What is IUPACnomenclature?
• A systematic method of naming organic chemical compounds
as recommended by the International Union of Pure and
Applied Chemistry (IUPAC).
• It provides an unambiguous structure.
• Official IUPAC naming recommendations are not always
followed in practice, and the common or trivial name may be
used.
3.
rules for alkanenomenclature
• Find and name the longest carbon chain
• Name the groups attached to the longest carbon chain
• Number the chain consecutively, starting at the end nearest a
substituted group
• Designate the location of each substituent group
• Assemble the name by listing groups in alphabetical order and
the main chain last
4.
Main chain andalkyl group
names
Main chain names
Name # of Carbons Name # of Carbons
methane 1 hexane 6
ethane 2 heptane 7
propane 3 octane 8
butane 4 nonane 9
pentane 5 decane 10
Alkyl group names
Name
# of
Carbons
Name
# of
Carbons
methyl 1 butyl 4
ethyl 2 pentyl 5
propyl 3 Hexyl 6
Group (CH3)2CH–
(CH3)2CH
CH2–
CH3CH2CH(CH3)– (CH3)3C–
Name Isopropyl Isobutyl sec-Butyl tert-Butyl
5.
Example
• Longest chain/mainchain:
• 7 carbons (circled)
• Name: heptane
• Side chain groups:
• 1-carbon group at position 3
• Name: 3-methyl
• 2-carbon group at position 4
• Name: 4-methyl
Answer:
4-ethyl-3-methylheptane
6.
Naming ring compounds
•Same rules as alkane nomenclature except:
• A cyclo- prefix is added to the root name
• Groups are numbered to give multiple substituents the lowest
possible numbers
• When there is only one substituent, it does not need to be
numbered
• A ring can also be named as a substituent
naming alkenes andalkynes
• -Ene suffix for alkene and -yne suffix for alkyne
• The root chain must be the longest chain that includes both
carbon atoms of the double bond
• Number the root chain from the end nearest a double bond
carbon atom (or triple bond carbon atom)
• The smaller of the two numbers designating the carbon atoms
of the double/triple bond is used as the locator of
alkenes/alkynes
Naming organic halides
•Same naming rules as before
• Halide substituents are named as fluoro (-F), chloror (-Cl),
bromo (-Br), or iodo (-I)
Answer:
2-chloropropane
Example:
11.
Naming Alcohols
• Dropthe –ane ending of the parent compound and adding –ol
• When there’s a higher priority group present, -OH can be
named as a substituent using the name hydroxy
Answer:
3-methyl-1-butanol
Example:
12.
Naming Ethers
• Nameeach of the two carbon groups followed by the word
ether (Common naming rule)
• -OR group can also be named as a substituent using the group
name alkoxy (IUPAC) Answer:
cyclopentyl methyl ether or
methoxycyclopentane
Example:
13.
Naming aldehydes andketones
• Aldehydes are named by dropping the –e of the parent name
and adding –al
• The substituent name for aldehyde group is formyl
• When one or more –CHO groups are attached to the ring, the
ring is named followed by carbaldehyde
• Ketones are named by dropping the –e ending and adding –
one
• The substituent name is oxo
Naming Amines
• PrimaryAmines (R-NH2):
• Replace the –e of the parent group with the word amine
• Can also name it as a substituent using the name amino
• Secondary Amines (R2NH):
• Use an upper case N to designate the second alkyl group that is on
the nitrogen atom
• Tertiary Amines (R3N):
• Named the same way as secondary amines
Naming carboxylic acids
•Carboxylic acids are named by dropping the –e ending and
adding the –oic acid
• The substituent name for a –COOH group is carboxy
Answer:
2-chlorocyclopentanoic acid
Example:
18.
Naming carboxylic acid
derivatives
•Acid Halides:
• Replace the –e ending and add –oyl halide
• Halide can be bromide, chloride, etc.
• Acid Anhydrides:
• Symmetrical acid anhydrides are named by replacing acid with
anhydride
• Unsymmetrical acid anhydrides are named by naming each
carboxylic acid component and then the word anhydride
• Esters:
• First name the group that came from the alcohol and drop the –oic
acid and add -oate
• Amides:
• Replace the –oic acid ending with -amide
References
• For moredetailed rules and examples including common
naming rules, please consult the organic chemistry by wade
textbook
• Workshop prepared by Qing Wang
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