Chapter 16
Alkanes and Aromatic
Hydrocarbons
Organic Compounds
Bonding in Hydrocarbons
Naming Alkanes
Properties of Alkanes
1
“The most important hypothesis in all of
biology…is that everything that animals do,
atoms do. In other words, there is nothing
that living things do that cannot be
understood from the point of view that
they are made of atoms acting according
to the laws of physics.”
Richard Feynman (1918-1988)
2
Organic Compounds
 Contain
carbon
 Have
covalent bonds
 Have
low melting points
 Have
low boiling points
 Burn
in air (oxygen)
 Are
soluble in nonpolar solvents
 Form
large molecules
3
Alkanes
 Contain
C and H only
 Contain
single bonds C-C
 Have
 Are
4 bonds to every carbon (C) atom
nonpolar
4
Complete Structural Formulas
Show the bonds between each of the
atoms
H
H

HCH
H
C
H

H
H
CH4 , methane
5
More Alkanes
H
H
H
H
C
C
H
H
Condensed Structural Formulas
H
CH3
CH3
Ethane
H
H
H
C
C
C
H
H
H
H
CH3 CH2 CH3
Propane
6
IUPAC Names
Name
# carbons
Structural Formula
Methane 1
CH4
Ethane
CH3CH3
2
Propane 3
CH3CH2CH3
Butane
CH3CH2CH2CH3
4
Pentane 5
CH3CH2CH2CH2CH3
7
IUPAC NAMES
Name # carbons
Structural Formula
Hexane 6
CH3CH2CH2CH2CH2CH3
Heptane 7
CH3CH2CH2CH2CH2CH2CH3
Octane
8
CH3CH2CH2CH2CH2CH2CH2CH3
Nonane 9
CH3 CH2 CH2CH2CH2CH2CH2CH2CH3
Decane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
8
Learning Check Alk1
A. What is the condensed formula for
H H H H
H
C
C
C
C
H
H
H H
H
B. What is its molecular formula?
C. What is its name?
9
Solution Alk1
A.
CH3CH2CH2CH3
B.
C4H10
C.
butane
10
Reactions of Alkanes
Combustion
alkane + O2
CO2 + H2O + heat
11
Combustion In the Cell
Metabolic oxidation is combustion
C6H12 O6 + 6O2
6CO2 + 6H2O + heat
glucose
12
Learning Check Alk2
Complete the combustion reaction for
C 3H 8 + O 2
+
Balance your equation
13
Solution Alk2
Step 1
C 3H 8 + O 2
CO2 + H2O
Step 2
C 3H 8 + O 2
3 CO2 + 4 H2O
Step 3
C 3H 8 + 5 O 2
3 CO2 + 4 H2O
14
Learning Check Alk3
Complete and balance the reaction for
the complete combustion of C7H16
15
Solution Alk3
Step 1
C7H16 + O2
CO2 + H2O
Step 2
C7H16 + O2
7 CO2 + 8 H2O
Step 3
C7H16 + 11 O2
7 CO2 + 8 H2O
16
Haloalkanes
An alkane in which one or more H atoms is
replaced with a halogen (F, Cl, Br, or I)
CH3Br
1-bromomethane
(methyl bromide)
Br
CH3CH2CHCH3
2-bromobutane
Cl
chlorocyclobutane
17
Learning Check HA1
Name the following:
Br
Cl
Cl
18
Solution HA1
Name the following:
Br
bromocyclopentane
Cl
1,3-dichlorocyclohexane
Cl
19
Substituents
List other attached atoms or group in
alphabetical order
Br = bromo, Cl = chloro
Cl
Br
CH3CHCH2CHCH2CH2CH3
4-bromo-2-chloroheptane
20
Learning Check HA2
The name of this compound is:
Cl
CH3
CH3CH2CHCH2CHCH3
1)
2,4-dimethylhexane
2)
3-chloro-5-methylhexane
3)
4-chloro-2-methylhexane
21
Solution HA2
The name of this compound is:
Cl
CH3
CH3CH2CHCH2CHCH3
3) 4-chloro-2-methylhexane
22
Haloalkanes as Anesthetics
Halothane (Fluothane)
F
F
Cl
C
C
Br
F
H
Fluothane is a haloalkane that is widely used as
an anesthetic, which is a compound that
decreases the ability of the nerve cells to
conduct pain.
23
Chapter 16
Haloalkanes, Alkenes, and Alkynes
Alkenes and Alkynes
Geometric Isomers of Alkenes
Addition Reactions
24
Saturated and Unsaturated
Compounds
Saturated compounds (alkanes) have
the maximum number of hydrogen
atoms attached to each carbon atom
 Unsaturated compounds have fewer
hydrogen atoms attached to the carbon
chain than alkanes
 Unsaturated compounds contain double
or triple bonds

25
Alkenes
 Carbon-carbon
double bonds
 Names end in -ene
H2C=CH2
ethene (ethylene)
H2C=CH-CH3
propene (propylene)
cyclohexene
26
Alkynes
 Carbon-carbon
triple bonds
 Names end in -yne
HCCH
ethyne(acetylene)
HCC-CH3
propyne
27
Naming Alkenes and Alkynes
When the carbon chain has 4 or more C atoms,
number the chain to give the lowest number to the
double or triple bond.
1
2 3 4
CH2=CHCH2CH3
1-butene
CH3CH=CHCH3
2-butene

2-butyne
CH3CH CHCH3
28
Learning Check HA3
Write the IUPAC name for each of the following
unsaturated compounds:
A.
CH3CH2CCCH3
CH3
CH3
B.
CH3C=CHCH3
C.
29
Solutions HA3
Write the IUPAC name for each of the following
unsaturated compounds:
A.
CH3CH2CH=CHCH3
2-pentyne
CH3
CH3
B.
CH3C=CHCH3
2-methyl-2-butene
C.
3-methylcyclopentene
30
Cis and Trans Isomers
 Double
bond is fixed
 Cis/trans Isomers are possible
CH3
CH3
CH = CH
cis
CH3
CH = CH
trans
CH3
31
Hydrogenation

Adds a hydrogen atom to each carbon
atom of a double bond
H H
H H
Ni
H–C=C–H + H2
H–C–C–H
H H
ethene
ethane
32
Products of Hydrogenation
Adding H2 to vegetable oils produces
compounds with higher melting points

Margarines

Soft margarines

Shortenings (solid)
33
Learning Check HA4
What is the product of adding H2 (Ni
catalyst) to 1-butene?
34
Solution HA4
What is the product of adding H2 (Ni
catalyst) to 1-butene?
Ni
CH2=CHCH2CH3 + H2
CH3CH2CH2CH3
35
Adding Halogens
Halogens also add to the double bond of an
alkene.
H2CCH2
+
Cl2
Cl Cl
H2C CH2
Br Br
CH3C CCH2CH3
+ Br2
CH3C CCH2CH3
Br Br
36
Learning Check HA5
Write the product of the following addition
reactions:
CH3CH=CHCH3 + H2
+ Br2
37
Solution HA5
Write the product of the following addition
reactions:
CH3CH=CHCH3 + H2
+ Br2
CH3CH2CH2CH3
Br
Br
38
Unsaturated Fatty Acids

Fatty acids in vegetable oils are omega-6 acids
(the first double bond occurs at carbon 6 counting
from the methyl group)
 A common omega-6 acid is linoleic acid
CH3CH2CH2CH2CH2CH=CHCH2CH=CH(CH2)7COOH
6
linoleic acid, a fatty acid
39
Trans Fats
 In
vegetable oils, the unsaturated fats usually
contain cis double bonds.
 During hydrogenation, some cis double bonds
are converted to trans double bonds (more
stable) causing a change in the fatty acid
structure
 If
a label states “partially” or “fully
hydrogenated”, the fats contain trans fatty
acids.
40
Trans Fats
 In
the US, it is estimated that 2-4% of our total
Calories is in the form of trans fatty acid.
 trans fatty acids behave like saturated fatty
acids in the body.
 Several studies reported that trans fatty acids
raise LDL-cholesterol. Some studies also
report that trans fatty acid lower HDLcholesterol
 The trans fatty acids controversy will continue
to be debated.
41
Fats and Atheroschlerosis

Inuit people of Alaska have a high fat diet
and high blood cholesterol levels, but a very
low occurrence of atherosclerosis and heart
attacks.

Fat in the Intuit diet was primarily from fish
such as salmon, tuna and herring rather than
from land animals (as in the American diet).
42
Omega-3 Fatty Acids

Fatty acids in the fish oils are mostly the omega-3
type (first double bond occurs at the third carbon
counting from the methyl group).

linolenic acid 18 carbon atoms
CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH


eicosapentaenoic acid (EPA) 20 carbon atoms
CH3CH2(CH=CHCH2)5(CH2)2COOH
43
Atherosclerosis

Plaques of cholesterol adhere to the walls of the
blood vessels

Blood pressure rises as blood squeezes through
smaller blood vessels

Blood clots may form

Omega-3 fatty acids decrease the “sticking” of
blood platelets (fewer blood clots)

Omega-3 fatty acids can increase bleeding time
44
Learning Check HA6
(1) Ture or (2) False
A. ____ There are more unsaturated fats in
vegetable oils.
B. ____ Vegetable oils have more omega-3 oils
than found in fish.
C. ____ Hydrogenation of oils converts some
cis-double bonds to trans- double bonds.
D. ____ Animal fats have more saturated fats.
45
Solution HA6
(1) True or (2) False
A. _T__ There are more unsaturated fats in
vegetable oils.
B. _F__ Vegetable oils have more omega-3 oils
than found in fish.
C. _T__ Hydrogenation of oils converts some
cis-double bonds to trans- double bonds.
D. _T__ Animal fats have more saturated fats.
46