1. Dr. Paul Charlesworth Michigan Technological University Dr. Paul Charlesworth Michigan Technological University C h a p t e rC h a p t e r C h a p t e rC h a p t e r 23 Organic Chemistry Chemistry 4th Edition McMurry/Fay Chemistry 4th Edition McMurry/Fay

2. Prentice Hall ©2004 Chapter 23Slide 2 Orbital Hybridization SP 3 Formed by mixing one s, and three p orbitals to form four equivalent sp 3 orbitals. SP 2 Formed by mixing one s, and two p orbitals to form three equivalent sp 2 orbitals and one unhybridized p orbital. 2 SP Formed by mixing one s, and one p orbitals to form two equivalent sp orbitals and two unhybridized p orbital. 1

3. Prentice Hall ©2004 Chapter 23Slide 3 Alkanes01 Alkanes: Have the general formula C n H 2n + 2, where n = 1, 2,.... Each carbon has a tetrahedral arrangement. These are saturated hydrocarbons: They contain the maximum number of atoms that can bond to a carbon atom.

4. Prentice Hall ©2004 Chapter 23Slide 4 Alkanes02

5. Prentice Hall ©2004 Chapter 23Slide 5 Alkanes 03 MethaneCH 4 EthaneCH 3 CH 3 PropaneCH 3 CH 2 CH 3 ButaneCH 3 (CH 2 ) 2 CH 3 PentaneCH 3 (CH 2 ) 3 CH 3 HexaneCH 3 (CH 2 ) 4 CH 3 HeptaneCH 3 (CH 2 ) 5 CH 3 OctaneCH 3 (CH 2 ) 6 CH 3 NonaneCH 3 (CH 2 ) 7 CH 3 DecaneCH 3 (CH 2 ) 8 CH 3 UndecaneCH 3 (CH 2 ) 9 CH 3 DodecaneCH 3 (CH 2 ) 10 CH 3 TridecaneCH 3 (CH 2 ) 11 CH 3 IcosaneCH 3 (CH 2 ) 18 CH 3 HenicosaneCH 3 (CH 2 ) 19 CH 3 DocosaneCH 3 (CH 2 ) 20 CH 3 TricosaneCH 3 (CH 2 ) 21 CH 3 TriacontaneCH 3 (CH 2 ) 28 CH 3 TetracontaneCH 3 (CH 2 ) 38 CH 3 HectaneCH 3 (CH 2 ) 98 CH 3

6. Prentice Hall ©2004 Chapter 23Slide 6 Alkanes 04 Nomenclature is based on the International Union of Pure and Applied Chemistry (IUPAC) system. Parent name is the longest continuous chain. Side chain numbering gives the lowest total count. A prefix such as: di-, tri-, or tetra- indicates the number of identical chains.

7. Prentice Hall ©2004 Chapter 23Slide 7 Alkanes 05 There are often many different substituents. If we cannot resolve them numerically, we may do so alphabetically. –NH 2 amino –Ffluoro –Clchloro –Brbromo –Iiodo –NO 2 nitro –CNcyano –CH=CH 2 vinyl

8. Prentice Hall ©2004 Chapter 23Slide 8 Alkanes 06 Alkyl substituents derive their names from their parent alkanes. The n- means attachment on end. The iso- means on a central atom. Methyl –CH 3 Ethyl –CH 2 CH 3 n-Propyl –CH 2 CH 2 CH 3 n-Butyl –CH 2 CH 2 CH 2 CH 2 CH 3 Isopropyl t-Butyl (tertiary butyl)

9. Prentice Hall ©2004 Chapter 23Slide 9 Cycloalkanes01 Cycloalkanes are joined in rings and have the general formula C n H 2n.

10. Prentice Hall ©2004 Chapter 23Slide 10 Cycloalkanes02 Cyclic structures are simplified by using polygons and lines. At every line junction it is understood that a carbon and the correct number of hydrogen atoms exist.

11. Prentice Hall ©2004 Chapter 23Slide 11 Cycloalkanes03 Start numbering substituted cycloalkanes with the group that has “alphabetical priority.” 1-ethyl-3-methylcylcopentane

12. Prentice Hall ©2004 Chapter 23Slide 12 Alkenes 01 Alkenes: Contain at least one carbon–carbon double bond. Alkenes have the general formula C n H 2n. Alkenes: Unsaturated hydrocarbons, which means that they do not have the maximum number of hydrogen atoms. These are taken up by double bonds.

13. Prentice Hall ©2004 Chapter 23Slide 13 Alkenes02 The names of compounds containing C=C bonds end in -ene. In naming alkenes we indicate the positions where the carbon–carbon double bonds begin. 1-butene2-butene H 2 CC H C H 2 CH 3 H 3 CC H C H 3

14. Prentice Hall ©2004 Chapter 23Slide 14 Alkenes 03 Double bonds are rigid and do not allow rotation. This creates geometric isomers. Geometric isomers have the same chemical formula, but a different structural arrangement. The two main isomers are: cis - meaning “on the same side.” trans - meaning “on opposing side.”

15. Prentice Hall ©2004 Chapter 23Slide 15 Alkenes 04

16. Prentice Hall ©2004 Chapter 23Slide 16 Alkenes 05 Cis–trans isomerism occurs because the electronic structure of the carbon–carbon double bond makes rotation energetically unfavorable.

17. Prentice Hall ©2004 Chapter 23Slide 17 Alkynes Alkynes: Contain at least one carbon–carbon triple bond. They have the general formula C n H 2n – 2. Names of compounds with the carbon–carbon triple bond end with -yne.

18. Prentice Hall ©2004 Chapter 23Slide 18 Aromatic Hydrocarbons01 The base unit for all aromatic hydrocarbons is the benzene ring. Its structure was proposed by Kekulé in 1865 (often represented as Ar–H).

19. Prentice Hall ©2004 Chapter 23Slide 19 Aromatic Hydrocarbons02 Benzene’s relative lack of reactivity is a result of its electronic structure which contains six sp 2 - hybridized orbitals. Benzene has two resonance forms shown in (c).

20. Prentice Hall ©2004 Chapter 23Slide 20 Aromatic Hydrocarbons 03 The naming of substituted benzenes, in which one hydrogen is replaced, is as follows:

21. Prentice Hall ©2004 Chapter 23Slide 21 Aromatic Hydrocarbons04 Some benzene compounds have common names:

22. Prentice Hall ©2004 Chapter 23Slide 22 Aromatic Hydrocarbons05 If more than one substituent exists, each has a numbered position. Generally, the 1-position is assigned arbitrarily. The 1-position is, however, taken by functional groups that are responsible for common names, such as -CH 3, -NH 2, -NO 2, and OH.

23. Prentice Hall ©2004 Chapter 23Slide 23 Aromatic Hydrocarbons06 If more than one substituent exists, each has a numbered position. Generally, the 1-position is assigned arbitrarily. The 1-position is, however, taken by functional groups that are responsible for common names, such as -CH 3, -NH 2, -OH, -COOH, and -COH.

24. Prentice Hall ©2004 Chapter 23Slide 24 Aromatic Hydrocarbons07 A common designation of the position of the second substituent is the use of the prefixes, ortho, meta, and para.

25. Prentice Hall ©2004 Chapter 23Slide 25 Aromatic Hydrocarbons08 1,3-dibromobenzene 1,2-dinitrobenzene meta-dibromobenzene ortho-dinitrobenzene

26. Prentice Hall ©2004 Chapter 23Slide 26 Aromatic Hydrocarbons09

27. Prentice Hall ©2004 Chapter 23Slide 27 Functional Groups: Alcohols01 Alcohols: Contain the hydroxyl functional group, – OH which replaces an –H in the alkane. Alcohols are named by replacing the “-e” ending of the alkane with a “-ol” ending. The carbon of attachment is indicated with the smallest number. methane, CH 4, gives methanol, CH 3 OH ethane, C 2 H 6, gives ethanol, C 2 H 5 OH Propane,, gives 2-propanol,

28. Prentice Hall ©2004 Chapter 23Slide 28 Functional Groups: Alcohols02 Primary Alcohols have their –OH bonded to a terminal carbon that is bonded to one carbon and two hydrogens. A common preparation is given below.

29. Prentice Hall ©2004 Chapter 23Slide 29 Functional Groups: Alcohols03 Secondary alcohols have their –OH bonded to a carbon that is bonded to two other carbons and one hydrogen. A common preparation is given below.

30. Prentice Hall ©2004 Chapter 23Slide 30 Functional Groups: Ethers01 Ethers: Contain the R–O–R’ linkage, where R and R’ are a hydrocarbon group. Their names derive directly from the two alkyl groups, R and R’, attached to the oxygen. CH 3 OCH 3 dimethyl ether CH 3 CH 2 OCH 3 ethylmethyl ether or methylethyl ether Ethers are inert chemically and make good solvents.

31. Prentice Hall ©2004 Chapter 23Slide 31 Functional Groups: Ethers02 Ethers can be produced from two alcohols:

32. Prentice Hall ©2004 Chapter 23Slide 32 Functional Groups: Amines01 Amines: Are organic bases with the general formula R 3 N where R may be H or a hydrocarbon group. Their names are derived from the alkyl groups attached to the nitrogen.

33. Prentice Hall ©2004 Chapter 23Slide 33 Functional Groups: Amines02 Amines are bases like ammonia. CH 3 NH 2 + H 2 O  CH 3 NH 3 + + OH – They are easily protonated (neutralized) in acid solution to form soluble amine salts. (CH 3 CH 2 ) 2 NH + HCl  (CH 3 CH 2 ) 2 NH 2 Cl(aq)

34. Prentice Hall ©2004 Chapter 23Slide 34 Functional Groups: Carbonyl01 Carbonyl (Pronounced Car–bo–neel): Has a carbon–oxygen double bond (C=O).

35. Prentice Hall ©2004 Chapter 23Slide 35 Functional Groups: Carbonyl02 Aldehydes: Have the terminal carbonyl functional group, -CHO, They are named by replacing the -e ending of the alkane by an -al ending. Numbering begins with the aldehyde carbon. ethanal 3-methylbutanal

36. Prentice Hall ©2004 Chapter 23Slide 36 Functional Groups: Carbonyl03 Aldehydes are prepared by oxidizing primary alcohols. An example is given below where methanal (formaldehyde) is prepared from methanol.

37. Prentice Hall ©2004 Chapter 23Slide 37 Functional Groups: Carbonyl04 Ketones: Have the carbonyl functional group bonded between two hydrocarbon units. Ketones are named by replacing the -e ending of the alkane with the -one ending and prefixing the name with the number of the carbonyl carbon.

38. Prentice Hall ©2004 Chapter 23Slide 38 Functional Groups: Carbonyl05 Ketones are prepared by the oxidation of secondary alcohols as the example below shows for the preparation of propanone (acetone).

39. Prentice Hall ©2004 Chapter 23Slide 39 Functional Groups: Carbonyl06 Carboxylic Acids: Contain the carboxyl functional group, –COOH or –CO 2 H. They are named by replacing the -e ending of the alkane with the -oic ending.

40. Prentice Hall ©2004 Chapter 23Slide 40 Functional Groups: Carbonyl07 Carboxylic acids are prepared by the oxidation of aldehydes or primary alcohols. Carboxylic acids dissociate as weak acids to give the carboxylate anion and the hydronium ion. CH 3 CO 2 H + H 2 O  CH 3 CO 2 – + H 3 O +

41. Prentice Hall ©2004 Chapter 23Slide 41 Functional Groups: Carbonyl08 Esters: have the general formula R’COOR or R’CO 2 R, where R’ can be H or a hydrocarbon group and R is a hydrocarbon group. They are the product of a reaction between a carboxylic acid and an alcohol, eliminating water and forming the “organic salt,” the ester.

42. Prentice Hall ©2004 Chapter 23Slide 42 Functional Groups: Carbonyl08 Ester names are derived from the acid name where the -oic ending is replaced by the -oate ending and prefixing this with the name of the attached alkyl group (which comes from the alcohol).

43. Prentice Hall ©2004 Chapter 23Slide 43 Functional Groups: Carbonyl09 Esters are commonly found or used in: Medicines (aspirin) Anesthetics (benzocaine) Polymers (Polyesters, Dacron, Mylar) Fragrant odors of food and flowers

44. Prentice Hall ©2004 Chapter 23Slide 44 Functional Groups: Carbonyl10 Amides: Often known in the peptide bond, it consists of a carbonyl and an amine group on the same carbon. Formed when an acid and a basic amine react.

45. Prentice Hall ©2004 Chapter 23Slide 45 Functional Groups: Carbonyl11 Amides are named by replacing the -oic ending of the acid by the -amide ending and then prefixing this name with the N-alkyl groups on the amine. N-ethylbutanamide N-methylethanamide (N-methylacetamide)

46. Prentice Hall ©2004 Chapter 23Slide 46 Functional Groups: Carbonyl12 The amide bond is the fundamental link used by organisms to form proteins. Some synthetic polymers and pharmaceutical agents are amides.