The document provides an overview of IUPAC nomenclature rules for naming organic compounds. It explains that organic compound names have three parts: a prefix, root, and suffix. The prefix indicates functional groups, the root name comes from the number of carbon atoms in the main chain, and the suffix denotes the type of compound. It provides examples of applying the rules to name alkanes, alkenes, alcohols, carboxylic acids, and cyclic and branched compounds.

1. IUPAC
NOMENCLATURE
Naming Organic Compounds

2. Naming Organic Compounds
• The name of any organic compound is comprised of three portions:
• PREFIX + ROOT+ SUFFIX
•The prefix identifies any groups attached to the main
chain.
•The root name of the compound is determined from the
number of C atoms in the longest continuous chain.
•The suffix indicates the type of organic compound, and
is placed after the root.
•Example:The suffix for an alkane is –ane.

3. Root names for Carbon Chains and Branches
Roots Number of C
Atoms
meth- 1
eth- 2
prop- 3
but- 4
pent- 5
hex- 6
hept- 7
oct- 8
non- 9
dec- 10

4. Explaining carbon “roots”
The “parent” part of the name tells you how many carbons are in
the main chain of the molecule
• The parent is named based on
the number of carbons
• 1 carbon = “meth”
• So a one-carbon alkane is called
methane
CH4
• 2 carbons = “eth”
• So a two carbon alkane is called
ethane.
CH3CH3

5. 5 carbons = “pent”
6 carbons = “hex”
3 carbons = “prop”
So a three carbon alkane is
called propane.
CH3CH2CH3
4 carbons = “but”
So a four carbon alkane is
called butane.
CH3CH2CH2CH3

6. Putting together a name…
• The rules for IUPAC nomenclature include:
Step 1: Identify the suffix (FUNCTIONAL GROUP)
Step 2 : Find the main chain
Step 2: Number the main chain
Step 3: Identify all prefixes and their position numbers
Step 5: Write the full name: Prefixes-Parent-Suffix

7. Now let’s take a look: Alkanes
• Step 1: Identify the suffix (FUNCTIONAL GROUP)
• This is an alkane
• Step 2: Find the main chain
• Step 3: Number the main chain
• It has 4 carbon atoms
• Step 4: Identify all prefixes and their position numbers
• prefix -but
• Step 5: Write the full name: Prefixes-Parent-Suffix
• Name : Butane

8. • Name the following alkane (shown as both condensed formula and
a displayed formula)
CH3CH2CH2CH2CH2CH3
or

9. Now let’s take a look: Alkenes
• Step 1: Identify the suffix (FUNCTIONAL GROUP)
• This is an alkene (suffix-ene)
• Step 2: Find the main chain
• Step 3: Number the main chain
• It has 4 carbon atoms
• Step 4: Identify all prefixes and their position numbers
• Prefix-but
• Step 5: Write the full name: Prefixes-Parent-Suffix
• Name : Butene

10. Now let’s take a look: Alcohols
• Step 1: Identify the suffix (FUNCTIONAL GROUP)
• This is an alcohol (suffix-ol)
• Step 2: Find the main chain
• Step 3: Number the main chain
• It has 3 carbon atoms
• Step 4: Identify all prefixes and their position numbers
• Prefix-prop
• Step 5: Write the full name: Prefixes-Parent-Suffix
• Name : Propanol

11. Now let’s take a look: Carboxylic acids
• Step 1: Identify the suffix (FUNCTIONAL GROUP)
• This is a carboxylic acid (suffix –anoic acid)
• Step 2: Find the main chain
• Step 3: Number the main chain
• It has 3 carbon atoms
• Step 4: Identify all prefixes and their position numbers
• prefix -prop
• Step 5: Write the full name: Prefixes-Parent-Suffix
• Name : Propanoic acid

12. Now let’s take a look: Rings
• Step 1: Identify the suffix (FUNCTIONAL GROUP)
• This is an alkane
• Step 2: Find the main chain
• Step 3: Number the main chain
• It has 6 carbon atoms
• Step 4: Identify all prefixes and their position numbers (we add the
prefix “cyclo” for rings (all carbons are connected to another carbon
in an enclosed arrangement)
• prefix – cyclo+pent
• Step 5: Write the full name: Prefixes-Parent-Suffix
• Name : cyclopentane

13. Try naming the following
1.
2.
3. 4.

14. Did you get?
1. Pentene
2. Hexanol
3. Hexanoic acid
4. cyclobutane
If you didn’t, review your rules step by step

15. Let’s look at branched chains
• There are a few more rules we must include for branched chains
• Choose the correct ending (-ane for alkanes, -ene for alkenes
• 2. Determine the longest carbon chain.Where a double or triple bond is present, choose the
longest chain that includes this bond.
• 3. Attach a prefix that corresponds to the number of carbons in the parent chain.
• 4. Assign numbers to each carbon of the parent chain. For alkenes the first carbon of the
multiple bond should have the smallest number. For alkanes the first branch (should have the
lowest number.
• 5. Determine the correct name for each branch (e.g. methyl, ethyl)
• 6.Attach the name of the branch, along with its carbon position, to the name of the parent as
a prefix. Separate numbers from words with hyphens. (e.g. 3-methylhexane).
• 7. List branches alphabetically when more than one branch group is present. (e.g. 4-ethyl-2-
methylheptane)
• 8.When two or more substituents are identical, use prefixes such as di-, tri-, tetra, etc. (e.g.
2,4-dimethylhexane). Note that prefixes such as di- and tri- ) are ignored when determining
alphabetical order. (e.g. 2,3,5-trimethyl-4-propylheptane)
• 9.When identical groups are on the same carbon, repeat the number of this carbon in the
name. (e.g. 2,2-dimethylhexane)

16. Let’s look at alkyl groups before
we move on
• Alkyl groups are named similarly to alkanes, based on the
number of carbons in the substituent.
• A substituent of methane, CH4, would be CH3-
• This substituent is called “methyl” where “meth” stands
for one carbon and “yl” stands for substituent (alkyl group).
• A two-carbon alkane is called ethane, CH3CH3. The
corresponding two-carbon fragment is always CH3CH2-,
which is called “ethyl”.

17. So in this case…
• Choose the correct ending. This is an alkane
• 2. Determine the longest carbon chain. This has a 5 carbon chain
• 3. Attach a prefix that corresponds to the number of carbons in the parent chain.
• This would be pentane
• 4. Assign numbers to each carbon of the parent chain. For alkanes the first branch
(should have the lowest number. )
• You would number from left to right, so the CH3 winds up on position # 2&3
carbon.
• If you numbered from the other end, the CH3 would be on #4&5 carbon.
• Always aim for the lowest possible number on the first substituent!
• . Determine the correct name for each branch (e.g. methyl -CH3, ethyl -CH3CH2)
• So far we have branched groups on 2 & 3 carbons atoms + methy+propane

18. • . Attach the name of the branch, along with its carbon position, to the name of
the parent as a prefix. Separate numbers from words with hyphens and
numbers with commas
• 2,3-methylpentane
• 7. List branches alphabetically when more than one branch group is present.
• Branches are the same
• 8.When two or more substituents are identical, use prefixes such as di-, tri-,
tetra, etc. (e.g. 2,4-dimethylhexane). Note that prefixes such as di- and tri- )
are ignored when determining alphabetical order.
• 2,3-dimethylpentane
• 9.When identical groups are on the same carbon, repeat the number of this
carbon in the name. (e.g. 2,2-dimethylhexane)
• Groups on different carbons in this compound
Name of compound: 2,3-dimethylpentane
Continuing…

19. So in this case…
• Choose the correct ending. This is an alkane
• 2. Determine the longest carbon chain. This has a 4 carbon chain
• 3. Attach a prefix that corresponds to the number of carbons in the parent chain.
• This would be butane
• 4. Assign numbers to each carbon of the parent chain. For alkanes the first branch
(should have the lowest number.
• You would number from right to left, so the CH3 winds up on position # 2 carbon.
• If you numbered from the other end, the CH3 would be on #3 carbon.
• Always aim for the lowest possible number on the first substituent!
• . Determine the correct name for each branch (e.g. methyl -CH3, ethyl -CH3CH2)
• So far we have 2 branched groups on # 2 carbon atom + methy + butane

20. • . Attach the name of the branch, along with its carbon position, to the name of
the parent as a prefix. Separate numbers from words with hyphens and
numbers with commas
• 2-methylbutane
• 7. List branches alphabetically when more than one branch group is present.
• Branches are the same
• 8.When two or more substituents are identical, use prefixes such as di-, tri-,
tetra, etc. (e.g. 2,4-dimethylhexane). Note that prefixes such as di- and tri- )
are ignored when determining alphabetical order.
• 2-dimethylbutane
• 9.When identical groups are on the same carbon, repeat the number of this
carbon in the name. (e.g. 2,2-dimethylhexane)
• 2 substituents present on same carbon:2,2-methylbutane
Name of compound: 2,2-dimethylbutane
Continuing…

21. So in this case…
• Choose the correct ending. This is an alkene
• 2. Determine the longest carbon chain. This has a 4 carbon chain
• 3. Attach a prefix that corresponds to the number of carbons in the parent chain.
• This would be butene
• 4. Assign numbers to each carbon of the parent chain. For alkanes the first branch
(should have the lowest number.
• You would number from left to right, so the double bond winds up between
position # 2 and 3 carbon.
• If you numbered from the other end, the double bond winds up between position
# 3 and 4 carbon.
• Always aim for the lowest possible number on the double bond!
• . Determine the correct name for each branch (e.g. methyl -CH3, ethyl -CH3CH2)
• So far we have 1 branched groups on # 3 carbon atom + methy + butene

22. • . Attach the name of the branch, along with its carbon position,
to the name of the parent as a prefix. Separate numbers from words
with hyphens and numbers with commas
• 3-methylbutene
• 7. List branches alphabetically when more than one branch group is present.
• Only one Branch
• 8.When two or more substituents are identical, use prefixes such as di-, tri-, tetra,
etc. (e.g. 2,4-dimethylhexane). Note that prefixes such as di- and tri- ) are ignored
when determining alphabetical order.
• Only one Branch
• 9.When identical groups are on the same carbon, repeat the number of this carbon
in the name. (e.g. 2,2-dimethylhexane)
• Only one Branch
Name of compound: 3-methylbutene
Continuing…

23. Try naming the following
1.
2.
3.

24. Did you get?
1. 2,3-dimethylbutane
2. 2,2,3-trimethylpentane
3. 2,2-dimethylbutene
If you didn’t, review your rules step by step

25. Just as you named organic
compounds from there drawings..you
can draw from their name!
•Try drawing the following compounds
1. 2- methylbutane
2. cyclohexane
3. butene
4. 3-ethyl-2-methylhexene
5. 2-methylpropane

26. References
Tindale, Ritchie et al, 2014, Chemistry for CSEC 2nd Edition, Nelson
Thornes. Chapter 10, p 232-235
• IUPAC Nomenclature -TigerWeb -Towson University
https://tigerweb.towson.edu › www › chapter1-4
• Chemistry -11, Unit 5 Hydrocarbons and energy, Lesson #74
http://www.chalkbored.com/lessons/chemistry-11.htm