1,1-Dimethylhydrazine

  • Unsymetrical dimethyl hydrazine
  • UDMH
  • Dimazine
  • N,N-Dimethylhydrazine
Formula
(CH3)2NNH2
Structure
Description
Fuming colorless liquid, gradually turns yellow in air, hygroscopic, ammonia or fish-like odor.
Uses
The base in rocket fuel formulations.

Registry Numbers and Inventories.
CAS
57-14-7
EC (EINECS/ELINCS)
200-316-0
EC Index Number
007-012-00-5
EC Class
Highly flammable; Carcinogenic Category 2; Toxic; Corrosive; Dangerous for the Environment
R 45 11 23/25 34 51/53
S 53 45 61
RTECS
MV2450000
RTECS class
Tumorigen; Mutagen; Reproductive Effector; Human Data
UN (DOT)
1163
Merck
13,3273
Beilstein/Gmelin
605261
Beilstein Reference
4-04-00-03322
RCRA
U098
EPA OPP
600018
Swiss Giftliste 1
G-1561
Canada DSL/NDSL
NDSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
C2H8N2
Formula mass
60.10
Melting point, °C
-58
Boiling point, °C
63
Vapor pressure, mmHg
157
Vapor density (air=1)
1.94
Saturation Concentration
136000 ppm (13.6%) at 20 C (calculated)
Odor Threshold Odor threshold 12.0 mg/m3
Critical temperature
250
Critical pressure
53.5
Density
0.801 g/cm3 (11 C)
Solubility in water
Very soluble
Viscosity
0.492 millipascal second @ 25C
Surface tension
24.09 g/s2 at 25 C
Refractive index
1.0001
pKa/pKb
6.79 (pKb)
Heat of fusion
10.1 kJ/mol
Heat of vaporization
32.6 kJ/mol
Heat of combustion
-1979 kJ/mol

Hazards and Protection.
Storage
Keep away from heat, sparks, and flame. Keep away from sources of ignition. Keep container closed when not in use. Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Refrigerator/flammables.
Handling
Wash thoroughly after handling. Use only in a well ventilated area. Ground and bond containers when transferring material. Empty containers retain product residue, (liquid and/or vapor), and can be dangerous. Keep container tightly closed. Avoid contact with heat, sparks and flame. Do not get on skin or in eyes. Avoid ingestion and inhalation. Discard contaminated shoes. Do not pressurize, cut, weld, braze, solder, drill, grind, or expose empty containers to heat, sparks or open flames.
Protection
Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166. Skin: Wear appropriate protective gloves to prevent skin exposure. Clothing: Wear appropriate protective clothing to prevent skin exposure.
Respirators
A respiratory protection program that meets OSHA's 29 CFR 1910.134 and ANSI Z88.2 requirements or European Standard EN 149 must be followed whenever workplace conditions warrant a respirator's use. Follow the OSHA respirator regulations found in 29CFR 1910.134 or European Standard EN 149. Always use a NIOSH or European Standard EN 149 approved respirator when necessary.
Small spills/leaks
Absorb spill with inert material, (e.g., dry sand or earth), then place into a chemical waste container. Clean up spills immediately, using the appropriate protective equipment. Remove all sources of ignition. Use a spark-proof tool. Provide ventilation. A vapor suppressing foam may be used to reduce vapors.
Disposal code
9
Stability
Stable under normal temperatures and pressures.
Incompatibilities
Halogens, mercury, strong acids, strong oxidizing agents, rubber, plastics.
Decomposition
Nitrogen oxides, carbon monoxide, irritating and toxic fumes and gases, carbon dioxide, nitrogen.

Fire.
Flash Point,°C
1
Autoignition, °C
249
Upper exp. limit, %
45
Lower exp. limit, %
2
Fire fighting
Wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear. During a fire, irritating and highly toxic gases may be generated by thermal decomposition or combustion. Use water spray to keep fire-exposed containers cool. Containers may explode in the heat of a fire. Will be easily ignited by heat, sparks or flame. Extinguishing media: For small fires, use dry chemical, carbon dioxide, water spray or alcohol-resistant foam. For large fires, use water spray, fog, or alcohol-resistant foam. Use water spray to cool fire-exposed containers. Water may be ineffective. Do NOT use straight streams of water.
Fire potential
Quite flammable. Easily ignited. The mixture with hydrazine.
Hazards
Vapor may explode if ignited in an enclosed area. Vapors may travel to a source of ignition and flashback. Runoff to sewer may create fire or explosion hazard. When it decomposes, 1,1-dimethylhydrazine gives off toxic nitrogen compound fumes. Dissolves, swells, and disintegrates many plastics. Dangerous when exposed to heat, flame, or oxidizers. Hazardous polymerization may not occur.
Combustion products
Toxic oxides of nitrogen are produced during combustion of this material.
Health
4
 
Flammability
4
 
 
Reactivity
1
 

Health.
Exposure limit(s)
OSHA PEL: TWA 0.5 ppm (1 mg/m3) skin NIOSH REL: Ca C 0.06 ppm (0.15 mg/m3) 2-hr See Appendix A NIOSH IDLH: Potential occupational carcinogen 15 ppm
Carcinogin
G-A3, I-2B, N-2, CP65
Poison_Class
1*
Exposure effects
Possible cancer hazard based on tests with laboratory animals. Chronic exposure may cause liver damage.
   Ingestion
Harmful if swallowed. May cause severe and permanent damage to the digestive tract. Causes gastrointestinal tract burns. May cause liver damage.
   Inhalation
Harmful if inhaled. Causes chemical burns to the respiratory tract. Exposure produces central nervous system depression. Vapors may cause dizziness or suffocation.
   Skin
Causes skin burns. May be harmful if absorbed through the skin.
   Eyes
Causes eye burns. May result in corneal injury.

First aid
 
   Ingestion
Do NOT induce vomiting. If victim is conscious and alert, give 2-4 cupfuls of milk or water. Never give anything by mouth to an unconscious person. Get medical aid immediately.
   Inhalation
Get medical aid immediately. Remove from exposure to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. DO NOT use mouth-to-mouth respiration.
   Skin
Get medical aid immediately. Immediately flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing before reuse. Destroy contaminated shoes.
   Eyes
Get medical aid immediately. Do NOT allow victim to rub or keep eyes closed. Extensive irrigation is required (at least 30 minutes).

Transport.
UN number
1163
Response guide
Hazard class
6.1
PRTC
T
Packing Group
I
 
USCG CHRIS Code
DMH
 
HS Code
2928 00 90
 
Std. Transport #
4921202