CHAPTER 13
Unsaturated Hydrocarbons
General, Organic, & Biological Chemistry
Janice Gorzynski Smith
CHAPTER 13: Unsaturated Hydrocarbons
Learning Objectives:
Identify unsaturated hydrocarbons: alkenes, alkynes,
aromatic compounds
Alkene, Alkyne, Aromatic nomenclature
Stereoisomers
Addition Reactions
Polymers
Substitution Reactions
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Functional
Groups
Overview
Hydrocarbon
Functional
Groups
Alkane
C−C
Alkene
C=C
Alkyne
C=C
Aromatic
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Hydrocarbon
Alkane
Alkene
Alkyne
Chemical formulas
C−C
CnH2n+2
CnH2n
C=C
CnH2n
CnH2n-2
C=C
Aromatic
Smith. General Organic & Biolocial Chemistry 2nd Ed.
CnH2n-2
if a chain
if a cycloalkane
if a chain with 1 dbl bond
if a cycloalkene with 1 dbl bond
if a chain with 1 triple bond
C6H6
4
Molecule
Shape
Drawing Alkenes
SIMPLIFY!
..
H
H
H
H
H
C
C
C
C
H
H
H
H
CH3CH2CH2=CH2
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Alkanes
Nomenclature
#
1
prefix +
prefix
6
4
2
1
2
3
4
5
6
7
8
9
10
3
5
parent +
suffix
Greek Straight Chain
Root Alkane Name
methane
meth
ethane
eth
propane
prop
butane
but
pentane
pent
hexane
hex
heptane
hept
octane
oct
nonane
non
decane
dec
What, where are the substituents?
Example: 2,4- dimethyl
parent
How many carbons in longest chain?
Example: hex
suffix
What is the functional group?
Example: ane
2,4-dimethylhexane
#
Carbons
1
2
3
4
5
6
Alkyl Group
Structure
Name
CH3methyl
CH3CH2ethyl
CH3CH2CH2propyl
CH3CH2CH2CH2butyl
CH3CH2CH2CH2CH2pentyl
CH3CH2CH2CH2CH2CH2hexyl
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Alkenes & Alkynes
Nomenclature
#
1
prefix +
prefix
6
4
2
1
2
3
4
5
6
7
8
9
10
3
5
parent +
suffix
Greek Straight Chain
Root Alkane Name
methane
meth
ethane
eth
propane
prop
butane
but
pentane
pent
hexane
hex
heptane
hept
octane
oct
nonane
non
decane
dec
First give location and type of substituents
Second give location of double bond
parent
How many carbons in longest chain?
suffix
How many of the functional group and
what is it?
Alkene = ene; Alkyne = yne
2,4-dimethyl 1,5- hexa diene
#
Carbons
1
2
3
4
5
6
Alkyl Group
Structure
Name
CH3methyl
CH3CH2ethyl
CH3CH2CH2propyl
CH3CH2CH2CH2butyl
CH3CH2CH2CH2CH2pentyl
CH3CH2CH2CH2CH2CH2hexyl
* Note: when we have more then 1 multiple bond the parent name has an “a” added on: hexa instead of hex
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Alkenes & Alkynes
Nomenclature
#
3
2
1
2
3
4
5
6
7
8
9
10
1
4
5
prefix +
prefix
parent +
suffix
Greek Straight Chain
Root Alkane Name
methane
meth
ethane
eth
propane
prop
butane
but
pentane
pent
hexane
hex
heptane
hept
octane
oct
nonane
non
decane
dec
First give location and type of substituents
Second give location of double bond
parent
How many carbons in longest chain?
suffix
How many of the functional group and
what is it?
Alkene = ene; Alkyne = yne
4-methyl 2- pent yne
#
Carbons
1
2
3
4
5
6
Alkyl Group
Structure
Name
CH3methyl
CH3CH2ethyl
CH3CH2CH2propyl
CH3CH2CH2CH2butyl
CH3CH2CH2CH2CH2pentyl
CH3CH2CH2CH2CH2CH2hexyl
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Alkenes & Alkynes
Nomenclature
#
4
5
3
2
prefix +
prefix
1
2
3
4
5
6
7
8
9
10
1
parent +
suffix
Greek Straight Chain
Root Alkane Name
methane
meth
ethane
eth
propane
prop
butane
but
pentane
pent
hexane
hex
heptane
hept
octane
oct
nonane
non
decane
dec
First give location and type of substituents
Second give location of double bond
parent
How many carbons in longest chain?
suffix
How many of the functional group and
what is it?
Alkene = ene; Alkyne = yne
3-methyl 1- cyclo pent ene
#
Carbons
1
2
3
4
5
6
Alkyl Group
Structure
Name
CH3methyl
CH3CH2ethyl
CH3CH2CH2propyl
CH3CH2CH2CH2butyl
CH3CH2CH2CH2CH2pentyl
CH3CH2CH2CH2CH2CH2hexyl
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Aromatics: Benzene
Nomenclature
5
6
o-
1
2
4
m-
3
prefix +
parent
prefix
Give location, number, and type of
substituent. You can also replace location &
number with o, m, p
parent
“Benzene”
pPolysubstituted Benzenes:
1,2-dimethyl benzene
o-dimethyl benzene
1.
2.
3.
Number to give lowest #s around ring
Alphabetize substituents
If part of common root name the
molecule as a derivative of a
monosubstituted benzene with
common root at C1.
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
Practice naming Alkenes & Alkynes!
11
Bond
Angles
Alkenes & Alkynes
ethylene
120°
180°
acetylene
Alkenes
Stereoisomers
R
R
R
CIS
R
TRANS
Alkenes
Stereoisomers
Linoleic Acid
Alkenes
Stereoisomers
Stereoisomers
Different 3-D shape
Same bonds
Conformational
Isomers
Different bonds
between atoms
Alkene
Reactions
Addition
Addition Rxns: when elements are added to a compound
X
Y
X
Y
Alkene
Reactions
Addition
H
H
X
X
H
X
H
OH
H2
Metal catalyst
Hydrogenation
X2
X = Cl or Br
Halogenation
HX
X = Cl or Br
Hydrohalogenation
H2O
H2SO4
Hydration
Nucleophile vs Electrophile
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Alkene
Reactions
Polymers
Polymerization: joining together of monomers
Aromatic
Reactions
Substitution
Substitution Rxns: when an atom is replaced by another
atom or group of atoms
H
X
X
Y
H
Y
Aromatic
Reactions
Substitution
Cl
H
Cl2
Clorination
HNO3
NO2
H2SO4
Nitration
SO3
H2SO4
Sulfonation
SO3H