1. Chapter 11-12 Organic Chemistry: Hydrocarbons Suggested Problems: Chapter 11: 5,10, 18, 20, 22, 28-48 even Chapter 12: 3,4,5,6,8a,c, 20,21,39,52,53,73

2. Organic Chemistry Organic chemistry is the study of the compounds containing carbon –Although inorganic cyanides and carbonates are generally excluded from this list

3. Organic Chemistry The term “organic” says nothing about the source or purity of a compound While many compounds found in living organisms are organic, most organic compounds do not come from living sources Most organic compounds are synthetic, but ultimately come from petroleum

4. Structural Formulas In organic and biochemistry it is much more useful to think of molecules in terms of structural formulas, rather than molecular formulas

5. Example Butane is the stuff in lighters, and has a molecular formula C 4 H 10Butane is the stuff in lighters, and has a molecular formula C 4 H 10 a full structural formula a condensed structural formula

6. Bonding and Carbon Carbon always has four covalent bonds

7. Functional Groups It is helpful to think of organic molecules as having two distinct parts –A carbon backbone that is relatively inert –One (or more) functional group(s) A functional group is a set of atoms bonded together in a specific way Functional groups largely define the chemical and physical properties of the compound

8. Summary of the Functional Groups Alkane C-C single bond Aldehyde Terminal carbonyl (C=O), RCHO Alkene C=C double bond Ketone Carbonyl (C=O), R 2 C=O Alkyne C≡C triple bond Carboxylic Acid Carboxyl group, RCO 2 H Aromatic Benzene ring Ester Carboxylic acid + alcohol, RCO 2 R’ Alcohol Hydroxyl group, ROH Amide Carboxylic acid + amine, RCONR 2 Ether Oxygen bridge, ROR’ Amine Nitrogen, R 3 N

9. Hydrocarbon Functional Groups Hydrocarbons contain only hydrogen and carbon The hydrocarbon functional groups include –Alkanes –Alkenes –Alkynes –Aromatics

10. Alkanes Alkanes are the simplest functional group An older name for alkanes is parafins The functional group is the C-C single bond Methane and ethane are examples of alkanes CH 3 —CH 3 ethane CH 4 methane

11. Alkane Models a space-filling model of ethane a ball-and stick model of ethane

12. Single Bonds There is free rotation around carbon- carbon single bondsThere is free rotation around carbon- carbon single bonds –For example both of these structures represent the same compound (butane)

13. The Normal Alkanes CH 4 methane CH 3 –CH 3 ethane CH 3 –CH 2 –CH 3 propane CH 3 –CH 2 –CH 2 –CH 3 butane CH 3 –CH 2 –CH 2 –CH 2 –CH 3 pentane

14. The Normal Alkanes CH 3 –(CH 2 ) 4 –CH 3 hexane CH 3 –(CH 2 ) 5 –CH 3 heptane CH 3 –(CH 2 ) 6 –CH 3 octane CH 3 –(CH 2 ) 7 –CH 3 nonane CH 3 –(CH 2 ) 8 –CH 3 decane

15. Alkyl Groups A carbon chain stuck onto a larger molecule is called an alkyl group R is the symbol for a generic alkyl group Think of the R group as the (relatively uninteresting) carbon backbone

16. Some Alkyl Groups CH 3 – methyl CH 3 –CH 2 –ethyl CH 3 –CH 2 –CH 2 –propyl CH 3 –CH–CH 3 isopropyl

17. Isomerism Isomerism is one reason there are so many organic compounds Isomers are different compounds that have the same molecular formula

18. Example Draw 2 structural isomers of C 4 H 10

19. Alkane Nomenclature Rules Name the longest chain as the parent alkane Find and Name alkyl substituents Indicate the number of identical substituents di=2; tri=3; tetra=4; penta=5 Number the parent chaine to give the lowest possible numbers to each substituent to indicate its position on the parent chain Alphabetize the substituents by name: Prefixes di, tri, tetra, however the prefixes iso and cyclo are considered when alphabatizing

20. Example

21. Example

22. Example 3,5-diethyl-2,2,3-trimethyldecane

23. Halogens Name halogens as stick-on groups F = fluoro Cl = chloro Br = bromo I = iodo

24. Example Substituent’s are placed into the name in alphabetical order disregarding the prefix needed to identify the number of substituents

25. Example 1,3,5-tribromo-2,4,6-trichloro-2- isopropylhexane

26. Cycloalkanes Carbon chains can close on themselves to give cyclic structuresCarbon chains can close on themselves to give cyclic structures Add the prefix cyclo to indicate a cyclic structureAdd the prefix cyclo to indicate a cyclic structure cyclobutane cycloalkanes are sometimes drawn as geometric shapes

27. Example

28. Alkenes The functional group in an alkene is the C=C double bondThe functional group in an alkene is the C=C double bond An older name for alkenes is olefinsAn older name for alkenes is olefins Ethene (or ethylene) is an example of an alkeneEthene (or ethylene) is an example of an alkene ethene common name: ethylene CH 2 CH 2

29. Alkene Models a space-filling model of ethene a ball-and stick model of ethene

30. Alkene Nomenclature Name the longest chain as the parent Add suffix “-ene” Give double bond lowest number Name and number substituents Rules for alkanes are followed except for the double bond has to have the lowest number and you must tell where this is in the name if there are multiple places possible

31. Example

32. Example 2,3-dimethyl-2-hexene

33. Alkenes: Bonding There is NO free rotation around carbon- carbon double bonds

34. Cis-Trans Isomerism Since there is no rotation around the double bond, a special type of isomerism is possible for alkenes Cis-Trans isomerism is possible ONLY when neither alkene carbon (i.e. the two carbons making the double bond) has two identical substitutents

35. Cis and Trans Isomers cis-2-butene H’s on same side trans-2-butene H’s on opposite sides

36. Example Which compound exhibits cis-trans isomerism?Which compound exhibits cis-trans isomerism?

37. Example trans-4-methyl-2-pentene

38. Reactions of Alkenes Alkenes undergo addition reactionsAlkenes undergo addition reactions This reaction always “costs” the double bondThis reaction always “costs” the double bond

39. Addition of Hydrogen: Hydrogenation This is the addition of hydrogen to an alkeneThis is the addition of hydrogen to an alkene The product is an alkaneThe product is an alkane This reaction requires a Pt catalystThis reaction requires a Pt catalyst

40. Examples

41. Unsaturation A saturated compound has the maximum possible amount of hydrogens per carbon atom Since alkenes react with hydrogen, they are called ‘unsaturated’

42. Fats Vegetable oils have double bonds These oils are unsaturated Addition of hydrogen to unsaturated fats gives ‘hydrogenated vegetable oils’

43. Alkynes The functional group in an alkyne is the C≡C triple bondThe functional group in an alkyne is the C≡C triple bond Ethyne (or acetylene) is an example of an alkyneEthyne (or acetylene) is an example of an alkyne ethyne common name: acetylene H-C C-H

44. Alkyne Models a space-filling model of ethyne a ball-and stick model of ethyne

45. Alkyne Nomenclature Name the longest chain as the parent Add suffix “-yne” Give triple bond lowest number Name and number substituents Rules for alkanes are followed except for the triple bond has to have the lowest number and you must tell where this is in the name if there are multiple places possible

46. Example

47. Example 4,4-dimethyl-2-pentyne

48. Aromatic Compounds The functional group of aromatic compounds is the benzene ringThe functional group of aromatic compounds is the benzene ring Benzene is the archetype aromatic compoundBenzene is the archetype aromatic compound benzene a space-filling model of benzene

49. Benzene: Where are the Double Bonds? Benzene appears to have alternating double and single bonds, but this is NOT the caseBenzene appears to have alternating double and single bonds, but this is NOT the case There are two identical structures for benzeneThere are two identical structures for benzene The actual benzene molecule is a hybrid of theseThe actual benzene molecule is a hybrid of these

50. Because the “double bonds” are delocalized equally over all six carbons, benzene is often drawn with a circleBecause the “double bonds” are delocalized equally over all six carbons, benzene is often drawn with a circle Benzene: Where are the Double Bonds?

51. Naming Aromatic Compounds Name benzene as the parent and then name the substituents

52. Examples

53. Ortho, Meta and Para Isomers ortho = 1,2; meta = 1,3; para = 1,4

54. Example Trinitrotoluene OK Really ?

55. Benzene as an Alkyl Group Benzene as a ‘stick-on’ group is called a phenyl groupBenzene as a ‘stick-on’ group is called a phenyl group When polymerized styrene will make a rigid plastic used in the production of plastic cutlery, license plate frames and CD Jewel cases.