1. Organic Chemistry Chapter 24 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 24.1 Common Elements in Organic Compounds

3. Organic Chemistry focusses on the chemistry of carbon. What do we remember about the bonding of carbon from Chem 1151? Carbon is a non-metal Carbon has an electronegativity of 2.5 (range is 0.7 - 4.0) Carbon is a Group 4A element has 4 valence electrons Carbon needs for electrons to complete its octet wants 4 bonds Carbon can form long chains C C CC

4. 24.1 Classification of Hydrocarbons

5. Alkanes Alkanes have the general formula C n H 2n+2 where n = 1,2,3,… only single covalent bonds saturated hydrocarbons because they contain the maximum number of hydrogen atoms that can bond with the number of carbon atoms in the molecule name ends with the suffix “-ane” CH 4 C2H6C2H6 C3H8C3H8 methaneethanepropane ………. C C HH H HH CC HH HH H

6. 24.2 Alkane Nomenclature

7. 24.2 Structural isomers are molecules that have the same molecular formula but different structures

8. How do you determine of two molecules are structural isomers? Count the number of atoms of each type to see if the structures have the same formula. (If the atom-count is different, they are not isomers !) Look for structural variations: If you can find differences between the number and types of bonds in each of the two molecules, the two structures are isomers of each other. If you can find no difference between the number and types of bonds in each of the two molecules, the two structures represent the same molecule, and are not isomers of each other. Be sure that the differences are not simply because of how you drew the structure.

9. How many structural isomers does pentane, C 5 H 12, have? CCCC C HHHHH H HHHHH H CCC C HCH 3 HH H HHHH H CC C H H H HH H n-pentane 2-methylbutane 2,2-dimethylpropane 24.2

10. Alkane Nomenclature 1.The parent name of the hydrocarbon is that given to the longest continuous chain of carbon atoms in the molecule. CH 3 CH 2 CHCH 2 CH 3 1234567 4-methylheptane 2.An alkane less one hydrogen atom is an alkyl group. CH 4 CH 3 methane methyl

11. 24.2 Alkane Nomenclature 3.When one or more hydrogen atoms are replaced by other groups, the name of the compound must indicate the locations of carbon atoms where replacements are made. Number in the direction that gives the smaller numbers for the locations of the branches. CH 3 CHCH 2 CH 3 12345 2-methylpentane CH 3 CH 2 CHCH 3 12345 4-methylpentane

12. 24.2 Alkane Nomenclature 4.Use prefixes di-, tri-, tetra-, when there is more than one alkyl branch of the same kind. CH 3 CH CH 2 CH 3 123456 2,3-dimethylhexane CH 3 CHCCH 2 CH 3 12 3 456 3,3-dimethylhexane

13. 24.2 Alkane Nomenclature 5.Use previous rules for other types of substituents. CH 3 CH CH 3 Br 1234 NO 2 2-bromo-3-nitrobutane CH 2 CHCH 3 Br 1234 NO 2 1-bromo-3-nitrobutane

14. What is the IUPAC name of the following compound? 24.2 1234567 8 CH 3 CHCH 2 CHCH 2 CH 3 C2H5C2H5 CH 2 CH 3 2-methyl-4-ethyloctane What is the structure of 2-propyl-4-methylhexane? 123456 CH 3 CHCH 2 CHCH 2 CH 3 C2H5C2H5

15. Alkane Reactions CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O (l)  H 0 = -890.4 kJ Combustion Halogenation CH 4 (g) + Cl 2 (g) CH 3 Cl (g) + HCl (g) light Cl 2 + energy Cl + Cl Cl + CH H H H CH H H + HCl CH H H + Cl Cl CCl H H H + Cl Free Radical - contains an unpaired electron => very, very reactive

16. achiral chiral All four substitutions around the carbon in question must be different to generate a chiral molecule. Optical Isomers are isomers that are nonsuperimposable mirror images of each other. There must be an asymmetric carbon atom.

17. 24.2 Cycloalkanes Alkanes whose carbon atoms are joined in rings are called cycloalkanes. They have the general formula C n H 2n where n = 3,4,…

18. Cycloalkanes 24.2

19. Alkenes Alkenes have the general formula C n H 2n where n = 2,3,… contain at least one carbon-carbon double bond also called olefins and are unsaturated hydrocarbons name ends with the suffix “-ene” CH 2 CHCH 2 CH 3 1-butene CH 3 CH CH 3 2-butene Naming: The parent name of the hydrocarbon is that given to the longest continuous chain of carbon atoms in the molecule. Number in the direction that gives the smaller number for the location of the double bond(s). Follow rules for branches andfunctional groups.

20. Alkenes CC Cl HH CC H H cis-dichloroethylenetrans-dichloroethylene Same sideOpposite side Double bonds are not as flexible and single bonds. Look for relative position of the larger group on each carbon atom in the double bond. Does either molecule have a dipole moment?

21. Cis isomer can interact with more of the surface of protein in the retina than the trans isomer. Light breaks carbon-carbon pi bond, allowing for conversion from the cis isomer to the trans isomer. The trans isomer separates from the protein, sending electrical signal to the brain => visual image.

22. Alkene Reactions Cracking Addition Reactions CH 2 CH 2 (g) + HBr (g) CH 3 CH 2 Br (g) CH 2 CH 2 (g) + Br 2 (g) CH 2 Br CH 2 Br (g) C 2 H 6 (g) CH 2 CH 2 (g) + H 2 (g) Pt catalyst

23. Alkynes Alkynes have the general formula C n H 2n-2 where n = 2,3,4,… contain at least one carbon-carbon triple bond 1-butyne2-butyne CH CCH 2 CH 3 CC Production of acetylene CaC 2 (s) + 2H 2 O (l) C 2 H 2 (g) + Ca(OH) 2 (aq)

24. Alkyne Reactions Addition Reactions Hydrogenation CH CH (g) + H 2 (g) CH 2 CH 2 (g) CH CH (g) + HBr (g) CH 2 CHBr (g) CH CH (g) + Br 2 (g) CHBr CHBr (g) CH CH (g) + 2Br 2 (g) CHBr 2 CHBr 2 (g) + 5O 2 (g) 4 CO 2 (g) + 2H 2 O (l)  H 0 = -2599.2 kJ Combustion 2 CH CH (g)

25. 24.3 Aromatic Hydrocarbons C C C CC C H H H H H H C C C CC C H H H H H H

26. 24.3 Aromatic Compound Nomenclature CH 2 CH 3 ethylbenzene Cl chlorobenzene NH 2 aminobenzene NO 2 nitrobenzene 1 2 3 4 5 6 Br 1,2-dibromobenzene Br 1,3-dibromobenzene

27. 24.3 Aromatic Compound Reactions H H H H H H Br H H H H H + HBr+ Br 2 FeBr 3 catalyst H H H H H H CH 2 CH 3 H H H H H + HCl+ CH 3 CH 2 Cl AlCl 3 catalyst Substitution reaction

28. 24.3 Polycyclic Aromatic Hydrocarbons

29. 24.4 Functional Group Chemistry Alcohols contain the hydroxyl functional group and have the general formula R-OH.

30. C 6 H 12 O 6 (aq) 2CH 3 CH 2 OH (aq) + 2CO 2 (g) enzyme CH 2 CH 2 (g) + H 2 O (g) CH 3 CH 2 OH (g) H 2 SO 4 Biological production of ethanol Commercial production of ethanol Metabolic oxidation of ethanol CH 3 CH 2 OH CH 3 CHO + H 2 alcohol dehydrogenase 24.4

31. Functional Group Chemistry Ethers have the general formula R-O-R’. CH 3 OH + HOCH 3 CH 3 OCH 3 + H 2 O H 2 SO 4 catalyst Condensation Reaction

32. 24.4 Functional Group Chemistry Aldehydes and ketones contain the carbonyl ( ) functional group. O C R C H O aldehydes have the general formulaR C R’ O ketones have the general formulaH C H O H C O CH 3 C O H3CH3C formaldehydeacetaldehydeacetone

33. 24.4 Functional Group Chemistry Carboxylic acids contain the carboxyl ( -COOH ) functional group.

34. 24.4 Functional Group Chemistry Esters have the general formula R’COOR, where R is a hydrocarbon group. CH 3 COOH + HOCH 2 CH 3 CH 3 C O CH 2 CH 3 + H 2 O O ethyl acetate

35. 24.4 Functional Group Chemistry Amines are organic bases with the general formula R 3 N. CH 3 NH 2 + H 2 O RNH 3 + + OH - CH 3 CH 2 NH 2 + HCl CH 3 CH 2 NH 3 + Cl -

36. 24.4

37. Chemistry In Action: The Petroleum Industry Crude Oil