B F 3 OH 2+
S n C l4 R C l+
Finish the following reactions:
CH 2 C
C H 3
C H 3
§ 4.2 Anionic
polymerization1,Introduction
1877,Wurtz,bases,epoxy ethane
1914,Na,Bd,Ip,St
1940,Ellis,BuLi,ethylene
1952,Higginson,styrene,KNH2,kinetic study
1956,Szwarc,sodium naphthalene,St,
living polymerization conception
60's,commercial SDS products were available
90?s,study on the living polymerization of polar
monomers
(1) History
(2) Carbanion
2,Monomer
(1) Olefin with polar substituent
CH 2 C H
C N
CH 2 C H
N
O O
CH 2 C
C O
C H 3
O C H 3
Acrylonitrile Nitroethene Methyl methacrylate
For example
(2) Conjugated diene
CH2 C H CH 2 C
C H
3
CH 2 C H C H C H 2 CH
2 C H C C H 2
C H 3
styrene a-Me-styrene
butadiene isoprene
(3) Reactivity of monomer (Substituting constant,s)
Group A:
Group B:
CH 2 C ( C N ) 2 CH 2 C
C N
C O O C 2 H 5 CH 2 C H
N O 2
( 1, 2 5 6 )
>
( 1, 1 5 0 ) ( 0, 7 7 8 )
>
CH 2 C H C N CH 2 C
C N
C H 3 CH 2 C H C
O
C H 3
( 0,6 6 )
>
( 0,4 9 ) ( 0,5 0 2 )
>
Group C,CH 2 C H
C O O C H 3
CH 2 C C H 3
C O O C H 3
(0,38 5)
>
(0,21 5)
Group D:
CH 2 C H C H C H 2
CH2 C H
(- 0.01)
CH
2
C
CH
3
(- 0.161)
Group A
Group B and group C
Group D
R
R R,
R R R +,,
>>
>>
Initiator should be
stronger
Stronger or
weaker
only
Reactivity Type of polymerization
3,Initiator and initiation
(1) alkali metal Lithium (Li)
Sodium (Na)
Potassium (K)
a,Species
b,Initiation
c,Solubility
-
Na CH 2 C H
e l e c t r o n
t r a n s f e r
C HC H
2
Na ++,
e
-
Na
-
C H C H 2Na C HC H 2 +
+di m e r i ze
r a di c a l c oupl e
K,soluble in ethers
Li and Na dispersion:
insoluble in hydrocarbon
Solubility of alkali metals
homogeneous or heterogeneous
Reaction on the surface
adsorbtion
reaction
desorption
(2) Alkali metal complex
-
Na Na
+
+ [ ]
co m p l ex (g ree n i sh b l u e co l o r)e
.
preparation
initiator
a,Species
b,Initiation
c,Solubility
Aromatic radical-anions:
Sodium naphthalene
Lithium naphthalene
Alkali metal Aromatic compound
-
Na CH
2
C H
+[ ]
.
+
Initiation:
-
e l e c t r o n
t r a n s f e r
C HC H
2
Na +,+
-
Na
-
C H C H 2Na C HC H
2
++
d i me ri ze
rad i cal co u p l e
soluble in polar solvents only
( such as,ether)
Solubility:
(3) Organometallic compounds
Alkyl metal compound,RLi
Metal amides,NaNH2,KNH2
Grignard reagent,RMgX
a,Species
b,Initiation
c,Solubility
C H
3
C H
2
C H
2
C H
2
Li
-
CH
2
C H
n - B u C H
2
C H Li
-
+
+
i nit i a ti on
(n-B uL i )
+
Initiation:
Soluble in nonpolar solvents
Solubility:
R 3 P R 3 N R O H H O H
..,.,.,.
(4) Nucleophilic initiator
A pair of isolated electrons on the heteroatoms
CH 2 C
C N
C
O
O C 2 H 5 OH
2+ P O L Y M E R
For example:
initiator
(1) Reactivity of initiator
Li,Na,NaR,LiR
RMgX,
ROLi,stronger bases
NR3,weaker bases,H2O
Strongest
weakest
4,Match of initiators and monomers
Table 4-6 (in textbook page 123)
(2) Reactivity of monomer
(3) Match of initiators and monomers
5,Mechanism of polymerization
(1) Initiation
Dissolve only in polar solvents
Dissolve in nonpolar solvents
Fast initiation!
Dicarbanion
Single carbanion
Electron transfer
Electron addition
a,Mechanism b,Number of carbanion
c,Solubility d,Activation energy
< 10 kJ/mol
(2) Propagation Li
C H
2
CH
2
C H
X
+-
? +
Active species exist in ion pair
a,Insertion propagation
C - Na
C
C - Na-
Na
+
+
+
+ M
M
M
M
M
M
Molecular weight
b,Single carbanion and dicarbanion
c,Activation energy
40—80 kJ/mol Fast initiation!
(3) Termination and chain transfer
a,Termination
No couple between two active centers
No fraction in counterions
Li +C Li + C+
CH
2
C H
n - B u L i
Nonpolar monomers polymerize in nonpolar solvents
OH
2C
H
Li
+
C H L i O H
R O HC
H
Li
+
C H R O L i
R C O O HC
H
Li
+
C H R C O O L i
+
+
+
+
+ +
Impurity No termination!
CH
2
C
C
C H
3
O
O M e
?+
?+
LiC H 2 +-
b,Chain transfer
C H
2
C
C
O
CH
3
CH
2 C H
2
C
C H
3
C O O C H
3
CH
3
C O O C H
3
CH
3
O+
The chain transfer reactions rarely happen in a system
with nonpolar monomers and nonpolar solvents
No chain transfer!
Condition,nonpolar monomers,nonpolar solvent
(4) Feature of anionic polymerization
Fast initiation
Slow propagation
No termination
No chain transfer
“living” polymerization
6,Living polymerization
（ 1） Definition
（ 2） application
a,Polymer with mono-distribution of molecular weight
b,Block copolymer
c,Telechelic polymers
d,Theoretical studies
A B-A B-A B-A B +++ +
Covalent
species Tight ion pair
Contact ion pair
Intimate ion pair
Loose ion pair
Solvent-separated
ion pair
Free ion pair
A B- +
Active center
positive counterion,positive charge
State of ion pair
A B
-
A B
-
A B
-
A B
+++
+
+
M
+
M
+
M
POLY ME R I Z A T I O N
rea cti v i ty
ca p ac it y o f
co n tro l l i n g stere o stru ctu re o f p o l y mer ch ai n
Stereo structure of polymer and polymerization rate
A B
-
A B
-
A B
-
A B ++
+
+
p o la rit y o f s o lv e n t
s iz e o f c o u n t e rio n
t e m p e ra t u re ( in n o n p o la r s o lv e n t )
Factors influencing the state of ion pair
(solvent,temperature,counterion)
CH 2 C H
n - B u L i
C H 2 C H
n
n
In cyclohexane,several hours in THF,10 min.
C H
2
C
H
Li
+
C H
2
C
H
Li
+
For example:
S n C l4 R C l+
Finish the following reactions:
CH 2 C
C H 3
C H 3
§ 4.2 Anionic
polymerization1,Introduction
1877,Wurtz,bases,epoxy ethane
1914,Na,Bd,Ip,St
1940,Ellis,BuLi,ethylene
1952,Higginson,styrene,KNH2,kinetic study
1956,Szwarc,sodium naphthalene,St,
living polymerization conception
60's,commercial SDS products were available
90?s,study on the living polymerization of polar
monomers
(1) History
(2) Carbanion
2,Monomer
(1) Olefin with polar substituent
CH 2 C H
C N
CH 2 C H
N
O O
CH 2 C
C O
C H 3
O C H 3
Acrylonitrile Nitroethene Methyl methacrylate
For example
(2) Conjugated diene
CH2 C H CH 2 C
C H
3
CH 2 C H C H C H 2 CH
2 C H C C H 2
C H 3
styrene a-Me-styrene
butadiene isoprene
(3) Reactivity of monomer (Substituting constant,s)
Group A:
Group B:
CH 2 C ( C N ) 2 CH 2 C
C N
C O O C 2 H 5 CH 2 C H
N O 2
( 1, 2 5 6 )
>
( 1, 1 5 0 ) ( 0, 7 7 8 )
>
CH 2 C H C N CH 2 C
C N
C H 3 CH 2 C H C
O
C H 3
( 0,6 6 )
>
( 0,4 9 ) ( 0,5 0 2 )
>
Group C,CH 2 C H
C O O C H 3
CH 2 C C H 3
C O O C H 3
(0,38 5)
>
(0,21 5)
Group D:
CH 2 C H C H C H 2
CH2 C H
(- 0.01)
CH
2
C
CH
3
(- 0.161)
Group A
Group B and group C
Group D
R
R R,
R R R +,,
>>
>>
Initiator should be
stronger
Stronger or
weaker
only
Reactivity Type of polymerization
3,Initiator and initiation
(1) alkali metal Lithium (Li)
Sodium (Na)
Potassium (K)
a,Species
b,Initiation
c,Solubility
-
Na CH 2 C H
e l e c t r o n
t r a n s f e r
C HC H
2
Na ++,
e
-
Na
-
C H C H 2Na C HC H 2 +
+di m e r i ze
r a di c a l c oupl e
K,soluble in ethers
Li and Na dispersion:
insoluble in hydrocarbon
Solubility of alkali metals
homogeneous or heterogeneous
Reaction on the surface
adsorbtion
reaction
desorption
(2) Alkali metal complex
-
Na Na
+
+ [ ]
co m p l ex (g ree n i sh b l u e co l o r)e
.
preparation
initiator
a,Species
b,Initiation
c,Solubility
Aromatic radical-anions:
Sodium naphthalene
Lithium naphthalene
Alkali metal Aromatic compound
-
Na CH
2
C H
+[ ]
.
+
Initiation:
-
e l e c t r o n
t r a n s f e r
C HC H
2
Na +,+
-
Na
-
C H C H 2Na C HC H
2
++
d i me ri ze
rad i cal co u p l e
soluble in polar solvents only
( such as,ether)
Solubility:
(3) Organometallic compounds
Alkyl metal compound,RLi
Metal amides,NaNH2,KNH2
Grignard reagent,RMgX
a,Species
b,Initiation
c,Solubility
C H
3
C H
2
C H
2
C H
2
Li
-
CH
2
C H
n - B u C H
2
C H Li
-
+
+
i nit i a ti on
(n-B uL i )
+
Initiation:
Soluble in nonpolar solvents
Solubility:
R 3 P R 3 N R O H H O H
..,.,.,.
(4) Nucleophilic initiator
A pair of isolated electrons on the heteroatoms
CH 2 C
C N
C
O
O C 2 H 5 OH
2+ P O L Y M E R
For example:
initiator
(1) Reactivity of initiator
Li,Na,NaR,LiR
RMgX,
ROLi,stronger bases
NR3,weaker bases,H2O
Strongest
weakest
4,Match of initiators and monomers
Table 4-6 (in textbook page 123)
(2) Reactivity of monomer
(3) Match of initiators and monomers
5,Mechanism of polymerization
(1) Initiation
Dissolve only in polar solvents
Dissolve in nonpolar solvents
Fast initiation!
Dicarbanion
Single carbanion
Electron transfer
Electron addition
a,Mechanism b,Number of carbanion
c,Solubility d,Activation energy
< 10 kJ/mol
(2) Propagation Li
C H
2
CH
2
C H
X
+-
? +
Active species exist in ion pair
a,Insertion propagation
C - Na
C
C - Na-
Na
+
+
+
+ M
M
M
M
M
M
Molecular weight
b,Single carbanion and dicarbanion
c,Activation energy
40—80 kJ/mol Fast initiation!
(3) Termination and chain transfer
a,Termination
No couple between two active centers
No fraction in counterions
Li +C Li + C+
CH
2
C H
n - B u L i
Nonpolar monomers polymerize in nonpolar solvents
OH
2C
H
Li
+
C H L i O H
R O HC
H
Li
+
C H R O L i
R C O O HC
H
Li
+
C H R C O O L i
+
+
+
+
+ +
Impurity No termination!
CH
2
C
C
C H
3
O
O M e
?+
?+
LiC H 2 +-
b,Chain transfer
C H
2
C
C
O
CH
3
CH
2 C H
2
C
C H
3
C O O C H
3
CH
3
C O O C H
3
CH
3
O+
The chain transfer reactions rarely happen in a system
with nonpolar monomers and nonpolar solvents
No chain transfer!
Condition,nonpolar monomers,nonpolar solvent
(4) Feature of anionic polymerization
Fast initiation
Slow propagation
No termination
No chain transfer
“living” polymerization
6,Living polymerization
（ 1） Definition
（ 2） application
a,Polymer with mono-distribution of molecular weight
b,Block copolymer
c,Telechelic polymers
d,Theoretical studies
A B-A B-A B-A B +++ +
Covalent
species Tight ion pair
Contact ion pair
Intimate ion pair
Loose ion pair
Solvent-separated
ion pair
Free ion pair
A B- +
Active center
positive counterion,positive charge
State of ion pair
A B
-
A B
-
A B
-
A B
+++
+
+
M
+
M
+
M
POLY ME R I Z A T I O N
rea cti v i ty
ca p ac it y o f
co n tro l l i n g stere o stru ctu re o f p o l y mer ch ai n
Stereo structure of polymer and polymerization rate
A B
-
A B
-
A B
-
A B ++
+
+
p o la rit y o f s o lv e n t
s iz e o f c o u n t e rio n
t e m p e ra t u re ( in n o n p o la r s o lv e n t )
Factors influencing the state of ion pair
(solvent,temperature,counterion)
CH 2 C H
n - B u L i
C H 2 C H
n
n
In cyclohexane,several hours in THF,10 min.
C H
2
C
H
Li
+
C H
2
C
H
Li
+
For example:
