Download Chapter 2 Atoms and Elements

Chapter 17 Organic
Chemistry
17.2 Alkenes, Alkynes, and
Polymers
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Basic Chemistry
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Unsaturated Compounds:
Alkenes and Alkynes
Unsaturated compounds
• have fewer hydrogen
atoms attached to the
carbon chain than alkanes
• are alkenes with C=C
double bonds
• are alkynes with triple
C≡C bonds
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Naming Alkenes and Alkynes
The names of alkenes and alkynes
• use the corresponding alkane names
• change the end to ene for alkenes
• change the end to yne for alkynes
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Naming Alkenes and Alkynes
4
Basic Chemistry
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Naming Alkenes and Alkynes
5
Basic Chemistry
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Example of Writing an Alkene
Name
Write the IUPAC name for the following:
CH3
|
CH3─CH=C─CH3
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Basic Chemistry
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Example of Writing an
Alkene Name (continued)
STEP 1 Name the longest carbon chain that
contains a double or triple bond.
butene
STEP 2 Number the carbon chain starting from
the end nearer the double or triple bond.
CH3
|
CH3─CH=C─CH3
4
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3
2
1
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Example of Writing an
Alkene Name (continued)
STEP 3 Give the location and name of each
substituent (alphabetical order) as a prefix to
the alkene or alkyne name.
CH3
|
CH3─CH=C─CH3
2-methyl-2-butene
4
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3
2
1
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Learning Check
Write the IUPAC name for the following:
Br

CH3─CH─CC─CH3
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Solution
STEP 1 Name the longest carbon chain that
contains a double or triple bond.
pentyne
STEP 2 Number the carbon chain starting from
the end nearer the double or triple bond.
Br

CH3─CH─C≡C─CH3
5
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Basic Chemistry
4
3
2
1
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Solution (continued)
STEP 3 Give the location and name of each
substituent (alphabetical order) as a prefix to
the alkene or alkyne name.
Br

CH3─CH─C≡C─CH3
5
4
3
2
1
4-bromo-2-pentyne
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Learning Check
Draw the condensed structural formula for
2-methyl-3-hexyne.
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Basic Chemistry
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Solution
STEP 1 Draw the main chain of carbon atoms. For
3-hexyne, there are six carbon atoms in the chain, with
a triple bond between carbons 3 and 4,
C─C─C≡C─C─C
STEP 2 Number the chain and place the
substituents on the carbons indicated by the
numbers.
CH3

C─C─C≡C─C─C
1
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Basic Chemistry
2
3
4
5
6
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Solution (continued)
STEP 3 Add the correct number of hydrogen
atoms to give four bonds to each C atom.
CH3

CH3─CH─C≡C─CH2─CH3
1
2
3
4
5
6
2-methyl-3-hexyne
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Polymers
Polymers are
• large, long-chain molecules
• found in nature, including cellulose in plants,
starches in food, and proteins and DNA in the
body
• also made synthetically, for example,
polyethylene and polystyrene, Teflon, and nylon
• made up of small repeating units called
monomers
• made by reaction of small alkenes
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Synthetic Polymers in Everyday
Items
16
Basic Chemistry
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Polymerization
In polymerization, small repeating units called
monomers join to form a long-chain polymer.
17
Basic Chemistry
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Some Alkenes and Their
Polymers
18
Basic Chemistry
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Learning Check
What is the name and condensed structural
formula of the starting monomer for
polyethylene?
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Solution
Ethene (ethylene)
CH2=CH2
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Basic Chemistry
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Learning Check
Name the monomer used to make Teflon, and use four
monomers to draw the condensed structural formula of
a portion of a Teflon polymer.
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Basic Chemistry
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Solution
F F
│ │
F─C═C─F tetrafluoroethene (monomer)
F F F F F F F F
│ │ │ │ │ │ │ │
─C─C─C─C─C─C─C─C─
│ │ │ │ │ │ │ │
F F F F F F F F
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portion of Teflon
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Recycling Plastics
Recycling is simplified by using codes found on
plastic items.
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Learning Check
What type of plastic is indicated by each of the
following codes?
A.
3
PVC
B.
5
PP
C.
6
PS
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Solution
A.
3
PVC
Polyvinyl chloride
B.
5
PP
Polypropylene
C.
6
PS
Polystyrene
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Basic Chemistry
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