11

Chapter 16Chapter 16Alkanes and Aromatic Alkanes and Aromatic

HydrocarbonsHydrocarbonsOrganic CompoundsOrganic Compounds

Bonding in HydrocarbonsBonding in Hydrocarbons

Naming AlkanesNaming Alkanes

Properties of AlkanesProperties of Alkanes

22

““The most important hypothesis in all ofThe most important hypothesis in all of

biology…is that everything that animals biology…is that everything that animals do,do,

atoms do. In other words, there is nothingatoms do. In other words, there is nothing

that living things do that cannot be that living things do that cannot be

understood from the point of view that understood from the point of view that

they are made of atoms acting according they are made of atoms acting according

to the laws of physics.” to the laws of physics.”

Richard Feynman (1918-1988)Richard Feynman (1918-1988)

33

Organic CompoundsOrganic Compounds

Contain carbonContain carbon

Have covalent bondsHave covalent bonds

Have low melting pointsHave low melting points

Have low boiling pointsHave low boiling points

Burn in air (oxygen) Burn in air (oxygen)

Are soluble in nonpolar solventsAre soluble in nonpolar solvents

Form large moleculesForm large molecules

44

AlkanesAlkanes

Contain C and H onlyContain C and H only

Contain single bonds C-CContain single bonds C-C

Have 4 bonds to every carbon (C) atomHave 4 bonds to every carbon (C) atom

Are nonpolarAre nonpolar

55

Complete Structural FormulasComplete Structural Formulas

Show the bonds between each of the Show the bonds between each of the atoms atoms

HH H H

H H C C H H H C HH C H HH H H

CHCH4 4 , methane, methane

66

More AlkanesMore Alkanes

H HH H Condensed Structural FormulasCondensed Structural Formulas

H C C HH C C H CHCH33 CH CH33

H HH H EthaneEthane

H H H H H H

H C C C HH C C C H CHCH33 CH CH22 CH CH33

H H H H H H PropanePropane

77

IUPAC NamesIUPAC Names

NameName # carbons Structural Formula# carbons Structural Formula

MethMethaneane 11 CHCH44

EthEthaneane 22 CHCH33CHCH33

PropPropaneane 33 CHCH33CHCH22CHCH33

ButButaneane 44 CHCH33CHCH22CHCH22CHCH33

PentPentaneane 55 CHCH33CHCH22CHCH22CHCH22CHCH33

88

IUPAC NAMESIUPAC NAMES

NameName # carbons # carbons Structural FormulaStructural Formula

HexHexane 6 CHane 6 CH33CHCH22CHCH22CHCH22CHCH22CHCH33

HeptHeptane 7 CHane 7 CH33CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

OctOctane 8 CHane 8 CH33CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

NonNonane 9 CHane 9 CH3 3 CHCH2 2 CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

DecDecane 10 CHane 10 CH33CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33

99

Learning Check Alk1Learning Check Alk1

A. What is the condensed formula forA. What is the condensed formula for H H H H H H H H

H C C C C HH C C C C H

H H H H H H H H

B. What is its molecular formula?B. What is its molecular formula?C. What is its name?C. What is its name?

1010

Solution Alk1Solution Alk1

A.A. CHCH33CHCH22CHCH22CHCH33

B. B. CC44HH1010

C.C. butanebutane

1111

Reactions of AlkanesReactions of Alkanes

Combustion Combustion

alkane + Oalkane + O22 CO CO22 + H + H22O + O + heatheat

1212

Combustion In the CellCombustion In the Cell

Metabolic oxidation is combustionMetabolic oxidation is combustion

CC66HH12 12 OO66 + 6O + 6O22 6CO 6CO22 + 6H + 6H22O + O + heatheat

glucoseglucose

1313

Learning Check Alk2Learning Check Alk2

Complete the combustion reaction forComplete the combustion reaction for

CC33HH88 + O + O22 + +

Balance your equationBalance your equation

1414

Solution Alk2Solution Alk2

Step 1Step 1

CC33HH88 + O + O22 CO CO22 + H + H22OO

Step 2Step 2

CC33HH88 + O + O22 3 CO 3 CO22 + 4 H + 4 H22OO

Step 3Step 3

CC33HH88 + 5 O + 5 O22 3 CO 3 CO22 + 4 H + 4 H22OO

1515

Learning Check Alk3Learning Check Alk3

Complete and balance the reaction for Complete and balance the reaction for the complete combustion of Cthe complete combustion of C77HH1616

1616

Solution Alk3Solution Alk3

Step 1Step 1

CC77HH1616 + O + O22 CO CO22 + H + H22OO

Step 2Step 2

CC77HH1616 + O + O22 7 CO 7 CO22 + 8 H + 8 H22OO

Step 3Step 3

CC77HH1616 + 11 O + 11 O22 7 CO 7 CO22 + 8 H + 8 H22OO

1717

HaloalkanesHaloalkanes

An alkane in which one or more H atoms An alkane in which one or more H atoms is replaced with a halogen (F, Cl, Br, or I)is replaced with a halogen (F, Cl, Br, or I)

CHCH33BrBr 1-bromomethane1-bromomethane

BrBr (methyl bromide)(methyl bromide)

CHCH33CHCH22CHCHCHCH33 2-bromobutane2-bromobutane

ClCl

chlorocyclobutanechlorocyclobutane

1818

Learning Check HA1Learning Check HA1

Name the following:Name the following:

Br

Cl

Cl

1919

Solution HA1Solution HA1

Name the following:Name the following:

bromocyclopentanebromocyclopentane

1,3-1,3-dichlorocyclohexanedichlorocyclohexane

Br

Cl

Cl

2020

SubstituentsSubstituents

List other attached atoms or group List other attached atoms or group in alphabetical orderin alphabetical order

Br = bromo, Cl = chloroBr = bromo, Cl = chloro

Cl BrCl Br

CHCH33CHCHCHCH22CHCHCHCH22CHCH22CHCH33

4-bromo-2-chloroheptane4-bromo-2-chloroheptane

2121

Learning Check HA2Learning Check HA2

The name of this compound is:The name of this compound is:

ClCl CH CH33

CHCH33CHCH22CHCHCHCH22CHCHCHCH33

1)1) 2,4-dimethylhexane2,4-dimethylhexane

2)2) 3-chloro-5-methylhexane3-chloro-5-methylhexane

3)3) 4-chloro-2-methylhexane4-chloro-2-methylhexane

2222

Solution HA2Solution HA2

The name of this compound is:The name of this compound is:

ClCl CH CH33

CHCH33CHCH22CHCHCHCH22CHCHCHCH33

3) 4-chloro-2-methylhexane3) 4-chloro-2-methylhexane

2323

Haloalkanes as AnestheticsHaloalkanes as Anesthetics

Halothane (Fluothane) Halothane (Fluothane)

F ClF Cl

FF C C Br C C Br

F HF HFluothane is a haloalkane that is widely Fluothane is a haloalkane that is widely used as an anesthetic, which is a used as an anesthetic, which is a compound that decreases the ability of the compound that decreases the ability of the nerve cells to conduct pain.nerve cells to conduct pain.

2424

Chapter 16Chapter 16Haloalkanes, Alkenes, and AlkynesHaloalkanes, Alkenes, and Alkynes

Alkenes and AlkynesAlkenes and Alkynes

Geometric Isomers of AlkenesGeometric Isomers of Alkenes

Addition ReactionsAddition Reactions

2525

Saturated and Unsaturated Saturated and Unsaturated CompoundsCompounds

Saturated compounds (alkanes) have Saturated compounds (alkanes) have the maximum number of hydrogen the maximum number of hydrogen atoms attached to each carbon atomatoms attached to each carbon atom

Unsaturated compounds have fewer Unsaturated compounds have fewer hydrogen atoms attached to the carbon hydrogen atoms attached to the carbon chain than alkaneschain than alkanes

Unsaturated compounds contain double Unsaturated compounds contain double or triple bondsor triple bonds

2626

AlkenesAlkenes

Carbon-carbon double bondsCarbon-carbon double bonds Names end in -Names end in -eneene

HH22C=CHC=CH22 ethetheneene (ethyl (ethyleneene))

HH22C=CH-CHC=CH-CH33 proppropeneene (propyl (propyleneene))

cyclohexcyclohexeneene

2727

AlkynesAlkynes

Carbon-carbon triple bondsCarbon-carbon triple bonds Names end in -Names end in -yneyne

HCHCCHCH ethethyneyne(acet(acetyleneylene))

HCHCC-CHC-CH33 proppropyneyne

2828

Naming Alkenes and AlkynesNaming Alkenes and Alkynes

When the carbon chain has 4 or more C atoms, When the carbon chain has 4 or more C atoms, number the chain to give the lowest number to number the chain to give the lowest number to the double or triple bond.the double or triple bond.

1 2 3 41 2 3 4

CHCH22=CHCH=CHCH22CHCH33 1-butene1-butene

CHCH33CH=CHCHCH=CHCH33 2-butene2-butene

CHCH33CHCHCHCHCHCH33 2-butyne2-butyne

2929

Learning Check HA3Learning Check HA3

Write the IUPAC name for each of the following Write the IUPAC name for each of the following unsaturated compounds:unsaturated compounds:

A.A. CHCH33CHCH22CCCCHCCH33

CHCH33

B. B. CHCH33C=CHCHC=CHCH33 C. C.

CH3

3030

Solutions HA3Solutions HA3

Write the IUPAC name for each of the following Write the IUPAC name for each of the following unsaturated compounds:unsaturated compounds:

A.A. CHCH33CHCH22CH=CHCHCH=CHCH33 2-pentyne2-pentyne

CHCH33

B. B. CHCH33C=CHCHC=CHCH33 C. C.

22-methyl-2-butene 3-methylcyclopentene-methyl-2-butene 3-methylcyclopentene

CH3

3131

Cis and Trans IsomersCis and Trans Isomers

Double bond is fixedDouble bond is fixed Cis/trans Isomers are possibleCis/trans Isomers are possible

CHCH33 CH CH33 CH CH33

CH = CHCH = CH CH = CH CH = CH

ciscis trans trans CH CH33

3232

HydrogenationHydrogenation

Adds a hydrogen atom to each carbon Adds a hydrogen atom to each carbon atom of a double bondatom of a double bond

H HH H H H H H

NiNi

H–C=C–H + H–C=C–H + HH2 2 HH––CC––CC––HH

H H H H

ethene ethaneethene ethane

3333

Products of HydrogenationProducts of Hydrogenation

Adding HAdding H2 2 to vegetable oils produces to vegetable oils produces

compounds with higher melting pointscompounds with higher melting points

MargarinesMargarines

Soft margarinesSoft margarines

Shortenings (solid)Shortenings (solid)

3434

Learning Check HA4Learning Check HA4

What is the product of adding HWhat is the product of adding H22 (Ni (Ni

catalyst) to 1-butene?catalyst) to 1-butene?

3535

Solution HA4Solution HA4

What is the product of adding HWhat is the product of adding H22 (Ni (Ni

catalyst) to 1-butene?catalyst) to 1-butene?

NiNi

CHCH22=CHCH=CHCH22CHCH33 + H + H22

CHCH33CHCH22CHCH22CHCH33

3636

Adding HalogensAdding Halogens

Halogens also add to the double bond of an Halogens also add to the double bond of an alkene.alkene.

HH22CCCHCH22 + + ClCl2 2

H2C CH2

Cl Cl

CH3C CCH2CH3 + Br2 CH3C CCH2CH3

Br Br

Br Br

3737

Learning Check HA5Learning Check HA5

Write the product of the following addition Write the product of the following addition reactions:reactions:

CHCH33CH=CHCHCH=CHCH33 + H + H22

+ Br2

3838

Solution HA5Solution HA5

Write the product of the following addition Write the product of the following addition reactions:reactions:

CHCH33CH=CHCHCH=CHCH33 + H + H22 CHCH33CHCH22CHCH22CHCH33

+ Br2Br

Br

3939

Unsaturated Fatty AcidsUnsaturated Fatty Acids

Fatty acids in vegetable oils are omega-6 acids Fatty acids in vegetable oils are omega-6 acids (the first double bond occurs at carbon 6 counting (the first double bond occurs at carbon 6 counting from the methyl group)from the methyl group)

A common omega-6 acid is linoleic acidA common omega-6 acid is linoleic acid

CHCH33CHCH22CHCH22CHCH22CHCH22CH=CHCHCH=CHCH22CH=CH(CHCH=CH(CH22))77COOHCOOH

66

linoleic acid, a fatty acid linoleic acid, a fatty acid

4040

TransTrans Fats Fats

In vegetable oils, the unsaturated fats usually In vegetable oils, the unsaturated fats usually contain contain ciscis double bonds. double bonds.

During hydrogenation, some During hydrogenation, some cis cis double bonds double bonds are converted to are converted to trans trans double bonds (more double bonds (more stable) causing a change in the fatty acid stable) causing a change in the fatty acid structure structure

If a label states “partially” or “fully If a label states “partially” or “fully hydrogenated”, the fats contain hydrogenated”, the fats contain transtrans fatty fatty acids. acids.

4141

TransTrans Fats Fats

In the US, it is estimated that 2-4% of our total In the US, it is estimated that 2-4% of our total Calories is in the form of Calories is in the form of transtrans fatty acid. fatty acid.

trans trans fatty acids behave like saturated fatty fatty acids behave like saturated fatty acids in the body. acids in the body.

Several studies reported that trans fatty acids Several studies reported that trans fatty acids raise LDL-cholesterol. Some studies also raise LDL-cholesterol. Some studies also report that trans fatty acid lower HDL-report that trans fatty acid lower HDL-cholesterolcholesterol

The trans fatty acids controversy will continue The trans fatty acids controversy will continue to be debated. to be debated.

4242

Fats and AtheroschlerosisFats and Atheroschlerosis Inuit people of Alaska have a high fat diet Inuit people of Alaska have a high fat diet

and high blood cholesterol levels, but a very and high blood cholesterol levels, but a very

low occurrence of atherosclerosis and heart low occurrence of atherosclerosis and heart

attacks. attacks.

Fat in the Intuit diet was primarily from fish Fat in the Intuit diet was primarily from fish

such as salmon, tuna and herring rather than such as salmon, tuna and herring rather than

from land animals (as in the American diet). from land animals (as in the American diet).

4343

Omega-3 Fatty AcidsOmega-3 Fatty Acids

Fatty acids in the fish oils are mostly the omega-3 type Fatty acids in the fish oils are mostly the omega-3 type (first double bond occurs at the third carbon counting (first double bond occurs at the third carbon counting from the methyl group). from the methyl group).

linolenic acid 18 carbon atoms linolenic acid 18 carbon atoms

CHCH33CHCH22CH=CHCHCH=CHCH22CH=CHCHCH=CHCH22CH=CH(CHCH=CH(CH22))77COOHCOOH

eicosapentaenoic acid (EPA)eicosapentaenoic acid (EPA) 20 carbon atoms 20 carbon atoms

CHCH33CHCH22(CH=CHCH(CH=CHCH22))55(CH(CH22))22COOH COOH

4444

AtherosclerosisAtherosclerosis

Plaques of cholesterol adhere to the walls of the Plaques of cholesterol adhere to the walls of the

blood vessels blood vessels

Blood pressure rises as blood squeezes through Blood pressure rises as blood squeezes through

smaller blood vessels smaller blood vessels

Blood clots may formBlood clots may form

Omega-3 fatty acids decrease the “sticking” of Omega-3 fatty acids decrease the “sticking” of

blood platelets (fewer blood clots) blood platelets (fewer blood clots)

Omega-3 fatty acids can increase bleeding timeOmega-3 fatty acids can increase bleeding time

4545

Learning Check HA6Learning Check HA6

(1) Ture or (2) False(1) Ture or (2) False

A. ____ There are more unsaturated fats in A. ____ There are more unsaturated fats in vegetable oils.vegetable oils.

B. ____ Vegetable oils have more omega-3 oils B. ____ Vegetable oils have more omega-3 oils than found in fish.than found in fish.

C. ____ Hydrogenation of oils converts some C. ____ Hydrogenation of oils converts some cis-cis-double bondsdouble bonds to trans- to trans- double bonds. double bonds.

D. ____ Animal fats have more saturated fats.D. ____ Animal fats have more saturated fats.

4646

Solution HA6Solution HA6

(1) True or (2) False(1) True or (2) False

A. A. _T___T__ There are more unsaturated fats in There are more unsaturated fats in vegetable oils.vegetable oils.

B. B. _F___F__ Vegetable oils have more omega-3 oils Vegetable oils have more omega-3 oils than found in fish.than found in fish.

C. C. _T___T__ Hydrogenation of oils converts some Hydrogenation of oils converts some cis-cis-double bondsdouble bonds to trans- to trans- double bonds. double bonds.

D. D. _T___T__ Animal fats have more saturated fats. Animal fats have more saturated fats.