1 Chapter 11 Introduction to Organic Chemistry: Alkanes 11.1 Organic Compounds Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Organic Compounds 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 Properties of Organic Compounds Typical organic compounds  Contain carbon.  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) Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

5 Comparing Organic and Inorganic Compounds TABLE 11.1 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

6 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

7 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

8 Writing 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

9 Tetrahedral Structure of Carbon  VSEPR theory predicts that a carbon atom with four single, covalent bonds has a tetrahedral shape. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

10 Organic Compounds with More Carbon Atoms 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

11 Tetrahedral Structure of Carbon  In molecules with two or more carbon atoms, each carbon atom with four single bonds has a tetrahedral shape. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

12 Chapter 11 Introduction to Organic Chemistry: Alkanes 11.2 Alkanes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

13 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.

14 IUPAC Names for Alkanes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings TABLE 11.2

15 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.

16 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

17 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

18 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.

19 Expanded and Condensed Structures TABLE 11.3 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

20 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.

21 Conformations The groups attached to a C-C single bond  Rotate around the bond,  Give different relative arrangements called conformations. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

22 Conformations of Butane  Rotation of the end CH 3 - provides different conformations for butane. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cumming

23 Some Structures for Butane TABLE 11.3 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

25 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?

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

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

28 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

29 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.

30 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

31 More Cycloalkanes Cyclopentane CH 2 CH 2 CH 2 CH 2 Cyclohexane CH 2

32 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.

33 Chapter 11 Introduction to Organic Chemistry: Alkanes 11.3 Alkanes with Substituents Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

34 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. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings branch

35 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

36 Naming Substituents In the IUPAC system,  A carbon branch is named as an alkyl group.  Halogen atoms are named as halo. TABLE 11.5 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

37 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

38 Naming Alkanes with Substituents Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

39 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 STEP 3 Locate substituents and name. 2,3-dimethylbutane

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

41 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 STEP 3 Locate substituents and name alphabetically. 3-chloro-2-methylpentane

42 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

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

44 Drawing Alkane Structures Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

45 What is In A Name? The structural formula is drawn from the IUPAC name. 2, 4-dimethylhexane 2, 4 dimethyl hexane Location of Two CH 3 - groups 6 carbon main chain branches on attachedwith single C-C bonds main chain

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

47 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 STEP 3 Add hydrogen to complete 4 bonds to each C. Br  CH 3 ─CH─CH 2 ─CH 2 ─Cl

48 Naming Cycloalkanes with 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

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

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

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

52 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 ─CH─CH 3 2,2-dimethylpropane │ CH 3 Solution

53 Chapter 11 Introduction to Organic Chemistry: Alkanes 11.4 Properties of Alkanes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

54 Some Properties of Alkanes The properties of alkanes include being  Nonpolar.  Insoluble in water.  Less dense than water  Flammable in air. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

56 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.

57 Alkanes with 18 or more Carbon Atoms 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. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

58 Boiling Points of Pentanes Boiling points of alkanes  Are lowest of organic compounds.  Increase with larger molecules due to increased dispersion forces.  Decrease for branched alkanes.  Increase for cycloalkanes. TABLE 11.6

59 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

60 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

61 Crude Oil The hydrocarbons in crude oil are  Separated by boiling points.  Heated to higher temperatures to produce gases that can be removed and cooled. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

62 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

63 Combustion of Alkanes Alkanes  Undergo combustion by reacting with oxygen to produce carbon dioxide, water, and energy.  Are typically not very reactive due to strong C-C single bonds. alkane + O 2 CO 2 + H 2 O + energy Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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 O 2 5CO 2 + 6H 2 O balanced Balancing A Combustion Equation

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

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

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 O 2 7CO 2 + 8H 2 O Balanced equation: C 7 H O 2 7CO 2 + 8H 2 O Solution

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

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 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 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 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 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 Chapter 11 Organic Chemistry 11.5 Functional Groups Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

75 Elements in Organic Compounds In organic molecules, C atoms form bonds  Mostly with H and other C atoms.  Sometimes atoms of O, N, S, and halogens F, Cl, and Br. TABLE 11.8 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

78 Alkenes and Alkynes  Alkenes contain a double bond between adjacent carbon atoms.  Alkynes contain a triple bond. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

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

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.  In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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

85 Functional Groups in Everyday Items Methyl amine (fish) Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

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 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