Methylhydrazine

Structural formula
General
Surname	Methylhydrazine
other names	Methylhydrazine; MMH; Methyldiazane (IUPAC);
Molecular formula	CH 6 N 2
Brief description	colorless, hygroscopic liquid with an ammonia- like odor
External identifiers / databases
EC number	200-471-4
ECHA InfoCard	100,000,429
PubChem	6061
Wikidata	Q417347
properties
Molar mass	46.07 g mol −1
Physical state	liquid
density	0.88 g cm −3
Melting point	−52 ° C
boiling point	87 ° C
Vapor pressure	49.6 hPa (20 ° C); 88 hPa (30 ° C);
solubility	very light in water (1000 g l −1 at 25 ° C)
Refractive index	1.4325 (20 ° C)
safety instructions
H and P phrases	H: 225-300 + 310 + 330-314-350-410
	P: 201-210-260-264-273-280
MAK	Switzerland: 0.2 ml m −3 or 0.35 mg m −3
Toxicological data	32 mg kg −1 ( LD 50 , rat , oral ) ; 95 mg kg −1 ( LD 50 , rat , transdermal ) ; 0.0641 mg l −1 ( LD 50 , rat , inh. , 4 h) ; 2.92 mg l −1 ( LD 50 , fish , 96 h , median value) ;
Thermodynamic properties
ΔH f 0	54.2 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Monomethylhydrazine abb. MMH is a chemical compound that consists of a hydrazine body that is simply methylated . It has the molecular formula CH ₆ N ₂ .

history

Monomethylhydrazine has been used increasingly in place of 1,1-dimethylhydrazine as a storable rocket fuel together with the oxidizer nitrous oxide since the 1990s, due to its somewhat greater density and therefore somewhat higher performance . In contrast, it has been used as fuel in satellites since the 1980s.

Occurrence and behavior in the environment

Spring lobster ( Gyromitra esculenta )

Natural sources of monomethylhydrazine are known. The in the morel ( Gyromitra esculenta ) and some other Ascomycetes known as toxin Gyromitrin is a derivative of monomethyl hydrazine. Due to its high reactivity (especially towards ozone ), widespread distribution is not to be expected when it enters the environment, and rapid degradation occurs.

Extraction and presentation

From methylamine and ammonia (dehydrogenative condensation over catalysts) or methylation of hydrazine.

properties

Monomethylhydrazine is a colorless, fish-like smelling liquid that smokes in the air. The vapors of monomethylhydrazine can irritate the skin and the mucous membranes (eyes, respiratory tract) or burn them in the event of severe exposure. The enthalpy of vaporization is 875 kJ / kg, the specific heat capacity is 2.921 kJ / kg · K at 20 ° C and 3.077 kJ / kg · K at 119.85 ° C. The dynamic viscosity is 0.855 · 10 ⁻³ Pa · s (20 ° C) and 0.40 · 10 ⁻³ Pa · s (70.8 ° C). The flash point of monomethylhydrazine is −8 ° C, the ignition temperature is 190 ° C and the explosion limits are between 2.5% (lower explosion limit) and 100% (upper explosion limit).

use

Monomethylhydrazine is the flammable component of liquid hypergolic rocket propellants , whereby it is used in combination with nitrous oxide as an oxidizing agent. The Aestus engine of the EPS upper stage of the Ariane 5 uses this fuel combination. It is very often used in satellites and space probes for attitude control.

physiology

Monomethylhydrazine is easily absorbed through the skin and has been shown to be clearly carcinogenic in animal experiments .

safety instructions

At the suggestion of the Dutch chemicals authority, the chemical classification of methylhydrazine was revised in 2015. The Committee for Risk Assessment (RAC) of the European Chemicals Agency (ECHA) changed the classification for methylhydrazine as follows on September 11, 2015: Methylhydrazine is classified as a carcinogen Carc 1B. The warning has been set to H350. This classification of the RAC has yet to be implemented by the EU Commission in applicable law, but with the publication it represents the state of knowledge that must be taken into account by companies and authorities.

literature

George P. Sutton and Oscar Biblarz: Rocket Propulsion Elements . 7th edition, Wiley-Interscience Publication, 2001; ISBN 0-471-32642-9 ; Pp. 244, 258

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ Entry on methylhydrazine in the GESTIS substance database of the IFA , accessed on December 30, 2019(JavaScript required) .
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-356.
↑ Entry on methylhydrazine in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on December 30, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 60-34-4 or methylhydrazine ), accessed on November 2, 2015.
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-20.
↑ RAC decision of September 11, 2015

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ Entry on methylhydrazine in the GESTIS substance database of the IFA , accessed on December 30, 2019(JavaScript required) .

[CRC90_3_356-2] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-356.

[CLP_100.000.429-3] Entry on methylhydrazine in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on December 30, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .

[4] Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 60-34-4 or methylhydrazine ), accessed on November 2, 2015.

[CRC90_5_20-5] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-20.

[6] RAC decision of September 11, 2015