Chapter 20 (part 2) Organic Chemistry

Section 20.7 Alkenes and Alkynes Alkenes: hydrocarbons that contain a carbon carbon double bond. [C n H 2n ] CH 3 CH=CH 2 propene Alkynes: hydrocarbons containing a carbon carbon triple bond. [C n H 2n 2 ] CH 3 CH 2 C CCH 3 2 pentyne Copyright Cengage Learning. All rights reserved 2

Section 20.7 Alkenes and Alkynes 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. C 2 H 4 is ethene 3. With more than 3 carbons, double bond is indicated by the lowest numbered carbon atom in the bond. CH 2 =CHCH 2 CH 3 1 2 3 4 1 butene 4. Substituents on the parent chain are treated the same way as in naming alkanes. ClCH=CHCH 2 CH 3 1-chloro-1-butene Copyright Cengage Learning. All rights reserved 3

Section 20.7 Alkenes and Alkynes Exercise Name each of the following: a) b) CH 3 H 3 C CH CH 2 C C CH 3 CH 3 CH 3 2,3,5-trimethyl-2-hexene CH 2 CH 3 CH 2 CH 3 CH 3 H 3 C C CH CH 2 CH CH 2 6-ethyl-3-methyl-3-octene Copyright Cengage Learning. All rights reserved 5

Section 20.7 Alkenes and Alkynes Addition Reactions New atoms form single bonds to the carbons formerly involved in a double or triple bond. Hydrogenation use H 2 as the reactant to be added Halogenation addition of halogen atoms Copyright Cengage Learning. All rights reserved 6

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. Copyright Cengage Learning. All rights reserved 9

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. Copyright Cengage Learning. All rights reserved 11

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. Copyright Cengage Learning. All rights reserved 13

Section 20.12 Properties and Uses of Alcohols Methanol Ethanol Starting material for making acetic acid and many adhesives, fibers and plastics Motor fuel Fermentation product Fuel additive used to make gasohol Copyright Cengage Learning. All rights reserved 14

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. Copyright Cengage Learning. All rights reserved 18