January 02, 2023
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Image of Methylhydrazine 3D Image of Methylhydrazine

We begin 2023 with the nasty molecule methylhydrazine. As shown in the hazard information table, the compound, also called monomethylhydrazine (MMH), is deadly to humans and environmentally harmful. It is, unexpectedly, found in nature.

Methylhydrazine has been known since at least 1888, when German chemist Gustav von Brüning initiated a series of articles on the molecule. In 1890, he reported a synthesis of MMH that began with the preparation of 1-nitroso-1-methylurea from methylurea nitrate and sodium nitrite. The nitroso compound was then reduced with zinc dust in acetic acid to produce MMH after an extensive workup procedure.

In 1954, L. F. Audrieth* and L. H. Diamond at the University of Illinois (Urbana–Champaign) reported a more concise synthesis: They prepared methylhydrazine and other monosubstituted hydrazines via the reaction of methylamine with chloramine. This process is used for the modern industrial production of MMH. The compound’s main uses are in rocket propellants and the synthesis of higher hydrazine derivatives and other organic chemicals.

Where does methylhydrazine turn up in nature? It is one of the deadliest compounds in poisonous mushrooms. It is found in Gyromitra spp., in which it is formed when the native toxin gyromitrin1 hydrolyzes. Other lethal mushroom poisons include α-amanitin2, orellanine3, and ergotamine4.

1. CAS Reg. No. 16568-02-8.
2. CAS Reg. No. 23109-05-9.
3. CAS Reg. No. 37338-80-0.
4. CAS Reg. No. 113-15-5.

Methylhydrazine hazard information

Hazard class* GHS code and hazard statement
Flammable liquids, category 2 H225—Highly flammable liquid and vapor Chemical Safety Warning
Acute toxicity, oral, category 2 H300—Fatal if swallowed Chemical Safety Warning
Acute toxicity, dermal, category 2 H310—Fatal in contact with skin Chemical Safety Warning
Skin corrosion/irritation, category 1B H314—Causes severe skin burns and eye damage Chemical Safety Warning
Serious eye damage/eye irritation, category 1 H318—Causes serious eye damage Chemical Safety Warning
Acute toxicity, inhalation, category 1 H330—Fatal if inhaled Chemical Safety Warning
Carcinogenicity, category 1B H350—May cause cancer Chemical Safety Warning
Short-term (acute) aquatic hazard, category 1 H400—Very toxic to aquatic life Chemical Safety Warning
Long-term (chronic) aquatic hazard, category 1 H410—Very toxic to aquatic life with long-lasting effects Chemical Safety Warning

*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms

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Methylhydrazine fast facts

CAS Reg. No. 60-34-4
SciFinder nomenclature Hydrazine, methyl-
Empirical formula CH6N2
Molar mass 46.07 g/mol
Appearance Fuming colorless liquid
Odor Similar to ammonia and small aminoalkanes
Boiling point 87.5 °C
Water solubility Miscible

MOTW update

Cubane1 was the Molecule of the Week for March 10, 2008. As its name implies, it is a highly symmetrical cubic molecule. It is thermally unstable because of the high strain of its 90° bond angles.

In December, Xujun Cheng, Stephen L. Craig, and co-workers at Duke University (Durham, NC) described the mechanochemistry of cubane. When a cubane derivative with polymeric side chains at the 1- and 2-positions was subjected to pulsed ultrasonication, the only product was the corresponding syn-tricyclooctadiene, in contrast to the cyclooctatetraene derivative formed by thermal isomerization.

1. CAS Reg. No. 277-10-1.

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