Diacetylene

Diacetylene (also known as butadiyne) is the organic compound with the formula C₄H₂. It is the simplest compound containing two triple bonds. It is first in the series of polyynes, which are of theoretical but not of practical interest.

Diacetylene

Names
Preferred IUPAC name Buta-1,3-diyne
Other names 1,3-Butadiyne Biacetylene Butadiyne
Identifiers
CAS Number	460-12-8 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1236317
ChEBI	CHEBI:37820 Y
ChemSpider	9603 Y
ECHA InfoCard	100.006.641
EC Number	207-303-9
PubChem CID	9997
UNII	6389J044O5 Y
CompTox Dashboard (EPA)	DTXSID8060036
InChI InChI=1S/C4H2/c1-3-4-2/h1-2H Y Key: LLCSWKVOHICRDD-UHFFFAOYSA-N Y InChI=1/C4H2/c1-3-4-2/h1-2H Key: LLCSWKVOHICRDD-UHFFFAOYAU
SMILES C#CC#C
Properties
Chemical formula	C4H2
Molar mass	50.060 g·mol−1
Appearance	Gas
Boiling point	10 °C (50 °F; 283 K)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Highly flammable; Peroxide forming
GHS labelling:
Pictograms
Signal word	Danger
Safety data sheet (SDS)	External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Occurrence

Diacetylene has been identified in the atmosphere of Titan and in the protoplanetary nebula CRL 618 by its characteristic vibrational spectrum. It is proposed to arise by a reaction between acetylene and the ethynyl radical (C₂H), which is produced when acetylene undergoes photolysis. This radical can in turn attack the triple bond in acetylene and react efficiently even at low temperatures. Diacetylene has also been detected on the Moon.

Preparation

This compound may be made by the dehydrohalogenation of 1,4-dichloro-2-butyne by potassium hydroxide (in alcoholic medium) at ~70°C:

${\ce {ClCH2C#CCH2Cl + 2 KOH -> HC#C-C#CH + 2 KCl + 2 H2O}}$

The bis(trimethylsilyl)-protected derivative may be prepared by the Hay coupling of (trimethylsilyl)acetylene:

${\ce {2 Me3Si-C#CH -> Me3Si-C#C-C#C-SiMe3}}$

See also

• Acetylene
• Diiodobutadiyne
• Butenyne
• Hydrocarbon

Further reading

• Maretina, Irina A; Trofimov, Boris A (2000). "Diacetylene: a candidate for industrially important reactions". Russian Chemical Reviews. 69 (7): 591. doi:10.1070/RC2000v069n07ABEH000564. S2CID 250889660.