chapter 11 unsaturated hydrocarbons
DESCRIPTION
Chapter 11 Unsaturated Hydrocarbons. 11.1 Alkenes and Alkynes. Saturated Hydrocarbons. Saturated hydrocarbons have the maximum number of hydrogen atoms attached to each carbon atom. are alkanes and cycloalkanes with single C-C bonds. CH 3 —CH 2 —CH 3. Unsaturated Hydrocarbons. - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 11 Unsaturated Hydrocarbons
11.1
Alkenes and Alkynes
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Saturated hydrocarbons• have the maximum number of hydrogen atoms
attached to each carbon atom.• are alkanes and cycloalkanes with single C-C
bonds.
CH3—CH2—CH3
Saturated Hydrocarbons
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Unsaturated hydrocarbons• have fewer hydrogen
atoms attached to the carbon chain than alkanes.
• are alkenes with double bonds.
• are alkynes with triple bonds.
Unsaturated Hydrocarbons
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Bond Angles in Alkenes and Alkynes
According to VSEPR theory: • the three groups bonded to
carbon atoms in a double bond are at 120° angles.
• alkenes are flat because the atoms in a double bond all lie in the same plane.
• the two groups bonded to each carbon in a triple bond are at 180° angles.
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Naming Alkenes
The names of alkenes • use the corresponding alkane name.• change the ending to –ene.
Alkene IUPAC Common
H2C=CH2 ethene ethylene
H2C=CH─CH3 propene propylene
cyclohexene
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Ethene (Ethylene)
Ethene or ethylene• is an alkene with the formula
C2H4.• has two carbon atoms connected
by a double bond. • has two H atoms bonded to each
C atom.• is flat with all the C and H atoms
in the same plane.• is used to accelerate the ripening
of fruits.
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Naming Alkynes
The names of alkynes • use the corresponding alkane name.• change the ending to –yne.
Alkyne IUPAC Common
HC≡CH ethyne acetylene
HC≡C─CH3 propyne
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Naming Alkenes and Alkynes
When the carbon chain of an alkene or alkyne has four or more C atoms, number the chain to give the lowest number to the first carbon in the double or triple bond.
CH2=CH─CH2─CH3 1-butene
1 2 3 4
CH3─CH=CH─CH3 2-butene
1 2 3 4
CH3─CH2─CC─CH3 2-pentyne
5 4 3 2 1
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Learning Check
Write the IUPAC name for each of the following:
1. CH2=CH─CH2─CH3
2. CH3─CH=CH─CH3
CH3
|3. CH3─CH=C─CH3
4. CH3─CC─CH3
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Solution
Write the IUPAC name for each of the following:
1. CH2=CH─CH2─CH3 1-butene
2. CH3─CH=CH─CH3 2-butene
CH3
|3. CH3─CH=C─CH3 2-methyl-2-butene
4. CH3─CC─CH3 2-butyne
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Learning Check
Write the IUPAC name for each of the following:
A. CH3─CH2─C≡C─CH3
CH3
B. CH3─CH2─C=CH─CH3
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Solution
Write the IUPAC name for each of the following:
A. CH3─CH2─C≡C─CH3 2-pentyne
CH3
B. CH3─CH2─C=CH─CH3 3-methyl-2-pentene