5-Decyne
{{Chembox
| ImageFile = Dec-5-yne 200.svg
| ImageSize = 200px
| ImageAlt =
| PIN = Dec-5-yne
| OtherNames = {{bulletedlist|Dibutylethyne|Dibutylacetylene|Dec-5-yne|1,2-Dibutylacetylene}}
| Section1 = {{Chembox Identifiers
| CASNo = 1942-46-7
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 88G1AII0AH
| PubChem = 16030
| ChemSpiderID = 15222
| SMILES = CCCCC#CCCCC
| StdInChI = 1S/C10H18/c1-3-5-7-9-10-8-6-4-2/h3-8H2,1-2H3
| StdInChIKey = JWBQJUFCNOLNNC-UHFFFAOYSA-N
| MeSHName = C028997
}}
| Section2 = {{Chembox Properties
| C=10|H=18
| Appearance =
| Density = 0.766 g/ml
| MeltingPt =
| BoilingPtC = 177
| Solubility =
}}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
}}
5-Decyne, also known as dibutylethyne, is a type of alkyne with a triple bond at its fifth carbon (the '5-' indicates the location of the triple bond in the chain). Its formula is C10H18. Its density at 25 °C and otherwise standard conditions is 0.766 g/ml.{{Sigma-Aldrich|id=545449 |name=5-Decyne|accessdate=16. August 2016}} The boiling point is 177 °C.David R. Lide (Hrsg.): CRC Handbook of Chemistry and Physics. 90. Auflage. (Internet-Version: 2010), CRC Press/Taylor and Francis, Boca Raton, Florida, Physical Constants of Organic Compounds, S. 3-136. The average molar mass is 138.25 g/mol.
5-Decyne forms a group of symmetric alkynes with 4-octyne, 3-hexyne, and 2-butyne.