Question

How do you name alkynes with two triple bonds?

Answer 1

The naming of the polyalkynes is similar to the naming of a simple alkyne.

Find the longest continuous chain of carbon atoms that goes through as many as possible of the triple bonds.

Number the chain from the end that is closest to a triple bond. If the triple bonds are the same distance from the ends of the chain, pick the one that gives the substituent closet to one end of the chain the lowest number possible.

Number the substituents according to this numbering scheme.

Use the multiplying prefixes di, tri, tetra ... to indicate the number of triple bonds.

Examples of naming polyalkynes are:

H-C≡C-C≡C-H buta-1,3-diyne

Note: 1,3-butadiyne is also an acceptable name, but the preferred practice is now to put the locating numbers immediately before the functional groups they locate.

H-C≡C-C≡C-CH(CH₃)₂ 5-methylhexa-1,3-diyne

H-C≡C-C≡C-CH₂-C≡C-H hepta-1,3,6-triyne