Unsymmetrical dimethylhydrazine

  • UDMH
  • Unsymmetrical dimethylhydrazine ( UDMH )
  • N, N- dimethyl

Colorless, amine-like smelling liquid


0.78 g · cm -3

-58 ° C

63 ° C.

145 hPa ( 20 ° C)

Miscible with water

1.4075 (20 ° C)


48.9 kJ / mol

Template: Infobox chemical / molecular formula search available

1,1 -dimethylhydrazine ( UDMH cast off for unsymmetrical dimethylhydrazine ) is a doubly methylated derivative of hydrazine. In contrast to the symmetrical dimethylhydrazine (1,2- dimethylhydrazine ) are both methyl groups on the same nitrogen atom are attached here.


1,1- dimethyl hydrazine is used as rocket fuel since the 1950s due to its good shelf life. Now serves as the oxidizing agent to mostly dinitrogen tetroxide, often before nitric acid was used.

Extraction / representation

1,1- dimethylhydrazine may be made of a catalysed reaction between ammonia and dimethylamine. In Germany it is no longer manufactured.


UDMH is a colorless, fishy -smelling liquid which fumes in the air. The vapors of 1,1- dimethylhydrazine can irritate or corrode under heavy load the skin and mucous membranes (eyes, respiratory tract). It has at 20 ° C has a dynamic viscosity of 0.56 · 10-3 Pa · s

Due to its low vapor pressure and high reactivity ( especially against ozone) is not expected to be long-range distribution of entry into the environment; it will execute a fast degradation.


  • For preparing dyes, pharmaceuticals and synthetic fibers.
  • As gas absorbent for carbon dioxide and sulfur dioxide.
  • 1,1 -dimethylhydrazine is the combustible component ( heptyl, in Russian) hypergolischer liquid rocket propellants, when it along with the oxidizers dinitrogen tetroxide ( amyl, Russian) or fuming (fuming nitric acid, AK- 27I or melange, in Russian) is used. The Proton launch vehicle used 1,1 -dimethylhydrazine as fuel several or all stages, which leads to contamination with false starts in the area around the crash. In the first Gulf War, used Soviet Scud missiles contained 1000 kg 3500 kg UDMH and fuming.
  • 1,1 -dimethylhydrazine is not only pure but also mixed with hydrazine used as rocket fuel. Known mixtures with different concentrations of the two components are mutually Aerozin 50 and UH 25


1,1 -dimethylhydrazine is easily absorbed through the skin and has been proven in animal studies to be carcinogenic.