Chapter 12 Alkenes Alkynes and Aromatic Compounds 12

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Chapter 12 Alkenes, Alkynes, and Aromatic Compounds 12. 1 Alkenes and Alkynes General, Organic,

Chapter 12 Alkenes, Alkynes, and Aromatic Compounds 12. 1 Alkenes and Alkynes General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 1

Unsaturated Hydrocarbons Unsaturated hydrocarbons § have fewer hydrogen atoms attached to the carbon chain

Unsaturated Hydrocarbons Unsaturated hydrocarbons § have fewer hydrogen atoms attached to the carbon chain than do alkanes § are alkenes with double C=C bonds § are alkynes with triple C≡C bonds General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 2

Bond Angles in Alkenes According to VSEPR theory: § Three groups in a double

Bond Angles in Alkenes According to VSEPR theory: § Three groups in a double bond are bonded at 120° angles. § Alkenes are flat because the atoms in a double bond lie in the same plane. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 3

Bond Angles in Alkynes According to VSEPR theory: § The atoms in a triple

Bond Angles in Alkynes According to VSEPR theory: § The atoms in a triple bond have a 180° angle. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 4

Naming Alkenes The names of alkenes § use the corresponding alkane name § change

Naming Alkenes The names of alkenes § use the corresponding alkane name § change the ending from -ane to -ene Alkene H 2 C=CH 2 H 2 C=CH─CH 3 IUPAC Common Ethene Ethylene Propylene Cyclohexene General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 5

Ethene (Ethylene) Ethene, or ethylene, § is the alkene C 2 H 4 §

Ethene (Ethylene) Ethene, or ethylene, § is the alkene C 2 H 4 § 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 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 6

Naming Alkynes The names of alkynes § use the corresponding alkane name § change

Naming Alkynes The names of alkynes § use the corresponding alkane name § change the ending from -ane to -yne Alkyne HC≡CH HC≡C─CH 3 IUPAC Ethyne Propyne Common Acetylene General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 7

Guide to Naming Alkenes and Alkynes General, Organic, and Biological Chemistry Copyright © 2010

Guide to Naming Alkenes and Alkynes General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 8

Example of Naming Alkenes Write the IUPAC name for CH 2═CH─CH 2─CH 3 and

Example of Naming Alkenes Write the IUPAC name for CH 2═CH─CH 2─CH 3 and CH 3─CH≡CH─CH 3. STEP 1 Name the longest carbon chain with a double of triple bond: butene, butyne STEP 2 Number the chain from the end nearer the double or triple bond: CH 2═CH─CH 2─CH 3 1 2 3 4 CH 3─CH≡CH─CH 3 1 2 3 4 STEP 3 Give the location and name of the double or triple bond. 1 -butene 2 -butyne General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 9

Names for Alkanes, Alkenes, and Alkynes General, Organic, and Biological Chemistry Copyright © 2010

Names for Alkanes, Alkenes, and Alkynes General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 10

Examples of Naming Alkenes with Substituents Write the IUPAC name for STEP 1 Name

Examples of Naming Alkenes with Substituents Write the IUPAC name for STEP 1 Name the longest carbon chain: pentene STEP 2 Number the chain from the end nearer the double or triple bond: STEP 3 Give the location and name of the substituent and double or triple bond: 4 -methyl-2 -pentene General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 11

Naming Alkynes with Substituents Write the IUPAC name for STEP 1 Name the longest

Naming Alkynes with Substituents Write the IUPAC name for STEP 1 Name the longest carbon chain: butyne STEP 2 Number the chain from the triple bond: STEP 3 Give the location and name of the substituent and double or triple bond: 3 -Methyl-1 -butyne General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 12

Learning Check Write the IUPAC name for each of the following: General, Organic, and

Learning Check Write the IUPAC name for each of the following: General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 13

Solution Write the IUPAC name for each of the following: 1 -butene 2 -methyl-2

Solution Write the IUPAC name for each of the following: 1 -butene 2 -methyl-2 -butene 4 -methyl-2 -pentyne General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 14

Learning Check Draw the condensed structural formula for each of the following: A. 2

Learning Check Draw the condensed structural formula for each of the following: A. 2 -Hexyne B. 3 -Methyl-3 -hexene General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 15

Solution Draw the condensed structural formula for each of the following: A. 2 -hexyne

Solution Draw the condensed structural formula for each of the following: A. 2 -hexyne B. 3 -methyl-3 -hexene General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 16