Copper(I) acetylide

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Copper(I) acetylide
Copper-acetylide-16.jpg
When acetylene gas, produced by adding water to calcium carbide, is passed through a solution of copper(I) chloride, the reddish copper(I) acetylide is being produced.
Names
IUPAC name
Copper(I) acetylide
Other names
Cuprous acetylide
Dicuprous acetylide
Properties
Cu2C2
Molar mass 151.114 g/mol
Appearance Reddish solid
Odor Odorless
Melting point 100 °C (212 °F; 373 K) (explosive decomposition)
Boiling point Decomposes
Insoluble
Solubility Reacts with acids
Insoluble in organic solvents
Vapor pressure ~0 mmHg
Hazards
Safety data sheet None
Related compounds
Related compounds
Silver acetylide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Copper(I) acetylide or cuprous acetylide, is a chemical compound with the formula Cu2C2. It is a reddish solid, that easily explodes when dry.

Properties

Chemical

Copper(I) acetylide explodes when dry, but it's more stable when wet. It is one of the very few explosive materials that do not liberate any gaseous products upon detonation.

Thermal decomposition of copper acetylide in vacuum is not explosive and leaves copper metal as a fine powder at the bottom of the flask, while depositing a fluffy very fine carbon powder on the walls. On the basis of spectral data, this powder was claimed to be carbyne C(−C≡C−)nC rather than graphite as expected.

Copper(I) acetylide can be used as catalyst in the preparation of 1,4-butynediol from acetylene gas and formaldehyde.[1]

Physical

Copper(I) acetylide is a reddish powder that is insoluble in water and organic solvents.

Explosive

When dry, copper acetylide is a heat and shock sensitive high explosive, though more thermally sensitive than silver acetylide. It explodes when heated above 100 °C.

Availability

Copper(I) acetylide is not sold due to its instability and has to be made in situ.

Preparation

Copper acetylide can be prepared by bubbling acetylene gas through an aqueous solution of copper(I) chloride and ammonia:[2][3]

C2H2 (g) + 2 CuCl (s) → Cu2C2 (s) + 2 HCl (g)

The resulting Cu acetylide precipitates as a reddish solid.

Projects

  • Pyrotechnic demonstrations
  • Synthesis of 1,4-butynediol
  • Purify acetylene

Handling

Safety

Copper(I) acetylide is stable when wet, but the dry pure form is highly sensitive to shock and heat, and will explode if disturbed.

Storage

Should not be stored and used up as soon as possible.

Disposal

Can be safely neutralized when wet, by carefully adding and acid, like hydrochloric acid. This produces a copper salt and acetylene gas, so this process must be done outside.

References

  1. https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202101932
  2. https://www.youtube.com/watch?v=YtTnYCZJw94
  3. https://www.youtube.com/watch?v=uPuhAU8SjdE

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