IUPAC Nomenclature is discussed

1. IUPAC Rules for Naming Alcohols
I. Select the longest chain to which the OH group is directly attached. Change “”e’’ of
the alkane corresponding to this chain to “ol”. This gives the basic name of the
alcohol.
2. Number the above chain so as to give the carbon bearing the OH group the lowest
possible number. Indicate the position of the OH group by using this number. The
numbering of the chain is done as above irrespective of whether a double or triple bond
is or is not a part of the parent chain.
3. Prefix the names of alkyl substituents with locator numbers as for alkanes. Thus
4. Molecules containing more than one OH group are referred to as diols (2-OH),
triols (3-OH), etc., in the IUPAC system

2. Write the IUPAC names of following compounds
IUPAC Rules for Naming Aldehydes
The IUPAC name for aldehydes (RCHO) is Alkanals. For naming an individual
aldehyde, the final “e” of the parent alkane is replaced with “al”. Since the functional
group CHO is always present at the end of the parent chain, it is not necessary to
designate its position. When other substituents are present, the parent chain including
the CHO group is numbered with carbon of CHO as number one.

3. IUPAC Rules for Naming Ketone
The IUPAC name of ketones (R—CO—R) is Alkanones and the functional
group —CO— is referred to as carbonyl group. The name of an individual
ketone is obtained by replacing the final “e” of the corresponding alkane
(containing same number of carbons) with “one”.
(I) Select the longest chain containing the -CO- group and write the basic
name after the parent alkane as shown above.
(2) Number the chain from the end that gives the -CO- group the lowest
possible number. This is the locator number of carbonyl group on the parent
chain.
(3) If the structure contains a double bond, name the ketone as Alkenone and
insert the position numbers.
(4) When there are present two carbonyl groups in a saturated parent chain the
compound is named as Alkanedione with position numbers prefixed to it.

4. IUPAC Rules for Naming Carboxylic acids
The IUPAC name of aliphatic carboxylic acids (RCOOH) is Alkanoic acids, while
the functional group COOH is referred to as carboxyl group.
(1) The longest chain containing COOH is selected and the basic name is derived
by changing ane of the corresponding alkane to oic acid.
(2) The chain is numbered starting with carboxyl carbon as one. Thus it is
unnecessary to give the number of COOH.
(3) A dicarboxylic acid is named as Alkanedioic acid with position numbers of
COOH groups prefixed with it.

5. IUPAC Rules for Naming Amines
• In the IUPAC system this class of compounds are named as Alkanamines. To
name a particular amine 'e, of the hydrocarbon name in deleted and the ending -
amine added.
• For naming Substituted amines, the longest chain bearing NH, group is
numbered and the position of the amino group prefixed to the basic name of the
amine. The names with locator numbers of the other substituents are described
as usual.
• A substituent on nitrogen atom is designated by capital N.

6. When present in molecules as a substituent, amino group is designated as amino.
Write the IUPAC names of following compounds

7. Nomenclature example
1-chloropropan-2-one
3-ethyl-4,5-dimethyloctane
2,5-dimethyloctane

8. ▪ More complicated organic molecule sometimes is known
by its trivial name NOT IUPAC systematic name
Methyl 8-methyl-3-[(phenylcarbonyl)oxy]-8-azabicyclo[3.2.1]octane-2-
carboxylate
Cocaine

10. IUPAC Rules for Naming Multifunctional compounds
1. Note the functional groups present in the given structure and then find out
from the priority Table given in next slide as to which of these stands nearest
to the top. This is the principal function and determines the family or class of
the compound.
2. When both a double and triple bond are present in a hydrocarbon, the chain is
numbered to give the multiple bonds (regardless of double or triple bond) the
lowest possible numbers. The locator numbers of double and triple bonds are
then inserted in the alkenyl name.

11. Nomenclature Priority for Citation as Principal Function
(IUPAC)
(Highest Priority is at the top)
Denoted by
Class Name Functional Group Prefix Suffix
Carboxylic acid —COOH - - -ole acid
Sulphonic acid - SO3H - -sulphonic acid
Acid halide -COX- - oyl chloride
Amide —CONH2 Amido- -amide
Nitrile -CN- Cyano- -nitrile
Aldehyde- —CHO Alkanoyl- -al
Ketone -CO- — Oxo- -one
Thiol —SH- Mercapto- -thiol
Amine —NH- Amino -amine
Alkene >C=C< - -ene
Alkyne —C≡C— - -yne
Alkane —C—C - -ane
Ether —OR Alkoxy -
Halides —F, —Cl, —Br, -I Halo- -
Nitro —NO2 Nitro- -

12. • When it has only substituents and no principal function.
The groups -F, - Cl, -Br, -I and –NO2, are always treated as substituents while naming
complex molecules. Thus a compound containing these functions has no principal
function.

13. For IUPAC nomenclature of substituted benzene compounds, the
substituent is placed as prefix to the word benzene as shown in
the following examples.

14. If benzene ring is disubstituted, the position of substituents is
defined by numbering the carbon atoms of the ring such that the
substituents are located at the lowest numbers possible.
In the trivial system of nomenclature the terms ortho (o), meta
(m) and para (p) are used as prefixes to indicate the relative
positions 1,2- ;1,3- and 1,4- respectively.

16. Name the following compounds
● 1) CH2=CH-CH=CH2
But-1,3-diene
● 2) HOCH2(CH2)3CH2 COCH3 7-hydroxy hexane-2-one
● 3) CH3CH(CH3)CH2CH=CH2 4-methylpentene
● 4)COOHCH2CH2CH2CH2CH2COOH 1,7-diheptanoic acid

17. Starter questions
1. Name this molecule:
2. Draw these molecules:
(a) 3-ethyloctane
(b) 1,4-dibromohexane
(c) 2,3,4-trimethylheptane
(d) 3,4-diethyl-3,4,5-trimethyldecane