Chapter 11
Haloalkanes, Alkenes, and Alkynes
Alkenes and Alkynes
Geometric Isomers of Alkenes
Addition Reactions
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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
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Alkenes
Carbon-carbon double bonds
Names end in -ene
H2C=CH2
ethene (ethylene)
H2C=CH-CH3
propene (propylene)
cyclohexene
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Alkynes
Carbon-carbon triple bonds
Names end in -yne
HCCH
ethyne(acetylene)
HCC-CH3
propyne
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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
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Learning Check HA3
Write the IUPAC name for each of the following
unsaturated compounds:
A.
CH3CH2CCCH3
CH3
CH3
B.
CH3C=CHCH3
C.
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Solutions HA3
Write the IUPAC name for each of the following
unsaturated compounds:
A.
CH3CH2CH=CHCH3
2-pentyne
CH3
CH3
B.
CH3C=CHCH3
C.
2-methyl-2-butene
3-methylcyclopentene
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Cis and Trans Isomers
Double bond is fixed
Cis/trans Isomers are possible
CH3
CH3
CH3
CH = CH
cis
CH = CH
trans
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CH3
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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
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Products of Hydrogenation
Adding H2 to vegetable oils produces
compounds with higher melting points
 Margarines
 Soft margarines
 Shortenings (solid)
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Learning Check HA4
What is the product of adding H2 (Ni
catalyst) to 1-butene?
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Solution HA4
What is the product of adding H2 (Ni
catalyst) to 1-butene?
Ni
CH2=CHCH2CH3 + H2
CH3CH2CH2CH3
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Adding Halogens
Halogens also add to the double bond of an
alkene.
H2CCH2
Cl Cl
+
Cl2
H2C CH2
Br Br
CH3C CCH2CH3
+ Br2
CH3C CCH2CH3
Br Br
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Learning Check HA5
Write the product of the following addition
reactions:
CH3CH=CHCH3 + H2
+ Br2
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Solution HA5
Write the product of the following addition
reactions:
CH3CH=CHCH3 + H2
CH3CH2CH2CH3
Br
+ Br2
Br
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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
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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.
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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.
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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).
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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
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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
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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.
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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.
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