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 2H225—Highly flammable liquid and vaporChemical Safety Warning
Acute toxicity, oral, category 2H300—Fatal if swallowedChemical Safety Warning
Acute toxicity, dermal, category 2H310—Fatal in contact with skinChemical Safety Warning
Skin corrosion/irritation, category 1BH314—Causes severe skin burns and eye damageChemical Safety Warning
Serious eye damage/eye irritation, category 1H318—Causes serious eye damageChemical Safety Warning
Acute toxicity, inhalation, category 1H330—Fatal if inhaledChemical Safety Warning
Carcinogenicity, category 1BH350—May cause cancerChemical Safety Warning
Short-term (acute) aquatic hazard, category 1H400—Very toxic to aquatic lifeChemical Safety Warning
Long-term (chronic) aquatic hazard, category 1H410—Very toxic to aquatic life with long-lasting effectsChemical 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 nomenclatureHydrazine, methyl-
Empirical formulaCH6N2
Molar mass46.07 g/mol
AppearanceFuming colorless liquid
OdorSimilar to ammonia and small aminoalkanes
Boiling point87.5 °C
Water solubilityMiscible

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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