dr. wolf's chm 201 & 202 4- 1 chapter 4 alcohols and alkyl halides

Dr. Wolf's CHM 201 & 202 4- 1

Chapter 4Chapter 4

Alcohols and Alkyl HalidesAlcohols and Alkyl Halides

Dr. Wolf's CHM 201 & 202 4- 2

(1) alcohol + hydrogen halide(1) alcohol + hydrogen halide

ROH + HX ROH + HX RX + H RX + H22OO

(2) alkane + halogen(2) alkane + halogen

RH + XRH + X22 RX + HX RX + HX

Both are substitution reactionsBoth are substitution reactions

Overview of ChapterOverview of Chapter

This chapter introduces chemical reactions and This chapter introduces chemical reactions and their mechanisms by focusing on two reactionstheir mechanisms by focusing on two reactionsthat yield alkyl halides.that yield alkyl halides.

Dr. Wolf's CHM 201 & 202 4- 3

4.14.1

Functional GroupsFunctional Groups

Dr. Wolf's CHM 201 & 202 4- 4

a structural unit in a molecule responsible for itsa structural unit in a molecule responsible for itscharacteristic behavior under a particular set ofcharacteristic behavior under a particular set ofreaction conditionsreaction conditions

Functional GroupFunctional Group

Dr. Wolf's CHM 201 & 202 4- 5

AlcoholAlcohol ROHROH

Alkyl halideAlkyl halide RRXX ( (XX = F, Cl, Br, I) = F, Cl, Br, I)

AmineAmine primary amine: Rprimary amine: RNHNH22

secondary amine: Rsecondary amine: R22NHNH

tertiary amine: Rtertiary amine: R33NN

Families of organic compoundsFamilies of organic compoundsand their functional groupsand their functional groups

Dr. Wolf's CHM 201 & 202 4- 6

EtherEther RROOR'R'

NitrileNitrile RRCNCN

NitroalkaneNitroalkane RRNONO22

SulfideSulfide RSR'RSR'

ThiolThiol RSHRSH

EpoxideEpoxide CC CC

OO

Families of organic compoundsFamilies of organic compoundsand their functional groupsand their functional groups

Dr. Wolf's CHM 201 & 202 4- 7

OO

CC

Carbonyl groupCarbonyl group

OO

CC

Acyl groupAcyl group

RR

Many classes of organic compounds contain Many classes of organic compounds contain a carbonyl groupa carbonyl group

Dr. Wolf's CHM 201 & 202 4- 8

OO

CC


OO

CC

AldehydeAldehyde

RR HH


Dr. Wolf's CHM 201 & 202 4- 9

OO

CC


OO

CC

KetoneKetone

RR R'R'


Dr. Wolf's CHM 201 & 202 4- 10

OO

CC


OO

CC

Carboxylic acidCarboxylic acid

RR OHOH


Dr. Wolf's CHM 201 & 202 4- 11

OO

CC


OO

CC

EsterEster

RR OR'OR'


Dr. Wolf's CHM 201 & 202 4- 12

OO

CC


OO

CC

AmideAmide

RR NHNH22


Dr. Wolf's CHM 201 & 202 4- 13

4.24.2

IUPAC NomenclatureIUPAC Nomenclature

of Alkyl Halidesof Alkyl Halides

Dr. Wolf's CHM 201 & 202 4- 14

The two that are most widely used are:The two that are most widely used are:functional class nomenclaturefunctional class nomenclaturesubstitutive nomenclaturesubstitutive nomenclature

Both types can be applied to alcohols andBoth types can be applied to alcohols andalkyl halides.alkyl halides.


There are several kinds of IUPAC nomenclature.There are several kinds of IUPAC nomenclature.

Dr. Wolf's CHM 201 & 202 4- 15

Name the alkyl group and the halogen asName the alkyl group and the halogen asseparate words (separate words (alkylalkyl + + halidehalide))

Functional Class Nomenclature of Alkyl HalidesFunctional Class Nomenclature of Alkyl Halides

CHCH33FF CHCH33CHCH22CHCH22CHCH22CHCH22ClCl

CHCH33CHCH22CHCHCHCH22CHCH22CHCH33

BrBr

HH

II

Dr. Wolf's CHM 201 & 202 4- 16

Name the alkyl group and the halogen asName the alkyl group and the halogen asseparate words (separate words (alkylalkyl + + halidehalide))

Functional Class Nomenclature of Alkyl HalidesFunctional Class Nomenclature of Alkyl Halides

CHCH33FF CHCH33CHCH22CHCH22CHCH22CHCH22ClCl

CHCH33CHCH22CHCHCHCH22CHCH22CHCH33

BrBr

Methyl fluorideMethyl fluoride Pentyl chloridePentyl chloride

1-Ethylbutyl bromide1-Ethylbutyl bromide Cyclohexyl iodideCyclohexyl iodide

HH

II

Dr. Wolf's CHM 201 & 202 4- 17

Name as halo-substituted alkanes.Name as halo-substituted alkanes.

Number the longest chain containing theNumber the longest chain containing thehalogen in the direction that gives the lowesthalogen in the direction that gives the lowestnumber to the substituted carbon.number to the substituted carbon.

Substitutive Nomenclature of Alkyl HalidesSubstitutive Nomenclature of Alkyl Halides

CHCH33CHCH22CHCH22CHCH22CHCH22FF CHCH33CHCHCHCH22CHCH22CHCH33

BrBr

CHCH33CHCH22CHCHCHCH22CHCH33

II

Dr. Wolf's CHM 201 & 202 4- 18

Name as halo-substituted alkanes.Name as halo-substituted alkanes.

Number the longest chain containing theNumber the longest chain containing thehalogen in the direction that gives the lowesthalogen in the direction that gives the lowestnumber to the substituted carbon.number to the substituted carbon.


CHCH33CHCH22CHCH22CHCH22CHCH22FF CHCH33CHCHCHCH22CHCH22CHCH33

BrBr1-Fluoropentane1-Fluoropentane

3-Iodopentane3-Iodopentane

2-Bromopentane2-BromopentaneCHCH33CHCH22CHCHCHCH22CHCH33

II

Dr. Wolf's CHM 201 & 202 4- 19


Halogen and alkyl groupsHalogen and alkyl groupsare of equal rank when are of equal rank when it comes to numberingit comes to numberingthe chain.the chain.

Number the chain in theNumber the chain in thedirection that gives the direction that gives the lowest number to thelowest number to thegroup (halogen or alkyl)group (halogen or alkyl)that appears first.that appears first.

CHCH33

ClCl ClCl

CHCH33

Dr. Wolf's CHM 201 & 202 4- 20


5-Chloro-2-methylheptane5-Chloro-2-methylheptane

2-Chloro-5-methylheptane2-Chloro-5-methylheptane

CHCH33

ClCl ClCl

CHCH33

Dr. Wolf's CHM 201 & 202 4- 21

4.34.3


of Alcoholsof Alcohols

Dr. Wolf's CHM 201 & 202 4- 22

Name the alkyl group and add "alcohol" as aName the alkyl group and add "alcohol" as aseparate word.separate word.

Functional Class Nomenclature of AlcoholsFunctional Class Nomenclature of Alcohols

CHCH33CHCH22OHOH

CHCH33CHCHCHCH22CHCH22CHCH22CHCH33

OHOH

CHCH33CCHCCH22CHCH22CHCH33

OHOH

CHCH33

Dr. Wolf's CHM 201 & 202 4- 23

Name the alkyl group and add "alcohol" as aName the alkyl group and add "alcohol" as aseparate word.separate word.

Functional Class Nomenclature of AlcoholsFunctional Class Nomenclature of Alcohols

CHCH33CHCH22OHOH


OHOH


OHOH

CHCH33

Ethyl alcoholEthyl alcohol

1-Methylpentyl alcohol1-Methylpentyl alcohol

1,1-Dimethylbutyl1,1-Dimethylbutylalcoholalcohol

Dr. Wolf's CHM 201 & 202 4- 24

Name as "alkanols." Replace -e ending of alkaneName as "alkanols." Replace -e ending of alkanename by -ol.name by -ol.

Number chain in direction that gives lowest numberNumber chain in direction that gives lowest numberto the carbon that bears the —OH group.to the carbon that bears the —OH group.

Substitutive Nomenclature of AlcoholsSubstitutive Nomenclature of Alcohols

CHCH33CHCH22OHOH


OHOH


OHOH

CHCH33

Dr. Wolf's CHM 201 & 202 4- 25

Name as "alkanols." Replace -e ending of alkaneName as "alkanols." Replace -e ending of alkanename by -ol.name by -ol.

Number chain in direction that gives lowest numberNumber chain in direction that gives lowest numberto the carbon that bears the —OH group.to the carbon that bears the —OH group.


CHCH33CHCH22OHOH


OHOH


OHOH

CHCH33

EthanolEthanol

2-Hexanol2-Hexanol2-Methyl-2-pentanol2-Methyl-2-pentanol

Dr. Wolf's CHM 201 & 202 4- 26

OHOH

CHCH33


Hydroxyl groups outrank Hydroxyl groups outrank alkyl groups when alkyl groups when it comes to numberingit comes to numberingthe chain.the chain.

Number the chain in theNumber the chain in thedirection that gives the direction that gives the lowest number to thelowest number to thecarbon that bears thecarbon that bears theOH groupOH group

CHCH33

OHOH

Dr. Wolf's CHM 201 & 202 4- 27


6-Methyl-3-heptanol6-Methyl-3-heptanol

5-Methyl-2-heptanol5-Methyl-2-heptanol

OHOH

CHCH33

CHCH33

OHOH

Dr. Wolf's CHM 201 & 202 4- 28

4.44.4

Classes of AlcoholsClasses of Alcohols

and Alkyl Halidesand Alkyl Halides

Dr. Wolf's CHM 201 & 202 4- 29

Alcohols and alkyl halides are classified asAlcohols and alkyl halides are classified asprimaryprimarysecondarysecondarytertiarytertiary

according to their "degree of substitution."according to their "degree of substitution."

Degree of substitution is determined by countingDegree of substitution is determined by countingthe number of carbon atoms directly attached tothe number of carbon atoms directly attached tothe carbon that bears the halogen or hydroxyl group.the carbon that bears the halogen or hydroxyl group.

ClassificationClassification

Dr. Wolf's CHM 201 & 202 4- 30

CHCH33CHCH22CHCH22CHCH22CHCH22FF

CHCH33CHCHCHCH22CHCH22CHCH33

BrBr

primary alkyl halideprimary alkyl halide

secondary alkyl halidesecondary alkyl halide

ClassificatioClassificationn


OHOH

CHCH33

tertiary alcoholtertiary alcohol

HH

OHOH

secondary alcoholsecondary alcohol

Dr. Wolf's CHM 201 & 202 4- 31

4.54.5

Bonding in AlcoholsBonding in Alcohols

and Alkyl Halidesand Alkyl Halides

Dr. Wolf's CHM 201 & 202 4- 32

HH

HH

HH

alcohols and alkyl halides are polaralcohols and alkyl halides are polar

= 1.7 D= 1.7 D = 1.9 D= 1.9 D

HH

HH

CC OO

HH

HH

CC ClCl++

––––++

++

Dipole MomentsDipole Moments

Dr. Wolf's CHM 201 & 202 4- 33

alcohols and alkyl halides are polaralcohols and alkyl halides are polar

= 1.7 D= 1.7 D = 1.9 D= 1.9 D

Dipole MomentsDipole Moments

Dr. Wolf's CHM 201 & 202 4- 34

+ + – –

– – + +

+ + – – + + – – + + – –

Dipole-Dipole Attractive ForcesDipole-Dipole Attractive Forces

Dr. Wolf's CHM 201 & 202 4- 35

+ + – –

– – + +

+ + – – + + – – + + – –

Dipole-Dipole Attractive ForcesDipole-Dipole Attractive Forces

Dr. Wolf's CHM 201 & 202 4- 36

Boiling pointBoiling point

Solubility in waterSolubility in water

DensityDensity

4.64.6

Physical Properties of Physical Properties of

Alcohols and Alkyl Halides:Alcohols and Alkyl Halides:

Intermolecular ForcesIntermolecular Forces

Dr. Wolf's CHM 201 & 202 4- 37

4444 4848 4646

-42-42 -32-32 +78+78

00 1.91.9 1.71.7

CHCH33CHCH22CHCH33 CHCH33CHCH22FF CHCH33CHCH22OHOH

MolecularMolecularweightweight

BoilingBoilingpoint, °Cpoint, °C

DipoleDipolemoment, Dmoment, D

Effect of Structure on Boiling PointEffect of Structure on Boiling Point

Dr. Wolf's CHM 201 & 202 4- 38

4444

--4242

00

CHCH33CHCH22CHCH33




Intermolecular forcesIntermolecular forcesare weak.are weak.

Only intermolecularOnly intermolecularforces are inducedforces are induceddipole-induced dipoledipole-induced dipoleattractions.attractions.


Dr. Wolf's CHM 201 & 202 4- 39

4848

-32-32

1.91.9

CHCH33CHCH22FF




A polar molecule;A polar molecule;therefore dipole-dipoletherefore dipole-dipoleand dipole-inducedand dipole-induceddipole forces contributedipole forces contributeto intermolecular to intermolecular attractions.attractions.


Dr. Wolf's CHM 201 & 202 4- 40

4646

+78+78

1.71.7

CHCH33CHCH22OHOH




Highest boiling point;Highest boiling point;strongest intermolecularstrongest intermolecularattractive forces.attractive forces.

Hydrogen bonding isHydrogen bonding isstronger than otherstronger than otherdipole-dipole attractions.dipole-dipole attractions.


Dr. Wolf's CHM 201 & 202 4- 41

++––

––++

Figure 4.4 Hydrogen bonding in ethanolFigure 4.4 Hydrogen bonding in ethanol

Dr. Wolf's CHM 201 & 202 4- 42

Figure 4.4 Hydrogen bonding in ethanolFigure 4.4 Hydrogen bonding in ethanol

Dr. Wolf's CHM 201 & 202 4- 43

Boiling point increases with increasingBoiling point increases with increasingnumber of halogensnumber of halogens

CHCH33ClCl -24°C-24°C

CHCH22ClCl22 40°C40°C

CHCHClCl33 61°C61°C

CCClCl44 77°C77°C

CompoundCompound Boiling PointBoiling Point

Even though CClEven though CCl4 4 is the only compound in this list without a is the only compound in this list without a

dipole moment, it has the highest boiling point.dipole moment, it has the highest boiling point.

Induced dipole-induced dipole forces are greatest in Induced dipole-induced dipole forces are greatest in CClCCl44 because it has the greatest number of Cl atoms. because it has the greatest number of Cl atoms.

Cl is more polarizable than H. Cl is more polarizable than H.

Dr. Wolf's CHM 201 & 202 4- 44

But trend is not followed when halogenBut trend is not followed when halogenis fluorineis fluorine

CHCH33CHCH22FF -32°C-32°C

CHCH33CHCHFF22 -25°C-25°C

CHCH33CCFF33 -47°C-47°C

CCFF33CCFF33 -78°C-78°C


Dr. Wolf's CHM 201 & 202 4- 45

But trend is not followed when halogenBut trend is not followed when halogenis fluorineis fluorine

CHCH33CHCH22FF -32°C-32°C

CHCH33CHCHFF22 -25°C-25°C

CHCH33CCFF33 -47°C-47°C

CCFF33CCFF33 -78°C-78°C


Fluorine is not very polarizable and induced dipole-Fluorine is not very polarizable and induced dipole-induced dipole forces decrease with increasing induced dipole forces decrease with increasing fluorine substitution.fluorine substitution.

Dr. Wolf's CHM 201 & 202 4- 46

Solubility in waterSolubility in water

Alkyl halides are insoluble in water.Alkyl halides are insoluble in water.

Methanol, ethanol, isopropyl alcohol areMethanol, ethanol, isopropyl alcohol arecompletely miscible with water.completely miscible with water.

The solubility of an alcohol in waterThe solubility of an alcohol in waterdecreases with increasing number of decreases with increasing number of carbons (compound becomescarbons (compound becomesmore hydrocarbon-like).more hydrocarbon-like).

Dr. Wolf's CHM 201 & 202 4- 47

++––

––

++

––++

Figure 4.5 Hydrogen Bonding Figure 4.5 Hydrogen Bonding Between Ethanol and WaterBetween Ethanol and Water

Dr. Wolf's CHM 201 & 202 4- 48

DensityDensity

Alkyl fluorides and alkyl chlorides Alkyl fluorides and alkyl chlorides areareless dense than water.less dense than water.

Alkyl bromides and alkyl iodides are Alkyl bromides and alkyl iodides are more dense than water.more dense than water.

All liquid alcohols have densities of All liquid alcohols have densities of about 0.8 g/mL.about 0.8 g/mL.

Dr. Wolf's CHM 201 & 202 4- 49

4.74.7

Preparation of Alkyl Halides fromPreparation of Alkyl Halides from

Alcohols and Hydrogen HalidesAlcohols and Hydrogen Halides

ROH + HX ROH + HX RX + H RX + H22OO

Dr. Wolf's CHM 201 & 202 4- 50

RROOHH + + HHXX R RXX + + HHOOHH

Hydrogen halide reactivityHydrogen halide reactivity

HHFF HHClCl HHBrBr HHII

Reaction of Alcohols with Hydrogen HalidesReaction of Alcohols with Hydrogen Halides

least reactiveleast reactive most reactivemost reactive

Dr. Wolf's CHM 201 & 202 4- 51

Alcohol reactivityAlcohol reactivity

CHCH33OOHH RCH RCH22OOH H RR22CHCHOOH H RR33CCOOHH

MethanolMethanol PrimaryPrimary SecondarySecondary TertiaryTertiary

RROOH H + + HHXX R RXX + + HHOOHH

Reaction of Alcohols with Hydrogen HalidesReaction of Alcohols with Hydrogen Halides

least reactiveleast reactive most reactivemost reactive

Dr. Wolf's CHM 201 & 202 4- 52

(CH(CH33))33CCOHOH + H + HClCl (CH(CH33))33CCClCl + H + H22OO

78-88%78-88%

25°C25°C

CHCH33(CH(CH22))55CHCH22OHOH + H + HBrBr

CHCH33(CH(CH22))55CHCH22BrBr + H + H22OO

87-90%87-90%

120°C120°C

Preparation of Alkyl HalidesPreparation of Alkyl Halides

73%73%

80-100°C80-100°C

OHOH ++ HHBrBr

BrBr ++ HH22OO

Dr. Wolf's CHM 201 & 202 4- 53

CHCH33CHCH22CHCH22CHCH22OHOH CHCH33CHCH22CHCH22CHCH22BrBr

NaNaBrBrHH22SOSO44

70-83%70-83%heatheat

A mixture of sodium bromide and sulfuric A mixture of sodium bromide and sulfuric acid may be used in place of HBr.acid may be used in place of HBr.

Preparation of Alkyl HalidesPreparation of Alkyl Halides

dr. wolf's chm 201 & 202 4- 1 chapter 4 alcohols and alkyl halides

Documents

carbonyl group slide

alkyl group

o c carbonyl group o

classes of organic compounds

functional groups

kinds of iupac nomenclature

alcoholroh alkyl haliderx

nh tertiary amine