100 Nano-Stories: Naming Alkynes!

Episode #39: Follow-Along Alkyne Examples!

Carlos Manuel Jarquín Sánchez
5 min readMar 1, 2021

Preface! → ✨

It’s your favorite material science & nanotechnology enthusiast! Yesterday, I made an introductory article on alkenes & alkynes! These names are essentially double and triple bonds between carbon atoms in an organic compound/chemical. Check out the introductory article below! :)

But for today’s topic, we will discuss how to name alkynes!

Note: I highly recommend reading my article on how to name alkenes! Alkenes are carbon atoms that contain double bonds, while alkynes have triple bonds between carbon atoms. Understanding how double bonds will help you understand how triple bonds work without being confused. Check out the article below! :))

Alkyne Examples! → 😤

Example 1! → 🔑

This alkyne is called prop-1-yne. But why propyne? From the article on alkenes, the suffix for an alkene is “ene”, and the suffix for alkanes is “ane”. But for alkynes, we use the suffix “yne”.

If we see the number of carbon atoms in the example, there are 3 carbons. The prefix for 3 carbon atoms is “prop”.

Finally, we have to pay attention to the number of carbon atoms and how to number them. We want to number the carbon atoms with the triple bond with the lowest number possible.

If we number the carbon atoms from the right, the carbon atoms with the triple bond will have the number 2, but if we count from the left, the carbon atoms with the triple bond will have the number 1. Number 1 it is!

The final answer is prop-1-yne! 🔑

prop-1-yne

Example 2! → 🔑

Now let’s crank up the difficulty, reader!

Name That Alkyne!

The first step is to ignore the hydrogen atoms. They don’t matter when it comes to naming an alkyne. Only focus on the carbon atoms.

The next step is to count the number of carbon atoms themselves. If we count the carbon atoms all up, there are 5 carbon atoms. The prefix for 5 carbon atoms is “pent”. The suffix for an alkyne is “yne”.

The final step is to number the carbon atoms with the triple bond with the lowest number possible.

If we count from the left, the carbon atom(s) with the triple bond starts with the number 3, but if we count from the right, we end up with the number 2. So carbon number 2 it is!

Finally, we have to properly name the alkyne! We add the prefix (pent), the carbon number (2), and the suffix (yne).

The final answer is pent-2-yne! 🔑

pent-2-yne

Example 3! → 🔑

The last example. . . and the final boss! 😤

The first thing to do is add numbers to this alkyne! That way, naming this organic compound will come much easier for us!

Now let’s focus our attention on the substituents (chemicals with “1”). One carbon atom begins with the prefix “meth”. But because this is a substituent, we use the suffix “yl.”

Since there are 2 methyl groups, we name the methyl group “di-methyl”. We will start with the substituents and the carbon number given by the order to name the organic compound.

The reason the carbon numbers are given in that order is because of the triple bond in the carbon atoms.

There is a lower number if we count from the left. The other reason why there are two numbers on the triple bond is that two atoms are sharing three pairs of electrons (6 electrons).

Because the main carbon chain is 5 carbon atoms long, the prefix used for 5 carbon atoms is “pent”.

Now that we have the methyl groups, the numbers, and the main prefixes/suffixes, let’s name this alkyne! 😤

We first start with the number where the substituents are located (4, 5), then the name of the substituents (methyl), then the number of where the triple bond is located (2), and finally, the name of the main carbon chain (pentyne).

The final answer is 4, 5- di-methylpent-2-yne! 🔑

Closing Thoughts! → 💭

That’s how you name alkanes, alkenes, and alkynes! We completed the organic chemistry treble, reader!

However, there are a couple of mistakes when naming alkanes, alkenes, and alkynes that I haven’t discussed yet.

See you tomorrow to solve these mistakes! 👋🏽

Vocabulary! → 📓

Alkane → An organic compound that is only made out of carbon & hydrogen atoms, only single covalent bonds.

Single-bond There is two electrons (or one pair) being shared between two atoms.

Double-bond There is four electrons (or two pairs) being shared between two atoms.

Alkenes → Double Bonds occur between carbon atoms in a molecule in organic chemistry.

Alkynes → An organic compound that is only made out of carbon & hydrogen atoms, only triple covalent bonds.

Triple-bond → There is six electrons (or three pairs) being shared between two atoms.

“yl”/moieties → A substituent, or chemically bonded parts of molecules attached to a larger backbone/ring. Essentially, it is not part of the main carbon chain.

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© 2021 by Carlos Manuel Jarquin Sanchez. All Rights Reserved.

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