Naming Alkynes - IUPAC Nomenclature & Common Names

Summary

This video provides a comprehensive guide on naming alkynes, focusing on both common and IUPAC naming conventions. The video demonstrates how to name various alkyne compounds with examples, from simple molecules like acetylene to more complex structures with multiple substituents such as methyl, ethyl, and phenyl groups. The tutorial also covers how to handle compounds with multiple functional groups like alkynes and alcohols, as well as the priority rules for IUPAC nomenclature. By the end of the video, viewers will be equipped to name alkynes confidently using both common and systematic methods.

Takeaways

• 😀 Alkynes are hydrocarbons that contain a carbon-carbon triple bond, and their names can be given using both common and IUPAC nomenclature.
• 😀 The simplest alkyne, C2H2, is commonly known as **acetylene**.
• 😀 When a methyl group is attached to the acetylene portion, the common name becomes **methyl acetylene**.
• 😀 If two methyl groups are attached to the acetylene, the common name is **dimethyl acetylene**.
• 😀 In IUPAC naming, alkynes use the suffix **-yne** and the position of the triple bond is numbered to give the lowest possible number.
• 😀 The IUPAC name for a molecule like C3H5-C≡CH (with a methyl group attached) is **1-butyne**, while the common name is **ethyl acetylene**.
• 😀 The common name for a molecule with an ethyl group and a methyl group attached to acetylene is **ethyl methyl acetylene**.
• 😀 For molecules with a benzene ring attached to an alkyne, the common name is **phenyl acetylene**.
• 😀 In IUPAC naming, when numbering the carbon chain, the triple bond should get the lowest number possible, and the substituents should be listed alphabetically.
• 😀 If a molecule contains both an alkyne and an alcohol functional group, the alcohol takes priority in the naming, and it is numbered first.
• 😀 When there are multiple alkynes in a molecule, such as **1,5-nonadiyne**, the name includes the number of triple bonds (diyne) and the positions of the alkynes.

Q & A

What is the common name for the alkyne C-H?

The common name for the alkyne C-H is acetylene.

How do you name a molecule with a methyl group attached to acetylene?

A molecule with a methyl group attached to acetylene is commonly named methyl acetylene.

What is the common name for a molecule with two methyl groups attached to acetylene?

The common name for a molecule with two methyl groups attached to acetylene is dimethyl acetylene.

How do you determine the IUPAC name for an alkyne with a chain of four carbon atoms and a triple bond at the first carbon?

The IUPAC name for an alkyne with a chain of four carbon atoms and a triple bond at the first carbon is 'butyne,' specifically '1-butyne.'

What is the common name for an alkyne with an ethyl group attached to acetylene?

The common name for an alkyne with an ethyl group attached to acetylene is ethyl acetylene.

How do you name an alkyne with a methyl group on carbons 2 and 5, and a triple bond between carbons 2 and 3?

The IUPAC name for this molecule is '2,5-dimethyl-3-hexyne,' while the common name is 'ethyl methyl acetylene.'

What is the common name for a molecule with a benzene ring attached to acetylene?

The common name for a molecule with a benzene ring attached to acetylene is 'phenylacetylene.'

What is the IUPAC name for a molecule with a chlorine atom and a methyl group on a six-carbon chain with a triple bond at carbon 3?

The IUPAC name for this molecule is '3-chloro-5-methylhex-1-yne.'

How do you name a molecule with two triple bonds, one at the 1st and the other at the 5th carbon of a nine-carbon chain?

The IUPAC name for this molecule is '1,5-nonadiyne,' with the common name including the substituent group '7-methyl.'

When naming a molecule with both an alkene and an alkyne functional group, which group takes priority?

The alkyne functional group takes priority over the alkene when naming the molecule, and it is given the lowest possible number.