1. 1 Chapter 10 Introduction to Organic Chemistry: Alkanes 10.1 Organic Compounds Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

2. 2 Organic Chemistry An organic compound: is a compound made from carbon atoms. has one or more C atoms. has many H atoms. may also contain O, S, N, and halogens.

3. 3 Organic Compounds Typical organic compounds: have covalent bonds. have low melting points. have low boiling points. are flammable. are soluble in nonpolar solvents. are not soluble in water. oil (organic) and water (inorganic)

4. 4 Organic vs. Inorganic Propane, C 3 H 8, is an organic compound used as a fuel. NaCl, salt, is an inorganic compound composed of Na + and Cl - ions. Why is propane organic, but NaCl is not?

5. 5 Comparing Organic and Inorganic Compounds Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Property Bonding Polarity of bonds Melting Point Boiling Point Flammability Solubility in water Organic Mostly covalent Nonpolar, unless a more electronegative atom is present Usually low High Not soluble, unless a polar group is present Inorganic Many are ionic, some covalent Most are ionic or polar covalent, a few are nonpolar covalent Usually high Low Most are soluble, unless nonpolar

6. 6 Learning Check Identify each characteristic as most typical of compounds that are 1) inorganic 2) organic. A. has a high melting point B. is not soluble in water C. has a formula CH 3 ─CH 2 ─CH 3 D. has a formula MgCl 2 E. burns easily in air F. has covalent bonds 1 2 2 1 2 2

7. 7 Writing Formulas for Alkanes In organic compounds: carbon has 4 valence electrons and hydrogen has 1. C H to achieve an octet, C forms four bonds. H H  H  C  H H C H  H H CH 4, methane

8. 8 Tetrahedral Structure of Carbon VSEPR theory predicts that a carbon atom with four single, covalent bonds, has a tetrahedral shape.

9. 9 Organic Molecules In organic molecules: valence electrons are shared. covalent bonds form between carbon atoms. H H H H H  C  C  HH C C H H H H H ethane, CH 3 ─CH 3

10. 10 Tetrahedral Structure of Carbon In molecules with two or more carbon atoms, each carbon atom with four single bonds has a tetrahedral shape.

11. 11 Chapter 10 Introduction to Organic Chemistry: Alkanes 10.2 Alkanes Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

12. 12 Alkanes Alkanes: are a class or family of organic compounds that contain only carbon and hydrogen atoms and only form single bonds. are commonly used as fuel sources. Propane

13. 13 Structural Formulas Alkanes are written with structural formulas that are: expanded to show each bond. condensed to show each carbon atom and its attached hydrogen atoms. Expanded H H C H H Condensed CH 4, methane

14. 14 Expanded and Condensed Structures

15. 15 Structural Formulas Condensed formulas are written for expanded structural formula by showing each carbon and the attached hydrogen atoms. Expanded Condensed H H H H │ │ │ │ H─C ─C ─C ─C ─ H CH 3 ─CH 2 ─CH 2 ─CH 3 │ │ │ │ H H H H

16. 16 Names of Alkanes The names of alkanes: are determined by the IUPAC (International Union of Pure and Applied Chemistry) system. end in –ane. with 1-4 carbons in a chain use prefixes as follows. Name # Carbons Structural Formula Methane1CH 4 Ethane2CH 3 CH 3 Propane3CH 3 CH 2 CH 3 Butane4CH 3 CH 2 CH 2 CH 3

17. 17 Names of Alkanes Alkanes with 5-10 carbon atoms in a chain use Greek prefixes. Name # Carbons Structural Formula Pentane 5 CH 3 CH 2 CH 2 CH 2 CH 3 Hexane 6 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 Heptane 7 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Octane 8 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Nonane 9 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Decane 10 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3

18. 18 Learning Check A. Write the condensed formula for: H H H H H H C C C C C H H H H H H B. What is its molecular formula? C. What is its name? A.CH 3 ─CH 2 ─CH 2 ─CH 2 ─CH 3 B. C 5 H 12 C. pentane

19. 19 Writing Structural Formulas Carbon atoms in a chain: maintain tetrahedral shape. are connected in a zig-zag pattern. are drawn as 2-dimensional. can be written in several conformations.

20. 20 Some Structures for Butane

21. 21 Hexane has Six Carbon Atoms Hexane: is an alkane with six carbon atoms in a continuous chain. has a “zig-zag” look because each carbon atom is at the center of a tetrahedron. is represented by a ball-and-stick model as shown below.

22. CH 3 ─CH 3 CH 3 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 3 Write the condensed structural formula for: A. ethane. B. heptane. 22 Learning Check

23. 23 Cycloalkanes Cycloalkanes: are cyclic alkanes. have two hydrogen atoms fewer than the open chain. are named by using the prefix cyclo- before the name of the alkane chain with the same number of carbon atoms.

24. The structural formulas of cycloalkanes are usually represented by geometric figures: Cyclopropane Cyclobutane 24 Cycloalkanes CH 2 CH 2 CH 2 CH 2

25. CH 2 CH 2 25 More Cycloalkanes Cyclopentane Cyclohexane CH 2 CH 2 CH 2 CH 2

26. 26 Learning Check Name the following: A. CH 3 ─CH 2 ─CH 2 ─CH 3 B. C. CH 3 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 3 D. A.Butane B.Cyclopropane C.Octane D. Cyclohexane

27. 27 Chapter 10 Introduction to Organic Chemistry: Alkanes 10.3 Alkanes with Substituents

28. 28 Isomers of Butane Isomers: have the same molecular formula. have different atom arrangements. of butane (C 4 H 10 ) are a straight chain and a branched chain.

29. 29 Alkyl groups Alkyl groups are: alkanes that are missing one H. substituents attached to carbon chains. named with a –yl ending. H H C CH 3 methyl H H H H C C CH 3 CH 2 ethyl H H

30. 30 Naming Substituents In the IUPAC system: a carbon branch is named as an alkyl group. halogen atoms are named as halo. Table 10.6

31. 31 Alkanes with Substituents CH 3 CH 3 CH CH 3 methylpropane methyl groups CH 3 CH 3 CH 3 CH CH 2 CH CH 3 2,4-dimethylpentane

32. 32 Naming Alkanes Give the name of CH 3 CH 3  CH 3 ─CH─CH─CH 3 STEP 1 Name the longest continuous chain. CH 3 CH 3  CH 3 ─CH─CH─CH 3 butane

33. 33 Naming Alkanes Give the name of CH 3 CH 3  CH 3 ─CH─CH─CH 3 STEP 2 Number chain. CH 3 CH 3  CH 3 ─CH─CH─CH 3 1 2 3 4 STEP 3 Locate substituents and name. 2,3-dimethylbutane

34. 34 Learning Check Write the name of Cl CH 3  CH 3 ─CH 2 ─CH─CH─CH 3

35. 35 Solution STEP 1 Longest chain is pentane. STEP 2 Number chain from end nearest substituent. Cl CH 3  CH 3 ─CH 2 ─CH─CH─CH 3 5 4 3 2 1 STEP 3 Locate substituents and name alphabetically. 3-chloro-2-methylpentane

36. 36 Learning Check A. CH 3 CH 3 | CH 3 ─CH─CH 2 ─CH─CH 3 1 2 3 4 5 B. Cl CH 3 | | CH 3 ─CH 2 ─CH─CH 2 ─C─CH 2 ─CH 3 | Cl 7 6 5 4 3 2 1 2,4-dimethylpentane more substituents = C3 3,5-dichloro-3-methylheptane

37. 37 Learning Check Draw the condensed structural formula for 2-bromo-4-chlorobutane.

38. 38 Solution 2-bromo-4-chlorobutane STEP 1 Longest chain has 4 carbon atoms. C─C─C─C STEP 2 Number chain and add substituents. Br  C ─ C ─ C ─ C ─ Cl 1 2 3 4 STEP 3 Add hydrogen to complete 4 bonds to each C. Br  CH 3 ─CH─CH 2 ─CH 2 ─Cl

39. 39 Naming Cycloalkanes with Substituents The name of a substituent is placed in front of the cycloalkane name. methylcyclobutane CH 3 chlorocyclopentane Cl

40. 40 Learning Check Name each of the following: 1. CH 3 CH 2 ─CH 3 2. 1. methylcyclopropane 2. ethylcyclohexane

41. 41 Chapter 10 Introduction to Organic Chemistry: Alkanes 10.4 Properties of Alkanes Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

42. 42 Some Properties of Alkanes Alkanes are: nonpolar. insoluble in water. less dense than water. flammable in air.

43. 43 Some Properties of Alkanes Alkanes with 1-4 carbon atoms are methane, ethane, propane, and butane. gases at room temperature. used as heating fuels.

44. 44 Some Properties of Alkanes Alkanes with 5-8 carbon atoms are liquids at room temperature. pentane, hexane, heptane, and octane. very volatile. used to make gasoline. Alkanes with 9-17 carbon atoms are liquids at room temperature have higher boiling points. are found in kerosene, diesel, and jet fuels.

45. 45 Some Properties of Alkanes Alkanes with 18 or more carbon atoms have high molar masses. are waxy solids at room temperature. used in waxy coatings of fruits and vegetables.

46. 46 Combustion In combustion reactions: alkanes react with oxygen. CO 2, H 2 O and energy are produced. Alkane + O 2 CO 2 + H 2 O + heat

47. 47 Learning Check Write a balanced equation for the complete combustion of propane.

48. 48 Solution Unbalanced equation C 3 H 8 + O 2 CO 2 + H 2 O Balance C C 3 H 8 + O 2 3CO 2 + H 2 O Balance H C 3 H 8 + O 2 3CO 2 + 4H 2 O Balance O C 3 H 8 + 5O 2 3CO 2 + 4H 2 O (Balanced)

49. 49 Chapter 10 Introduction to Organic Chemistry: Alkanes 10.5 Functional Groups Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

50. 50 Elements in Organic Compounds In organic molecules, carbon atoms bond with four bonds mostly with H and other C atoms sometimes to O, N, S sometimes to halogens F, Cl, and Br

51. 51 Functional groups are: a characteristic feature of organic molecules that behave in a predictable way. composed of an atom or group of atoms. groups that replace a hydrogen atom in the corresponding alkane. a way to classify families of organic compounds. Functional Groups

52. 52 Alkenes and Alkynes Alkenes contain a double bond between adjacent carbon atoms. Alkynes contain a triple bond. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

53. 53 Alcohols and Ethers An alcohol contains the hydroxyl (-OH) functional group. In an ether, an oxygen atom is bonded to two carbon atoms. –C–O–C– Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

54. 54 Aldehydes and Ketones An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom. In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

55. 55 Carboxylic Acids and Esters Carboxylic acids contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group. O ║ — C—OH An ester contains the carboxyl group between carbon atoms. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

56. 56 Amines and Amides In amines, the functional group is a nitrogen atom. | — N — In amides, the hydroxyl group of a carboxylic acid is replaced by a nitrogen group. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

57. 57 Functional Groups Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

58. 58 Learning Check Classify each of the following as: alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine or amide. 1)CH 3 ─CH 2 ─CH 2 ─OH 2) CH 3 ─O─CH 2 ─CH 3 3) CH 3 ─CH 2 ─NH 2 O ║ 4) CH 3 ─C─OH 1.Alcohol 2.Ether 3.Amine 4.Carboxylic acid 5.Ester O ║ 5) CH 3 ─C─O─CH 3