1-Butyne

1-Butyne is an organic compound with the formula CH₃CH₂C≡CH. It is a terminal alkyne. The compound is a common terminal alkyne substrate in diverse studies of catalysis. It is a colorless combustible gas.^[1] In 2017, 3.9 million pounds (1,700 long tons) was produced in the USA.^[4]

1-Butyne

${\displaystyle {\ce {H-C#C}}{-}{\ce {\overset {\displaystyle {H} \atop |}{\underset {| \atop \displaystyle {H}}{C}}}}{-}{\ce {\overset {\displaystyle {H} \atop |}{\underset {| \atop \displaystyle {H}}{C}}}}{\ce {-H}}}$
Full displayed formula
Space-filling model
Names
Preferred IUPAC name But-1-yne
Other names Ethylacetylene Ethylethyne, UN 2452
Identifiers
CAS Number	107-00-6 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:48087 Y
ChemSpider	7558 Y
ECHA InfoCard	100.003.139
EC Number	203-451-3
PubChem CID	7846
UNII	A6B47CPN6W Y
UN number	2452
CompTox Dashboard (EPA)	DTXSID4029141
InChI InChI=1S/C4H6/c1-3-4-2/h1H,4H2,2H3 Y Key: KDKYADYSIPSCCQ-UHFFFAOYSA-N Y InChI=1/C4H6/c1-3-4-2/h1H,4H2,2H3 Key: KDKYADYSIPSCCQ-UHFFFAOYAI
SMILES C#CCC
Properties[1]
Chemical formula	C4H6
Molar mass	54.091 g/mol
Odor	Acetylenic[2]
Density	0.6783 g cm−3[1]
Melting point	−125.7 °C (−194.3 °F; 147.5 K)[1]
Boiling point	8.08 °C (46.54 °F; 281.23 K)[1]
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H220
Precautionary statements	P210, P377, P381, P403
Flash point	7°C (45°F)[3]
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

1-Butyne participates in reactions typical for terminal alkynes, such as alkyne metathesis,^[5] hydrogenation, condensation with formaldehyde. Based on its heat of combustion, it is slightly more stable than its isomer 2-butyne.^[6]

The combustion of 1-Butyne produces propargyl radicals, a pre-cursor to soot and polycyclic aromatic hydrocarbons, as the propargyl radicals can form basic aromatic rings, making butyne's fuel usage a concern for emissions.^[7]

1-Butyne is in unsaturated C₄ petroleum cuts, and has to be separated out in industrial hydrorefining to make 1-butene, which is used to make low density polyethylene and polybutene. Distillation is impractical due to similar boiling points, so 1-butyne is removed by catalytic hydrogenation.^[8] Usually the catalyst is palladium, operated with liquid hydrocarbon and hydrogen gas at 20-60°C and pressures up to 10 bar.^[9]

See also

• 2-Butyne
• Butadiene
• Cyclobutene