12 Examples of Alkynes

A few common examples of alkynes include ethyne (acetylene), propyne, and butyne. Ethyne has the simplest structure (C₂H₂) with a triple bond between two carbons while propyne (C₃H₄) and butyne (C₄H₆) have triple bonds with longer carbon chains. Other basic alkynes are 2-pentyne, 3-hexyne, and 1-heptyne, which have 5, 6, and 7 carbon chains respectively featuring highly reactive triple bonds.

The electron density around the carbon-carbon triple bonds causes alkynes to display increased reactivity compared to other hydrocarbons.

Refreneces : [1] [2]

Examples of Alkynes

Here are 10 examples of alkynes:

1: Terminal Alkynes

General Formula: CnH2n-2 where n>=2

Terminal alkynes have a carbon-carbon triple bond at the end of the carbon chain. This bond consists of 1 sigma and 2 perpendicular pi bonds between two sp-hybridized carbon atoms.

Examples

• Ethyne (Acetylene): C₂H₂
• Propyne: CH≡C-CH₃
• But-1-yne: CH≡C-CH₂-CH₃
• Pent-1-yne: CH≡C-CH₂-CH₂-CH₃
• Hex-1-yne: CH≡C-(CH2)₃-CH₃

2: Symmetrical Internal Alkynes

General Formula: CnH2n-4 where n>=4

Symmetrical internal alkynes have a carbon-carbon triple bond between two internal carbons equidistant from the ends of the chain.

Examples

• Buta-2,3-diyne: CH≡C-C≡CH
• Penta-2,4-diyne: CH≡C-CH₂-C≡CH
• Hepta-2,4-diyne: CH≡C-(CH₂)₂-C≡CH
• Nona-2,5-diyne: CH≡C-(CH2)₃-C≡CH
• Undeca-3,6-diyne: CH≡C-(CH₂)₄-C≡CH

3: Asymmetrical Internal Alkynes

General Formula: R1-CnH2n-5-R2 where n>=3

Asymmetrical alkynes contain a triple bond located internally at unequal distances from the ends of the carbon chain.

Examples

• 3-Hexyne: CH≡C-CH₂-CH₂-CH₃
• 5-Decyne: CH3-(CH2)3-C≡C-(CH₂)₄-CH₃
• 2-Nonyne: CH₃(CH₂)₆-C≡CH
• 4-Tetradecene: CH≡C-(CH₂)₁₁-CH₃
• 7-Hexadecene: CH≡C-(CH₂)₁₃-CH₃

4: Cycloalkynes

General Formula: CnH₂n-2 where n>=3

Cycloalkynes contain a carbon-carbon triple bond within a saturated or unsaturated carbon ring structure.

Examples

• Cyclopropyne: c-C₃H₄
• Cyclohexyne: c-C₆H₈
• Cyclododecyne: c-C₁₂H₂₀
• 1,3,5-Cyclodecatriyne

5: Fluoroalkynes

General Formula: R1R₂C≡CR₃R₄ where at least one R is F

Fluoroalkynes have at least one carbon substituted with a fluorine atom. The electronegativity affects reactivity.

Examples

• 3,3,3-Trifluoropropyne
• 4,4,4-Trifluorobutyne
• Perfluorobutyne
• 1-(Trifluoromethyl)-1-propyne
• 3,3,4,4,4-Pentafluorobutyne

6: Aryl Alkynes

General formula: Ar-C≡C-R

Aryl alkynes contain a carbon-carbon triple bond with at least one aryl group (benzene ring structure) attached.

Examples

• Phenylacetylene: C₆H₅-C≡CH
• 4-Ethynyltoluene: CH₃-C₆H₄-C≡CH
• 3-Ethynylpyridine: NC₅H₄-C≡CH
• 1-Naphthylacetylene: C₁₀H₇-C≡CH
• 4-tert-Butylphenylacetylene: (CH₃)₃CC₆H₄-C≡CH

7: Haloalkynes

General formula: X-C≡C-R

Haloalkynes contain one or more halogen atoms (F, Cl, Br, I) substituted on a carbon of the carbon-carbon triple bond.

Examples

• Chloroacetylene: Cl-C≡CH
• Dichloroacetylene: Cl-C≡C-Cl
• 1-Chloropropyne: Cl-C≡C-CH₃
• 4-Bromopentyne: Br-(CH₂)₂-C≡CH
• 1-Iodo-3-hexyne: I-CH₂-CH₂-CH₂-C≡CH

8: Alkynols

General formula: RC≡CCH₂OH

Alkynols feature a hydroxy group (-OH) on the carbon adjacent to the alkyne carbon-carbon triple bond.

Examples

• Propargyl alcohol: HC≡CCH₂OH
• 1-Butyn-3-ol: CH₃CH₂C≡CCH₂OH
• 3-Hexyn-1-ol: CH₃(CH₂)2C≡CCH₂OH
• 1-Octyn-4-ol: CH₃(CH₂)5C≡CCH₂OH
• 2-Nonyn-6-ol: CH₃(CH₂)4C≡CCH₂CH₂CH₂CH₂OH

9: Carbonyl Alkynes

General formula: RC≡COR

Carbonyl alkynes contain two alkyl or aryl groups attached to a carbon-carbon triple bond having a carbonyl group on one end.

Examples

• Propiolaldehyde: HC≡CCHO
• Hex-3-yn-2-one: CH₃CH₂CH₂C≡C(C=O)CH₃
• Phenyl propiolic acid: C₆H₅-C≡C-COOH
• Ethynyl p-tolyl ketone: CH₃-C₆H₄-C≡C(C=O)-CH₃
• 5-Undecynal: CH≡C-(CH₂)₈-CHO

10: Enynes

General Formula: R1C≡CR₂-CH=CH₂

Enynes contain a carbon-carbon triple bond conjugated with a C=C double bond. This alternation affects reactivity.

Examples

• 3,7-Octadiyne: HC≡C-CH=CH-C≡CH
• 1,3,7-Decatriene: CH≡CH-CH=CH-CH₂-CH=CH₂
• 5,9-Hexadecadiene: CH≡C-(CH₂)₇-CH=CH-(CH₂)₇-CH₃
• 2-Buten-1-yne: CH≡C-CH=CHCH₃
• 5-Undecene-8-yne: CH₂=CH-(CH₂)3C≡C(CH₂)5CH₃

11: Cumulenes

General Formula: R1C≡C-C≡CR₂

Cumulenes contain two or more triple bonds in a carbon chain with no single bonds in between. This builds up angle strain.

Examples

• Butatriene: H-C≡C-C≡C-H
• Octatetrayne: HC≡C-C≡C-C≡C-C≡CH
• Dodecapentayne: HC≡C-C≡C-(CH₂)₃-C≡C-(CH₂)₃-C≡CH
• Diphenylbutadiyne: C₆H₅-C≡C-C≡C-C₆H₅
• Hexylheptatetrayne: CH₃(CH₂)₅-C≡C-C≡C-(CH₂)₂-C≡C-C≡CH

12: Trialkynes

General Formula: (RC≡C)₃CH

Trialkynes have an sp hybridized central carbon bound to three separate alkynyl groups in a tetrahedral geometry.

Examples

• Ethyl 3-(buta-1,3-diynyl)pent-2-ynoate
• Propane-1,1,1-triyltris(benzene-4,1-diyl) triacetate
• 4-(Prop-2-yn-1-yl)-6-(but-3-yn-1-yl)phenyl 4-(pent-4-yn-1-yl)benzoate
• 1,1,1-tris(phenylethynyl)ethane
• 5-(4-bromophenylethynyl)-10,15-bis(phenylethynyl)zinc porphyrin