Chemistry

Examples of Alkynes

We explain that what are examples of Alkynes? In chemistry, alkynes or acetylenes are compounds that are made up of carbon (C) and hydrogen (H) atoms. Like alkanes and alkenes, they are chains of covalent bonds between carbon atoms and offset by hydrogen atoms to complete the carbon octet rule (its eight electrons in the last shell). However, in the case of alkynes, there is a C tripleC carbon-carbon triple bond at some position in the main chain.

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The physical properties of alkynes are similar to those of other hydrocarbons, but they have clear differences. Its polarity is greater because the triple bond marks two sides due to the greater attraction exerted by the “sp” carbon on the electrons. They are the most volatile , that is, their boiling point is very low and the short chain ones are gaseous at room temperature. If you heat an alkane, an alkene, and an alkyne, the latter will evaporate faster .

The chemical properties of alkynes are also similar and more pronounced than those of alkanes and alkenes. Alkynes are more reactive , because it is easier to break the π bonds and the σ bond between the carbons. For this reason, they rust easily. Since the carbon-hydrogen bond C – H is polarized, it tends to ionize. In addition, it is easier to add substituents such as alkyl radicals or halogens (chlorine Cl, bromine Br, iodine I), breaking one of the bonds in C ≡C .

The most important alkyne is acetylene , which can be represented as C 2 H 2 or CH ≡CH . In fact, all other alkynes are considered derivatives of it, as it carries the triple bond. For this reason they are called acetylenes. This gas is much lighter than air and highly flammable.

It can be found as one of the components of natural gas, or it can also be formed by the hydration of calcium carbide rocks CaC 2 . When water is added to them, the rocks begin to release acetylene gas, which can be used for combustion . This is how some mining gas lamps work. The residue is calcium oxide CaO.

The reaction that occurs is the following:

CaC 2 + H 2 O -> C 2 H 2 + CaO

Acetylene receives multiple uses in the industrial field. For example, it is confined in tanks for autogenous welding; here it is used as fuel, which provides an intense and rapid calorific power due to its flammability. The other alkynes are used as reagents for various reactions . The triple bond can be broken to add atoms of other elements (such as halogens, already mentioned) or to separate the chains and place them in other reagents as substituents. The product will be more extensive chains.

Nomenclature of alkynes

Alkynes are named based on the following requirements:

  1. The longest chain that has the triple bond is detected ; that will be the main one.
  2. The carbons in the main chain are counted; so we will know what hydrocarbon is being talked about.
  3. The substituents , either halogens or hydrocarbon chains, that accompany the main chain are identified .
  4. Are the positions write where there are substituents, counting from carbon to which is closer to the triple bond C ≡C .
  5. If there are two or more triple links in the chain, their positions are named, starting from the one closest to the edge of the chain. They are accompanied by number prefixes (2: di, 3: tri, 4: tetra)
  6. The prefix of the hydrocarbon we are talking about is written . (buta-, pent-, hex-, hept-)
  7. The ending -ino is written . Thus the alkyne has been named completely.

30 examples of alkynes

  1. Ethine or acetylene CH≡CH
  2. Propine or methylacetylene CH≡C – CH 3
  3. 1-butyne or ethylacetylene CH≡C – CH 2 –CH 3
  4. 2-butyne or dimethylacetylene CH 3 –C≡C – CH 3
  5. 1-pentyne or propylacetylene CH≡C – CH 2 –CH 2 –CH 3
  6. 2-pentino or methylethylacetylene CH 3 –C≡C – CH 2 –CH 3
  7. 1-hexyne or butylacetylene CH≡C – CH 2 –CH 2 –CH 2 –CH 3
  8. 2-hexene or methylpropylacetylene CH 3 –C≡C – CH 2 –CH 2 –CH 3
  9. 3-hexene or diethylacetylene CH 3 –CH 2 –C≡C – CH 2 –CH 3
  10. 1-heptyne or pentylacetylene CH≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  11. 2-heptyne or methylbutylacetylene CH 3 –C≡C – CH 2 –CH 2 –CH 2 –CH 3
  12. 3-heptyne or ethylpropylacetylene CH 3 –CH 2 –C≡C – CH 2 –CH 2 –CH 3
  13. 1-octine or hexylacetylene CH≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  14. 2-octino or methylpentylacetylene CH 3 –C≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  15. 3-octino or ethylbutylacetylene CH 3 –CH 2 –C≡C – CH 2 –CH 2 –CH 2 –CH 3
  16. 4-octino or dipropylacetylene CH 3 –CH 2 –CH 2 –C≡C – CH 2 –CH 2 –CH 3
  17. 1-nonino or heptylacetylene CH≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  18. 2-nonino or methylhexylacetylene CH 3 –C≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  19. 3-nonino or ethylpentylacetylene CH 3 –CH 2 –C≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  20. 4-nonino or propylbutylacetylene CH 3 –CH 2 –CH 2 –C≡C – CH 2 –CH 2 –CH 2 –CH 3
  21. 1-decino or octylacetylene CH≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  22. 2-decino or methylheptylacetylene CH 3 –C≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  23. 3-decino or ethylhexylacetylene CH 3 –CH 2 –C≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  24. 4-decino or propylpentylacetylene CH 3 –CH 2 –CH 2 –C≡C – CH 2 –CH 2 –CH 2 –CH 2 –CH 3
  25. 5-decino or dibutylacetylene CH 3 –CH 2 –CH 2 –CH 2 –C≡C – CH 2 –CH 2 –CH 2 –CH 3
  26. 2,4 hexadiino CH 3 –C≡C – C≡C – CH 3
  27. 1,4 heptadiino C≡C – CH 2 –C≡C – CH 2 –CH 3
  28. 1,5 heptadiino C≡C – CH 2 –CH 2 –C≡C – CH 3
  29. 2,6 octadiino CH 3 –C≡C – CH 2 –CH 2 –C≡C – CH 3
  30. 3.5 octadiino CH 3 –CH 2 –C≡C – C≡C – CH 2 –CH 3

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