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IUPAC name Prop-1-yne
Other names Methylacetylene
Methyl acetylene
CAS number 74-99-7
Molecular formula C3H4
Molar mass 40.0639 g/mol
Density 0.53 g/cm³
Melting point

-102 7°C

Boiling point

-23.2 °C

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Methylacetylene (propyne) is an alkyne with the chemical formula CH3CCH. It is a component of MAPP gas along with its isomer 1,2-propadiene (allene), which is commonly used in gas welding.

Use as a rocket fuel

Research by European space concerns into using light hydrocarbons with liquid oxygen as a relatively high performing propellant combination which would also be less toxic than the commonly used MMH/NTO (monomethylhydrazine/nitrogen tetroxide) systems, showed that propyne would be highly advantageous as a rocket fuel for craft intended for low Earth orbital operations. This conclusion was reached based upon a specific impulse expected to reach 370s if oxygen is used as oxidiser, a high density, and energy/volume ratio, and the moderate boiling point, which causes the chemical to present fewer problems in storage than for example a fuel that needs to be kept at extremely low temperatures. (See cryogenics.)

Use in organic chemistry

Propyne is a convenient three-carbon building block for synthesis. When propyne is condensed and treated with n-Butyllithium, solid propynyllithium is formed. This nucleophilic reagent can then be added to a carbonyl, producing a secondary alcohol. While purified propyne is expensive, in this reaction it can be replaced with MAPP gas to cheaply generate large amounts of the reagent.


  • German Aerospace Center
  • Nova Chemicals
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Methylacetylene". A list of authors is available in Wikipedia.
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