Which of the following names are correct? Correct those that...

Key Concepts

Multiplicity Prefixes

When more than one identical substituent is present on the carbon chain, prefixes like di-, tri-, and tetra- are used to indicate the number of such substituents. These prefixes are combined with the substituent's name and their positions within the chain, ensuring clarity and precision in the compound’s overall name.

Numbering Direction and Lowest Set of Locants

The numbering of the carbon chain must be carried out in a direction that results in the lowest set of locants for both the principal functional group and any substituents. This rule is critical for consistency and minimizes errors in compound nomenclature, ensuring that the most significant features of the molecule are clearly indicated in its name.

Substituent Locant Assignment

Proper assignment of locants to substituents ensures that the molecule is named with the lowest possible numbers for all substituents. This minimizes ambiguity and follows IUPAC guidelines, which require that substituents and functional groups, including the triple bond, are assigned positions that reflect the most accurate structure.

Longest Carbon Chain Identification

Choosing the longest continuous chain of carbon atoms in a molecule is essential because it forms the parent name of the compound. The longest chain must include the highest priority functional groups, such as triple bonds in alkynes, and is used to provide the base name and numbering for substituents.

Alkyne Naming Rules

Alkyne nomenclature focuses on compounds with a carbon-carbon triple bond. The triple bond is treated as a principal functional group, and its position is indicated by the lowest possible locant number during chain numbering. This ensures that the name accurately reflects the structure and functional group placement.

IUPAC Nomenclature

This concept covers the standardized system used internationally for naming organic compounds. The IUPAC rules specify how to identify the longest carbon chain, assign numbers to atoms in that chain, and correctly name substituents and functional groups so that each molecule has a unique and descriptive name.

Transcript

00:06 This question asks which of the names are correct and which are incorrect.

00:12 So the way i like to approach these types of questions is to draw out what is given and then see if the name matches up with the way that i would name it.

00:19 So starting with four heptine.

00:22 So we'll have one, two, three, four.

00:28 Here's our alkyne, five, six, seven carbons.

00:33 Okay.

00:33 So the way that normally you would name this is to make the alkyne.

00:37 Lowest number it can possibly be.

00:39 So we would actually number from the opposite side over here, one, two, three.

00:44 So this would be three heptine.

00:49 Part b, two ethyl three hexines.

00:53 So if we draw this out, one, two, and this has an ethel group on it, and then three is our alkyne, four, five, six carbons.

01:07 So if we look at this one, the longest carbon chain is actually right here, which is seven carbons long.

01:16 So we're going to start numbering from over here to make the alkyne the lowest.