Basic Chemistry Copyright © 2011 Pearson Education, Inc. 1 Chapter 17 O rganic Chemistry 17.2 Alkenes, Alkynes, and Polymers

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 2 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

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 3 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

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 4 Naming Alkenes and Alkynes

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 5 Naming Alkenes and Alkynes

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 6 Example of Writing an Alkene Name Write the IUPAC name for the following: CH 3 | CH 3 ─CH=C─CH 3

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 7 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. CH 3 | CH 3 ─CH=C─CH

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 8 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. CH 3 | CH 3 ─CH=C─CH 3 2-methyl-2-butene

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 9 Learning Check Write the IUPAC name for the following: Br  CH 3 ─CH─C  C─CH 3

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 10 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  CH 3 ─CH─C ≡ C─CH

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 11 Solution (continued) STEP 3 Give the location and name of each substituent (alphabetical order) as a prefix to the alkene or alkyne name. Br  CH 3 ─CH─C ≡ C─CH bromo-2-pentyne

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 12 Learning Check Draw the condensed structural formula for 2-methyl-3-hexyne.

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 13 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. CH 3  C─C─C ≡ C─C─C

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 14 Solution (continued) STEP 3 Add the correct number of hydrogen atoms to give four bonds to each C atom. CH 3  CH 3 ─CH─C ≡ C─CH 2 ─CH methyl-3-hexyne

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 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 15

Basic Chemistry Copyright © 2011 Pearson Education, Inc. Synthetic Polymers in Everyday Items 16

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 17 Polymerization In polymerization, small repeating units called monomers join to form a long-chain polymer.

Basic Chemistry Copyright © 2011 Pearson Education, Inc. Some Alkenes and Their Polymers 18

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 19 Learning Check What is the name and condensed structural formula of the starting monomer for polyethylene?

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 20 Solution Ethene (ethylene) CH 2 =CH 2

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 21 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.

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 22 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─ portion of Teflon │ │ │ │ │ │ │ │ F F F F F F F F

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 23 Recycling Plastics Recycling is simplified by using codes found on plastic items.

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 24 Learning Check What type of plastic is indicated by each of the following codes? A. B. C. 3 PVC 5 PP 6 PS

Basic Chemistry Copyright © 2011 Pearson Education, Inc. 25 Solution A. Polyvinyl chloride B.Polypropylene C.Polystyrene 5 PP 6 PS 3 PVC