11 - Introduction to Organic Chemistry: Alkanes Study Goals ● Identify characteristic properties of organic or inorganic compounds. ● Describe the tetrahedral shape of carbon with single bonds in organic compounds. ● Write IUPAC names and condensed structural formulas for alkanes. ● Write the IUPAC names for alkanes with substituents. ● Identify the properties of alkanes, and write chemical equations for combustion. ● Classify organic molecules according to their functional groups.

11.1 Organic Compounds Figure 11-T01 Title: Some Typical Properties of Organic and Inorganic Compounds Caption:

Alkanes, alkenes, alkynes Hydrocarbons Alkanes, alkenes, alkynes Figure 11-01-01UN Title: Expanded Structural Formula of Methane Caption: An expanded structural formula is written when we show the bonds between all of the atoms.

11_02.JPG Figure 11-02 Title: Representations of Methane Caption: Representations of methane, CH4: (a) tetrahedron, (b) ball-and-stick model, (c) space-filling model, (d) expanded structural formula.

11_03.JPG Figure 11-03 Title: Representations of Ethane Caption: Representations of ethane, C2H6: (a) tetrahedral shape of each carbon, (b) ball-and-stick model, (c) space-filling model, (d) expanded structural formula.

Figure 11-T08 Title: Covalent Bonds for Elements in Organic Compounds Caption:

Chapter 11 — Introduction to Organic Chemistry: Alkanes 1. All of the following are formulas of organic compounds except: a. C4H10 b. CH3CH2OH c. KCl d. CH3CH2Cl 3 Timberlake: General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education Inc.

11.2 Alkanes  saturated hydrocarbons Figure 11-T02 Title: IUPAC Names for the First Ten Alkanes Caption:

11_T03.JPG Figure 11-T03 Title: Structural Representations for Butane, C4H10 Caption:

Cycloalkanes Even condensed structures become awkward when we work with large molecules that contain rings. A more streamlined way of drawing structures is often used in which cycloalkanes are represented simply by polygons. Prentice Hall © 2007 Chapter Twelve

11_T04.JPG Figure 11-T04 Title: Formulas of Some Common Cycloalkanes Caption:

SAMPLE PROBLEM 11.2 Naming Alkanes Give the IUPAC name for each of the following:

SAMPLE PROBLEM 11.1 Drawing Structural Formulas for Alkanes A molecule of butane, C4H10, has four carbon atoms in a row. What are its expanded, condensed, and line-bond structural formulas?

Compounds can be: Straight-chain alkane: An alkane that has all its carbons connected in a row. Branched-chain alkane: An alkane that has a branching connection of carbons. Fall-08 AVC-CHEM-CH

Straight and branched compounds ca be related as: Constitutional isomers: Compounds with the same molecular formula but different connections among their atoms. Fall-08 AVC-CHEM-CH

Chapter 11 — Introduction to Organic Chemistry: Alkanes 4. Compounds comprised of the same number and kinds of atoms but different in their atomic arrangement are known as: a. isotopes b. isomers c. homologs d. allotropes 3 Timberlake: General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education Inc.

Chapter 11 — Introduction to Organic Chemistry: Alkanes 5. How many compounds having the formula C3H8 are possible? a. one b. two c. three d. four 3 Timberlake: General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education Inc.

Distillation of crude oil  mixtures of hydrocarbons Figure 11-08-01UN Title: Distillation of Crude Oil Caption: Crude oil, or petroleum, contains a wide variety of hydrocarbons. At an oil refinery, the components in crude oil are separated by fractional distillation, a process that removes groups or fractions of hydrocarbons by continually heating the mixture to higher temperatures. (See Table 11.7.) Fractions containing alkanes with longer carbon chains require higher temperatures before they reach their boiling temperature and form gases. The gases are removed and passed through a distillation column where they cool and condense back to liquids. The major use of crude oil is to obtain gasoline. To increase the production of gasoline, heating oils are broken down using specialized catalysts to give the lowerweight alkanes.

Figure 11-T07 Title: Typical Alkane Mixtures Obtained by Distillation of Crude Oil Caption:

11.3 Alkanes with Substituents When the substituent is a C structure it is called a branch. Branches are named as alkyls. Alkyls are alkanes whose structures are missing a H. Fall-08 AVC-CHEM-CH

11_T05.JPG Figure 11-T05 Title: Names and Formulas of Some Common Substituents Caption:

In the IUPAC system for organic compounds, a chemical name has three parts: prefix, parent, and suffix. Fall-08 AVC-CHEM-CH

11_05-15UN.JPG Figure 11-05-15UN Title: Naming Alkanes Caption: Guide to Naming Alkanes 23

Name? Figure 11-05-05UN Title: 2-Methylpentane Caption: In the IUPAC system, a carbon chain with a substituent is numbered to give the location of that substituent. Let's take a look at how we use the IUPAC system to name the following alkane. 24

If there are two substituents on the same carbon, assign the same number to both. There must always be as many numbers in the name as there are substituents. Write the name as a single word, using hyphens to separate the numbers from the different prefixes and commas to separate numbers if necessary. If two or more different substituent groups are present, cite them in alphabetical order. Fall-08 AVC-CHEM-CH

Name? Figure 11-05-10UN Title: Naming Alkanes Example Caption: Use a prefix (di, tri, tetra) to indicate a group that appears more than once. Use commas to separate two or more numbers. However, prefixes are not used to determine the alphabetical order. 26

Name? Figure 11-05-09UN Title: Naming Alkanes Example Caption: More examples giving the locations of the substituents. Place the names of different substituents in alphabetical order. 27

Name? Figure 11-05-13UN Title: 4-Bromo-2,4-dimethylhexane Caption: Give the IUPAC name for the alkane. 28

Name? Figure 11-05-11UN Title: Naming Alkanes Example Caption: When there are two or more substituents, the main chain is numbered in the direction that gives the lowest set of numbers. 29

The name of a substituent is placed in front of the cycloalkane name. Naming cycloalkanes One substituent The name of a substituent is placed in front of the cycloalkane name. CH3 methylcyclobutane Two substituents Number ring with two substituents  #1 to 1st in alphabet 1-ethyl-3-methylcyclohexane 1-ethyl-2-fluorocyclopentane F CH2CH3 Fall-08 AVC-CHEM-CH

Three or more substituents Begin @ sub that leads to the lowest set of locants. CH3 CH2CH3 4-chloro-2-ethyl-1-methylcyclohexane Cl Fall-08 AVC-CHEM-CH

11_05-46UN.JPG Name? Figure 11-05-46UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 32

11_05-44UN.JPG Name? Figure 11-05-44UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 33

11_05-42UN.JPG Name? Figure 11-05-42UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 34

11_05-45UN.JPG Name? Figure 11-05-45UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 35

11_05-47UN.JPG Name? Figure 11-05-47UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 36

11_08-84UN.JPG Name? Figure 11-08-84UN Title: Cycloalkane Caption: ANSWERS TO STUDY CHECKS 11.23d 37

Name? Figure 11-05-43UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 38

Name? Figure 11-05-48UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 39

Name? Figure 11-05-49UN Title: Alkanes with Substituents Question Caption: Give the IUPAC name for the following. 40

11_05-19UN.JPG Figure 11-05-19UN Title: Drawing Alkane Formulas Caption: Guide to Drawing Alkane Formulas 41

SAMPLE PROBLEM 11.5 Drawing Condensed Structural Formulas from IUPAC Names Write the condensed structural formula for 2,3-dimethylbutane. 42

11.4 Properties of Alkanes Odorless or mild odor; colorless; tasteless; nontoxic Nonpolar; insoluble in water but soluble in nonpolar organic solvents; less dense than water Flammable; otherwise not very reactive The first four alkanes are gases at room temperature and pressure, alkanes with 5–15 carbon atoms are liquids; those with 16 or more carbon atoms are generally low-melting, waxy solids. Prentice Hall © 2007 Chapter Twelve

11_00-03UN.JPG The properties of alkanes include being Nonpolar. Insoluble in water. Less dense than water Flammable in air. Figure 11-00-03UN Title: Vegetable Oil and Water Caption: Typically, organic compounds are not soluble in water. For example, vegetable oil, which is a mixture of organic compounds, does not dissolve in water, but floats on top. Many organic compounds undergo combustion and burn vigorously in air. 44

Chapter 11 — Introduction to Organic Chemistry: Alkanes 7. If octane and water are mixed, the result is: a. an emulsion b. a clear solution of hexane dissolved in water c. a layer of octane sitting on top of a layer of water d. a layer of water sitting on top of a layer of octane 3 Timberlake: General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education Inc. 45

Reactions of Alkanes Alkanes do not react with acids, bases, or most other common laboratory reagents. Their only major reactions are with oxygen (combustion) and with halogens (halogenation). Combustion: A chemical reaction that produces a flame, usually because of burning with oxygen. Carbon dioxide and water are the products of complete combustion of any hydrocarbon, and a large amount of heat is released. Alkanes typically not very reactive due to strong C-C single bonds. alkane + O2  CO2 + H2O + energy Prentice Hall © 2007 Chapter Twelve

SAMPLE PROBLEM 11.7 Combustion Write a balanced equation for the complete combustion of butane. 47

Composed of an atom or group of atoms. 11.5 Functional Groups 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. Fall-08 AVC-CHEM-CH

Figure 11-08-09UN Title: Alkenes, Alkynes, and Aromatic Compounds Caption: The benzene structure is represented as a hexagon with a circle in the center. 49

Figure 11-08-10UN Title: Aldehydes and Ketones Caption: In a ketone, the carbonyl group is bonded to two other carbon atoms. 50

11_T09.JPG Figure 11-T09 Title: Classification of Organic Compounds Caption: 51

Chapter 11 — Introduction to Organic Chemistry: Alkanes 9. Sunscreens contain compounds that absorb UV light, such as 2-ethylhexyl p-methoxycinnamate. The functional groups in this compound are: a. alkane, ether, alcohol, aldehyde b. aromatic, ether, ester, ketone c. alkene, ester, aromatic, alcohol d. aromatic, ether, alkene, ester 4 Timberlake: General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education Inc.

SAMPLE PROBLEM 11.9 Identifying Functional Groups Classify the following organic compounds according to their functional groups: 53

SAMPLE PROBLEM 11.8 Classifying Organic Compounds Classify the following organic compounds according to their functional groups: 54