Unsymmetrical dimethylhydrazine
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, heptyl or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell typical for organic amines. Samples turn yellowish on exposure to air and absorb oxygen and carbon dioxide. It is miscible with water, ethanol, and kerosene. In concentration between 2.5% and 95% in air, its vapors are flammable. It is not sensitive to shock. Symmetrical dimethylhydrazine (1,2-dimethylhydrazine) is also known but is not as useful. UDMH can be oxidized in air to form many different substances, including toxic ones.
Names | |
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Preferred IUPAC name
1,1-Dimethylhydrazine | |
Other names
Dimazine | |
Identifiers | |
3D model (JSmol) |
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605261 | |
ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.000.287 |
EC Number |
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KEGG | |
MeSH | dimazine |
PubChem CID |
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RTECS number |
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UNII | |
UN number | 1163 |
CompTox Dashboard (EPA) |
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Properties | |
H2NN(CH3)2 | |
Appearance | Colorless liquid |
Odor | Ammoniacal, fishy |
Density | 791 kg m−3 (at 22 °C) |
Melting point | −57 °C; −71 °F; 216 K |
Boiling point | 64.0 °C; 147.1 °F; 337.1 K |
Miscible | |
Vapor pressure | 13.7 kPa (at 20 °C) |
Refractive index (nD) |
1.4075 |
Thermochemistry | |
Heat capacity (C) |
164.05 J K−1 mol−1 |
Std molar entropy (S⦵298) |
200.25 J K−1 mol−1 |
Std enthalpy of formation (ΔfH⦵298) |
48.3 kJ mol−1 |
Std enthalpy of combustion (ΔcH⦵298) |
−1982.3 – −1975.1 kJ mol−1 |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards |
Carcinogen, spontaneously ignites on contact with oxidizers |
GHS labelling: | |
Danger | |
H225, H301, H314, H331, H350, H411 | |
P210, P261, P273, P280, P301+P310 | |
NFPA 704 (fire diamond) | |
Flash point | −10 °C (14 °F; 263 K) |
248 °C (478 °F; 521 K) | |
Explosive limits | 2–95% |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
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LC50 (median concentration) |
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NIOSH (US health exposure limits): | |
PEL (Permissible) |
TWA 0.5 ppm (1 mg/m3) [skin] |
REL (Recommended) |
Ca C 0.06 ppm (0.15 mg/m3) [2 hr] |
IDLH (Immediate danger) |
Ca [15 ppm] |
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).
Infobox references |
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