Organic ChemistryOrganic ChemistryAP Notes Chapter 10

HydrocarbonsHydrocarbons

Alkanes and Alkanes and CycloalkanesCycloalkanes

AlkanesAlkanes

Alkanes:Alkanes: hydrocarbons hydrocarbons containing only carbon-containing only carbon-carbon single bondscarbon single bondsthe first two alkanes are the first two alkanes are methane and ethanemethane and ethane

Hydrocarbon:Hydrocarbon: a a compound composed of compound composed of

only carbon and only carbon and hydrogenhydrogen

AlkanesAlkanes

the first 10 alkanes with the first 10 alkanes with unbranched chainsunbranched chains

Generic Alkane Formula: CnH2n+2

Constitutional IsomerismConstitutional Isomerism

Constitutional isomers:Constitutional isomers: compounds that have the compounds that have the same molecular formula same molecular formula but different structural but different structural formulas (connected formulas (connected

differently)differently)

Constitutional IsomerismConstitutional Isomerism

CH3CH2CH2CH3 CH3CHCH3

CH3

Butane(bp -0.5°C)

2-Methylpropane(bp -11.6°C)

sameconnectivity

Stereoisomers

Chiral

Enantiomers Diastereomers

Constitutional Isomers

Cis-Trans Isomers

withstereocenters

without stereocenters

Achiral

differentconnectivity

Isomers

Map of Organic Map of Organic IsomerizationIsomerization

CH3CHCH3

CH3

2-Methylpropane

12

3

Nomenclature ExampleNomenclature Example

CycloalkanesCycloalkanes

Cyclic hydrocarbon: a hydrocarbon that a hydrocarbon that

contains carbon contains carbon atoms joined to atoms joined to

form a ringform a ring

CycloalkanesCycloalkanes

Cyclopentane Cyclohexane

Alkenes and AlkynesAlkenes and Alkynes Alkene:Alkene: a hydrocarbon that a hydrocarbon that

contains one or more carbon-contains one or more carbon-carbon double bondscarbon double bonds ethylene is the simplest alkeneethylene is the simplest alkene

H

C C

H

H H

H-C C-H

Acetylene(an alkyne)

Ethylene(an alkene)

Alkenes and AlkynesAlkenes and Alkynes AlkyneAlkyne:: a hydrocarbon that a hydrocarbon that

contains one or more carbon-contains one or more carbon-carbon triple bondscarbon triple bonds acetylene is the simplest alkyneacetylene is the simplest alkyne

H

C C

H

H H

H-C C-H

Acetylene(an alkyne)

Ethylene(an alkene)

AlkenesAlkenes Cis-trans isomerismCis-trans isomerism

because of restricted rotation about because of restricted rotation about a carbon-carbon double bond, an a carbon-carbon double bond, an alkene with two different groups on alkene with two different groups on each carbon of the double bond each carbon of the double bond shows cis-trans isomerismshows cis-trans isomerism

trans-2-Butenemp -106°C, bp 1°C

cis-2-Butenemp -139°C, bp 4°C

HC C

CH3

H3C H

HC C

H

H3C CH3

Benzene and its Derivatives

Aromatic CompoundsAromatic Compounds Aromatic compound:Aromatic compound: a a

hydrocarbon that contains one hydrocarbon that contains one or more benzene-like ringsor more benzene-like rings arene:arene: a term used to describe a term used to describe aromatic compoundsaromatic compounds

Ar-Ar-:: a symbol for an aromatic a symbol for an aromatic group derived by removing an -H group derived by removing an -H from an arenefrom an arene

Kekulé structure for Kekulé structure for benzene (1872)benzene (1872)

The electrons of Benzene The electrons of Benzene are Delocalizedare Delocalized

sp2 hybridized

Nomenclature ExampleNomenclature Example

CH3NO2

Cl

OH

Br

BrBrNO2

CH2CH3

Br

43

2

1

5

6

43

21

43

1 2

4-Chloro-2-nitrotoluene

2,4,6-Tribromophenol 2-Bromo-1-ethyl-4-nitrobenzene

Functional Functional Groups and Groups and Reactions of Reactions of

Organic Organic CompoundsCompounds

AlkanesAlkanes

They burn!They burn! Hydrocarbon Hydrocarbon

and Oxygen and Oxygen yields Carbon yields Carbon Dioxide and Dioxide and WaterWater

Reactions of Alkenes:Reactions of Alkenes:ADDITION REACTIONSADDITION REACTIONS

Alkenes are Alkenes are unsaturatedunsaturated — more — more bonds can form to the C atomsbonds can form to the C atoms

Molecules such as BrMolecules such as Br22, H, H22, HCl, HBr, , HCl, HBr,

and Hand H22O O addadd to the double bond to the double bond

C CCH

H

H

HC

Br BrH H

HH

+ Br2

1,2-dibromoethane

C CCH

H

H

HC

Br BrH H

HH

+ Br2

1,2-dibromoethane

An Addition ReactionAn Addition Reaction

Fat Fat placed placed in Brin Br22

vaporvapor

An Addition An Addition ReactionReaction

The fat in bacon is partially The fat in bacon is partially unsaturated. The fat adds unsaturated. The fat adds

BrBr22 to the C=C bonds. to the C=C bonds.

An Addition ReactionAn Addition Reaction Fats can be “hydrogenated” with HFats can be “hydrogenated” with H22..

Peanut butter has partially Peanut butter has partially hydrogenated vegetable oil.hydrogenated vegetable oil.

Peanut butter has partially Peanut butter has partially hydrogenated vegetable oil.hydrogenated vegetable oil.

Saturated Fats

Reactions of AromaticsReactions of Aromatics SubstitutionsSubstitutions — not additions — not additions

— are typical.— are typical.

AlClAlCl33 is a catalyst. Catalysts typically is a catalyst. Catalysts typically

used in aromatic substitutions.used in aromatic substitutions.

+ CH3Cl

CH3

+ HClAlCl3

Functional GroupsFunctional Groups

See CD-ROM Screens 10.5 & 10.6See CD-ROM Screens 10.5 & 10.6See CD-ROM Screens 10.5 & 10.6See CD-ROM Screens 10.5 & 10.6

AlcoholsAlcohols Characterized by –OH group Characterized by –OH group

[R-OH[R-OH Name: add – ol to name of Name: add – ol to name of

hydrocarbonhydrocarbon

MethanolButanol

Structures of AlcoholsStructures of AlcoholsCC33HH55OH: how many structural isomers?OH: how many structural isomers?

C C C OH

H

H

H

H

H

H

H

1-propanol

C C C H

H

H

OH

H

H

H

H

2-propanol

Add -ol to name of 3-C hydrocarbon. Add -ol to name of 3-C hydrocarbon. Indicate position of OH with number.Indicate position of OH with number.

Alcohol PropertiesAlcohol Properties Alcohols are a derivative of water Alcohols are a derivative of water Many alcohols dissolve in waterMany alcohols dissolve in water

Methanol Methanol dissolves in water.dissolves in water.Methanol Methanol dissolves in water.dissolves in water.

Butanol is NOT Butanol is NOT soluble in water. soluble in water. Butanol is NOT Butanol is NOT soluble in water. soluble in water.

““SternoSterno””

Alcohols burn in air Alcohols burn in air

A mixture of A mixture of

ethanol + calcium ethanol + calcium

acetate = STERNOacetate = STERNO

GLYCOLSGLYCOLSAlcohols with Two OH Alcohols with Two OH

GroupsGroups

Propylene Propylene glycolglycol

EthyleneEthylene glycolglycol

Alcohol ReactionsAlcohol ReactionsScreen 11.6Screen 11.6

Substitution Elimination

Sugars: Related to Sugars: Related to AlcoholsAlcohols

Sugars are carbohydrates, compounds Sugars are carbohydrates, compounds with the formula Cwith the formula Cxx(H(H22O)O)yy..

O

H

HO

H

HO

HOHH

OH

OHCHO

OHH

HHO

OHH

OHH

CH2OH

O

H

HO

H

HO

OHOHH

H

OH

1

23

4 5

12

3

45

1

2

3

4

5

-D-glucose -D-glucose

Open chain form

H H

AminesAminesAminesAminesAlcohols are derivatives of HAlcohols are derivatives of H22OO

(R–OH) and (R–OH) and aminesamines are are derivatives of NHderivatives of NH33..

MethylamineMethylamine Dimethylamine TrimethylamineTrimethylamine

AminesAminesAminesAminesAmines generally have terrible Amines generally have terrible

odors!odors!

CadaverineCadaverinePyridinePyridine

AminesAminesAminesAminesAmines, like NHAmines, like NH33, are bases, are bases

2 C6H5NH2 (aq) + H2SO4(aq) 2 C6H5NH3+(aq) + SO4

2-(aq)

Aniline Anilinium ion

AminesAminesAminesAmines Many natural Many natural products products and drugs and drugs (such as (such as

nicotine and nicotine and cocaine) are cocaine) are

bases.bases.

NicotineNicotine

Structures of Structures of AldehydesAldehydes

CinnamaldehydeCinnamaldehydeOdors from Odors from

aldehydes and aldehydes and ketonesketones

O

C

carbonyl group

O

C

methanalFORMALDEHYDE

HH

O

C

propanal

HCH3CH2

O

C

HR

an ALDEHYDE

O

C

CH3CH3

dimethylketonepropanoneACETONE

O

C

CH2CH2CH3CH3

2-pentanone

O

C

CH2CH3CH3CH2

3-pentanone

O

C

R’R

a KETONE

Carboxylic AcidsCarboxylic AcidsBenzoic acidBenzoic acid

Carboxylic acid group Carboxylic acid group with acidic Hwith acidic H++

All are All are WEAKWEAK acids acids

Acetic acidAcetic acid

Acids are found in Acids are found in many natural many natural substances: bread, substances: bread, fruits, milk, winefruits, milk, wine

Acids are found in Acids are found in many natural many natural substances: bread, substances: bread, fruits, milk, winefruits, milk, wine

CarboxylCarboxylic Acidsic Acids

Formic acid, HCOFormic acid, HCO22H, H,

gives the sting to ants.gives the sting to ants.

Formic acid, HCOFormic acid, HCO22H, H,

gives the sting to ants.gives the sting to ants.

O

C

HOH

methanoic acidFORMIC ACID

O

C

CH3OH

ethanoic acidACETIC ACID

O

C

CH2CH2CH3OH

butanoic acidBUTYRIC ACID

O

C

ROH

a CARBOXYLIC ACID

an AMINO ACID

H2N C C

O

OHH

R

Acids + Alcohols --> Acids + Alcohols --> ESTERSESTERS

Esters have generally pleasant odorsEsters have generally pleasant odors

Acids + Alcohols --> Acids + Alcohols --> ESTERSESTERS

H+

O O

CH3COH + CH3CH2OH CH3COCH2CH3 + H2O

Acetic acid Ethanol Ethyl acetate

Acids + Alcohols --> Acids + Alcohols --> ESTERSESTERS

O

RC —O —HH+

O

+ R'—O —H RC —O —R' + H2O

Carboxylic acid Alcohol Ester

C

OC

O O

H

O

CH3Aspirin, Aspirin, acetylsalicylic acid,acetylsalicylic acid,

Acid and EsterAcid and Ester

Fats and OilsFats and OilsFats with C=C bonds are usually LIQUDSFats with C=C bonds are usually LIQUDSFats with C=C bonds are usually LIQUDSFats with C=C bonds are usually LIQUDS

Oleic acid: a Oleic acid: a monounsaturated monounsaturated fatty acid fatty acid

Oleic acid: a Oleic acid: a monounsaturated monounsaturated fatty acid fatty acid

C=C BondC=C Bond

Fats and OilsFats and Oils

Fats with saturated acids (no C=C bonds) Fats with saturated acids (no C=C bonds) are SOLIDS.are SOLIDS.

Fats with saturated acids (no C=C bonds) Fats with saturated acids (no C=C bonds) are SOLIDS.are SOLIDS.

Saturated fats Saturated fats are more are more

common in common in animals. animals.

Saturated fats Saturated fats are more are more

common in common in animals. animals.

Trans Fatty AcidsTrans Fatty Acids

C=C BondC=C Bond

Acidand

Alkene

Acidand

Alkene

Trans Fatty AcidsTrans Fatty Acids•Oleic acid is a mono–Oleic acid is a mono–unsaturated cis-fatty acidunsaturated cis-fatty acid•Trans fatty acids have Trans fatty acids have deleterious health effects. deleterious health effects. •Trans fatty acids raise plasma Trans fatty acids raise plasma LDL cholesterol and lower HDL LDL cholesterol and lower HDL levels.levels.

Acids + Amines --> Acids + Amines --> AMIDESAMIDES

N-methylacetamideN-methylacetamide

Acids + Amines --> Acids + Amines --> AMIDESAMIDES

AcetoaminophenTylenol, Datril, Momentum, ...AcetoaminophenTylenol, Datril, Momentum, ...

C

C

C

C

C

C

H

H

N

H

O

HCC

O

H

HH

H

H

Amide link

PolymersPolymersPolymersPolymers Giant molecules made by joining Giant molecules made by joining

many small molecules called many small molecules called monomersmonomers

Average production is 150 kg per Average production is 150 kg per person annually in the U.S.person annually in the U.S.

Polymer Classifications

ThermoplasticsThermoplastics (polyethylene) soften and (polyethylene) soften and flow when heatedflow when heated

ThermosettingThermosetting plastics — plastics — soft initially but set to soft initially but set to solid when heated. solid when heated. Cannot be resoftened.Cannot be resoftened.

Polymer Classifications

Other classification: Other classification: plastics, fibers, plastics, fibers, elastomers, elastomers, coatings, adhesivescoatings, adhesives

Polymer Preparation

Addition polymers — polymers — directly adding monomer directly adding monomer units togetherunits together

Condensation polymers — polymers — combining monomer units combining monomer units and splitting out a small and splitting out a small water (water)water (water)

Polyethylene: Addition Polymer

H2C CH2 C C

H

H

H

H

n

n

EthyleneEthylene PolyethylenePolyethylene

A polymer with a molar A polymer with a molar mass of a million has mass of a million has

about 36,000 units.about 36,000 units.

Mechanism of Addition

Polymerization

Addition Polymerization

1.1. InitiationInitiation

2.2. AdditionAddition

3.3. PropagationPropagation

4.4. TerminationTermination

Types of Polyethylene

Linear, high Linear, high density PE (HDPE)density PE (HDPE)

Branched, low Branched, low density PE, LDPEdensity PE, LDPE

Cross-linked Cross-linked PE, CLPEPE, CLPE

Types of Polyethylene

CH2CH

OH

CH2CH

OCCH3

CH2CH

n n n

polyvinyl alcohol polyvinyl acetate polystyrene

Polymers based on Substituted Ethylenes, CH2=CHX

O

Table 11.12: others are PVC, Table 11.12: others are PVC, acrylonitrile, polypropylene, polymethyl acrylonitrile, polypropylene, polymethyl

methacrylatemethacrylate

Polystyrene

Polystyrene is nonpolar material and Polystyrene is nonpolar material and dissolves in organic solvents.dissolves in organic solvents.

PS foam is mostly air, and when it PS foam is mostly air, and when it dissolves it collapses to a much smaller dissolves it collapses to a much smaller volume.volume.

Condensation

PolymersHOC

O

COH

O

CO

COCH2CH2OO

+ n HOCH2CH2OH

terephthalic acid ethylene glycol

+ H2 O

Polyethylene terephthalate (PET), a polyester

n

n

Polyesters, PET

Jackets made from recycled Jackets made from recycled PET soda bottlesPET soda bottles

Soda bottles, mylar Soda bottles, mylar film.film.

Polyesters: Mechanism

Reaction of Diacid and Diol

Polyamides: Nylon

Nylon Rope Trick

Polyamides: Nylon

•Each monomer has 6 C atoms in its chain.Each monomer has 6 C atoms in its chain.•A polyamide link forms on elmination of HClA polyamide link forms on elmination of HCl•Result = nylon 66Result = nylon 66•Proteins are Proteins are polyamidespolyamides

Polymer Recycling

Symbols

LDPE = LDPE = Low density PE = 0.910-0.925 g/cmLow density PE = 0.910-0.925 g/cm33

HDPE = High density PE = 0.941-0.965PP = PP = Polypropylene = 0.90Polypropylene = 0.90

V = PVC (Vinyl chloride) = 1.30-1.58