Living Anionic Polymerization of Benzofulvene:
Highly Reactive Fixed Transoid 1,3-Diene
Yuki Kosaka, Keita Kitazawa, Sotaro Inomata, and Takashi Ishizone*
ACS Macro Lett. 2013, 2, 164−167
Advisor : Professor Guey-Sheng Liou
Speaker : Yi-Chun Yeh
Date : 2014.12.26
Outline
• Author
• Anionic polymerization
• Living anionic polymerization
• Introduction
• Synthesis process
• SEC data
• Copolymerization
• Free radical & Anionic polymerization
• Concluding Remarks
1
Author
• He was born in Saitama, Japan, in April, 1963.
•
He received his M.S in polymer chemistry from Tokyo Institute of
Technology in 1988 under supervision of Professors Seiichi Nakahama and
Akira Hirao and started his academic career as Assistant Professor from
1989.
• After receiving doctorate degree in 1994, he spent a postdoctoral research
at The University of Chicago with Professor P. E. Eaton on organic
chemistry in 1995.
• Since 2000 he is Associate Professor of Department of Organic and
Polymeric Materials at Tokyo Institute of Technology. His current research
interests are centered on
石曽根 隆
synthesis of novel thermally-stable polymers possessing adamantyl groups
Takashi Ishizone
synthesis of novel water-soluble thermo-responsive polymers by means of
living anionic polymerization.
2
Anionic polymerization
Anionic polymerization is a form of chain-growth polymerization or addition
polymerization that involves the polymerization of vinyl monomers with strong
electronegative groups.
This polymerization is carried out through a carbanion active species.
A B
+ CH2
CH
Y
B
CH2
CHA
Y
(n -1)CH2
CHX
CH2
CH
Y
n
Anionic polymerizations are used in the production of polydiene synthetic rubbers, solution
styrene/butadiene rubbers (SBR), and styrenic thermoplastic elastomers.
3
Anionic polymerization
The reactivity of initiators used in anionic polymerization should be similar
to that of the monomer is the propagating species.
The least reactive monomers have the largest pKa values for their
corresponding conjugate acid and thus, require the most reactive initiator.
Initiation by Electron Transfer
Initiation involve the transfer of an electron from the alkali metal to the
monomer to form an anion-radical.
Initiation by Strong Anions
The initiation process involves the addition of a neutral (B:) or negative (B:-)
nucleophile to the monomer.
Nucleophilic initiators include metal amides, alkoxides, and organometallic
compounds (alkyllithium compounds and Grignard reagents).
4
Anionic polymerization
Anionic polymerization characteristics that distinct from free radical polymerization :
1. High selectivity of monomers
2. Water can’t exist in the reaction system
3. Polymerization rate fast, low activation energy, usually occurs in
low temperature
4. Without termination or chain transfer
By controlling the effects of counterion, solvent, temperature, Lewis base additives,
and inorganic solvents, increase the potential of anionic polymerizations
5
Living Anionic polymerization
Living polymerization of features:
rapid initial, slow growth, no termination, no transfer reaction.
Monomer had been consumed, the anion remains active. Add new monomers,
polymerization can continue; molecular weight increased with conversion in present,
narrow molecular weight distribution; the end groups of the polymer, the composition,
structure and molecular weight can be controlled.
6
Introduction
Fulvene (FV), C6H6 one of isomer of
Benzene, show high reactivity toward
various derivatives.
(strongly polarized!)
Nakano, T.; Yade, T.; Fukuda, Y.; Yamaguchi, T.; Okumura, S.
Macromolecules 2005, 38, 8140−8148.
Possible to anionic polymerization
Fixed Transoid
1,3-Diene
Only 1,2-addition!
Nakano, T.; Yade, T.;
Fukuda, Y.; Yamaguchi,
T.; Okumura, S.
Macromolecules 2005,
38, 8140−8148.
7
Synthesis process
8
SEC
Table 1. Anionic Polymerization of BF in THF at −78 °C for 1 ha
∼ 100%.
bMn(calcd) = (MW of monomer) × [M]/[I] + MW of initiator.
cMn(obsd) was determined by SEC-RALLS equipped with refractive index (RI), light
scattering (LS), and viscometer detectors.
dMw/Mn was determined by SEC calibration using polystyrene standards in THF.
eFor 15 h.
fFor 20 h.
aYield
9
Copolymerization
Poly(MMA)-block-poly(BF)
Scheme 1. Block Copolymerization of BF with
Living Poly(MMA)
Poly(MMA)
Poly(BF)-block-poly(MMA)
Poly(BF)
relative acidity of conjugated acid for indene (pKa = 20.1)
is significantly higher than that of ethyl acetate (pKa = 24.4)
Anionic polymerizability of BF was remarkably
high and comparable to that of MMA.
10
Free radical & Anionic polymerization
Poly(BF-a)
Poly(BF-r)
Polymerization modes of BF and four possible diad units in poly(BF).
11
Concluding Remarks
• we have succeeded in the living anionic polymerization of a
novel exomethylene monomer, BF, to afford polymers with
predicted molecular weights and narrow MWDs.
• The extremely high anionic polymerizability of this
hydrocarbon is newly demonstrated and comparable to
MMA.
• BF acts as a conjugated 1,3-diene to give only polymers
containing the 1,2- and 1,4-addition modes.
12
Thank you!
1
3
1
1
2
2
3
2
4
3
4
4
addition
陰離子聚合
自由基
addition
陰離子聚合
自由基
addition
陰離子聚合
自由基
1,2
76 %
19 %
1,2
20 %
28 %
1,2
41 %
9%
1,4
24 %
81 %
1,4
X
10 %
1,4
59 %
91 %
3,4
80 %
62 %
對diene來說1,2加成和1,4加成的介穩態是
相同的，溫度提高，單體會有更多機會進
行1,4加成。(動力學)
而對此單體2號為有大的立體障礙，所
以3、4位置的雙鍵反應性較高。
考慮中間體的穩定性，對自由基來說2
號位(三級碳)穩定，因此1,2加成比例
提高。除此之外，還要考慮動力學。
BF是上個單體環化後的
結果，反而環外的1、2
位的雙鍵反應性較高。
，以4n+2的規則來看，
2號位的碳陰離子穩定
性提高，而自由基反而
穩定性下降，傾向1,4加
成。
須綜合考慮動力學及單體中間體的穩定性(反應性)