Basic Organic Nomenclature

An Introduction

Dave Woodcock,
Associate Professor Emeritus UBC (Okanagan)
©1996,2000, 2008

2. Alkanes

II Branched Alkanes (iii)

Index
Branches can have any number of carbon atoms in them and each different branch name is prefixed on the root name with its relevant position identifier.

Rule for ordering the prefixes:
The order of listing the branch prefixes is alphabetic before the addition of the multiple prefix identifiers such as di, tri, etc..

Thus the correct order is: butyl, ethyl, methyl, propyl for example.

Example 1: Give the following compound an appropriate IUPAC name.

Analysis:
root: non
family: ane
branches (numbering from left):2-methyl, 4-ethyl, 5-propyl, 6-propyl.

Putting these together, a IUPAC name for the compound is:

4-ethyl-2-methyl-5,6-dipropylnonane.

Example 2: Give the following compound a IUPAC name.

Analysis:
root: dec
family: ane
branches (numbering from right):2-methyl, 3-ethyl, 5-methyl, 5-ethyl, 7-methyl, 7-ethyl.

Putting these together, a IUPAC name for the compound is:

3,5,7-triethyl-2,5,7-trimethyldecane.

Now try the following Self-study questions
Review : Branched Alkanes (ii)

Next page : Branched Alkanes (iv)

Index

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