1) Isomers2) Naming with Substituents

3) Naming Cycloalkanes4) Properties of Alkanes

5) Combustion of Alkanes6) Functional Groups

Recall the basics of naming….

Root Names:

1 meth 2 eth 3 prop 4 but 5 pent6 hex 7 hept 8 oct 9 non 10

dec

Prefix (attached groups)Root (number of carbons in the main chain)Suffix (functional group)

Substituents…Alkanes with four or more carbons can have side groups called branches or substituents, which are attached to the carbon chain.that replace at least one H on the alkane chain.

When two compounds have the same molecular formula, but differ in the order in which the atoms are bonded, they are called structural isomers.

Chapter 11, Section 4© 2013 Pearson Education, Inc. 4

Structural Isomers of C4H10

Isomershave the same

molecular formula.have different

structural arrangements.

of C4H10 consist of a straight chain and a branched chain, each with 4 carbon atoms.

branch or substituent

4

Chapter 11, Section 4© 2013 Pearson Education, Inc. 5

Isomers of Pentane (C5H12)

Isomers of pentanehave the same molecular formula.have different structural arrangements.consist of a straight chain and two

branched chains.

5

Chapter 11, Section 4© 2013 Pearson Education, Inc. 6

Isomers of Alkanes

The number of structural isomers of alkanes increases rapidly as the number of carbon atoms increases.

Insert table of structuralisomers middle pg 420

6

Chapter 11, Section 4© 2013 Pearson Education, Inc. 7

Learning Check

Identify each pair of condensed structural formulas as structural isomers or the same molecule.

CH3 CH2 CH2 CH3CH3 CH CH3

CH3

CH3 CH2 CH2 CH2CH2 CH2 CH3

CH3CH2H3C

7

A.

B.

C.

Chapter 11, Section 4© 2013 Pearson Education, Inc. 8

Solution

Identify each pair of condensed structural formulas as structural isomers or the same molecule.

8

A.

B.

C.

structural isomers

structural isomers

same molecule

CH3 CH2 CH2 CH3CH3 CH CH3

CH3

CH3 CH2 CH2 CH2CH2 CH2 CH3

CH3CH2H3C

Each isomer of a given molecular formula will have its own unique structure and name. Let’s look at how to name compounds that have attachments….

First…what are some of the commonAttachments?....(next slide).

Common AttachmentsCH3

CH2CH3

Methyl

Ethyl

CH2CH2CH3

CH

CH3

CH3

Propyl

Isopropyl

F = f luoro Cl = chloro Br = bromo I = iodo

What is the base name of this compound?…What is the name Of the attachment? One final thing is needed. A number! What would the number be for this attachment?

Attachment “Rules”1) Select the longest chain of carbons first, then

go back and determine what the attachments are.

2) Name the attachment(s). The name of the attachments is in the prefix part of the name of the compound (in front).

3) The attachment needs a number so you know where it is attached on the chain of carbons.

4) Number so that the attachment gets the smallest possible number.

Your book’s way of naming Alkanes with Substituents

14

What would this name be?

Number so that

Let’s try to name this compound…

What would this name be?

Typical alkyl

4-ethyl octane

Try to draw 4-isopropyl decane….

A few ways to draw 4-isopropyl decane….

If you have groups that are the same, there are prefixes thatcan be used … so let’s work on this name…

Typical alkyl

With two different groups, you put theattachments alphabetically

Br

4-bromo-6-ethyl nonane

Br

Naming Cycloalkanes with attachments…1 attachment, just add it to the front of the

name.

Cl

So this name is…Chloro cyclobutane

Cl

Naming Cycloalkanes with 2 (or more) attachments…

Alphabatize the attachments &Give the smallest possible numbers.

Br

So this name is…

1-bromo-3-methyl cyclopentane

Br

Try to draw 1,4-dichloro cyclohexane…

Ways to draw 1,4-dichloro cyclohexane…

Cl

Cl

Cl

Cl

Note the use of “di” since the attachments were the same.

Two groups…With two groups, you can have stereoisomers

Cis = both groups are on the same side (top or bottom)

Trans = groups are on opposite sides

Cl

Cl

H

H

H

H

Cl

Cl

H

Cl

Cl

H

Cis Trans

Naming with two groups…Let’s try naming a few compounds together….(There are some hints on the following slides)…

ClH

H

H

F

CH3

HBr

HH

Naming with two groups…Is this cis or trans ? (remember, that is in the prefixPart of the name when there are two groups)….

ClH

H

This one is cis since the ethyl group and chlorineare both on the top of the ring (or on the bold lines)

What is the whole name?

ClH

H

ethyl group

chlorine

Cis 1-chloro – 4 – ethyl cyclohexane

ClH

H

What is the stereochemistry of this ring?(Then we will work on the rest of the name!)

a) Cisb) trans

HBr

H

This is trans because the bromine and the isopropylgroups are on opposite sides of the ring. The bromineis on a dashed line (meaning it’s on the back) and the isopropy is on a bold line (meaning it’s on the front)…

What is the rest of the name?

HBr

H

bromine (back)

isopropyl (front)

The full name is…

Trans 1-bromo-2-isopropyl cyclobutane

HBr

H

Last one together…Is this a) cis or b) trans?....

H

H

F

CH3

Cis…It is cis since both of the groups are on the

“back” of the structure (on the dashed lines)…

H

H

F

CH3

f luorine (on the back)

methyl (on the back)

This is…

H

H

F

CH3

Cis-1-fluoro-2-methylcyclopentane

You try one in your composition books (I will walk around & check)…

Draw trans-1,3-difloro cyclohexane

Should look something like this…

Draw trans-1,3-difloro cyclohexane

H

F

F

H

Chapter 11, Section 4© 2013 Pearson Education, Inc. 42

Alkanes: Physical StatesAlkanes are…gases when they

have only 1 to 4 carbon atoms.

liquids when they have 5 to 8 carbon atoms.

solids when they have 9 or more carbon atoms.

Chapter 11, Section 4© 2013 Pearson Education, Inc. 43

Alkanes: Solubility and Density

Alkanes arenonpolar.insoluble in water.less dense than

water (1.0 g/mL) with a density from (0.62 g/mL to 0.79 g/mL). Vegetable oil, an organic

compound, is not soluble in water.

Chapter 11, Section 4© 2013 Pearson Education, Inc. 44

Alkanes in OilIf there is an oil spill,alkanes in the oil do

not mix with the water,

alkanes form a thin layer on the surface of the water spreading large distances,

cleanup includes mechanical, chemical, and microbiological methods

In oil spills, large quantities of oil spread over the surface of the water.

Chapter 11, Section 4© 2013 Pearson Education, Inc. 45

Alkanes: Melting and Boiling Points

Alkaneshave the lowest melting and boiling

points of all organic compounds.have only nonpolar bonds, C—C and C—

H.have weak dispersion forces which

increase when more carbons are present.

Chapter 11, Section 4© 2013 Pearson Education, Inc. 46

Branched Alkanes: Melting and Boiling Points

The boiling and melting points of branched alkanes are lower than their straight-chain isomers because they are more compact.

There is more contact betweenhexane molecules (red and blacklicorice) than between the surfaces of 2,3-dimethylbutane molecules (tennis balls).

Analogy…

Neatly stacked, fit well vs. Random packing

Cycloalkanes: Melting and Boiling Points

Cycloalkanes have higher boiling points

than straight-chain alkanes with the same number of carbon atoms.

restricted rotation around C—C bonds, maintaining rigid structures.

Learning Check

For the following pairs of hydrocarbons, which one has the higher boiling point? Why?

1. Butane or octane

2. Hexane or 2,3-dimethylbutane

Solution

For the following pairs of hydrocarbons, which one has the higher boiling point? Why?

1. Butane or octane Octane (has more carbon atoms) and,

therefore, a higher boiling point.

2. Hexane or 2,3-dimethylbutane Both alkanes have the same number of carbon atoms. Hexane is not branched and, therefore, has the higher boiling point.

Combustion of Alkanes

Alkanes… contain single C—C bonds which are difficult to

break.are the least reactive group of organic compounds.burn readily in the presence of oxygen. undergo combustion to produce carbon dioxide,

water, and energy.

Combustion of Alkanes

We use methane gas to cook food and heat homes.

Propane gas is used in portable heaters and gas barbecues.

Our cells get energy from the combustion of glucose.

Balancing a Combustion Equation…

Write the equation:

Balance C:

Balance H:

Balance O with O2:

Recommended Order…

Crude Oil

Hydrocarbons in crude oil are separated by their different boiling points in a process called fractional distillation which removes groups of hydrocarbons by continually heating the mixture to higher temperatures.

Crude Oil

Chapter 11, Section 4© 2013 Pearson Education, Inc. 57

Learning CheckPropane gas is used to provide heat for cooking. Write a balanced equation for the combustion ofpropane.

Step 1: What is the equation?

Unbalanced equation:

Propane has 3 carbons and therefore 2n+2 hydrogens, or 8 hydrogens(or you can draw it out & count the # of hydrogens)

Step 2: Balance the carbons…

Unbalanced equation:

Balance C:

Step Three: Balance the Hydrogens

Unbalanced equation:

Balance C:

Balance H:

Step 4: Balance the oxygens…

Unbalanced equation:

Balance C:

Balance H:

Balance O:

Write a balanced equation for the reaction for the complete combustion of heptane, C7H16.

Learning Check (You can work this one at home)…

Write a balanced equation for the reaction for the complete combustion of heptane, C7H16.

Balanced equation:

Solution

Chapter 11, Section 4© 2013 Pearson Education, Inc. 64

Elements in Organic Compounds

In organic molecules, carbon atoms can form bonds with atoms of O, S, N, P, or halogens,F, Cl, Br and I.

64

Functional groups…are a characteristic feature of organic

molecules that behave in a predictable way. are composed of an atom or a group of

atoms.are groups that replace a H in the

corresponding alkane.provide a way to classify families of organic

compounds.

Functional Groups

65

Chapter 11, Section 5© 2013 Pearson Education, Inc.

Alkenes and Alkynes

Alkenes contain a double bond between adjacent carbon atoms.

Alkynes contain a triple bond.

Aromatic compounds contain a benzene ring.

C C

C C

66

Alcohols, Thiols, and Ethers

An alcohol contains the hydroxyl (–OH) functional group.

Thiols contain a thiol (–SH) functional group.

In an ether, an oxygen atom is bonded to two carbon atoms (–C–O–C–).

H3C CH2 OH

H3C CH2 SH

H3C O CH3

Thiol

67

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 atom.

In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms.

C

O

H3C H

C

O

H3C CH3

68

Carboxylic Acids and Esters

Carboxylic acids contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group.

An ester has a

carbon attached to the oxygen (not a hydrogen).

C

O

H3C OH

C

O

H3C OCH3

69

Chapter 11, Section 4© 2013 Pearson Education, Inc. 70

Amines and Amides

In an amine, the functional group is a nitrogen atom.

In an amide, the hydroxyl group of a carboxylic acid is replaced by a nitrogen group.

NH3C

H

H NH3C

CH3

H NH3C

CH3

CH3

H3C C

O

NH2

70

Learning Check

Classify each of the following as alcohol, ether, aldehyde, ketone, carboxylic acid, ester, or amine.

A.

B.

C.

D.

E.

CH2 CH2 CH3HO

O CH2 CH3H3C

H3C CH2 NH2

H3C C

O

OH

H3C C

O

O CH3

71

Learning Check

Classify each of the following as alcohol, ether, aldehyde, ketone, carboxylic acid, ester, or amine.

A.

B.

C.

D.

E.

CH2 CH2 CH3HO

O CH2 CH3H3C

H3C CH2 NH2

H3C C

O

OH

H3C C

O

O CH3

72

alcohol

ether

amine

carboxylic acid

ester