Module 1: Nomenclature
Basic Nomenclature
Nomenclature
n-Alkanes are the Simplest Organic Compounds
The straight-chain alkanes make up a family of hydrocarbons that have the general formula: H−(CH2)n−H or
CnH2n+2.
Alkanes are sometimes called saturated hydrocarbons. This term means that the carbon skeleton is “saturated”
with hydrogen (attached to the MAXIMUM number of hydrogens). In saturated hydrocarbons there are only single
bonds: each carbon has a tetrahedral shape (sp3 hybridized).
methane CH4
Tetrahedral:
methyl alcohol or wood alcohol
Greek methy (wine) hyle (wood)
ethane
C2H6
109.5o
C
H
Same plane as page
H into page
H
out of page
H
H
CH3-CH3
Greek- aithein “to kindle or blaze”
Same plane as page
H
H
C
C
H
propane C3H8
Greek proto (first) and pion (fat)
H
H
H
C
C
H
H
H
CH3-CH2-CH3
Taken from Propionic acid
ball and stick
H
H
C
H
H
2
butane
CH3-(CH2)2-CH3
C4H10
Taken from butyric acid
odorous component of rancid butter Latin butyrum (butter)
2
4
1
each vertex and end is a carbon
with the appropriate number of hydrogens
pentane
CH3-(CH2)3-CH3
C5H12
CH3-(CH2)4-CH3
C6H14
CH3-(CH2)5-CH3
C7H16
CH3-(CH2)6-CH3
C8H18
CH3-(CH2)7-CH3
C9H20
CH3-(CH2)8-CH3
C10H22
3
Greek
hexane
Greek
heptane
Greek
octane
Greek
nonane
Latin
decane
Greek
Stick Structures
3
Alkane Substituents/Branches
4
Nomenclature of Branched-Chain Alkanes (IUPAC)
What is the name of the following compound?
1) Find the longest continuous chain (the parent chain), which may or may not be shown in a straight line
and name this chain
2) Number the parent chain from one end in such a way that the smaller number is used at the first point of
difference.
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3) Name each substituent/appendage group that is attached to this principle chain.
3
6
7
5
4
2
1
4) Alphabetize the substituent/appendage groups.
5) Assign to each substituent/appendage group a number signifying its point of attachment to the parent
chain (if more than one of the same add the following prefix: 2 = di, 3 = tri, 4 = tetra, etc.).
6)
Numbers are separated by commas and number and names are separated by a dash.
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When two chains of equal length compete to be parent, choose the chain with the greatest number of substituents
When branching first occurs at an equal distance from either end of the parent chain, choose the name that gives the
lower number at the first point of difference
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Common Branched Alkyl Groups
8
Shown below is the progression for drawing line structures. Note that hydrogens bonded to carbons are not drawn;
however, hydrogens bonded to heteroatoms are. Heteroatoms refer to atoms other than carbon such as oxygen or
nitrogen. Lone pairs of electrons on heteroatoms are typically not drawn either.
Classification of Carbons and Hydrogens
Primary (1o) is an sp3 carbon bonded to one other carbon
Secondary (2o) is an sp3 carbon bonded to two other carbons
Tertiary (3o) is an sp3 carbon bonded to three other carbons
Quaternary (4o) is an sp3 carbon bonded to four other carbons
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Alkenes and Alkynes
CH3-CH3
Ethane
Common Name:
CH2=CH2
ethene
ethylene
CHΞCH
ethyne
acetylene
C
5-chloro-4-ethyl-6-methyl-2-heptene
or
5-chloro-4-ethyl-6-methylhept-2-ene
IUPAC:
Trivial (older):
CH
phenylethyne
phenylacetylene
2-pentyne
ethylmethylacetylene
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Functional Groups
isopropyl
alkene
alkyne
ether
isobutyl
vinyl
sec-butyl
allyl
aryl
tert-butyl
alkane
benzyl
neopentyl
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Nomenclature Priorities of Selected Functional Groups
increasing
priority
Partial Structure
Name
R-COOH
R-COOR
R-CONH2
R-C≡N
R-CHO
R-CO-R
R-OH
R-NH2
R2C = CR2
RC≡CR
R-O-R, C6H5-, Cl-, Br-, NO2- etc
-oic acid
-oate
-amide
-nitrile
-al
-one
-ol
-amine
-ene
-yne
ether, phenyl, halo, nitro
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Question 1.1: Draw the following structures:
3,6-diethyl-2,7-dimethyloctane
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Question 1.1: Draw the following structures:
3-chloro-5-methyl-1-cyclohexene
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Question 1.2: How many carbons does the following molecule have?
a)
b)
c)
d)
e)
O
12
13
14
15
16
Question 1.3: How many hydrogens does the above molecule have?
(Remember each carbon has four bonds)
A) 13
B) 14
C) 15
D) 16
E) 17
O
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Question 1.5: Match the following compounds with their functional group:
a) CH3CH2CHO
b) CH3COCH3
c) CH3OCH3
1)
2)
3)
4)
alcohol
aldehyde
ketone
ether
1 – a, 3 – b, 4 – c
3 – a, 2 – b, 1 – c
2 – a, 3 – b, 4 – c
4 – a, 1 – b, 2 – c
1 – a, 2 – b, 3 – c
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