Chapter 11 Haloalkanes, Alkenes, and Alkynes

1. Chapter 11Haloalkanes, Alkenes, and Alkynes Alkenes and Alkynes Geometric Isomers of Alkenes Addition Reactions LecturePLUS Timberlake

2. Saturated and Unsaturated Compounds • Saturated compounds (alkanes) have the maximum number of hydrogen atoms attached to each carbon atom • Unsaturated compounds have fewer hydrogen atoms attached to the carbon chain than alkanes • Unsaturated compounds contain double or triple bonds LecturePLUS Timberlake

3. Alkenes • Carbon-carbon double bonds • Names end in -ene H2C=CH2 ethene (ethylene) H2C=CH-CH3 propene (propylene) cyclohexene LecturePLUS Timberlake

4. Alkynes • Carbon-carbon triple bonds • Names end in -yne HCCH ethyne(acetylene) HCC-CH3 propyne LecturePLUS Timberlake

5. Naming Alkenes and Alkynes When the carbon chain has 4 or more C atoms, number the chain to give the lowest number to the double or triple bond. 1 2 3 4 CH2=CHCH2CH3 1-butene CH3CH=CHCH3 2-butene CH3CHCHCH3 2-butyne LecturePLUS Timberlake

6. Learning Check HA3 Write the IUPAC name for each of the following unsaturated compounds: A. CH3CH2CCCH3 CH3 B. CH3C=CHCH3 C. LecturePLUS Timberlake

7. Solutions HA3 Write the IUPAC name for each of the following unsaturated compounds: A. CH3CH2CH=CHCH3 2-pentyne CH3 B. CH3C=CHCH3 C. 3-methyl-2-butene 3-methylcyclopentene LecturePLUS Timberlake

8. Cis and Trans Isomers • Double bond is fixed • Cis/trans Isomers are possible CH3 CH3 CH3 CH = CH CH = CH cis trans CH3 LecturePLUS Timberlake

9. Hydrogenation • Adds a hydrogen atom to each carbon atom of a double bond H H H H Ni H–C=C–H + H2 H–C–C–H H H ethene ethane LecturePLUS Timberlake

10. Products of Hydrogenation Adding H2 to vegetable oils produces compounds with higher melting points • Margarines • Soft margarines • Shortenings (solid) LecturePLUS Timberlake

11. Learning Check HA4 What is the product of adding H2 (Ni catalyst) to 1-butene? LecturePLUS Timberlake

12. Solution HA4 What is the product of adding H2 (Ni catalyst) to 1-butene? Ni CH2=CHCH2CH3 + H2 CH3CH2CH2CH3 LecturePLUS Timberlake

13. Adding Halogens Halogens also add to the double bond of an alkene. H2CCH2 + Cl2 LecturePLUS Timberlake

14. Learning Check HA5 Write the product of the following addition reactions: CH3CH=CHCH3 + H2 LecturePLUS Timberlake

15. Solution HA5 Write the product of the following addition reactions: CH3CH=CHCH3 + H2 CH3CH2CH2CH3 LecturePLUS Timberlake

16. Unsaturated Fatty Acids • Fatty acids in vegetable oils are omega-6 acids (the first double bond occurs at carbon 6 counting from the methyl group) • A common omega-6 acid is linoleic acid CH3CH2CH2CH2CH2CH=CHCH2CH=CH(CH2)7COOH 6 linoleic acid, a fatty acid LecturePLUS Timberlake

17. Trans Fats • In vegetable oils, the unsaturated fats usually contain cis double bonds. • During hydrogenation, some cis double bonds are converted to trans double bonds (more stable) causing a change in the fatty acid structure • If a label states “partially” or “fully hydrogenated”, the fats contain trans fatty acids. LecturePLUS Timberlake

18. Trans Fats • In the US, it is estimated that 2-4% of our total Calories is in the form of trans fatty acid. • trans fatty acids behave like saturated fatty acids in the body. • Several studies reported that trans fatty acids raise LDL-cholesterol. Some studies also report that trans fatty acid lower HDL-cholesterol • The trans fatty acids controversy will continue to be debated. LecturePLUS Timberlake

19. Fats and Atheroschlerosis • Inuit people of Alaska have a high fat diet and high blood cholesterol levels, but a very low occurrence of atherosclerosis and heart attacks. • Fat in the Intuit diet was primarily from fish such as salmon, tuna and herring rather than from land animals (as in the American diet). LecturePLUS Timberlake

20. Omega-3 Fatty Acids • Fatty acids in the fish oils are mostly the omega-3 type (first double bond occurs at the third carbon counting from the methyl group). • linolenic acid 18 carbon atoms CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH  • eicosapentaenoic acid (EPA)20 carbon atoms CH3CH2(CH=CHCH2)5(CH2)2COOH LecturePLUS Timberlake

21. Atherosclerosis • Plaques of cholesterol adhere to the walls of the blood vessels • Blood pressure rises as blood squeezes through smaller blood vessels • Blood clots may form • Omega-3 fatty acids decrease the “sticking” of blood platelets (fewer blood clots) • Omega-3 fatty acids can increase bleeding time LecturePLUS Timberlake

22. Learning Check HA6 (1) Ture or (2) False A. ____ There are more unsaturated fats in vegetable oils. B. ____ Vegetable oils have more omega-3 oils than found in fish. C. ____ Hydrogenation of oils converts some cis-double bonds to trans- double bonds. D. ____ Animal fats have more saturated fats. LecturePLUS Timberlake

23. Solution HA6 (1) True or (2) False A. _T__ There are more unsaturated fats in vegetable oils. B. _F__ Vegetable oils have more omega-3 oils than found in fish. C. _T__ Hydrogenation of oils converts some cis-double bonds to trans- double bonds. D. _T__ Animal fats have more saturated fats. LecturePLUS Timberlake