Question

How do you name alkynes?

Answer 1

Here are some of the rules for naming alkynes.

Explanation:

Alkynes are unsaturated hydrocarbons containing a triple bond, `"R-C≡C-R"`.

You name them the same way as you name alkanes, but you replace the ending -ane with -yne.

When there is more than one triple bond, you use the multiplying prefixes to
get -diyne, -triyne, etc.

Step 1. Find the longest continuous chain of carbons containing the triple bond.

For example, `"CH"_3"CH"_2"CH"_2"C≡CCH"_3` has six carbon atoms, so its base name is hexyne.

Step 2. Number the carbon atoms in the main chain from the end closer to the triple bond.

`stackrelcolor(blue)(6)("C")"H"_3stackrelcolor(blue)(5)("C")"H"_2stackrelcolor(blue)(4)("C")"H"_2stackrelcolor(blue)(3)("C")≡stackrelcolor(blue)(2)("C")stackrelcolor(blue)(1)("C")"H"_3`

Insert the first number of the alkyne carbons as close as possible before the
ending -yne.

The name becomes hex-1-yne.

Step 3. If there are other substituents, list them alphabetically with their locating numbers.

`"H"stackrelcolor(blue)(1)("C")"≡"stackrelcolor(blue)(2)("C")stackrelcolor(blue)(3)("C")"H"("CH"_3)stackrelcolor(blue)(4)("C")"≡"stackrelcolor(blue)(5)("C")stackrelcolor(blue)(6)("C")"H"_3`

For example, the compound above is 3-methylhexa-1,4-diyne.