Chapter6-6-Chem207
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Transcript of Chapter6-6-Chem207
Chem 207 B. R. Kaafarani 1
+ A—BC C A C C B
The characteristic reaction of alkenes isaddition to the double bond.
Chapter 6Reactions of Alkenes:
Addition Reactions
Chem 207 B. R. Kaafarani 2
+ H—H
C C H C C
H H
H H
H
H
H
H
H
Exothermic ∆H° = –136 kJ/mol.
Catalyzed by finely divided Pt, Pd, Rh, Ni.
The metals are insoluble in solvents used in this reaction:heteregeneous reactions. Reaction occurs at the interfaceof the two phases.
6.1. Hydrogenation of Alkenes Hydrogenation of Ethylene
Chem 207 B. R. Kaafarani 3
H2, Pt
(73%)
CH2H3C
H3C
CH3
HH3C
H3C
Example
Chem 207 B. R. Kaafarani 4
H2, Pt
Problem 6.1
What three alkenes yield 2-methylbutane on catalytic hydrogenation?
Chem 207 B. R. Kaafarani 5
Mechanism of Catalytic Hydrogenation: Mechanism 6.1
Chem 207 B. R. Kaafarani 6
Can be used to measure relative stabilityof isomeric alkenes.
Correlation with structure is same aswhen heats of combustion are measured.
6.2. Heats of Hydrogenation
Chem 207 B. R. Kaafarani 7
CH3CH2CH2CH3
126
119115
Heats of Hydrogenation of Isomers
Chem 207 B. R. Kaafarani 8
Ethylene 136
Monosubstituted 125-126
cis-Disubstituted 117-119
trans-Disubstituted 114-115
Terminally disubstituted 116-117
Trisubstituted 112
Tetrasubstituted 110
Heats of Hydrogenation (KJ/mol)
Chem 207 B. R. Kaafarani 9
Match each alkene of Problem 6.1 with its correctheat of hydrogenation.
126 kJ/mol
118 kJ/mol
112 kJ/mol
highest heat ofhydrogenation;least stable isomer
lowest heat ofhydrogenation;most stable isomer
Problem 6.2
Chem 207 B. R. Kaafarani 10
6.3. Stereochemistry of Alkene Hydrogenation
A reaction in which a single starting material can givetwo or more stereoisomeric products but yields one ofthem in greater amounts than the other (or even to theexclusion of the other) is said to be stereoselective.
Two spatial (stereochemical) aspects ofalkene hydrogenation:
(1) Syn addition of both H atoms to double bond.
(2) Hydrogenation is stereoselective, correspondingto addition to less crowded face of double bond.
Chem 207 B. R. Kaafarani 11
syn addition anti addition
syn-Additon versus anti-Addition
Chem 207 B. R. Kaafarani 12
CO2CH3
CO2CH3
(100%)
H2, PtCO2CH3
CO2CH3H
H
Example of Syn Addition
Chem 207 B. R. Kaafarani 13
H3C CH3
H3C
H
D2, cat
Both productscorrespond tosyn additionof H2.
CH3H3C
DH
CH3
D
But only this one if formed!
Example of Stereoselective
Reaction
CH3H3C
H3CD
D
H
Chem 207 B. R. Kaafarani 14
CH3H3C
H3CH
H
H
H3C CH3
H3C
H
H2, catTop face of doublebond blocked bythis methyl group
H2 adds to bottom face of double bond.
Example of Stereoselective
Reaction
Chem 207 B. R. Kaafarani 15
+ E—Y –
C C E YC C
General equation for electrophilic addition
6.4. Electrophilic Addition of Hydrogen Halides to Alkenes
Chem 207 B. R. Kaafarani 16
+ H—Y –
C C H YC C
When E+ is a hydrogen halide:
Chem 207 B. R. Kaafarani 17
CH3CH2 CH2CH3
H H
CH3CH2CH2CHCH2CH3
Br
(76%)
CHCl3, -30°CC CHBr
Example
Chem 207 B. R. Kaafarani 18
Electrophilic addition ofhydrogen halides to alkenesproceeds by rate-determiningformation of a carbocationintermediate.
Electrons flow from the system of the alkene (electronrich) toward the positivelypolarized proton of thehydrogen halide.
Mechanism
Chem 207 B. R. Kaafarani 19
XH
C C
..
..:
HC C....X:
..
..:X:–
HC C+
Mechanism
Chem 207 B. R. Kaafarani 20
HF << HCl < HBr < HI
least acidic most acidic
Reactivity of Hydrogen Halide
Chem 207 B. R. Kaafarani 21
6.5. Regioselectivity of Hydrogen Halide Addition: Markovnikov's Rule
When an unsymmetrically substituted alkenereacts with a hydrogen halide, the hydrogenadds to the carbon that has the greater numberof hydrogen substituents, and the halogen addsto the carbon that has the fewer hydrogensubstituents.
Chem 207 B. R. Kaafarani 22
acetic acidBr
CH3CH2CHCH3
Example 1
CH2CH3CH2CHHBr
(80%)
CH3
CH3
CH3 C
Br(90%)
C Cacetic acid
HBrCH3
CH3
H
H
Example 2
Markovnikov's Rule
Chem 207 B. R. Kaafarani 23
(100%)
Example 3
HClCH3
CH3
Cl0°C
Protonation of double bond occurs in directionthat gives more stable carbocation.
Markovnikov's Rule
Chem 207 B. R. Kaafarani 24
Br
CH3CH2CHCH3CH2CH3CH2CH
HBr
CH3CH2CH—CH3 + Br –+
CH3CH2CH2—CH2
+
primary carbocation is less stable: not formed
6.6. Mechanistic Basis for Markovnikov's Rule: Example 1
Chem 207 B. R. Kaafarani 25
HCl
H
CH3
CH3
Cl
H H
CH3+
secondary carbocation is less stable: not formed
CH3
H
+
H
Cl–
Mechanistic Basis for Markovnikov's Rule: Example 3
Chem 207 B. R. Kaafarani 26
HCl, 0°C
CH3CHCH(CH3)2
+
H2C CHCH(CH3)2
+CH3CHC(CH3)2
H
CH3CHCH(CH3)2
Cl (40%)
CH3CH2C(CH3)2
Cl(60%)
6.7. Carbocation Rearrangements in Hydrogen Halide Addition to Alkenes
Rearrangements sometimes occur!
Chem 207 B. R. Kaafarani 27
CH3CHCH3
OSO2OH
CH3CH CH2HOSO2OH
Isopropylhydrogen sulfate
6.8. Addition of Sulfuric Acid (H2SO4) to Alkenes
- Follows Markovnikov's rule- Yields an alkyl hydrogen sulfate
Chem 207 B. R. Kaafarani 28
+CH3CH CH2 H..
SO2OH..
slow
+CH3CH CH3 +
..SO2OH..:
–O
O
fast CH3CHCH3
OSO2OH..:
Mechanism
Chem 207 B. R. Kaafarani 29
H—OHCH3CHCH3
O SO2OH
HO—SO2OH+
heat
CH3CHCH3
O H
+
Alkyl hydrogen sulfates undergo hydrolysis in hot water
Chem 207 B. R. Kaafarani 30
1. H2SO4
2. H2O, heat
(75%)
OH
Application: Conversion of alkenes to alcohols
Chem 207 B. R. Kaafarani 31
Not all alkenes yield alkyl hydrogen sulfateson reaction with sulfuric acid
These do:
H2C=CH2, RCH=CH2, and RCH=CHR'
These don't:
R2C=CH2, R2C=CHR, and R2C=CR2
But...
Chem 207 B. R. Kaafarani 32
H—OHC C + OHC CH
6.9. Acid-Catalyzed Hydration of Alkenes
Reaction is acid catalyzed; typical hydration medium is 50% H2SO4-50% H2O.
Chem 207 B. R. Kaafarani 33
(90%)
50% H2SO4
50% H2O
H3C
H3C CH3
H
C C
OH
C CH2CH3CH3
CH3
Follows Markovnikov's Rule
Chem 207 B. R. Kaafarani 34
50% H2SO4
50% H2O
(80%)
OH
CH3CH2
Follows Markovnikov's Rule
Chem 207 B. R. Kaafarani 35
+ H2OH+
H3C
H3C
C CH2
OH
C CH3CH3
CH3
Involves a carbocation intermediate. Is the reverse of acid-catalyzed dehydration ofalcohols to alkenes.
Mechanism
Chem 207 B. R. Kaafarani 36
Step (1): Protonation of double bond
+
H3C
H3C
C CH2 O+
H
H
H
:
slow
+H3C
H3C
C CH3
H
+ O
H
::
Mechanism
Chem 207 B. R. Kaafarani 37
Step (2): Capture of carbocation by water
+H3C
H3C
C CH3
H
+ O
H
::
fast
+
H
O
H
:C
CH3
CH3
CH3
Mechanism
Chem 207 B. R. Kaafarani 38
Step (3): Deprotonation of oxonium ion
+
H
O
H
:C
CH3
CH3
CH3 O
H
::
H
+
fast
O+
H
H
H
:+
H
O:C
CH3
CH3
CH3
..
Mechanism
Chem 207 B. R. Kaafarani 39
Ethylene CH2=CH2 1.0
Propene CH3CH=CH2 1.6 x 106
2-Methylpropene (CH3)2C=CH2 2.5 x 1011
Acid-catalyzed hydration
The more stable the carbocation, the faster it isformed, and the faster the reaction rate.
Relative Rates
Chem 207 B. R. Kaafarani 40
+ H2OH+
H3C
H3C
C CH2
OH
C CH3CH3
CH3
In an equilibrium process, the same intermediatesand transition states are encountered in the forwarddirection and the reverse, but in the opposite order.
Principle of Microscopic Reversibility
Chem 207 B. R. Kaafarani 41
6.11Hydroboration-Oxidation of Alkenes
Chem 207 B. R. Kaafarani 42
Suppose you wanted to prepare 1-decanol from 1-decene?
OH
Needed: a method for hydration of alkenes with aregioselectivity opposite to Markovnikov's rule.
Synthesis
Chem 207 B. R. Kaafarani 43
Two-step reaction sequence called hydroboration-oxidation converts alkenes to alcohols with aregiochemistry opposite to Markovnikov's rule.
1. Hydroboration2. Oxidation
OH
Synthesis
Chem 207 B. R. Kaafarani 44
+ H—BH2C C H BH2C C
Hydroboration can be viewed as the addition ofborane (BH3) to the double bond. But BH3 is notthe reagent actually used.
Hydroboration Step
Chem 207 B. R. Kaafarani 45
Hydroboration reagents:
H2B
H
H
BH2
Diborane (B2H6)normally used in an ether- like solventcalled "diglyme"
+ H—BH2C C H BH2C C
2-Methoxyethyl ether or diglymeO
O O
Hydroboration Step
Chem 207 B. R. Kaafarani 46
Hydroboration reagents:
Borane-tetrahydrofurancomplex (H3B-THF)+O
BH3–
••
+ H—BH2C C H BH2C C
Hydroboration Step
Chem 207 B. R. Kaafarani 47
H2O2, HO–
H BH2C C H OHC C
Organoborane formed in the hydroborationstep is oxidized with hydrogen peroxide.
Oxidation Step
Chem 207 B. R. Kaafarani 48
1. B2H6, diglyme2. H2O2, HO–
(93%)
OH
Example
Chem 207 B. R. Kaafarani 49
(98%)
H3C
H3C
CH3
H
C C1. H3B-THF
2. H2O2, HO–H
C CCH3
CH3
CH3
H OH
Example
Chem 207 B. R. Kaafarani 50
Features of Hydroboration-Oxidation
Hydration of alkenes.
Regioselectivity opposite to Markovnikov's rule.
No rearrangement.
Stereospecific syn addition.
Chem 207 B. R. Kaafarani 51
+ X2 X X
Electrophilic addition to double bond. Forms a vicinal dihalide.
C CC C
General features
6.14. Addition of Halogens to Alkenes
Chem 207 B. R. Kaafarani 52
CH3CHCHCH(CH3)2
(100%)
CHCl30°C
CHCH(CH3)2CH3CHBr2
Br Br
Example
Chem 207 B. R. Kaafarani 53
- Limited to Cl2 and Br2.
- F2 addition proceeds with explosive violence.
- I2 addition is endothermic: vicinal diiodidesdissociate to an alkene and I2.
Scope
Chem 207 B. R. Kaafarani 54
Br2
trans-1,2-Dibromocyclopentane80% yield; only product
Example
H
H
Br
Br
H
H
6.15. Stereochemistry of Halogen Addition
anti additionanti addition
Chem 207 B. R. Kaafarani 55
Cl2
trans-1,2-Dichlorocyclooctane73% yield; only product
H
H
H
H
Cl
Cl
Example
Chem 207 B. R. Kaafarani 56
6.16. Mechanism of Halogen Addition to Alkenes: Halonium Ions
Mechanism is electrophilic addition
Br2 is not polar, but it is polarizable.
Two steps:(1) Formation of bromonium ion.(2) Nucleophilic attack on bromonium
ion by bromide.
Chem 207 B. R. Kaafarani 57
Ethylene H2C=CH2 1
Propene CH3CH=CH2 61
2-Methylpropene (CH3)2C=CH2 5400
2,3-Dimethyl-2-butene (CH3)2C=C(CH3)2 920,000
Table 6.3. Relative Rates of Bromination
More highly substituted double bonds react faster.Alkyl groups on the double bond make it more “electronrich.”
Chem 207 B. R. Kaafarani 58
H2C CH2 BrCH2CH2Br+ Br2
?
+
: :..
..: :..Br
–C C
Br
+
No obvious explanation for anti addition provided by this mechanism.
Mechanism?
Chem 207 B. R. Kaafarani 59
H2C CH2 BrCH2CH2Br+ Br2
+C C
Br: :+
..: :..Br
–
Cyclic bromonium ion
Mechanism
Chem 207 B. R. Kaafarani 60
Br
Br
Mutual polarization ofelectron distributions ofBr2 and alkene
Formation of Bromonium Ion
Br
Br
–
++
Electrons flow from alkene toward Br2
Chem 207 B. R. Kaafarani 61
Br–
Br+
electrons ofalkene displaceBr– from Br.
Formation of Bromonium Ion
Chem 207 B. R. Kaafarani 62
Attack of Br– from side oppositeC—Br bond of bromonium ion givesanti addition.
+
–Br: :..
..
Br..
..
Br
Br..:
..
..::
..
Stereochemistry
Chem 207 B. R. Kaafarani 63
Br2
trans-1,2-Dibromocyclopentane80% yield; only product.
H
H
Br
Br
H
H
Example
Chem 207 B. R. Kaafarani 64
Cyclopentene +Br2
–
Bromonium ion
Chem 207 B. R. Kaafarani 65
–
–
trans-Stereochemistry in vicinal dibromide
Bromide ion attacks thebromonium ion from sideopposite carbon-bromine bond.
Chem 207 B. R. Kaafarani 66
+ X2 X XC CC C
+ H2O OH
+ H—X
+ X2 X C CC C
Alkenes react with X2 to form vicinal dihalides. Alkenes react with X2 in water to give vicinal
halohydrins.
6.17. Conversion of Alkenes to Vicinal Halohydrins
Chem 207 B. R. Kaafarani 67
H2C CH2 BrCH2CH2OH+ Br2
H2O
(70%)
anti addition: only product
Cl2
H2OH
H
OH
Cl
H
H
Examples
Chem 207 B. R. Kaafarani 68
+Br..
..
Br..
:..
:..O
..O+
Bromonium ion is intermediate.Water is nucleophile that attacks bromonium ion.
Mechanism
Chem 207 B. R. Kaafarani 69
(77%)
H3C
C CH2
H3C
CH3
OH
C CH2BrCH3
Br2
H2O
Regioselectivity
Markovnikov's rule applied to halohydrin formation:the halogen adds to the carbon having the greaternumber of hydrogens.
Chem 207 B. R. Kaafarani 70
H3C CH2
H3C
Br: :
H
OH ..
C CH2
H3C
CH3C
Br: :
H
O H..
SN2 StereochemistrySN1 Regiochemistry
Transition state for attack of water on bromonium ion hascarbocation character; more stable transition state (left) haspositive charge on more highly substituted carbon
Explanation
Chem 207 B. R. Kaafarani 71
Br
HO
N
O
O
Br
NBS
H2O/DMSO
N-Bromosuccinimide (NBS)
Few alkenes are soluble in water
NBS is a source of Br2 in low concentration:radical addition. Works for allylic susbstitution.
Chem 207 B. R. Kaafarani 72
The "peroxide effect"
6.18. Free-radical Addition of HBr to Alkenes
Chem 207 B. R. Kaafarani 73
acetic acidBr
CH3CH2CHCH3CH2CH3CH2CHHBr
(90%)
Markovnikov's Rule
Chem 207 B. R. Kaafarani 74
CH3CH2CH2CH2Br
only product inabsence of peroxides
only product when peroxides added to
reaction mixture
Br
CH3CH2CHCH3
CH2CH3CH2CH
HBr
Addition of HBr to 1-Butene
Chem 207 B. R. Kaafarani 75
CH3CH2CH2CH2Br
only product when peroxides added to reaction mixture
CH2CH3CH2CH
HBr
Addition opposite to Markovnikov's rule occurs with HBr (not HCl or HI)
Addition of HBr to 1-Butene
Chem 207 B. R. Kaafarani 76
+ HBrh
(60%)
CH2
CH2Br
H
Addition of HBr with a regiochemistry oppositeto Markovnikov's rule can also occur wheninitiated with light with or without added peroxides.
Photochemical Addition of HBr
Chem 207 B. R. Kaafarani 77
..
..O R...
..O RR O....
O .R ....
+
+ BrO .R ....
H ....
: +OR ....
H . Br....
:
Addition of HBr opposite to Markovnikov's ruleproceeds by a free-radical chain mechanism.
Initiation steps:
Mechanism
Chem 207 B. R. Kaafarani 78
Propagation steps:
+CH3CH2CH CH2. Br..
..:
.CH3CH2CH CH2 Br:
....
..
+.CH3CH2CH CH2 Br:
....
H Br....
:
CH3CH2CH2CH2Br:..
. Br....
:
Mechanism
Chem 207 B. R. Kaafarani 79
H2C CH2
O
H2C CHCH3
O
Epoxides are examples of heterocyclic compoundsthree-membered rings that contain oxygen.
Ethylene oxide Propylene oxide
6.19. Epoxidation of Alkenes
Chem 207 B. R. Kaafarani 80
H2C CHCH3
O
CHCH3
O
C
H3C
H3C
1
2 3 4
1,2-epoxypropane 2-methyl-2,3-epoxybutane
Substitutive nomenclature: named as epoxy-substituted alkanes.
“epoxy” precedes name of alkane.
Epoxide Nomenclature
Chem 207 B. R. Kaafarani 81
cis-2-Methyl-7,8-epoxyoctadecane
OH
H
Problem 6.22. Give the IUPAC name, including stereochemistry, for disparlure
Chem 207 B. R. Kaafarani 82
peroxy acidC C +
O
RCOOH
CC
O
+
O
RCOH
Epoxidation of Alkenes
Chem 207 B. R. Kaafarani 83
+ CH3COOH
O
(52%)
+ CH3COH
O
O
Example
Chem 207 B. R. Kaafarani 84
C C +
O
RCOOH
CC
O
+
O
RCOH
syn addition
Stereochemistry of Epoxidation
Chem 207 B. R. Kaafarani 85
peroxy acid
OH H
H H
Problem 6.23. Give the structure of the alkene,including stereochemistry, that you would choose asthe starting material in a preparation of syntheticdisparlure.
Chem 207 B. R. Kaafarani 86
Ethylene H2C=CH2 1
Propene CH3CH=CH2 22
2-Methylpropene (CH3)2C=CH2 484
2-Methyl-2-butene (CH3)2C=CHCH3 6526
More highly substituted double bonds react faster.Alkyl groups on the double bond make it more “electronrich.”
Relative Rates of Epoxidation
Chem 207 B. R. Kaafarani 87
+ O3 C CO
O O
C C
Ozonolysis has both synthetic and analyticalapplications.
- Synthesis of aldehydes and ketones.
- Identification of substituents on the double bond ofan alkene.
6.20. Ozonolysis of Alkenes
First step is the reaction of the alkene with ozone.The product is an ozonide.
Chem 207 B. R. Kaafarani 88
+ O3 C CO
O O
C C
C O CO+
H2O, Zn
Second step is hydrolysis of the ozonide.Two aldehydes, two ketones, or an aldehydeand a ketone are formed.
Ozonolysis of Alkenes
Chem 207 B. R. Kaafarani 89
As an alternative to hydrolysis, the ozonide canbe treated with dimethyl sulfide.
+ O3 C CO
O O
C C
C O CO+
(CH3)2S
Ozonolysis of Alkenes
Chem 207 B. R. Kaafarani 90
1. O32. H2O, Zn
CH3
CH2CH3H
C C
CH2CH3
(38%) (57%)
CH2CH3
CO
CH2CH3
C O
CH3
H
+
Example
Chem 207 B. R. Kaafarani 91
H3C
H3C
KMnO4
AcetoneHO2C CO2H
R
R H
H
NaIO4
OsO4
R OH
H
H
R OH
RO
H
H
RO
I
OH
O
O
2RCHO
C=C bond cleavage
KMnO4: Potassium permanganateNaIO4: Sodium periodateOsO4: Osmium tetroxide
Cyclic periodate intermediate
Chem 207 B. R. Kaafarani 92
Introduction to OrganicChemical Synthesis: RETROSYNTHESIS
Chem 207 B. R. Kaafarani 93
Devise a synthetic plan:- Reason backward from the target molecule.- Always use reactions that you are sure of.
OH
Prepare cyclohexane from cyclohexanol
Chem 207 B. R. Kaafarani 94
Ask yourself the key question:
–"Starting with anything, how can I make cyclohexane in a single step by a reaction that will work?"
Prepare cyclohexane from cyclohexanol
Chem 207 B. R. Kaafarani 95
The only reaction covered so far for preparingalkanes is catalytic hydrogenation of alkenes.
This leads to a new question. "Starting withanything, how can I prepare cyclohexene in a singlestep by a reaction I am sure will work?"
H2
Pt
Prepare cyclohexane from cyclohexanol
Chem 207 B. R. Kaafarani 96
Alkenes can be prepared by dehydration ofalcohols.
The synthesis is complete.
H2SO4
heatOH
H2
Pt
Prepare cyclohexane from cyclohexanol
Chem 207 B. R. Kaafarani 97
(CH3)3COH (CH3)2CCH2Br
OH
"Starting with anything, how can I make thedesired compound in a single step by a reaction thatwill work?"
The desired compound is a vicinal bromohydrin.How are vicinal bromohydrins prepared?
Prepare 1-bromo-2-methyl-2-propanol from tert-butyl alcohol
Chem 207 B. R. Kaafarani 98
(CH3)2CCH2Br
OH
Vicinal bromohydrins are prepared by treatment of alkenes with Br2 in water.
How is the necessary alkene prepared?
Br2
H2O(CH3)2C CH2
Prepare 1-bromo-2-methyl-2-propanol from tert-butyl alcohol
Chem 207 B. R. Kaafarani 99
2-Methylpropene is prepared from tert-butyl alcohol by acid-catalyzed dehydration.
The synthesis is complete.
(CH3)2CCH2Br
OH
Br2
H2O(CH3)2C CH2
(CH3)3COH
H2SO4
heat
Prepare 1-bromo-2-methyl-2-propanol from tert-butyl alcohol
Chem 207 B. R. Kaafarani 100
6.21. Reactions of Alkenes with Alkenes: Polymerization
Cationic polymerization
Free-radical polymerization
Coordination polymerization
Chem 207 B. R. Kaafarani 101
H2SO4
monomer(C4H8)
Dimerization of 2-methylpropene
(CH3)2C CH2
+
two dimers(C8H16)
CH3CCH
CH3
CH3
C(CH3)2 CH3CCH2C
CH3
CH3
CH2
CH3
Dimerization
Chem 207 B. R. Kaafarani 102
+
CH3
H2C C
CH3
CH3C
CH3
+
CH3
CH3CCH2C
CH3
CH3
CH3
CH3
+
Mechanism of Dimerization
Chem 207 B. R. Kaafarani 103
CH3CCH
CH3
CH3
C(CH3)2CH3CCH2C
CH3
CH3
CH2
CH3
CH3CCH2C
CH3
CH3
CH3
CH3
+
Mechanism of Dimerization
Chem 207 B. R. Kaafarani 104
Cationic Polymerization
CH3
H3C
CH3
Cl AlCl3
CH3
H3C
CH3
+AlCl4-
Ar
+
CH3
H3C
CH3
+
AlCl4-
CH3
H3C
H3C +
AlCl4-
ArAr
CH3
H3C
H3C+
AlCl4-
Ar Ar
Ar
Chem 207 B. R. Kaafarani 105
200 °C2000 atm
O2 orperoxides
H2C CH2
polyethylene
CH2 CH2 CH2 CH2 CH2 CH2 CH2
Free-Radical Polymerization of Ethylene
Chem 207 B. R. Kaafarani 106
H2C CH2
RO. H2C CH2
OR
.H2C CH2
OR
.H2C CH2
H2C CH2
OR
.H2C CH2
H2C CH2
H2C CH2
OR
.H2C CH2
H2C CH2
OR
H2C CH2
H2C CH2.
H2C CH2
OR
H2C CH2
H2C CH2.H2C CH2
H2C CH2
OR
H2C CH2
H2C CH2
.H2C CH2
Mechanism
Chem 207 B. R. Kaafarani 107
H2C CHCH3
polypropylene
CH CH2 CHCH2CHCH CH2
CH3 CH3 CH3 CH3
Free-Radical Polymerization of Propene
Chem 207 B. R. Kaafarani 108
H2C CHCH3
RO. H2C CHCH3
OR
. H2C CHCH3
OR
.H2C CHCH3
H2C CHCH3
OR
.H2C CHCH3
H2C CHCH3
H2C CHCH3
OR
.H2C CHCH3
H2C CHCH3
OR
H2C CHCH3
H2C CHCH3.
H2C CHCH3
OR
H2C CHCH3
H2C CHCH3.H2C CHCH3
H2C CHCH3
OR
H2C CHCH3
H2C CHCH3
.H2C CHCH3
Mechanism
Chem 207 B. R. Kaafarani 109
H2C=CHCl polyvinyl chlorideH2C=CHC6H5 polystyreneF2C=CF2 Teflon
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