuvering engines, monomethylhydrazine is used instead due to its slightly higher specific impulse. In some kerosene-fueled rockets, UDMH functions as a starter fuel to start combustion and warm the rocket engine prior to switching to kerosene.

UDMH has higher stability than hydrazine, especially at elevated temperatures, and can be used as its replacement or together in a mixture. UDMH is used in many European, Russian, Indian, and Chinese rocket designs. The Russian SS-11 Sego (aka 8K84) ICBM, SS-19 Stiletto (aka 15A30) ICBM, Proton, Kosmos-3M, R-29RMU2 Layner, R-36M, Rokot (based on 15A30) and the Chinese Long March 2 are the most notable users of UDMH (which is referred to as "heptyl" (codename from Soviet era)[citation needed] by Russian engineers[14]). The Titan, GSLV, and Delta rocket families use a mixture of 50% hydrazine and 50% UDMH, called Aerozine 50, in different stages.[15] There is speculation that it is the fuel used in the ballistic missiles that North Korea has developed and tested in 2017.[16]

Safety

Hydrazine and its methyl derivatives are toxic but LD50 values have not been reported.[17] It is a precursor (via oxidation) to dimethylnitrosamine, which is carcinogenic.[18] According to scientific data, usage of UDMH in rockets at Baikonur Cosmodrome has had adverse effects on the environment.[19] One such instance was the Nedelin catastrophe in 1960 when UDMH and dinitrogen tetroxide leaked from a rocket after an explosion and killed a number of bystanders through burn injuries and its toxicity.

See also

References

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  1. ^ Page Module:Citation/CS1/styles.css has no content."dimazine – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification. Retrieved 21 February 2012.
  2. ^ a b c d Page Module:Citation/CS1/styles.css has no content.NIOSH Pocket Guide to Chemical Hazards. "#0227". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ Page Module:Citation/CS1/styles.css has no content."1,1-Dimethylhydrazine". Immediately Dangerous to Life or Health Concentrations. National Institute for Occupational Safety and Health.
  4. ^ Page Module:Citation/CS1/styles.css has no content.Semenkov, Ivan; Koroleva, Tatyana (1 December 2022). "Review on the environmental impact of emissions from space launches: a case study for areas affected by the Russian space programme". Environmental Science and Pollution Research. 29 (60): 89807–89822. Bibcode:2022ESPR...2989807S. doi:10.1007/s11356-022-23888-8. ISSN 1614-7499. PMID 36346528. S2CID 253396676.
  5. ^ a b Script error: No such module "Template wrapper".
  6. ^ Page Module:Citation/CS1/styles.css has no content.Aleksey Milyushkin, Anastasia Karnaeva (2023). "Unsymmetrical dimethylhydrazine transformation products: A review". Science of the Total Environment. 891 164367. Bibcode:2023ScTEn.89164367M. doi:10.1016/j.scitotenv.2023.164367. PMID 37236454. S2CID 258899003.
  7. ^ Page Module:Citation/CS1/styles.css has no content.Ul'yanovskii, Nikolay V.; Lakhmanov, Dmitry E.; Pikovskoi, Ilya I.; Falev, Danil I.; Popov, Mark S.; Kozhevnikov, Alexander Yu.; Kosyakov, Dmitry S. (15 July 2020). "Migration and transformation of 1,1-dimethylhydrazine in peat bog soil of rocket stage fall site in Russian North". Science of the Total Environment. 726 138483. Bibcode:2020ScTEn.72638483U. doi:10.1016/j.scitotenv.2020.138483. ISSN 0048-9697. PMID 32315849. S2CID 216073493.
  8. ^ Page Module:Citation/CS1/styles.css has no content.Koroleva, T. V.; Semenkov, I. N.; Lednev, S. A.; Soldatova, O. S. (1 February 2023). "Unsymmetrical Dimethylhydrazine (UDMH) and Its Transformation Products in Soils: A Review of the Sources, Detection, Behavior, Toxicity, and Remediation of Polluted Territories". Eurasian Soil Science. 56 (2): 210–225. Bibcode:2023EurSS..56..210K. doi:10.1134/S1064229322602001. ISSN 1556-195X. S2CID 257903133.
  9. ^ Page Module:Citation/CS1/styles.css has no content.Horst Kunz (2002). "Emil Fischer – Unequalled Classicist, Master of Organic Chemistry Research, and Inspired Trailblazer of Biological Chemistry". Angewandte Chemie International Edition. 41 (23): 4439–4451. doi:10.1002/1521-3773(20021202)41:23<4439::AID-ANIE4439>3.0.CO;2-6. PMID 12458504.
  10. ^ Page Module:Citation/CS1/styles.css has no content.Fischer, Emil (July 1875). "Ueber die Hydrazinverbindungen der Fettreihe". Berichte der Deutschen Chemischen Gesellschaft. 8 (2): 1587–1590. doi:10.1002/cber.187500802203. ISSN 0365-9496.
  11. ^ Page Module:Citation/CS1/styles.css has no content."Organic Syntheses Procedure". orgsyn.org. Retrieved 2 November 2024.
  12. ^ Page Module:Citation/CS1/styles.css has no content.Semenkov, Ivan; Koroleva, Tatyana (1 December 2022). "Review on the environmental impact of emissions from space launches: a case study for areas affected by the Russian space programme". Environmental Science and Pollution Research. 29 (60): 89807–89822. Bibcode:2022ESPR...2989807S. doi:10.1007/s11356-022-23888-8. ISSN 1614-7499. PMID 36346528. S2CID 253396676.
  13. ^ Page Module:Citation/CS1/styles.css has no content."Performance Specification Propellant, uns-Dimethylhydrazine (MIL-PRF-25604F)". ASSIST Database Quicksearch. 11 March 2014. Retrieved 26 May 2020.
  14. ^ Page Module:Citation/CS1/styles.css has no content."Following Russian rocket explosion, experts warn of 'major contamination'". 2 July 2013.
  15. ^ Page Module:Citation/CS1/styles.css has no content.Clark, John D. (1972). Ignition! An Informal History of Liquid Rocket Propellants. Rutgers University Press. p. 45. ISBN 0-8135-0725-1.
  16. ^ Page Module:Citation/CS1/styles.css has no content.Broad, William J.; Sanger, David E. (17 September 2017). "The Rare, Potent Fuel Powering North Korea's Weapons". The New York Times.
  17. ^ Page Module:Citation/CS1/styles.css has no content."unsym-Dimethylhydrazine Safedy data" (4 ed.). Archived from the original on 6 July 2018. Retrieved 23 January 2018.
  18. ^ Page Module:Citation/CS1/styles.css has no content.Gangadhar Choudhary, Hugh Hansen (1998). "Human health perspective of environmental exposure to hydrazines: A review". Chemosphere. 37 (5): 801–843. Bibcode:1998Chmsp..37..801C. doi:10.1016/S0045-6535(98)00088-5. PMID 9717244.
  19. ^ Page Module:Citation/CS1/styles.css has no content.Abdrazak, P. Kh; Musa, K. Sh (21 June 2015). "The impact of the cosmodrome 'Baikonur' on the environment and human health". International Journal of Biology and Chemistry. 8 (1): 26–29. doi:10.26577/2218-7979-2015-8-1-26-29. Archived from the original on 8 August 2016. Retrieved 2 August 2016 – via ijbch.kaznu.kz.

Further reading

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