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Chapter 20 (part 2) Organic Chemistry
Chapter 20(part 2)
Organic Chemistry
Section 20.7
Alkenes and Alkynes
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• Alkenes: hydrocarbons that contain a carbon–carbon double bond. [CnH2n]
CH3CH=CH2 propene
• Alkynes: hydrocarbons containing a carbon–carbon triple bond. [CnH2n – 2]
CH3CH2C≡CCH3 2–pentyne
Section 20.7
Alkenes and Alkynes
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Rules for Naming Alkenes
1. Select the longest continuous chain of carbon atoms that contains the double bond.
2. Root hydrocarbon name ends in –ene.
C2H4 is ethene
3. With more than 3 carbons, double bond is indicated by the lowest–numbered carbon atom in the bond.
CH2=CHCH2CH3
1 2 3 4
1–butene
4. Substituents on the parent chain are treated the same way as in naming alkanes.
ClCH=CHCH2CH3
1-chloro-1-butene
Section 20.7
Alkenes and Alkynes
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Rules for Naming Alkynes
• Same as for alkenes except use –yne as suffix.
CH3CH2C≡CCH2CH2CH2CH3
3–octyne
Section 20.7
Alkenes and Alkynes
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Exercise
Name each of the following:
a)
2,3,5-trimethyl-2-hexene
b)
6-ethyl-3-methyl-3-octene
H3C CH CH2 C C CH3
CH3
CH3
CH3
H3C C CH CH2 CH CH2
CH2 CH2CH3 CH3
CH3
Section 20.7
Alkenes and Alkynes
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Addition Reactions
• New atoms form single bonds to the carbons formerly involved in a double or triple bond.
Hydrogenation – use H2 as the reactant to be added
Halogenation – addition of halogen atoms
Section 20.8
Aromatic Hydrocarbons
• Cyclic unsaturated hydrocarbons with strong aromas.
• Benzene – simplest aromatic hydrocarbon
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Section 20.9
Naming Aromatic Compounds
Monosubstituted Benzenes
• Use the substituent name as a prefix of benzene.
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Section 20.9
Naming Aromatic Compounds
Disubstituted Benzenes
• Use numbers to indicate the position of substituents and the substituent name as a prefix of benzene.
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Section 20.9
Naming Aromatic Compounds
Complex Aromatic Molecules
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Section 20.10
Functional Groups
• Additional atom or groups of atoms (containing elements in addition to H and C) found on a mostly hydrocarbon molecule.
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Section 20.11
Alcohols
• All alcohols contain the –OH group.
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Section 20.11
Alcohols
Rules for Naming Alcohols
1. Select the longest chain of carbon atoms containing the –OH group.
2. Number the chain such that the carbon with the –OH group gets the lowest possible number.
3. Obtain the root name from the name of the parent hydrocarbon chain by replacing the final –e with –ol.
4. Name any other substituents as usual.
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Section 20.12
Properties and Uses of Alcohols
• Methanol
Starting material for making acetic acid and many adhesives, fibers and plastics
Motor fuel
• Ethanol
Fermentation product
Fuel additive used to make gasohol
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Section 20.12
Properties and Uses of Alcohols
Other Alcohols
• Ethylene glycol – automotive antifreeze
• Phenol – production of adhesives and plastics
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Section 20.13
Aldehydes and Ketones
Carbonyl Group
• Carbon oxygen group found in both aldehydes and ketones.
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Section 20.13
Aldehydes and Ketones
Ketone
• Carbonyl group is bonded to two carbon atoms.
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Section 20.13
Aldehydes and Ketones
Aldehyde
• Carbonyl group always appears on the end of the hydrocarbon chain and has at least one H atom bonded to the carbonyl group.
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Section 20.13
Aldehydes and Ketones
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Some Common Aldehydes
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