1. 1 Chapter 10 Introduction to Organic Chemistry: Alkanes 10.1 Organic Compounds Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

2. 2 Organic Compounds An organic compound  Hydrocarbons = compds of C and H  May also contain O, S, N, and halogens. Oil (organic) and water (inorganic)

3. 3 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 an organic compound, but NaCl is not? Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

4. 4 Organic C 3 H 8 (propane) Inorganic NaCl (salt) Bonding Polarity,Solubility Melting point Boiling point Flammability Covalent Ionic Nonpolar not H 2 O sol Polar most H 2 O sol Low Low -188 o C -42 o C High 800 o C High 1413 o C HighLow Organic vs. Inorganic

5. 5 Learning Check Identify each characteristic as most typical of compounds that are (I) inorganic or (O) organic. 1. Has a high melting point 2. Is not soluble in water 3. Has a formula CH 3 ─CH 2 ─CH 3 4. Has a formula MgCl 2 5. Burns easily in air 6. Has covalent bonds

6. 6 Solution Identify each characteristic as most typical of compounds that are (I) inorganic or (O) organic. I 1. Has a high melting point O 2. Is not soluble in water O 3. Has a formula CH 3 ─CH 2 ─CH 3 I 4. Has a formula MgCl 2 O 5. Burns easily in air O 6. Has covalent bonds

7. 7 Formulas for Carbon Compounds In carbon compounds  Carbon has 4 valence electrons and hydrogen has 1. C H  To achieve an octet, C forms four bonds. H  H  C  H H C H  H H CH 4, methane

8. 8 Tetrahedral Carbon C HH H Cl C HH H ++++ ---- e-’s in 4 directions = 109.5 o Tetrahedral  In molecules with > 2 C’s, each C with 4 single bonds has a tetrahedral shape.

9. 9 Organic Compounds with More C’s In organic molecules with more carbon atoms,  Valence electrons are shared.  Covalent bonds form between carbon and carbon atoms.  Covalent bonds form between carbon and hydrogen 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 > 2 C’s, each C with 4 single bonds has a tetrahedral shape.

11. 11 10.2 Alkanes

12. 12 Names of Alkanes The names of alkanes  Are determined by the IUPAC (International Union of Pure and Applied Chemistry) system.  Use a prefix to indicate the number of carbons in a chain.  End in –ane.

13. 13 IUPAC Names for Alkanes TABLE 11.2

14. 14 Learning Check A. Give the name of each compound: 1) CH 3 —CH 3 2) CH 3 —CH 2 —CH 3 3) CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH 3 B. Write the condensed structural formula of pentane.

15. 15 Solution A. Give the name of each compound: 1) CH 3 —CH 3 ethane 2) CH 3 —CH 2 —CH 3 propane 3) CH 3 —CH 2 —CH 2 —CH 2 —CH 2 —CH 3 hexane B. Write the condensed structural formula of pentane. CH 3 —CH 2 —CH 2 —CH 2 —CH 3

16. 16 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 Condensed H H C HCH 4, methane H

17. 17 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.

18. 18 Expanded and Condensed Structures

19. 19 Line-Bond Formulas  Because each C atom has a tetrahedral arrangement, the order of atoms is not a straight line, but a zigzag pattern.  A line-bond formula abbreviates the carbon atoms and shows only the zigzag pattern of bonds from carbon atom to carbon atom.

20. 20 Some Structures for Butane Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

21. 21 Hexane has Six Carbon Atoms Hexane  Is an alkane with 6 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

22. 22 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?

23. 23 Solution A.CH 3  CH 2  CH 2  CH 2  CH 3 B. C 5 H 12 C. pentane

24. 24 Learning Check Write the condensed structural formula for A. ethane B. heptane

25. 25 Solution Write the condensed structural formula for A. ethane CH 3 ─CH 3 B. heptane CH 3 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 3

26. 26 Cycloalkanes  Are cyclic alkanes.  Have 2H 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.

27. 27 Cycloalkanes The structural formulas of cycloalkanes are usually represented by geometric figures, Cyclopropane CH 2 CH 2 CH 2 Cyclobutane CH 2 CH 2 CH 2

28. 28 More Cycloalkanes Cyclopentane CH 2 CH 2 CH 2 CH 2 Cyclohexane CH 2

29. 29 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.

30. 30 Solution Name the following: A. CH 3 ─CH 2 ─CH 2 ─CH 3 butane B. cyclopropane C. CH 3 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 3 octane D. cyclohexane

31. 31 10.3 Alkanes with Substituents

32. 32 Isomers of Butane Isomers  Have the same molecular formula.  Have different atom arrangements.  Of butane (C 4 H 10 ) consist of a straight chain and a branched chain each with 4 carbon atoms. branch

33. 33 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

34. 34 Naming Substituents IUPAC system,  A carbon branch is named as an alkyl group.  Halogen atoms are named as halo.

35. 35 Alkanes with Alkyl Groups 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

36. 36 Naming Alkanes with Substituents

37. 37 Guide to Naming Alkanes Give the name of CH 3 CH 3  CH 3 ─CH─CH─CH 3 STEP 1 Longest chain is butane. 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

38. 38 Learning Check Write the IUPAC name for Cl CH 3  CH 3 ─CH 2 ─CH─CH─CH 3

39. 39 Solution STEP 1 Longest chain is pentane. STEP 2 Number chain from end nearest substituent. Cl CH 3 (nearest end)  CH 3 ─CH 2 ─CH─CH─CH 3 5 4 3 2 1 STEP 3 Locate substituents and name alphabetically. 3-chloro-2-methylpentane

40. 40 Learning Check Give the IUPAC name for each of the following: A. CH 3 CH 3 | CH 3 ─CH─CH 2 ─CH─CH 2 ─CH 3 B. Cl CH 3 | | CH 3 ─CH 2 ─CH─CH 2 ─C─CH 2 ─CH 3 | Cl

41. 41 Solution A. CH 3 CH 3 | CH 3 ─CH─CH 2 ─CH─CH 2 ─CH 3 2,4-dimethylhexane 1 2 3 4 5 6 B. Cl CH 3 more substituents on C3 | | CH 3 ─CH 2 ─CH─CH 2 ─C─CH 2 ─CH 3 | Cl 7 6 5 4 3 2 1 3,5-dichloro-3-methylheptane

42. 42 Drawing Alkane Structures

43. 43 What is In A Name? Location of branches main chain Draw the structure for: 2,2,4-trimethylpentane 2,2,4trimethylpentane Three CH 3 - groups attached 5 carbon main chain with single C-C bonds

44. 44 What is In A Name? Draw the structure for: 2,2,4-trimethylpentane 2,2,4trimethylpentane

46. 46 Classification of Carbon Atoms The classification of carbon atoms indicates the number of carbon atoms attached.  A primary carbon (1°) bonds to one carbon atom.  A secondary carbon (2°) bonds to two carbon atoms.  A tertiary carbon (3°) bonds to three carbon atoms. CH 3 | CH 3 —CH 2 —CH 2 —CH 3 CH 3 —CH—CH 3 primary secondary tertiary

47. 47 Learning Check Draw the condensed structural formula for 2-bromo-4-chlorobutane.

48. 48 Solution 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

49. 49 Naming Cycloalkanes w/ Substituents The name of a substituent is placed in front of the cycloalkane name. CH 3 methylcyclobutane Number ring with two substituents 1-bromo-2-chlorocyclopentane Br Cl

50. 50 Learning Check Name each of the following: 1. CH 3 CH 2 ─CH 3 2. Cl

51. 51 Solution Name each of the following: 1. methylcyclopropane 2. 3-chloro-1-ethylcyclohexane

52. 52 Write three isomers of C 5 H 12 and name each. Learning Check

53. 53 A chain of 5 carbon atoms CH 3 ─CH 2 ─CH 2 ─CH 2 ─CH 3 pentane A chain of 4 carbon atoms and 1 carbon branch CH 3 │ CH 3 ─CH─CH 2 ─CH 3 2-methylbutane A chain of 3 carbon atoms and 2 carbon branches CH 3 │ CH 3 ─C─CH 3 2,2-dimethylpropane │ CH 3 Solution

54. 54 10.4 Properties of Alkanes

55. 55 Some Properties of Alkanes The properties of alkanes include being  Nonpolar.  Insoluble in water.  Less dense than water  Flammable in air.

56. 56 Alkanes with 1-4 Carbon Atoms Alkanes with 1-4 carbon atoms are  Methane, ethane, propane, and butane.  Gases at room temperature.  Used as heating fuels.

57. 57 Alkanes with 5-17 Carbon Atoms 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.

58. 58 Alkanes with 18 or more Carbon Atoms Alkanes with 18 or more carbons  Have high molar masses.  Are waxy solids at room temperature.  Used in waxy coatings of fruits and vegetables. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

59. 59 Boiling Points of Pentanes Bps of alkanes  lowest of organic compounds.  > with larger molecules due to > dispersion forces.  < for branched alkanes.  > for cycloalkanes.

60. 60 Learning Check For the following pairs of hydrocarbon, which one has the higher boiling point? Why? 1. butane or octane 2. hexane or 2,3-dimethylbutane

61. 61 Solution For the following pairs of hydrocarbon, which one has the higher boiling point? Why? 1. butane or octane octane has more carbon atoms 2. hexane or 2,3-dimethylbutane hexane is not branched

62. 62 Distillation of Crude Oil C1-C4 C5-C12 C12-C16 C15-C18 C18-C25 > 25 C’s

63. 63 Combustion of Alkanes Alkanes  Undergo combustion  Are typically not very reactive due to strong C-C single bonds. alkane + O 2 CO 2 + H 2 O + energy

64. 64 Write the equation C 5 H 12 + O 2 CO 2 + H 2 O Balance C C 5 H 12 + O 2 5CO 2 + H 2 O Balance H C 5 H 12 + O 2 5CO 2 + 6H 2 O Balance O with O 2 C 5 H 12 + 8O 2 5CO 2 + 6H 2 O balanced Balancing A Combustion Equation

65. 65 Learning Check Propane is used to provide heat for cooking or warming a room. Write a balanced equation for the complete combustion of propane.

66. 66 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)

67. 67 Write a balanced equation for the reaction for the complete combustion of heptane C 7 H 16. Learning Check

68. 68 C 7 H 16 + O 2 CO 2 + H 2 O C 7 H 16 + O 2 7CO 2 + 8H 2 O C 7 H 16 +11O 2 7CO 2 + 8H 2 O Balanced equation: C 7 H 16 + 11O 2 7CO 2 + 8H 2 O Solution

69. 69 Write the combustion reaction for ethane and balance. Learning Check

70. 70 Write the combustion reaction for ethane and balance. ethane CH 3 CH 3 = C 2 H 6 C 2 H 6 + O 2 2CO 2 + 3H 2 O C 2 H 6 + 7 O 2 2CO 2 + 3H 2 O C 2 H 6 + 7/2 O 2 2CO 2 + 3H 2 O Multiply through by 2 to clear 2C 2 H 6 + 7O 2 4CO 2 + 6H 2 O balanced Solution

71. 71 Halogenation of Alkanes (Substitution) When alkanes react with halogens,  The reaction is called substitution, one or more H atoms are replaced with a halogen usually Cl or Br.  Light or heat is required.  A mixture of halogenated products result, but we write the equation with the monosubstituted product. Example: ethane and chloride light CH 3 —CH 3 + Cl 2 CH 3 —CH 2 —Cl

72. 72 Learning Check Give the structures and names of the possible monosubstituted products for the reaction of propane with bromine in the presence of light.

73. 73 Solution Give the structures and names of the possible monosubstituted products for the reaction of propane with bromine in the presence of light. CH 3 —CH 2 —CH 2 — Br 1-bromopropane; propyl bromide Br | CH 3 —CH—CH 3 2-bromopropane; isopropyl bromide

74. 74 Chapter 10 Organic Chemistry 10.5 Functional Groups Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

75. 75 Elements in Organic Compounds TABLE 11.8 C atoms bond  Mostly with H and other C atoms.  Sometimes with O, N, S, and halogens F, Cl, and Br.

76. 76 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 H in the corresponding alkane.  A way to classify families of organic compounds. Functional Groups

77. 77 Some Functional Groups Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings TABLE 11.9

78. 78 Alkenes and Alkynes  Alkenes contain a double bond between adjacent carbon atoms.  Alkynes contain a triple bond.

79. 79 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–.

80. 80 More Functional Groups Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

81. 81 Aldehydes and Ketones  An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom, attached to at least one hydrogen. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms.

82. 82 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 © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

83. 83 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 © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

84. 84 Summary of Functional Groups

85. 85 Functional Groups in Everyday Items Methyl amine (fish)

86. 86 Learning Check Classify each of the following as alcohol, ether, aldehyde, ketone, carboxylic acid, ester, or amine. 1)CH 3 – CH 2 – CH 2 – OH 2) CH 3 – O – CH 2 – CH 3 3) CH 3 – CH 2 – NH 2 O O || || 4) CH 3 – C – OH 5) CH 3 – C – O – CH 3

87. 87 Solution Classify each of the following as alcohol, ether, aldehyde, ketone, carboxylic acid, ester, or amine. 1)CH 3 ─CH 2 ─CH 2 ─OH 2) CH 3 ─O─CH 2 ─CH 3 alcohol ether 3) CH 3 ─CH 2 ─NH 2 amine O O || || 4) CH 3 ─C─OH 5) CH 3 ─C─O─CH 3 carboxylic acid ester