LIVING POLYMERIZATION OF POLAR
MONOMERS CATALYZED BY RARE EARTH
BIS (CYCLOPENT ADIENYL) METAL COMPLEXESA Doctoral Thesis

by
MASAHIRO YAMASHITA

Department of Applied Chemistry,
Faculty of Engineering, Hiroshima University

1995

LIVING POLYMERIZATION OF POLAR
MONOMERS CATALYZED BY RARE EARTH
BIS(CYCLOPENTADIENYL)METAL COMPLEXESA Doctoral Thesis
by

MASAHIRO YAMASHITA

Department of Applied Chemistry,
Faculty of Engineering, Hiroshima University
1995

Acknowledgement

This research has been performed under the
direction of Professor Dr. Hajime Yasuda at the
Department of Applied Chemistry, Faculty of Engineering,
Hiroshima University.
The author is greatly indebted to Professor Hajime
Yasuda for his constant guidance, helpful suggestion andencouragement throughout this study.

The author isdeeply grateful to Dr. Eiji Ihara for his constantadvice and valuable discussions during the course ofthis study.

The author also thanks Dr. Hitoshi Yamamotofor giving me the information concerning the techniques
for experiments.

Thanks are extended to all the membersof Yasuda laboratory for their helpful discussions andkind friendships.
Finally, the author expresses his deep appreciation
to his parents, Mr. Katsutoshi Yamashita and Mrs. Yasuko
Yamashita, and to his wife Mrs. Aiko Yamashita for theirconstant assistance and encouragement.

~

r

1/

~~

YAMASHITA, Masahiro

Department of Applied Chemistry,
Faculty of Engineering,
Hiroshima University
January, 1995

CONTENTS

Chapter 1

Chapter 1

General Introduction

1

General Introduction
Chapter 2

Living Polymerization of Lactones

7

Organometallic chemistry of rare earth element had

Catalyzed by Rare Earth Metal Alkyl

attracted little attention before 1980.

Complexes.

In general, theisolation of rare earth metal complexes was difficult
Chapter 3

Living Polymerization of Lactones

50

because of their strong tendency to form ate complexes

Catalyzed by Rare Earth Metal Alkoxideowing to the high Lewis acidity and the large ionicComplexes.

radius of the element.

Characterization of thecomplexes was also troublesome due to their low
Chapter 4

Polymerization of Methyl Methacrylate

75

solubility to organic solvent.

Moreover, rare earth

Catalyzed by Rare Earth Metal Enolate

metal complexes have been thought to exhibit only

Complexes.

analogous reactivity to Grignard or organolithium
reagents.

Chapter 5

Living Polymerization of Trimethylsilyl

100

Use of cyclopentadienyl ligands (CsHs and CsMe s ) has

Substituted Methacrylate Catalyzed bychanged the situation since 1980.

Rare Earth Metal Complexes.

complexes with these ligands are soluble in organic
solvent.

Rare earth metal

A large number of rare earth metal complexes

have been synthesized and their structures wereList of Publications

characterized by X-ray analysis.

In addition, thereactivities characteristic of these complexes have been
revealed l ).

Various interesting reactions of thecomplexes with unsaturated compounds have beendeveloped.

In particular, catalytic activity for olefin

polymerization has been attracted much attention sincerare earth metal complexes show the activity without any-1-

Chapter 1

Chapter 1

General Introduction

General Introduction

polymerization of methyl methacrylate are also described.

cocatalyst and their activity is comparable to that ofZiegler type catalyst 2 ).
On the other hand, our group has developed polymerization of polar monomers by rare earth metal complexes.
Living polymerization of methyl methacrylate has beenachieved by the use of initiators such as [8mB (C SMe S )2]2
and 8mMe(C sMe s )2(THF).

High molecular weight (~ > 105)poly(methyl methacrylate) (PMMA) with extremely narrow
molecular weight distribution
obtained.

(~/~< 1.05) was

Furthermore, the polymerization proceeded Ina stereoselective manner giving highly syndiotactic PMMA
(rr~95%) .

1: 2 adduct of 5mB (CsMe s ) 2 and methyl meth--acrylate was isolated and its structure was identified
by X-ray analysis and it was revealed that the polymerization proceeded through samarium enolate as anpropagating species 3 ).
Judging from the above successful result of me't hyl
methacrylate polymerization, further extension of thisstudy is desirable.

In this thesis, I focused on theapplication of the rare earth metal ini tiating
lactone monomers4).

systE~mto

Living polymerization of themonomers are described and the exact mechanism of thepolymerization is discussed on the basis of stoichiometric reaction.

In addition, I examined polymerizationof protected methacrylate monomers which afforded poly(methacrylic acid) or its derivatives after
deprotection.

Some related investigations about

-2-

-3-

Chapter 1
General Intrcxiuction

Chapter 1
General Intrcxiuction

propagation mechanisms are discussed.
Chapter 4 describes the polymerization of methyl

Outline of Each Chapter

methacrylate catalyzed by organo rare earth metal
Chapter 2 describes the living polymerization ofenolate complexes Sm( OCR' =R" 2) (CsRs ) 2(R=H, Me), as has been

lactones catalyzed by organo rare earth metal alkyl

indicated as the active species of polymerization ofcomplexes.

methacrylate in the previous work.

Polymerization of o-valerolactone and E-

solvent was also investigated in this part.

caprolactone catalyzed by SmMe(C sMe s )2(THF) or [8mB
(C S Me S )2]2 gave polyesters with very narrow polydispersity(~/~ < 1.05) and high molecular weight (~ > lOs).

The

Chapter 5 describes the living polymerization oftrimethylsilyl substituted methacrylate catalyzed byorgano rare earth metal complexes.

fact that the number average molecular weight increases
linearly in proportion to the conversion indicates that
this polymerization proceeds in a living fashion.

Basedon the stoichiometric reactions of rare earth metal
complexes with the monomers , initiation and propagat,ion
mechanisms are discussed for this system.
Chapter 3 describes the living polymerization of
lactones catalyzed by organo rare earth metal alkoxide

synthesized by conventional anionic polymerization was
obtained upon hydrolysis.

Based on the stoichiometric

reactions of rare earth metal complexes with themonomers, the possibility of block copolymerization of
methyl methacrylate and trimethylsily~ethacrylate wasdiscussed.

Polymerization of 0-

valerolactone and E-caprolactone catalyzed by YOMe(C s Rs )2(R=H,Me) gave polyesters with very narrow polydispersity
and high molecular weight.

The fact that the number

average molecular weight increases linearly inproportion to the conversion indicates that thispolymerization system belongs to the living system.
Based on the stoichiometric reactions between rare earth
metal alkoxide and the monomers, initiation and-4-

In this case,monodispersed poly(methacrylic acid) which has not been

complexes, Ln(OR)(C sR's)2' as has been indicated as
active species in chapter 2.

The effect of-5-

Chapter 1
General Intrcx:iuction

References

Chapter 2

1) Molander G. A. Chern. Rev., 1992, 92, 29.
2) Jeske, G.; Shrock, L.

E.; Swepston,

P. N. Schumann,H.; Marks, T. J. J. Am. Chern. Soc., 1985,
107, 8091.
3) (a)Yasuda, H.; Yamamoto, H.; Yokota, R.,. Miyake,

Living Polymerization of Lactones Catalyzed byRare Earth Metal Alkyl complexes

S. ;Nakamura, A. J. Am. Chem. Soc., 1992, 114, 4908.
(b)Yasuda, H.; Yamamoto, H.; YamashitaM.
., Yokota,R.; Nakamura, A.; Miyake, S.; Rai, Y.,· Kanehisa

Introduction

Macromolecules, 1993, 26, 7134.

Ring-opening polymerization of lactones such as £-

,

, N.

(c)Yasuda, H.;

Yamamoto, H.; Takemoto, Y.; Yamashita, M.; Yokota,

caprolactone, o-valerolactone, andR.; Miyake, S.; Nakamura, A. Macromol. Chern.,

provides a convenient route to biodegradable polyesters

Macramal. Symp. 1993, 67, 187. (d)Yasuda, H.; Ihara
E.; Yoshioka, S.; Nodono, M.; Morimoto M.

which are of great interest for a variety of practical,

Yamashita, M.

.,

Catalyst Design for Tailor-madePOlyolefins , 1994, 237-248.

4) Yasuda, H.; Tamai, H. Prog. Polym.
42, 2265.

.

Sc~.,

~-propiolactone

applications. 1-4) These lactones can be polymerized by
the use of initiators such as alkalimetal,5) alkaline
earth metal,5) AlR 3 -H 2 0, 6) aluminum-porphyrin, 7) dialkyl-

Japan, 1993,

zinc-H 2 0 8 )and CpTi(OR)Cl/) systems.

Recently, it has

been reported that lanthanide alkoxide(III)l O) andorganolanthanide (II) complexes ll ) can be used as
extremely active catalysts for the living polymerizationof these monomers.
A series of organo rare earth metal (III) complexes
shows excellent catalytic activity for living polymerization of methyl methacrylate which leads to highly
syndiotactic polymers with very narrow polydispersity
and high molecular weight.

In this study I haveexamined the catalytic action of organo rare earth metal
-6-

-7-

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare EaIti Metal Alkyl Complexes

complexes in polymerization of lactones, in order torealize the living polymerization and to obtain highmolecular weight polymers with extremely narrow polydispersity.

stoichiometric reactions were also

investigated to learn the initiation and propagation
mechanism for the lanthanide assisted polymerization.
Ul~

I describe herein the efficient catalytic activity

o

+J

cd

of organo rare earth metal (III) complexes towards the

.r!
+J
.r!

ring opening polymerization of lactones, which provides

I=!
'r!

high molecular weight polyesters with extremely narrow
molecular weight distribution 12 ).

r-1

cd

This chapter also

+J

OJ

8

deals with the initiation mechanism for polymerization

..c:

+J

of caprolactone and valerolactone by [SmH(C SMe S )2]2' SrnMe-

~

cd
ill

(CsMe s ) 2 ( THF), LuMe ( CsMe s ) 2 (THF ) and YMe ( CsMe s ) 2 (THF )

ill
H
cd

(Figure 1).

~

o

I=!
cd

ty\

~

o

-8-

-9-

Chapter 2

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

IT:

Results and Discussion

IT:

IT:

o

IT:

Ul

o

(l)

x
(l)

r1

~
o

Rare Earth Metals Initiated Polymerizationof Lactones.

u

Organo rare earth metal (III) complexes(l)Isuch as [ 8mB ( CsMe s ) 2] 2' LnMe (CsMe s ) 2( THF ) (Ln = 8m, Yb, Y,~I~ILu) and Ln (C sMe s ) 2Me 2AlMe2 (Ln = Sm, Yb, Y, Lu) were found
+

:r:

(~

~/~ =

1.02, in

~

+J

~

cU

~I

r1

o
~

cU
tJI

Qrr

> 50,000) with extremely

narrow molecular weight distribution,

~

..c

/
I
IT:

IT:

a wide range of polymerization temperature to give highmolecular weight polymers

. .1

0

I

to polymerize methyl methacrylate in a living mannE!r at

'D

I

IT:

0

~

o

:>;

.0

'D

(l)

high conversion in a short period (Table 1) 13) •

This

N

:>-t

r1

type of polymerization was first realized by the effect

cO
+J
cO

of large ionic radius of rare earth metal elementU~otogether with large steric bulk of auxiliary ligand(C sMe s ) in the complexes.

. .1

+J

In order to explore the

cO
N

. .1

applicability of the initiating system, ring opening~(l)

Table 2 shows the result of lactone polymerization
by rare earth metal complexes.

Both c-caprolactone and~Cr:polymerization of various lactone monomers was examined.

I

"

o

I

o

II

I

0
0

"o

r1

0

o={)

/

II

I

tJl

o

~

o

.r-1

:>

o-valerolactone can be polymerized efficiently giving

. .1

H
::J

high molecular weight polyesters with narrow molecularweight distribution.
molecular weight
(~/~)

~

(~)

In Figure 3, number averageand molecular weight distribut.ionof the polymers are plotted against conversion.

-1

IT:

I

~

E

N

I

CJ)

- I

~

>- 0
II

c

-1

1\

a:

increases linearly with the conversion while ~/~lvalue remains below 1.10.

These results indicate that

-10-

o

~

-11-

Table 1. Characterization of Poly(methyl methacrylate) Initiated by Organo Rare
Earth Metal (III) a)

10-3~

Mw/~

0

77

1.03

82.4

16.8

0.8

98(lh)

-95

41

1.04

93.7

6.3

0.0

97(150h)

0

52

1.03

82.8

16.8

1.0

96(2h)

-40

105

1.06

88.6

11.2

0.2

98(8h)

0

48

1.04

84.8

14.3

0.9

99(2h)Yb (CsMe s ) 2Me2AlMe2

0

55

1.04

84.3

14.9

0.8

93(2h)

LuMe (CsMe s ) 2(THF)

0

61

1.04

83.7

15.8

0.5

98(2h)Lu (CsMe s ) 2Me2AlMe2

0

51

1.04

83.2

16.1

0.7

98(2h)

Y(CsMe s ) 2Me2AlMe2

0

53

1.03

84.7

14.5

0.8

99(2h)[YMe(C sHs )2]2

0

82

1.22

76.3

21.3

2.4

98(2h)

initiators

temp. 1°C

[ 8rnH ( CsMe s ) 2] 2
8rnMe (CsMe s ) 2(THF)
I
f-l

rv

YbMe (CsMe s ) 2(OEt 2)

ItacticitYl %
rr
rrn
rom

conversion, %a)Reaction conditions: initiator concentration, 0.2 mol% of monomer;
solvent, toluene.

Table 2. polymerization of Lactones Initiated by Organo Rare
Earth Metal (III) a)
10-3~
lvt/~
temp. 1°C
monomer
initiator

conversion, %

4.0

1.04

7.2(5h)

0

56.1

1.16

6S.8(5h)

0

78.0

1.lS

93.0(7h)

20

7S.2

1.07

80.1(5h)

0

72.8

1.09

61.S(Sh)

0

86.9

1.09

80.3(7h)

20

130.1

1.06

94.8(Sh)

20

71.1

1.19

28.7(5h)[8mB (CsMe s ) 2] 2

f-caprolactone
f-caprolactone

20

18.3

1.29

4.6(5h)[ YbMe ( C5 Me 5 ) 2 ] 2

8mMe (C 5 Me s ) 2(THF)~-propiolactone

0

B-butyrolactone

0o-valerolactone
I
f-l

w
I

f-caprolactone

0.2 mol% ofa)Reaction conditions: initiator concentration,
monomer; solvent, toluene.

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

the polymerization proceeded in a living manner.

Figure4 shows the relationship between ~ and catalyst
concentration.

It is clearly seen that ~ of thepolymer can be controlled by changing the feed ratio of

c 1.20~ 1.10~~ 1.00~monomer to initiator.

50

0

Cd

100

100

The molecular weight distribution varies with thechange of polymerization temperatures, i.e. themolecular weight distribution becomes wider,~/~=

1.70, when polymerization was conducted at 50°C while
it becomes narrower(~/~= 1.08) when the polymer-

ization was carried out at 0 °C (Table 3, Figure 5).

75

In contrast to the above results of valerolactone
a

(Y)

0

and caprolactone, polymerization of ~-propiolactone has~............

c50

failed with organo rare earth metal complexes such as~

SmMe ( CsMe s ) 2(THF ) or [SmB ( CsMe s ) 2] 2.

bstarted.

25

No initiation

On the other hand, high molecular weight poly(~-propiolactone)

was obtained by the use of rare earth

metal alkoxide complexes such as SmOEt(C sMe s )2(Et 20),oo~----~------~------~----~

50

100

Conversion (%)

Fig. 3 Conversion vs Mn and Mw/Mn plot (a)SrnMe(C s Me S )2(THF) 0.2 mol% (b)O.S mol% (c)1.0 mol%

[YOMe (CsHs) 2] 2 and YOMe (CsMe s ) 2(THF) .

Rare earth metal

alkoxide initiated polymerization will be described inchapter 3.

Random Copolymerization of Lactones with
Polar Monomers.

The random copolymerization ofcaprolactone with valerolactone was performed withSmMe(C sMe s )2(THF) in order to find the respective monomer

-14-

-15-

Table 3. Effect of Polymerization Temperature a )temp.jOC
10 -3~~j~conversion, %
-78
1.2

I

c

~

1.1 -

~

1

•

•

•

-

I

o

86.9

1.09

BO.3

20

109.4

1.10

92.0

50

205.1

1.70

92.B

a)Reaction conditions: initiator SrnMe(C S Me s ) 2(THF),
initiator concentration, 0.2 mol% of monomer;
solvent, toluene; polymn. time, 7h.

150

•...

trace

90.1%(1h)93.6% (2h)• 80.3% (7h)
C"')

0
T""-

c
---~

75

o

o

3

6

1/( catalyst concentration) (1 /mol%)I

22

Fig. 4

Catalyst concentration vs. Mn andplots.

-16-

M~/Mn

26

30

22

26

24

28

Elution volume/ml
Fig. 5 GPC profile of poly(caprolactone)-17-Chapter 2

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

reactivity ratios (Table 4).
and r 2(CL)=As a result, r1(VL)

=:

2.82

0.20 (r 1• r 2 = 0.56) were obtained to indicatethat reactivity of o-valerolactone was much higher thanthat of £-caprolactone (Figure 6).
Al though homopolymerization of f3-propiolacton~2 hasfailed with organo rare earth metal complexes such as
8rnMe (CsMe s ) 2(THF) or [8mB (CsMe s ) 2] 2' random copolymerization with caprolactone or valerolactone occurred
easily.

Table 4. Random Copolymerization of Valerolactone(VL) with Caprolactone(CL) a)
VL/CL
VL/CL
10-3~
M..,/~(in monomer) (in polymer)
10/90

33/67

27.0

1.07

25/75

56/44

44.9

1.04

50/50

83/17

59.4

1.08

75/25

87/13

34.9

1.09

a)Reaction conditions: initiator SrnMe(C s Me s )2( THF),
initiator concentration, 0.1 mol% of monomer;
solvent, toluene.

The random copolymerization of propiolactone iNith
valerolactone was performed with SrnMe(C sMe s )2(THF) in
100

order to find the respective monomer reactivity rat.ios(Table 5).

As a result, r1(PL) = 6.73 and r 2(VL) = 0.32

(r 1·r 2 = 2.14) were obtained to indicate that reactivityof f3-propiolactone was much higher than that of 0valerolactone (Figure 7).

And the random copolymer-

ization of propiolactone with caprolactone was performed

~

•

<D

E

~

0

0....

c
-:!2.

°<D

50

C

0

-+-J

wi th SrnMe ( CsMe s ) 2 (THF ) in order to find the respective
monomer reactivity ratios (Table 6).

As a result,r 1( PL ) = 96. 6 and r 2( CL ) = O. 22 (r 1· r 2 = 21. 5) were

()

cu

0
loo<D

cu

>

0

obtained to indicate that reactivity of f3-propiolactone

0

was much higher than that of £-caprolactone (Figure 8).

50

100

Valerolactone % in Monomer

These results indicate that smaller ring lactone
which is highly strained readily polymerize.

-18-

Fig. 6

Copolymer composition curve for rancopoly(valerolactone/caprolactone)-19-

Table 5. Random Copolymerization of Propiolactone(PL) with Valerolactone(VL)a)Table 6. Random Copolymerization of propiolactone(PL) with Caprolactone(CL) a)
PL/CL
PL/CL
10 -3 ~~/~
(in monomer)(in polymer)
1.12
10/90
19/81
22.2

PL/VL
(in monomer)
10/90

PL/VL
(in polymer)
8/92

10-3~

Mw/~

20.3

1.08

25/75

54/46

10.6

1.54

25/75

98/2

3.32

1.17

50/50

88/12

6.73

1.16

50/50

99/1

4.52

1.13

75/25

95/5

6.02

1.38

75/25

100/0

5.26

1.12

a)Reaction conditions: initiator SrnMe(C s Me s )2(THF),
initiator concentration, 0.05 mol% of monomer;
solvent, toluene.

a)Reaction conditions: initiator SrnMe(C S Me s ) 2(THF),
initiator concentration, 0.05 mol% of monomer;
solvent, toluene.

:......

:I-

Q)

Q)

E

E

>-

0

0...

0...

c

c

Q)

--

>-

0

~
a

-

100

100

~
a

50

Q)

50

C

C

0
.....
0

0
.....
0

C'd
0
0...

C'd
0

on.

0
:......

:......

0...

0...

•

0

•

0
0

0
50

100

Copolymer composition curve for rancopoly(propiolactone/valerolactone)

-20-

I

0

50

100

Propiolactone % in Monomer

Propiolactone % in Monomer
Fig. 7-

Fig. 8

Copolymer cc,mposi tion curve for rancopoly(propiolactone/caprolactone)-21-Cha pter 2
Living Polymerization of Lac tones Catalyze d by Rare Earth Metal Alkyl Compl exes

Block Copolymerization of Lactones with
Polar Monomers.

Block copolymerization between

capro l actone and valerolactone proceeded smoothly glvlng
AB type block copolymers (Table 7).
Next, block copolymerization of lactones withmethyl methacrylate was examined.

('Y")

r-I

If)

co

Addition of laci:one

monomer after polymerization of methyl methacrylate
resulted in the formation of poly(methyl methacrylate)poly(lactone) AB type block copolymer.

On the other

hand, monomer addition in the reverse order afford€~d
only poly(lactone) homopolymer.

These results clearly

indicate that the metal-alkoxide end group of lactone
polymerization can not initiate the polymerization of
methyl methacrylate, while metal-enolate end group of
methyl methacrylate polymerization can initiate the ring

co

co

r--

N

N

0

N
('Y")

If)

r--

co

r-I

o

en

Q)

r::

o

+J

o

r-I

N
N

cd

H

4-l

o
r::
o

·rl

+J
cd

o

r--

('Y")
0

If)

('Y")

0\
0

If)

N

o

0

r-I

r--

co

co

co

co

N

opening polymerization of lactones.

·rl

H

~

.-i

Initiation Mechanism for the Polymerizationof Lactones.

Initiation mechanism for polymerizationof various lactones by SmH(C SMe S )2 was examined first.
The addition and reaction of equimolar valerolactone to

o
~-;
o en

U

.Y:

o

~

o

('<1

I

o

r-I

H
H

~

If)

r-I

r-I

H

Q)

e0

o r::
0
:s

.-i
~

H
U

I

the samariumhydride was conducted at -78°C in toluene.

~..........
cd

After continuing the reaction for 30 min, the reaction
mixture was hydrolyzed with water to give 1,5-pentanediol In ca. 50 % yield, and 1,6-hexanediol in the caseof caprolactone in place of 5-hydroxyhexanol and 6hydroxyheptanol, respectively (Figure 9).

-22-This result-23-Chapter 2

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

strongly indicates occurrence of reduction at the

I

o

I

o

carbonyl group.

By contrast to the reaction of SrnH-(C SMe S )2' reaction of SmMe(C sMe s ) 2(THF) with valerolactone
or caprolactone gave 5-hydroxy-2-hexanone o r 7-hydroxy2-heptanone upon hydrolysis of the product.

Therefore,Q)calkyl addition to carbonyl group occurs preferentially,uin this case.

0
+J

0

0

I

~

I

0

N

::c

:0

::c

U

0

u
0

00

00

tI

tI

\E

/(J)",°0 °0(Figure 10)

To understand the mode of alkyl addition, the 1:1

Q)

r-l

cO

reaction of valerolactone and a diamagnetic complex,..r::

LuMe(C sMe s )2(THF), was carried out and monitored by NMR'M

spectroscopy (Figure 11).

+J
~
N
N

l[)

OJ

::s
u
::c
S
(J)

SrnMe(C sMe s ) 2(THF) can not be

used for this purpose because of the paramagnetic natureof this species.

As a result, it was observed thatlanthanide methyl group added to the carbonyl group ofvalerolactone forming an acetal linkage (ketonic carbon
did not appear at around 140-149 ppm in 13 C NMR

~

0

c
0

+

spectrum).

In addition, the reaction of YMe(C sMe s )2(THF)'M

was carried out, and gave the same result as that ofU

LuMe (CsMe s ) 2 (THF)

+J

~~
/(J)\
I

H

l[)

/
+

0

>

0

N

cO

r-l

cO
Q)

p:;
0\
tyl

I

'M

\E/

~

(Figure 12).

The reaction of LuMe(C 5 Me s )2(THF) with ~-propiolactone resulted in the formation of stable compound
which did not react with the lactone any more.

The

compound was isolated and its IH and 13 C NMR spectra are~f/shown in Figure 13, 14.

A2B2 pattern and the chemical

shifts of two methylene groups (b and c in Figure 13)

N'-clearly indicate that the structure is 1:1 adduct of

~

-24-

-25-

»t

0

0
0

Me

~n)'0

+

20°C

•

H2 O

•

HO~Me

0

0

+
I
1'V

20°C

•

H2 O

•

0

HO~

0'1

H1

I

\

[yolO
Fig. 10

Me

or

'" /0
o 1
}m~Me

Reaction of SmMe(C SMeS)2(THF) with valerolactone and caprolactone

~/o

~,{LU

~o

Cp*

a

d

THF

THF

I

a

I

1'V

-...J

I

I

-

9

I

Cp*

I

b

I

C

f,d I e-,---------,r------r- - - , -----.----.,.------,.---,------.----.,.------,.---,----,---,----,.----r---.---,.---------..,-----.,------,--,---

ppm

200

Fig. 11

150

100

50

13 c NMR spectrum of LuMe(C sMe s ) 2/ ca peolactone

,

0

a
d

e
9
THF

C6 06
I
I'V
00

I

Cp·

e
THF

c

9

fld i,ab

Cp·' "0 TTTnT'-,T TTT l'TnTl lTn I"

I"

i II ,

ppm,

I' i , 'TTT'fTl'TTlTTTTTf'TTnl"lT1"TTT''Trt.".rp-,., ITn"nTrt n ,n T, n -. n """n n ,n fTT"' '" "-..,." " "" ' '''''1'''' I n " •• , n ""'''' '1' TTl ' nnn" .yt·'''" ... , 'I ' I !Tln ,-"," !, , ... " "'f,n".,..,.,n"'''l T' , ."...,.,." ••.,." .... ,"TTf1 n .,ilT'f'TT''''-''' f"1 n ~ '

200

160

Fig. 12

i20

0

C

THF

)."JIJL\Jl

II Cp*

a

a

II

/

,,0

~u~o
I

40

C NMR spectrum of YMe(C sMe s )2/capeolactone

13

~

~

80

)b

c

b

THF

\.0

I

)\
~
i
j
G
~
~
-

\~

1

l ---r~--'-~-----'l----'

4.5

4.0

Fig. 13

~. ,

-

1

I

3.5

1----'-

-,- I

3.0

2.5

I

2.0

,n_

1

1.5

lH NMR spectrum of LuMe(C sMe s ) 2/propiolactone

--r-'

1.0

ppm

Chapter 2

Living Polymerizati on ot Lact ones Catalyzed by Rare Earth Me tal Alkyl Complexes

LuMe(C S Me s )2(THF) and ~-propiolactone in which 4-memberedlactone ring was opened by the attack of the methylgroup of the initiator to carbonyl carbon of theiC

lactone.

o

0..

0

As a result of coordination of carbonyl oxygen

to Lu, a stable 6 membered cyclic structure was formed~

LL

and the carbonyl coordination would prevent further

I
I-

reaction with the lactone monomer.

C'd

In accord with thestructure, the adduct yielded 4-acetoxy-2-butanone byoUtreatment with excess acetic anhydride.

LD

-0

LL

I
I-

If)

"""""

ill

::s

If)

u

ill

~

o
o

H

4-1

o

iC

0..

0

cu

z~

u

l1'~Y
0,

U

M
rl

0
'<::J/

~~1K
..0

-

E

0..
0..

-30-

-31-

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

calibration curve was obtained by using standard

Experimental Section

polystyrenes. 8.70 x 102

= 1.10), 2.63 x 10 3

(~/~

(Mw/~

= 1.05), 5.97 x 10 3 (M.,/~ = 1.02), 9.10 x 10 3

standard Schlenk techniques under an argon atmosphere.

(Mw/~= 1.02), 3.79 x 10 4

(M.,/~= 1.01), 4.36 x 10 4

NMR spectra were recorded on a JEOL EX-270 (270.0 MHz(Mw/~= 1.01), 9.64 x 10 4(~/~

= 1.01), 1.90 x lOs(Mw/~= 1.04), 3.55 x lOs(Mw/~ =

General.

for

1

All operations were conducted withHand 67.5 MHz for13

C nuclei), and a Brucker

AMX400wb (400.13 MHz for IH and 100.62 MHz for l3 C
nuclei).

Chemical shifts of lH are calibrated using

benzene (0 7. 20 ppm) in benzene-d 6 or chloroformppm) in chloroform-dl.

6(~/~ = 1.05), 1.09 x 10

(Mw/~

(~/~

1.02), 7.06 x lOs= 1.08) and 2.89 x 10 6

= 1.09) (Tosoh Manufacturing Co., Ltd. ) .

«) 7. 26

Chemical shift of l3 C resonances

Material.

are determined with reference to the carbon resonances

Tetrahydrofuran, hexane and tolueneof deuteration solvent (benzene-d 6 , 0 128.0; chloroform-

were dried over Na/K alloy and distilled just before

d l , 0 77.0 ppm).

use.

Gas chromatographic analysis andseparation of the reaction products were made with a
Yanaco gas chromatograph G3810 using a column packed
with Silicone DC-S50 or a Yanaco gas c h roma t ograph G3800
using a column packed with DEGS.

Number averaged

molecular weight and molecular weight distribution of

In the case of the solvent used in polymerization,

they were thoroughly degassed by trap-to-trap
distillation just before use.
lactones,~-propiolactone,

Commercially purchased

o-valerolactone and £-caprolactone were purified by the following procedure.
These monomers were dried over CaH 2 for 24 hours andpolymers were determined by gel permeation

distilled twice under argon.

chromatography (GPC) on a Tosoh SC-8010 high-speed

monomers still contain ca. 30 ppm of water, they wereliquid chromatograph equipped with a differential

dried over activated molecular sieves 3A under an

refractometer detector, using chloroform as a eluent at

atmosphere, and finally degassed and purified by trap-

40.0 aC.

to-trap distillation just be f ore use.

The column consisted of four columns: TSKgel

G2000Hxl, TSKgel G3000Hxl, TSKgel G400 OHxl and TSKgel
G5000Hxl (Tosoh Manufacturing Co., Ltd.) was used. The
flow rate was 1.0 ml min-I .

Pure Sm(C sMe s )2-(C sMe s ) 2 (OEt 2 ) and LuMe (CsMe s ) 2 (THF) 18) were obtained

The molecular weight-32-

Since the obtained-33-

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

according to the known method.

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Preparation of SmMe(C SMe S )2(THF) lS).

To astirred solution of Sm(C SMe S )2(THF)2 (4.50 g, 8.0 romol) in
Preparation of Sm (CsMe s ) 2 (THF) 2

14

100 ml of toluene was slowly added 5 equiv AIMe 3 (4.0
) •Slightexcess of pentarnethylcyclopentadiene (18 ml, 115 romol)

ml, 41 romol).

During stirring the mixture for 24 hours

blue-black precipitates was generated in a red solution.

was added to a stirred dispersion of KH (4.2 g, 104.5

Then the mixture was extracted with 500 ml of toluene tommol) in 250 ml of THF, and the mixture was refluxed forseparate the resulting SmMe(C s Me s )2 (THF) from AlMe 3 (THF)

4 hours to give a dispersion of (CsMes)K.

A solution of

C2H4 1 2 (13.4 g, 47.5 romol) in 40 ml of THF was added atonce to a stirred dispersion of 1.1 equiv of Sm metal
powder (40 mesh, 7.86 g, 52.3 romol) in 1000 ml of THF.
A magnetic stirring was continued for 3 hours at 20-30
aC.

The color of the solution gradually changed toblue-green, as SmI 2(THF)2 was formed.

Then the (CsMes)K

dispersion was added to the stirred solution of SmI 2(THF) 2·The color of the solution turned purple

and excess AIMe 3 •Slight concentration of the toluene

solution into ca. 400 ml followed by cooling to -20 aC
resulted in the formation of red crystals of (C SMe S )2SrnMe 2AIMe 2.

Recrystallization of the separated micro-

crystalline substances from THF/hexane afforded SrnMe(C sMe s )2(THF) as yellow-orange crystals.

Yield: 40.0%.

.
.
424 ([ lS4 Sm
ElMS : m/z (species, relative lntenslty)( C5Me 5) 2] +, 8 0) 4 2 2 ([ 152Sm ( C5Me 5 ) 2] + , 1 0 0 ) .

immediately after the addition of (CsMes)K and
precipitation of KI occurred.

After stirring the

mixture for 12 hours at ambient temperature, the THF was

Preparation of[SmH (CsMe s ) 2] 216 ) .

Crystalline

removed by evaporation and 500 ml of toluene was added

Sm(C S Me S)2(THF)2 (4.73 g, 8.4 mrnol) was mixed withto the residue.

diphenylacetylene (1.49 g, 8.4 romol) in the solid state

The resulting solution of Sm(C SMe S)2(THF) 2 containing (CSMeS)2SmIK(THF)x was stirred for 12

and 100 ml of hexane was added.

Immediately after

hours and then centrifuged to remove the salt.

mixing the solution turned black.

Removal of theThE=solvent was evaporated to dryness and the resultin9

solvent after stirring overni ght yielded a black

Sm(C SMe S )2 (THF) 2 was recrystallized from THF/hexane atmaterial.

-20aC to give purple crystals. Yield: 31% in one crop.

The material was extracted with 100 ml

degassed hexane.

Then the resulted black hexane

solution was allowed to react with H2 at ambient

-34-

-35-

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

temperature and at atmospheric pressure.

The solution

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexesof mixture of hydrated LuC1 3 and excess NH 4 CI wereturned orange and orange precipitate was formed by·obtained.

holding it for 4 hours.

water, the white solids were placed in a sublimation

The resulting solid of [SmH

(CsMe s ) 2] 2 was separated by centrifugation.

Yield:

21.2%.

ElMS: m/z (species, relative intensity) 426

1S4

1S4

([

SmH(C sMe s )2]++1, 21) 425 ([Pre par a t ion

0 f

SmH(C S Me S )2]+,88),424( CsM e 5) Na •in oil, 3.0 g, 75 mmol) and 120 ml of THF were placed.
Then C5Me sH (6. 5 ml, 41. 5 mmol) was added at once and the
mixture was refluxed for 24 hours.

Resulting pale-brownsolution was centrifuged to separate excess NaH, andevaporated to dryness.

The residue was washed with 40

ml of hexane and CsMesNa was obtained as pale-brown
powder.

tube and heated at 350-400 °C under reduced pressure,
until sublimation of NH 4 Cl

unobserved.

Residual gray

Yield: 80%.

Preparation of LuCl (CsMe s ) 2 (THF) 17) .

A

solution of CsMesNa (3.8 g, 24.0 mmol) in 62 ml of THF
was added to a stirred suspension of anhydrous LuCl 3(3.38 g, 12.0 mmol) in 100 ml of THF at room temperatureand the solution was refluxed for 24 hours.

Resultingbrown solution was centrifuged in order to separate NaCI
and THF was removed by evaporation.

Toluene (150 ml)

was added to the residue and the mixture was stirred for
24 hours at 25°C.

Yield: 91%.

lS

solids is used as anhydrous LuCI 3 .

In a 300 ml round-bottom flask equipped with a condenser NaH (about. 60%,

In order to remove excess NH 4 CI and hydrated

After separating the salt bycentrifugation, the solvent was evaporated and the crude
LuCI(C sMe s )2(THF) was recrystallized from THF/hexane togive pale brown prisms. Yield: 25%.
Preparation of LuC1 3 •(99.9%, 10.1 g, 25.3 mmol) and NH 4 CI (6.8 g, 127 rnmol)
in 500 ml round-bottom flask was added ca. 300 ml ofconc. HCI with stirring.

1H NMR (C6D6) 0

To a mixture of Lu 20 3

The mixture was heated on awater bath until the solution becomes clear.

Then the1 . 25 ( THF , 4 H ), 2. 07 (s , 30 H), 3. 54 ( THF , 4 H) .

13 C NMR(C6D6) 0 11. 8 (CsMe s )' 25.5 (THF), 72.3 (THF), 11 7 . 4(CsMe s ).

ElMS: m/z (species, relative intensity) 479([ 17S Lu 3S CI(C sMe s ) 2 ]+1, 94) 480 ([ 17S Lu 35 CI(C sMe s )2]' 100)excess HCI was removed using aspirator and white solids

481 ([17sLu37Cl(C sMes ) 2]+1, 47) 482 ([ 17sLu 37Cl(C sMe s ) 2] ' 33).

-36-

-37-

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Preparation of LuMe (CsMe s) 2 (THF) 18) •Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

To aPreparation of YC1 3 •To a mixture of Y20 3 (8.0

stirred solution of LuCI(C sMe s )2(THF) (1.57 g, 2.84 mmol)g, 35.4 mmol) and NH 4 CI (12 g, 224 mmol) in 500 ml

in 40 ml of THF was slowly added 2 equiv MeLi (5.7 mmol)

round-bottom flask was added ca. 300 ml of conc. BCl

In 7.4 ml hexane at 0 °C and then the mixture waswith stirring.

allowed to warm to room temperature.

until the solution became clear.

After stirring for

The mixture was heated on a water bath
Then the excess BCl

6 hours the THF was evaporated to dryness and kept~ at 75

was removed by using aspirator and white solids of°C in vacuo for 12 hours in order to remove coordinatedmixture of hydrated YC1 3 and excess NH 4 CI were obtained.

THF.

In order to remove excess NH 4 Cl and hydrated water, theToluene (45 ml) was added to the pale yellow

residue and 2 equiv of AIMe 3 (0.52 ml, 5.7 rnmol) was

white solids were placed in a sublimation tube andadded to the stirred suspension at room temperature.

heated at 360°C under reduced pressure, until

After the stirring was continued for 4 hours the

sublimation of NH 4 Cl was unobserved.

suspension was heated at 60°C for 1 hour to complete

solids is used as anhydrous YCI 3 •Residual gray

Yield: 4.77g, 34.4%.

the reaction and then a small amount of precipitate wasremoved by centrifugation.

Concentration of thesolution followed by cooling to -20°C resulted in theformation a pale yellow prisms of (CsMes)2LuMe2AlMe2.

The

crystals were separated from the solution and dissolvedin a small amount of THF in order to react thecoordinated AlMe 3 with THF.

After the addition of 3-5

A solutionof CsMesNa (16.3 rnmol) in 19.1 ml of THF was added to a
stirred suspension of anhydrous YC1 3 (1.68 g, 8.60 rnmol)
in 60 ml of THF at room temperature and the solution was
refluxed for 4 hours.

fold hexane, the solution was concentrated and cooled to-20°C to result in the formation of a pale yellow
prisms of LuMe (CsMe s ) 2 (THF) .

Yield: 35%. IH NMR (C 6D6) 0-0.6 (s,3H), 1.16 (THF,4H), 2.04 (s,30H), 3.29 (THF,4H).
13 C

NMR (

C6D6 )

0

11 . 7 (CsMe s ), 24.6 (THF), 25. 0 (Me), 70.5

( THF), 115. 3 ( CsMe 5) •Resulting pale-brown solution wasconcentrated to dryness.

Toluene (160 ml) was added to

the residue and the mixture was stirred for overnight.
After separating the salt by centrifugation, solvent wasevaporated and the residue was washed by 40 ml ofhexane.

The crude YCI(C sMe s ) 2(THF) was recrystallized

from THF/hexane to give pale brown prisms.
in one crop.

-38-

Yield: 23%

IH NMR (C 6D6) 0 1.24 (m,4H,THF), 2.06 (s,-39-Chapter 2
Living Polymerization of Lactone s Catalyzed by Rare Earth Me t a l Alkyl Complexes

30H,C SMe s )' 3.55 (m,4H, THF ) .

Chapter 2
Li v ing Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Me), 1.14 (m,4H,THF), 2.0 5 ( s ,3 0H, C sMe s )' 3.29 (m,4H,
THF) .

To a stirreds o l ution of YCI(C sMe s ) 2(THF)(1.32 g, 2.82 mrnol) in. 30 ml

Polymerization of o-Valerolactone Catalyzedof THF was slowly added 2 equiv MeLi (5.66 mrnol) in Et 20

by SmMe (C 5Me 5 ) 2 (THF) .

(7.25 ml) at 0 °C and then the mixture was allowed tovalerolactone (0.92 ml, 10 romol) in 20 ml o f to luen e waswarm to room temperature.

added a toluene solution of 1/500 equi val ent

SrnMe-

the THF was evaporated to dryness and the mixture was(C sMe s )2(THF) (0.010 g, 0.02 nunol) at O°C.

After

kept at 75°C in vacuo for 12 hours in order to remove

stirring for 3 hours the mixture was quenched by excess

coordinated THF.

methanol.

After stirring for 6 hours

Toluene (30 ml) was added to the pale

To a stirred s o l u tio n o fyellow residue and 2 equiv of AIMe 3 (0.55 ml, 5.66 mmol)
In toluene (5.5 ml) was added to the stirred suspension
at room temperature.

After the stirring was continued

for 4 hours the suspension was heated at 60°C

for 1

polymerization of £-Caprolactone Catalyzed
by SmMe (C 5 Me 5 ) 2 (THF) .

To a stirred solution ofhour to complete the reaction and then a small amount ofcaprolactone (1.11 ml, 10 mmol) in 40 ml of toluene was

precipitate was removed by centrifugation.

added a toluene solution of 1/500 equivalent SmMe-

Concentration of the solution followed by cooling to -20(CsMe s ) 2 (THF ) ( 0 . 010 g, O. 02 mmol) at 0 °C.

°C resulted in the formation a pale yellow prisms ofstirring for 3 hours the mixture was quenched by excess(C sMe s ) 2YMe 2AIMe 2 ·methanol.

The crystals were separated froIn the

Aftersolution and dissolved in a small amount of THF in orderto react the coordinated AIMe 3 with THF.

After thE~addition of 3-5 fold hexane, the solution was

Random copolymerization of~-propiolactone

concentrated and cooled to -20°C to result in thewi th £-caprolactone catalyzed by SmMe (C 5 Me s ) 2 (THF) .

formation of a pale yellow prisms of YMe (CsMe s ) 2 (THE') .

A toluene solution (1.0 ml) of SmMe(C SMe S ) 2(THF) (0.05

Yield : 25 % in one crop.

1

H NMR (C 6D6 ) 0 -0.60 (d,3H,mmol) was added to a mixture of propiolactone andcaprolactone (1:9, 25:75, 1:1, 25:75 molar ratio;

-40-

-41-

Chapter 2

Chapter 2

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

amounts of monomer: 20 mmol) dissolved in toluene (30mixture was concentrated in vacuum.

ml) with vigorous stirring at 0 °C.

liquid was analyzed by gas chromatograph.

The stirring was

The supernatantcontinued for 1.5 hours, and the reaction mixture waspoured into methanol.
evaporation.

The solvent was removed by

The resulting polymer was dried under

reduced pressure.

Equimolar Reaction of [SmH(C sMe s )2]2 with
Caprolactone.

£-

Caprolactone (0.19 ml, 1.75 rnmol) was

added to a stirred solution of [SmH(C SMe S )2]2 (0.74 g,
0.88 mmol) ln 5 ml of toluene at 0 °C and the mixture

Random copolymerization of p-propiolactone
wi th o-valerolactone catalyzed by SmMe (CsMe s ) 2-

was warmed to room temperature.

min the color of the solution changed from red-orange topale yellow.

(THF).

A toluene solution (1.0 ml) of SrnMe(C s Me s )2(THF)(0.05 mmol) was added to a mixture of propiolactone andvalerolactone (1:9, 25:75, 1:1, 25:75 molar ratio;

During stirring for 10

After the solution was quenched by H2 0 the

mixture was concentrated under reduced pressure.

The

supernatant liquid was analyzed by gas chromatograph.

amounts of monomer: 20 mmol) dissolved in toluene (20ml) with vigorous stirring at 0 °C.

The stirring wascontinued for 1 hours, and the reaction mixture waspoured into methanol.

The resulting polymer was dried

Equimolar Reaction of SmMe(C S Me S )2(THF) with
o-Valerolactone.

Valerolactone (0.043 ml, 0.46 mmol)

was added to a stirred solution of SmMe(C s Me s ) 2(THF)

under reduced pressure.

(0.23 g, 0.46 mmol) in 3 ml of toluene at 0 °C and the
mixture was allowed to react at room temperature.

Equimolar Reaction of [SmH (CsMe s ) 2] 2 wi th 0Valerolactone.

Valerolactone (0.12 ml, 1.3 mmol) was

added to a stirred solution of [SmH(C S Me S )2] 2 (0.56 g,
0.66 mmol) ln 3 ml of toluene at 0 °c and the mixture
was warmed to room temperature.

During stirring for 10

stirring for 10 min the color of the solution changed
from yellow-orange to pale yellow.

A few drops of H2 0

was added to the solution (the color of the solutionchanged pale-yellow) and white precipitate was
generated.

After concentration of the supernatant

min the color o f th e so1·
utlonchanged from red-orange toliquid, the resulting product was separated by gas

pale yellow.

chromatograph.

After the solution was quenched by H2 0 the

-42-

After

-43-

Chapter 2

Chapter 2

Living Polymerization of Lactones Catalyzed by Rare Eari:h Metal Alkyl CompJexes

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Equimolar Reaction of SmMe(C SMe S )2(THF) with
t-Caprolactone.

The reaction was carried out inadded at 0 °C, and the tube was sealed.
was completed in 5 min.

The reaction

IH NMR (C6D6) 0 1.2 - 1.4 (m,essentially the same manner as described for the

6H, d, e, f), 1. 46 (4H, THF), 1. 64 (s, 3H, a), 2. 09 (s ,reaction of valerolactone using 0.12 g (0.23 mmol) of

30H, CsMe s ), 2.14 (t, 2H, c), 3.62 (4H, THF), 4.44 (t,SmMe(C SMe S )2(THF) and 0.025 ml (0.23 romol) of
caprolactone.

2H, g).

13

C NMR (C6D6) 0 11.5 (CsMe s )' 14.2 (a), 22.2

( e ), 25. 8 ( THF ), 31. 2 - 31. 5 ( d, f), 42. 2 ( c ), 51. 8 (g),65 . 5 ( b ), 67. 8 ( THF ), 114. 8 ( CsMe 5 ) •Equimolar Reaction of LuMe(C sMe s )2(THF) With

To a stirred solution of LuMe-o-Valerolactone.

Equimolar Reaction of YMe(C s Me s )2(THF) with(C S Me S )2(THF) (0.35 g, 0.65 romol) in 0.2 ml of tolul=ne

t-Caprolactone.

was added 0.06 ml of valerolactone (0.65 rnmol) in 0.1 rnlof toluene at -78 °C.

Then the mixture was allowed towarm to room temperature.

The color of the solutionchanged from pale-yellow to pale orange.

Removal of

To a NMR tube charged with 0.026 g(0.058 romol) of YMe(C sMe s )2(THF) in 0.5 ml of degassed
C6D6, equimolar caprolactone (0.0065 ml, 0.058 mmol) was
added at 0 °C, and the tube was sealed.

The reaction

solvent by evaporation to dryness followed by extraction

was completed in 5 min.

of the product with degassed C6D6 gave the sample for NMR( CsMe s ), 14. 6 (a), 25. 1 ( e ), 26. 2 ( THF), 2 9 . 0 - 29. 5 ( d,studies.

f ), 3 4 . 3 ( c ), 5 2 . 0 (g), 6 4 . 2 ( b ) I 6 7 . 9 ( THF ), 115 . 5( e), 2 2 . 8 ( d), 2 5 . 7 ( THF)I

5 1 . 8 (f), 65. 9 ( b ), 7 0 . 0

l3

C NMR (C6D6) 0 11. 6

12.2(CsMe s ) .

( THF), 115. 3 ( CsMe s ) .
Equimolar Reaction of LuMe(C sMe s )2(THF) with
Equimolar Reaction of LuMe(C sMe s )2(THF) with£-Caprolactone.

To a NMR tube charged with 0.35 g~-Propiolactone.

propiolactone (0.003 ml, 0.048 rnmol)

in 0.1 ml of toluene was added to a stirred solution of(0.65 rnmol) of LuMe (CsMe s ) 2(THF) in 0.5 ml of degassed

LuMe(C sMe s )2(THF) (0.026 g, 0.048 mmol) in 0.2 ml ofC6 D6 1 equimolar caprolactone (0.069 ml, 0.65 romol) was

toluene at -78 °C and the mixture was allowed warm toroom temperature.

-44-

The color of the solution changed-45-

Chapter 2

Chapter 2

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

from pale yellow-green to pale-orange.

Removal ofsolvent by evaporation to dryness followed by

References

extracting with degassed C6D6 gave the NMR sample.

A NMR

tube was charged with the C6D6 solution and sealed .

1H

NMR

(C6D6) 61.45 (4H, THF), 1.63 (s, 3H, a), 2.06 (s,30H, CsMe s ), 2.08 (c), 3.64 (4H, THF), 4.15 (t, 2H, d).
13

C NMR (C 6D6) 0 11.6 (CsMe s ), 26.1 (THF), 33.0 (a), 47.3

(c),62.2 (d), 68.4 (THF), 115.8 (CsMe s ), 225.7 (b).

1 )Duvois,Ph.; Jacobs, C.; Jerome,R.; Teyssie,. Ph.

Macromolecules, 1991, 24, 2266.
2)Nijenhuis, A. J.; Grijpma, D. W.; Pennings, A. J.

Macromolecules, 1992, 25, 6419.
3)Duda, A.; Penczek, S. Macromolecules, 1990, 23, 1636.
4)Johns, D. B.; Lenz, R. W.; Luick, A. Ring-Opening

Polymerization; Ivin, K. J.; Saegusa, T., Eds.;
Elsevier Applied Science Publishers: London, GreatBritain, 1984; Vol. 1, Chapter 7, pp461.
5)Nomura,R.; Ueno, A.;

Endo,T. Macromolecules, 1994,

27, 620. Inoue, S.; Tomoi, Y.; Tsuruta, T.; Furukawa,
J. Makromol. Chern. 1961, 48, 229. Jedlinski, Z.;

Kowalczuk, M.; Kurock, P. Makromol. Chern. Macromol.

Symp. 1986, 3, 277.
6)K, Teranishi.; Iida, M.; Araki, T.; Yamashita, S.;
Tani, H. Macromolecules, 1974,

7, 421. H, Teranishi.

;T, Araki.; Tani, H. Macromolecules, 1972, 5, 660.
7)Yasuda, T.; Aida, T.; Inoue, S. Bull. Chem. Soc.

Jpn., 1986, 59, 3931. Shimasaki, K.; Aida, T.; Inoue,
S. Macromolecules, 1987, 20, 3076. Endo, M.; Aida,T.; Inoue, S. Macromolecules, 1987, 20, 2982.
8)Vergara, J.;

Figini, R. V. Makromol. Chern., 1977,

178, 267.

9)Okuda, J.; Rushkin, I.L. Macromolecules, 1993, 26,
5530.

-46-

-47-

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes10)McLain, S. J.; Drysdale, N. E.
1991 (assigned tou.s. Patent 5,028,667,

E. I. du Pont de Nemours and. Co.).

Chapter 2
Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes

Ziller, J. W. J. Am. Chern. Soc., 1988, 110, 6432.
17) (a)Watson, P. L. J. C. S. Chern. Commun., 1980, 652.

McLain, S.J.; Ford, T, M.; Drysdale,N. E. Am. Chern.

(b)Gong, L.; Streitwieser, A.; Jr. Zalkin, A. J. C.

Soc., Div. Polym. Chern., 1992, 33, 463. McLain I' S.

S. Chern. Commun., 1987, 460.

J.; Drysdale, N. E., 203rd National Meeting of the18) (a)Watson, P. L. J. C. S. Chern. Commun., 1980, 652.

American Chemical Society, Sanfranscisco, April 1992,(b)Watson, P. L.i Roe, D. C. J. Am. Chern. Soc., 1982,

POLY-160.

104, 6471. (c)Evans, W. J.; Wayda, A. L.; Hunter, W.

11)Evans, W. J.; Katsumata, H. Macromolecules, 1994, 27,

E.;Atwood, J. L. J. C. S. Chern. Commun., 1981, 292.

2330. Evans, W. J.; Katsumata, H. Macromolecules,

1994, 27, 4011.
12) For a preliminary report, Yamashita, M.; Takemoto,Y.; Yasuda, H. Rare Earths '92. Kyoto, Japan, June
1992, Paper PIK-05.
13) (a)Yasuda,

H.; Yamamoto, H.; Yokota, R.; Miyake,

S.;Nakamura, A. J. Am. Chern. Soc., 1992, 114, 4908.
(b)Yasuda, H.; Yamamoto, H.; Yamasahita, M.; Yokota,
K.; Nakamura, A.; Miyake, S.; Kai, Y.; Kanehisa, N.

Macromolecules, 1993, 26, 7134. (c)Yasuda, H.;
Yamamoto, H.; Takemoto, Y.; Yamashita, M.; Yokota,

R.; Miyake, S.; Nakamura, A. Macromol. Chern.
Macromol. Symp. 1993, 67, 187. (d)Yasuda, H.; Tarnai,
H. Prog. Polym. Sci., 1993, 18, 1097.
14)Evans, W. J.; Grate, J. W.; Choi, H. W.; Bloom, l.;Hunter, W. E. ; Atwood, J. L. J. Am. Chern. Soc., 1985,

107, 941.
15)Evans, W. J.; Bloom, I.; Hunter, W. E. ; Atwood, J. L.

J. Am. Chern. Soc., 1983, 105, 1401.
16)Evans, W. J.; Chamberlain, L. R.; Ulibarri, T. A.;

-48-

-49-

Chapter 3
Living Pol ymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes

Chapter 3

polymerization.

Stoichi ometric reactio ns were also

performed to understand t he po l ymeriza tion mechanism.

Living Polymerization of Lactones Catalyzed
by Rare Earth Metal Alkoxide Complexes

Introduction

In chapter 2, living polymerization of several
lactone monomers was achieved by the use of organo rareearth metal initiators with metal carbon bond (e.g.
SmMe ( CsMe s ) 2 ( THF), LuMe (CsMe s ) 2 (THF) ) .

High molecularweight polyesters with narrow molecular weight
distribution were easily obtained by the initiating
system.

Stoichiometric reaction of the initiator andlactone monomer revealed that the initiation of thepolymerization was nucleophilic addition of the alkyl
group of the initiator to carbonyl carbon of themonomer, resulting in the formation of rare earth metal
alkoxide complex after ring opening of the lactone.
This result indicated that the propagating species ofthis polymerization had metal oxygen bond into whichanother lactone monomer would insert.

Thus, it wassuggested that rare earth metal alkoxide complexes could
be used as initiators for lactone polymerization 1 ,2).
In this chapter, I attempted to apply rare ea.rth
metal alkoxide complexes to the initiation of lactone

-50-

-51-

Chapter 3

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Canplexes

...
o
.~
~

Results and Discussion

(/}

H

...c:
00

..c:::\0..c:::
r-..c:::

00..c:::

r-

r-i

...c:

...c:

r-i

r-i

00

00

(l)

:>

ONM\oOOO

o

r-i

{:!

o

o

t.f)

0'\

00

00

0

0

r-i

r-i

00
N

00
N

r-i

r-i

00

Rare Earth Metal Alkoxide Initiated
Polymerization of Lactones.

In the previous

chapter, it has been reported that a series of organo

r-i

r-i

r-i

r-i

r-i

o

00

00

N

t.f)

.;:ji

\0

rare earth metal complexes, (C5R5)2LnR' exhibits
excellent catalytic activity for living polymerizationof lactones.

o

\0

r-i

l11
r-i

I

proposed also the initiation and propagation mechanism
for the present polymerization of lactones.

I

r-i

The resulting polymers have very narrow

polydispersity and very high molecular weight.

~

t.f)

N

t.f)

N

l11

l11

N

o

0

0

o

0

o

0

Q)
{:!

OJ

Activespecies is metal alkoxide which is generated by additionof alkyl group of the initiator to carbonyl carbon of
the monomer followed by ring opening of the lactone.

Asan extension of this study, I have investigated theliving polymerization of lactones uSlng pure rare earth

-tJ

+J

o

cO

-tJ

o
.~

r-l
0

.;

cO
.;
~
~
I

CQ...

cO

H

~

cO
0

I

w

c::
o

o

o

H

Table 1 shows the result of lactone polymerizations

~

0
-tJ
0

o

metal alkoxide complexes as initiators.
with some organo rare earth metal complexes.

o

Q)
Q)
~

o

.;

o

-~

~

8

~

CQ...

w

H

cO

o
I

w

o

.;

~

H

~
I

Both £_-

desired high molecular weight polymers with very narrowNsince number averagemolecular weight, ~, increases linearly in propor-tion
to the conversion while molecular weight distribution,

It/ ~, remains below 1.10, the present polymerization is

-52-

~

0
-tJ
0
cO

cO

caprolactone (CL) and 6-valerolactone (VL) gave themolecular weight distribution.

(l)

-53-

0

0
I

Chapter 3
Living Polymerization of Lactones Cat.aJ.yzed by Rare Earth Metal Alkoxide Complexes

considered to proceed in a living fashion (Figure 1).
As described in chapter 2, rare earth metal alkyl
complexes (SrnMe (CsMe s ) 2 (THF ), LuMe ( CsMe s ) 2 (THF»

cannotinitiate the polymerization of propiolactone.

In

contrast, rare earth metal alkoxide complexes

1.10cefficiently polymerized the lactone affording~

monodisperse polymer of high molecular weight in high~conversion.

"3

1.05
1.00

EQJ ~
0

O~

ZS~

0

The mechanistic difference between the two

10.0

initiating systems will be discussed below.

0: 0.5 mol% [YOMe(C 5H 5hb-6. : 0.5 mol% YOMe(C 5Me 5b(THF)

8.0

0

Initiation Mechanism for the Polymerization: 0.2 mol% YOMe(C 5 Me5b(THF)

6.0

of Lactones Catalyzed by Rare Earth Metal Alkoxide~

In order to elucidate the mechanism of the0polymerization, stoichiometric reaction was carried out.

~

Complexes.

.,.--...
c

4.0

The addition of equimolar caprolactone to yttrium
methoxide complex followed by hydrolysis afforded only
the caprolactone monomer.

On the other hand, when 2

equivalent of caprolactone was used, 1:1 mixture ofcaprolactone and methyl 6-hydroxyhexanoate wasrecovered.

2.0

0.0

o

The latter compound was formed by the

25

50

75

100

Conversion (%)

addition of methoxy group to carbonyl carbon of thelactone followed by ring opening.

Accordingly, when

acetic anhydride was added after the 1:2 reaction,

1
·
F 19.

Conversion vs. Mn and ~/Mnof poly(caprolactone)

caprolactone and methyl 6-acetoxyhexanoate instead of
methyl 6-hydroxyhexanoate was obtained.

These results

clearly indicated that ring opening of lactone molecule
occurred only when additional monomers were preseni:.

-54-

-55-

Chapter 3

Living Polymerization of Laeton es Catalyzed by Rare Earth Met al Alkoxide Complexes

ill

C
0

Furthermore , it wa s r evealed tha t t he ring opening+J()

proceeded t hou gh a c y l-oxygen bond cleavage by theaDaD

addition o f a l koxide gr oup to carbonyl carbon of themonomer (Figure 2) .

+By t he r eaction of propiolactone and rare earth+Q)metal a l koxi de complex, five membered cyclic structure
wou l d be formed.

2

As described in chapter 2, when the

o

o

Q)

o

2

initiating group was rare earth metal alkyl, metal

i n Figure 3, in the case of metal alkoxide initiation,
the coordinating group is carbonyl oxygen of ester groupand the coordination is weaker than that of ketonic
group.

Thus, propiolactone could replace the carbonyl

coordination and the monomer can be polymerized by rareearth metal complexes was attempted.

Recrystallizationof the 1:1 reaction mixture of caprolactone, y-butyro-

Lf)

::s

Lf)

C)

o

/
/>-"",

Their IH NMR spectra

I

0

o
/

0

/

I

t

aD

r

aD
N

~

I.H

0

c

0
-r!
+J
()

cd
ill
H

0
-r!
H
+J

ill

0
-r!

~
()

-r!
0
+J
U)

+

N

tJI
-r!
~

The latter two complexes werE=stable since the two lactone monomers could not be
On the other hand, the adduct of easily

-56-

I

+

significantly different from those of free lactones

polymerized.

0

8show signals of coordinating lactone, which are(Figure 4, 6 and 7).

ill

::s

(")

II 11

/>-"",

t

0
0

/

0

~,,?{)

lactone and y-valerolactone with YOMe(C s Me s )2(THF)
afforded pure adduct respectively.

:r:::

ill

earth metal alkoxide complexes.
Isolation of 1:1 adduct of lactone monomer and rare~Ngroup and the coordination prevented further reaction
On the other hand, as shown

~

8

0

o

center was coordinated by carbonyl oxygen of ketonic
wi th the lactone monomer.

~

cd
0

~

0

o

H

+J

2
0

Q)

0

-r!

Q)

2
0

Q)

2

o

cd
r-1

-57-

0

06 ..

0

n(> ..

R~n~jo

No Polymerization

I
lJ1

0

CXl

~n""0

Fig. 30n06 ~000R~n~j)!If/OR 06

I

OR

•

•

n+ 1

Polymerization of ~-propiolactone initiated by rare earth metal
alkyl and alkoxide complexes.

~/OMe

OMe l

II C 5 Me 5~"' :bd
a

c
b

I
lJ1
\.D

I

e

a

1

4

-.

be

J

l
--,--,-~

_.

111'1

-,-----,--1-

3' - - , - ---,- -'---1--,---,---,-------.--)---. - ----, ---,-

2-- , - -1
PPM

Fig . 4

-H NMR spectrum of YOMe(C s Me s ) 2(caprolactone)Chapter 3
Living Polymerization of Lactones catalyzed by Rare Earth Metal Alkoxide C~~lexes

polymerizable caprolactone reacted gradually by standing
for several hours to give ring opening product.

Figure5 follows the reaction by IH_NMR spectroscopy.
Disappearance of Y-OMe signal (4.1 ppm) and appearance~\Iof Y-OCH 2 signal (4.4 ppm) demonstrated the ring openingrreaction.

CD

Jf

\

r

~f

C

0
+J
U

cd

r-l

~
0..
0..

~

~

II

0

~

~

cd
U

...-

~

N

-.
If"l

CD

::8If"l

I

rI

U
CD

::8
0

f

~

r

N

~

0

lJ
~

,

c

:- C0

\l

B
0

~
U)

c

cd

- --==:...,

~l

1
-61-

-01

+J
cd

r
---; r

1t

-60-

0

~

~

8

I

Lf)

.

r ~

-01

r

t:L!

tJl

V

'"

OMe
/'

OMe

Cp*
(l

I

m
N
I

c

a

~~

~

4

~ ._

_ _ _ _ ---""--r--"

r---'

~~

Jl _

l -~-~~-~- I --.-- I --.~-~~-~-.___,-~- I - . ---.~

3

Fig. 6

b

PPM

1

2

l H NMR spectrum of YOMe(C s Me s ) 2(y-butyrolactone)~ /OMe

OMe~'''~9

II

Me

Cp*

~b

I

m

w

c

I

c

a

Fig. 7bbll.__-,~Jj ~11~\L~~__~I~II~JhJL_~JL_JII".I.
4

c

3

2

1

PPM

l H NMR spectrum of YOMe(C s Me s ) 2(y-valerolactone)Chapter 3

Chapter 3

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes

Living polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes

flow rate was 1.0 ml ffiln

Experimental Section.

The molecular weightcalibration curve was obtained by using standard
polystyrenes

General.

-1

All operations were conducted with.. 8.70 x 10 z (Mw/~ = 1.10), 2.63 x 10 331.02), 9.10 x 10

(Mw/~ = 1.05), 5.97 x 10

3

(Mw/~

(~/~ = 1.02), 3.79 x 10

4(Mw/~ = 1.01), 4.36 x 10

C nuclei), and a Brucker(Mw/~ = 1.01), 9.64 x 10

4

(Mw/~

AMX400wb (400.13 MHz for 1H and 100.62 MHz for 13C(~/~ = 1.04), 3.55 x 105(~/~ = 1.02), 7.06 x 10

nuclei).

(Mw/~ = 1.05),

standard Schlenk techniques under an argon atmosphere.
NMR spectra were recorded on a JEOL EX-270 (270.0
f or

1

H an d 67. 5 MHz for

13

~ffiz

Chemical shifts of 1H are calibrated using

benzene (6 7.20 ppm) in benzene-d 6 or chloroform (6 7.26ppm) in chloroform-d 1 .

(~/~ = 1.09)

4

5= 1.01), 1.90 x 10
56
1.09 x 10 (~/~ = 1.0S) and 2.S9 x 10

6

(Tosoh Manufacturing Co., Ltd. ) .

Chemical shift of l3 C resonances

are determined with reference to the carbon resonancesof deuterated solvents (benzene-d 6 , 6 128.0; chloroformd l , 0 77.0 ppm).

Tetrahydrofuran, hexane and toluene

were dried over Na/K alloy and distilled.

Gas chromatographic analysis andIn the caseof the use of solvent for polymerization, they wereseparation of the reaction products were made with a
Yanaco gas chromatograph G3810 using a column packed
with Silicone DC-550 or a Yanaco gas chromatograph G3800
using a column packed with DEGS.

Material.

thoroughly degassed by trap-to-trap distillation justbefore use.

Commercially purchased lactones, ~­propiolactone, o-valerolactone and £-caprolactone were

Number averaged

molecular weight and molecular weight distribution of

purified by the following procedure.

These monomers

were dried over CaH z for 24 hours and distilled twice

polymers were determined by gel permeation

under argon.

chromatography (GPC) on a Tosoh SC-8010 high-speed

Since the obtained monomers still containliquid chromatograph equipped with a differential

ca. 30 ppm of water, they were dried over activatedrefractometer detector, using CHC1 3 as a eluent at 40.0

molecular sieves 3A under an atmosphere more than 4°C.

days, and was finally degassed and purified by trap-to-

The column consisted of four columns: TSKgel

G2000Hxl, TSKgel G3000Hxl, TSKgel G4000Hxl and TSKgel
G5000Hxl (Tosoh Manufacturing Co., Ltd.) was used.

-64-

trap distillation just before use.

The

-65-

Pure Sm(C 5 Me 5 ) 2(THF) 2'

Chapter 3

Chapter 3

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes[YOMe (CsHs) 2] 2' and YOMe (CsMe s ) 2 (THF) were obtained
according to the known method.

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes

Preparation of YCI (CsHs) 2 (THF) •A solution of(CSHs)Na (15.5 mmol) in 8.6 ml of THF was added to a
stirred suspension of anhydrous YC1 3 (1.51 g, 7.73 mmol)
in 40 ml of THF at room temperature and the solution was
The complex,

refluxed for 24 hr.

Resulting brown solution was

Sm (CsMe s ) 2 (THF ) 2 was prepared in the same procedure

centrifuged in order to separate NaCI and THF was

described in chapter 2.

removed by evaporation.

Toluene (80 ml) was added to

the residue and the mixture was stirred for 24 hr atroom temperature.
P rep a rat ion

0 f

SmMe ( CsM e s ) 2 ( THF) •The

After separation of the salt bycentrifugation, solvent was evaporated and the crude

complex, SrnMe(C SMe S)2(THF) was prepared in the same

YCl(C s Hs )2(THF) was recrystallized from THF/hexane toprocedure described in chapter 2.

give pale brown prisms. Yield: 59.5 %.

AnPreparation of [YOMe (CsHs) 2] 2.

orange powder of [SrnH(C SMe S)2]2 (0.71 g, 0.84 mmol) was

YCI(C SHS)2(THF)

dissolved in 20 ml of diethyl ether.

(0.13 g, 2.4 romol) in the solid state.

Immediately after

Crystalline(0.68 g, 2.10 romol) was mixed with NaOMe
Then 30 ml of

mixing the color of the solution changed from yellow-

THF was added with vigorous magnetic stirring.

orange to bright yellow.

stirring for 36 hr the THF suspension was evaporated to

After the mixture was held at

After

20°C for 30 min, volatiles were evaporated by flash

dryness and the solid was extracted with toluene todistillation to result in the formation of yellow

yield white powder of [YOMe(C sHs ) 2] 2.

powder.

ElMS: m/z (species, relative intensity) 219 ([(C SHS)2

The powder was extracted with 20 ml of hexane

and then the hexane solution was concentrated and cooled
to -20°C to give yellow crystals of Sm(OEt) (C SMe S)2(OEt 2 ) ·Yield: 42% (0.30 g).

-66-

-----

-67-

Yield: 9.0 %.

Chapter 3

Chapter 3

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes

Preparation of YCI (CsMe s ) 2 (THF) •A solut,ion

Polymerization of £-Caprolactone catalyzedof (CsMe s )Na (32.0 romol) in 49.5 ml of THF was added to aby [YOMe (CsHs) 2] 2.

stirred suspension of anhydrous YCl 3 (3.29 g, 16.8 rnmol)g, 0.05 romol) in 0.2 ml of toluene was added to ain 80 ml of THF at room temperature and the solution was

toluene solution of 1000 or 400 equivalent (500 and 200

refluxed for 3-4 hours.

equivalent as a monomeric YOMe(C sHs ) 2) caprolactone (5.54

Resul ting brown solution 'Wras

A solution of [YOMe (CsHs) 2] 2 (0.025

centrifuged in order to separate NaCl and THF was

ml, 50 romol and 2.22 ml, 20 romol) at 0 °C.

removed by evaporation.

stirring fixed time (0.5, 1, 3, 6, and 18 hours) the

Toluene (150 ml) was added to

the residue and the mixture was stirred for 24 hr a.t
room temperature.

Aftersolution was quenched with excess methanol.

After separation of the salt bycentrifugation, solvent was evaporated and the crude
YCI(C sMe s ) 2(THF) was recrystallized from THF/hexane togive pale brown prisms.

Yield: 63.5 %.

IH NMR (C 6D6)

6 1. 19 ( THF , 4 H), 2. 06 (s , 30 H ), 3. 53 ( THF , 4 H) .

13

C NMR

( CsMe 5 ) , 25. 3 ( THF ), 72. 2 ( THF ), 118. 0

Polymerization of £-Caprolactone catalyzed
by YOMe (CsMe s ) 2 (THF) .

A solution of YOMe (C sMe s ) 2 (THF)(0.023 g, 0.05 mmol) in 0.2 ml of toluene was added to atoluene solution of 500 or 200 equivalent caprolactone(5.54 ml, 50 romol and 2.22 ml, 20 mmol) at 0 °C.

After

stirring fixed time (1, 2, 5, 12, and 18 hours) thesolution was quenched with excess methanol.
Preparation of YOMe(C s Me s )2(THF).

Crystalline

YCl(C sMe s )2(THF) (1.01 g, 2.16 mmol) was mixed with NaOMe

Equimolar Reaction of SmOEt(C s Me s )2(OEt 2)(0.12 g, 2.2 nunol) in the solid state.

Then THF (40 ml)

with 6-Valerolactone.

was added and the mixture was stirred.

After stirringmmol) was added to a stirred solution of Sm(OEt) (C SMe S ) 2

for overnight the mixture was evaporated to dryness andthe resulting solid was extracted twice with toluene toyield white powder.

Recrystallization from THF/hexanegave pale yellow-green prisms of YOMe (C S Me S )2(THF).
Yield: 60.9%.

(OEt 2 ) (0.043 g, 0.08 mmol) in 3 ml of toluene at 0 °C
and the mixture was allowed to warm to room temperature.
During the mixture was stirred for 10 min stirring thecolor of the solution changed from yellow topale-yellow.

-68-

Valerolactone (0.0074 ml, 0.08

Then the solution was quenched by acetic-69-

Chapter 3

Chapter 3

Li ving Polymerization ot Lactones Catalyzed by Rare Earth Metal AlJcoxide Complexes

anhydride and concentrated.

The supernatant liquid wasanalyzed by gas chromatograph.

Living Polymerization of Lactones Catalyzed by Rare Earth Metal AlJcoxide Complexes(THF) (0.15 g, 0.31 mmol) in 5 ml of toluene at -78°C
and the mixture was allowed to react at room
temperature.

After stirring for 10 min the solution was

quenched with acetic anhydride (0.03 ml, 0.31 mmol) andEquimolar Reaction of SmOEt (CsMe s ) 2 (OEt 2 )with £- Caprolactone.

The reaction was carried out III

neutralized by aqueous NaHC0 3 • During these process,white precipitate was emerged.

After concentration of

essentially the same manner as described for thethe supernatant liquid, the resulting product wasreaction of valerolactone using 0.092 g (0.17 mmol) of

separated by gas chromatograph and TLC.

Sm(OEt) (C S Me S ) 2(OEt 2 ) and 0.019 ml (0.17 mmol) of
caprolactone.
Equimolar Reaction of YOMe (CsMe s ) 2 (THF) wi tho-Valerolactone (I).

The reaction was carried out inessentially the same manner as described for thewith ~-Propiolactone.

Propiolactone (0.13 ml, 2.13mmol) was added to a stirred solution of Sm(OEt) (C S Me S ) 2(OEt 2 ) (1.15 g, 2.13 mmol) in 5 ml of toluene ata ()Creaction of caprolactone using 0.21 g (0.45 mmol) ofYOMe(C sMe s )2(THF) and 0.042 ml (0.45 mmol) ofvalerolactone.

and the mixture was allowed to warm to room temperature.
During the mixture was stirred for 5 min the color of
the solution changed from yellow to pale-yellow.

Then

the solution was quenched by a few drops of H20.

The

supernatant liquid was analyzed by gas Chromatograph.

Equimolar Reaction of YOMe(C sMe s )2(THF) with
E-Caprolactone (II).

Caprolactone (0.085 ml, 0.77mmol) was added to a stirred solution of YOMe(C s Me s )2
(THF)

(0.36 g, 0.77 mmol) in 5 ml of toluene at -78°C

and the mixture was allowed to react at room
Equimolar Reaction of YOMe (CsMe s ) 2 (THF) wi th£-Caprolactone(I).

Caprolactone (0.035 ml, 0.31mmol) was added to a stirred solution of YOMe(C S Me S ) 2

temperature.

After stirring for 10 mln, the solution

was quenched with PhCH 2Br (0.18 ml, 1.54 mmol) andneutralized by aqueous NaHC0 3 • During these process,white precipitate was emerged.

-70-

-71-

After concentration ofChapter 3

Chapter 3

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Ccxnp.l exes

Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes

the supernatant liquid, resulting product was separated

valerolactone.

by gas chromatograph and TLC.

Equimolar Reaction of YOMe(C sMe s )2(THF)
c-Caprolactone (II).

1~ith

The reaction was carried out inessentially the same manner as described for thereaction of caprolactone using 0.59 9 (1.28 mmol) of(CsMe s ) 2Y(OMe) (THF) and 0.42 ml (0.45 nnnol) of

Equimolar Reaction of YOMe(C sMe s )2(THF) with
y-Butyrolactone.

The reaction was carried out inessentially the same manner as described for thereaction of caprolactone using 0.72 9 (1.56 mmol) ofYOMe(C sMe s )2(THF) and 0.13 ml (1.69 mmol) of ybutyrolactone.

valerolactone.

Equimolar Reaction of YOMe(C sMe s )2(THF) w'ith
c-Caprolactone (III).

Caprolactone (0.094 ml, 0.85mmol) was added to a stirred solution of YOMe(C sMe s )2
(THF) (0.39 g, 0.85 mmol) in 5 ml of toluene at -78°C.
White precipitate was formed and was washed by a small
amount of hexane.

Recrystallization from toluene gave

white crystalline solids of YOMe(C sMe s )2(caprolactone).

Equimolar Reaction of YOMe(C sMe s )2(THF) with
y-Valerolactone.

The reaction was carried out inessentially the same manner as described for thereaction of caprolactone using 0.027 9 (0.057 mmol) ofYOMe(C sMe s )2(THF) and 0.054 rnl (0.057 nnnol) of y-

-72-

-73-

Chapter 3

Living Polymerization of Lactones Catalyzed by Rare Earth Me t al Alkoxide Complexes

Chapter 4
References

1) Fo r a preliminary report, Yamashita, M.; Takemoto,Y.; Yasuda, H. Rare Earths '92. Kyoto, Japan, June

polymerization of Methyl Methacrylate Catalyzed by
Organo Rare Earth Metal Enolate Complexes

1992, Paper PIK-OS.
2)(a)Yasuda, H.; Yamamoto, H.; Yokota, K.; Miyake, S.;

Introduction

Nakamura, A. J. Am. Chern. Soc., 1992, 114, 4908.
(b)Yasuda, H.; Yamamoto, H.; Yamashita, M.; Yokot:a,K.; Nakamura, A.; Miyake, S.; Kai, Y.; Kanehisa, N.

It has been reported that organo rar e e arth metal

Macromolecules, 1993, 26, 7134. (c)Yasuda, H.;(III) complexes such as [SmB (C sMe s ) 2 ] 2 'Yamamoto, H.; Takemoto, Y.; Yamashita, M.; Yokota, K.;(Ln = Sm, Yb, Y, Lu) and Ln (C sMe s ) 2Me 2AlMe 2 (Ln = Sm, Yb,

LnMe ( CsMe s ) 2 (THF )Miyake, S.; Nakamura, A. Macromol. Chern. Macromol ..

Y, Lu) conduct the living polymerization of methyl

Symp. 1993, 67, 187. (d)Yasuda, H.; Tarnai, H. Prog.

methacrylate at wide range of polymerizati on temperature

Polym. Sci., 1993, 18, 1097.
4) Evans, W.

J.; Ulibarri, T. A.; Ziller, J. W.

Organometallics, 1991, 10, 134.

to give high molecular weight polymers(~> 50,000)with extremely narrow molecular weight distributi on,~/~= 1.02, in high conversion in a short period.
1:2 adduct of SmH(C SMe S ) 2 and methyl methacrylate

was isolated and its structure was revealed by X-ray
analysis.

In the complex, methyl methacryl ate dimer

bonded to Sm in an enolate form at one end and in a
carbonyl coordination in another end forming 8 membered
cyclic structure (Figure 1) 1,2 ) •When additional monomer

was added to the 1:2 adduct, living polymerizati on
restarted efficiently.

There fore such a cycl i c

structure with metal enolate bond was regarded as a realpropagation species.

-74-

-75-

Chapter 4

polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Complexes

The above result indicated that rare earth metal~"1complexes with enolate structure could polymerize methyl"0methacrylate in a living manner.

..Q
Q)

+J
cO

In this chapter, I

prepared rare earth metal enolate complexes and examined

-.-1

+J

their initiating ability for methyl methacrylate

-.-1

C
_'!!.
(f)

>c

-.-1

CO

+J
cO

CO

.--I

>-

$-I

CO
~

I

polymerization.

Q)

The effect of solvent on tacticity of poly(methyl
methacrylate) was also investigated in this part.

~

0
cO

X

...c::

I

8

This chapter also deals with the synthesis of+J

complexes which have the structure of as-symmetry and C1 -

Q)

II

IT:

symmetry and the polymerization of methyl methacrylate

.--I
~'1

...c::
+J
Q)

8
4-l

0

8U)

,.....;

~
Q)

.--I

of regulating the tacticity of poly(methyl methacrylate)8u

by modification of the steric environment around metal~

0

center .

•.-1

C

cO

...c::
U
Q)

8
C
0
-.-1

+J
cO
N

.r-!
$-I
Q)

catalyzed by these complexes to consider the possibility

H
H
H

8

::1

-.-1
$-I

cO

~

{J)

0

C
cO
Ol
H

~1 0

H

0
P4

~

..Q

,......-i

.

0'

-.-1
~

-76-

-77-

Chapter 4

Polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal En olate Compl exesErResu l ts and Discussion

I

Polymerization of Methyl MethacrylateoCatalyzed by Organo Rare Earth Metal Enolate
Complexes.

LL

I
f-

Following the procedure reported by Evanset a l e3) , rare earth metal enolate complexes with CsHe s 'Y(OCH 2=CH 2 ) (CsMe s ) 2(THF) (1) and CS H4 (TMS) [Y (OCH 2=CH 2)i{C S H4(TMS)} 2]2 (~.) were prepared.

0.
0.

•0.

o

o

N

--N

I f)

Q)

::s

If)

IH NMR spectra of theseuNcomplexes are shown in Figure 2, 3.

The enolate0structure of these complexes was confirmed by the

(f)

X
U
II

::c

u

o

~

appear ance of the characteristic signals of OCH=CH 2
LL

Igroup (1 3.93, 4.02 and 6.29 ppm, 2 4.07, 4.28 and 6.29

f-ppm) .

0..0

These complexes showed a good activity for

0

..q-

polymerization of methyl methacrylate giving highmolecular weight poly(methyl methacrylate) in excellent
yield (Table 1).

oThis result is in accord with the fact

illthat the X-ray structure of the 1: 2 adduct of 5mB (C~iMes) 2

Nand methyl methacrylate was samarium enolate form.
oCDInfluence of Solvent on Tacticity of Poly(methyl methacrylate) Catalyzed by SmMe(C SMe S )2
(THF) .

The effect of solvent on the tacticity ofpoly(methyl methacrylate) was investigated.

Hatada etale demonstr ated the effect of solvent on the tacticity

-78-

- 79-

b

TMS~

a

H c

# H
Hi
~TMS

I!./", / 0 "" ~~Y"" / Y'B

TMS~

Cp

I

co
o

f

H~ H

~TMS

H

I

----'--'

a

c b

t

U

I

,~~

7

6

Fig.

'~--r---'-.---,~---,-,

5

3

1

4

~
I

I

3

2

'---'

I

0

ppm

H NMR spectrum of [YOCH=CH 2 {C s H4 (TMS)} 2]2

Table 1. Polymerization of Methyl Methacrylate Initiated by Organo Rare
Earth Metal(III) enolate 8 )10-3~
conversion, %initiator
Cat.%
~/~
I
00

.-.
I

[YOCH=CH 2 {C 5 H4 (TMS) } 2 ] 2

0.5

24.7

1.53

100 (12h)

YOCH=CH 2 (C 5Me 5 ) 2 (THF)

0.2

50.4

1.98

100 (12h)a)solvent, toluene.

Chapter 4

Polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Canplexesof poly(methyl methacrylate) catalyzed by Grignard
reagents.

o
o

0
0

0
0

0
0

r-i

r-i

r-i

r-i

(Y)

co

The syndiotactic polymers were obtained III

toluene, while isotactic polymers were obtained whentetrahydrofuran was used as solvent 4 ).

Table 2 shows the

co

N

L.()

~

co

N

results of polymerization of methyl methacrylate invarious solvents.

All polymerizations afforded

syndiotactic polymers (rr ~ 80%), even when toluene andtetrahydrofuran was used as solvent.

~....-i

However, whenlH

triethylamine were used as solvent, polymers were

o

co

co

N

N
0'\

L.()

co

obtained in a bimodal fashion.

o
N

r-

o

0
~

co

In this case, whiteoprecipitate was generated after stirring the mixture for
1 minute.

This precipitate should be Sm[O-C(OMe)=CH-(CH 3 ) ] ( NEt 3) (C S Me S )2 or Sm(MMA)2Me(NEt3) (C S Me S )2-

L.()

o

(Y)

r-i

0

0

N
0

The use

r-i

N

~

r-i

L.()
L.()

N

....-i....-ior-iof ethyl acetate resulted in the formation of noopolymers, presumably due to the side reaction which
inactivated the active species.

N

Thus, the mode of thereaction differs greatly from that of Grignard reagent.

..c:
Q.l

.~

(Y)

0
N

~

0
N

~

co

0

co

o

0
N

(Y)

0
N

co

o

co

(f)

I

~

4J

U

Polymerization of Methyl Methacrylate

o

"'-

o

Catalyzed by ~- and C1-Symmetric Rare Earth MetalrI

Complexes.

r-

rI

I

In contrast to the polymerization by

o

'r!

4J

'r!

Grignard reagent, change of the solvent did not

'd
~

o

influence the tacticity of resulting poly(rnethyl
methacrylate).

r-

o

~

Next, I attempted to regulate the

o
.r!
+J

tacticity by modification of sterical environment aroundN

metal center.

r-1

o

cO

Q)

Q)

For the purpose, two types of new lilg and

~

.0
cO
8

-83-

-82-

~

.

.

Chapter 4
Polymerization of Methyl Methacrylat.e Cat.alyzed by Organo Rare Earth Met.al Enolat.e Ccmplexes

were prepared.
Three substituents were introduced into Me 2 Sibridged cyclopentadienyl rings.

since one of thesubstituent (tert-butyldimethylsilyl) was larger thanthe others, the ligand afforded highly unsyrrnnetrical (C 1symmetry) complex after complexation.

os-symmetriccomplex was obtained by using a ligand with Me 2 C-bridged
fluorenyl and cyclopentadienyl rings.

Steric effect ofthese modified ligands would be expected to result in

(j)

(j)

the stereoregulation of poly(methyl methacrylate).
As shown in Figure 4 and 5, bistrimethylsilyl-

N

N

(f)
N

(l)

(l)

(l)

:2:

:2:

2

methyl and hydride complexes with these ligands wereQ)

synthesized.

cTable 3 and 4 show the result of methyl

methacrylate polymerization by these complexes.

I

All ofsyndiotactic polymers (rr z

However,80%) were obtained in allcases, indicating that such ligand modifications were
not effective for the stereoregulation.

(j)
N

(l)

:2:

+
C")

o

E

(J)

-84-

Q)

::J

o
f--

them exhibited high activity for the polymerization to
give poly(methyl methacrylate) efficiently.

C'\J

-85-

~

j

,CI.

SU
,\\\

YCI 3

2 n-BuLi+

THF~ "'-CI"--"O•
tBu

LiCH(TMSh

,0

~

Au

Me2C~-CH(TMS12

Toluene

I
00
0"\
I

tBu

(.5)

tBu

(§)

H2
Toluene2

Fig. 5 Synthesis of Me2C(cyclopentadienyl) (2,7-di-tert-butylfluorenyl)YR

Table 3. Polymerization of Methyl Methacrylate Initiated by Organo Rare Earth
Metal(III) Complexes (3) and (1)a)
tacticity, %10-4~mm conversion, %initiator temp. 1°C time(h)rrrrn
M..,/~
I
00
~

I

(J)

(1)

o

24

-78

24

9.93

6.74

80.2

11.3

8.5

100

o

36

1.02

1.03

86.1

5.1

8.8

38.8

-78

12

2.80

9.75

84.2

7.9

8.0

100

trace

a)Reaction conditions: initiator, (3) 0.0672 mmol, (4) 0.0406 mmol;
methyl methacrylate, 8.0 ml; solvent, toluene.

Chapter 4

polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Complexes

~

s::

o

0'-;

Ul

H

Q)

~

o

00

~

N

00

~

If)

Experimental sectiono

A solutionoof CS H4 (TMS)Na (28.8 mmol) in 2 3 .6 ml o f THF was added t oa stirred suspension of anhydrous YCl 3 (3.1 3 g, 16.0
00

o

co

co

..--i

N

..--i

..--i

mmol) in 130 ml of THF at room t emperatur e and t h esolution was refluxed for 20 hours.
M

Resu lting p ale-brown solution was centrifuged in order to separ a te NaC lo

and THF was removed to dryness by evaporat ion and kept
at 75 °C ln vacuo for 12 hours i n order to removeocoordinated THF.

r--

Toluene (150 ml) was added to theresidue and the mixture was stirred for 24 hr at r oom
temperature.
If)ocentrifugation, recrystallization from toluene gave paleNo

After separation of the salt by

If)brown crystalline powder of [YCl{C s H4 (TMS)} 2] 2 ·..--i

Yi eld:60.5 %.

.c
Q)

o~

Ul

+J

s::

U
o

-.-; Q)

o ·

+J

s::

Preparation of YCl (CsMe s ) 2 (THF) .

The complex,-.-; Q)...........

o

o
N

I

00

r-I

o

co

'd ~
S::ri

YCI(C s Me s )2(THF) was prepared in the same procedure

I

o +J

described in chapter 3.

r--

o 0

-

Q)

,-;

cO

.Q

cO

Yield 29%.

Preparation of [Y(OCH=CH 2 ){C s H 4 (TMS)}2]2·

Li-(OCH=CH 2 ) (3.5 mol) in 7.0 ml of THF was added to theE-!

solution of [YCl{C s H4 (TMS)} 2] 2 (1.36 g, 1.71 mmol) at room

-88-

-89-

Chapter 4

Chapter 4

Polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Met al Enol at et emperature.

a~lexes(d, OCH=CHH, 1H), 4. 0 2 (d , OCH=CHH, 1H), 6.29 (dd, OCH=

I mmediate l y aft er t he addition whiteprec ipita te generated.

p ol ymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Ccrnplexes

Af ter stirring for 12 hours at

CH 2 ,

1H).

room t emper a t u r e t he THF was evaporated to dryness by
ke e p ing a t

7 5 °C in vacuo for 12 hours in order tor emove coor d i nated THF.

The white residue was extracted

Preparation of Lu (OCH = CH 2 ) (CsMe s ) 2 (THF) n .

The

4 - 5 t imes with 40 ml of toluene, and then a small

reaction was carried out in essenti al l y the same manneramount of precipitate was removed by centrifugation.

as described above using 0.64 g ( 1 .1 5 romo l ) o f

Evaporation of the solution to dryness resulted strruNcolored solids of [Y (OCH=CH 2 ) {C S H4 (TMS) }2] 2.

(CSMe S ) 2-

LuCI(THF) and 1.15 romol of Li(OCH=CH 2 )·IH NMR (C6D6'ppm) b 0.25 (s, TMS, 18H), 4.07 (d, OCH=CHH, 1H), 4.28
(d, OCH=CHH, 1H), 6.29 (dd, OCH=CH 2, 1H), 6.39 and 6.78

tPreparation of Y (OC Bu=CH 2 ) (CsMe s ) 2 (THF) •The

mixture of YCI(C sMe s )2(THF) (0.91 g, 1.95 romol) and Li(OC t Bu=CH 2 )Preparation of Y (OCH=CH 2 ) (CsMe s ) 2 (THF) •Li-(0.64 g, 6.05 mol) was dissolved i n 40 ml o ftetrahydrofuran at room temperature and then whit e( OCH=CH 2 ) ( 3 . 6 mol) in 7. 2 ml of THF was added to thE~

precipitate generated.

solution of YCI (CsMe s ) 2 (THF)

room temperature the tetrahydrofuran was evaporated totemperature.

(0.91 g, 1.95 mmol) at room

dryness.

Immediately after the addition white

precipitate generated.

After stirring for 12 hours atroom temperature the THF was evaporated to dryness.

The

white residue was extracted 4 - 5 times with 40 ml oftoluene, and then a small amount of precipitate wasremoved by centrifugation.

Evaporation of the solution

After stirring for 6 hours a t

The white residue was extracted wi th 80 ml oftoluene, and then a small amount of precipitate wasremoved by centrifugation.

Solid mass obtained byevaporation of the solution were further extracted wi th
80 ml of hexane.

Evaporation of the solution to dryness

resulted in the formation of straw-colored solids ofto dryness resulted straw-colored solids of Y(OCH=CH 2 )(C S Me S )2(THF).

IH NMR (C 6D6' ppm) b 0.34 (s, TMS, 18H),

1.31 (m, THF), 2.16 and 2.20 (C sMe s ), 3.53 (m, THF), 3.93

-90-

-91-

Chapter 4

Chapter 4

Polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Complexes

polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Complexes

Preparation of Me 3 Si{4-(tert-butyl-dimethyl-

Preparation of Me 3 Si{4-(tert-butyl-dimethyl-

silyl)-2-(trimethylsilyl)cyclopentadiene} (3-tert-silyl)-2-(trimethylsilyl)cyclopentadienyl}(3-tert-butylcyclopentadiene).

To a stirring solution of 1-

butylcyclopentadienyl)SmC1 2 Li(THF)2.

A hexane(tert-butyldirnethylsilyl)-3-(trirnethylsilyl)cyclopenta-

solution of 1.64 M n-butyllithium (11.0 ml, 18.0 mmol)

diene (7.06 g, 0.028 mol) in hexane (40 ml) was added

was added to a solution of Me 3 Si{4-{tert-butyldimethyl-

hexane solution of 1.64 M n-butyllithium (19.0 ml,

silyl)-2-{trimethylsilyl)cyclopentadiene} (3-tert-butyl-0.0312 mol) at 0 °c, and stirred for 20 hours at room

cyclopentadiene) (3.17 g, 7.36 mmol) in tetrahydrofuran

temperature.

(100 ml) at 0 °c, and the mixture was stirred at room

To a resulted solution tetrahydrofuran (40ml) was added, and then dirnethylsilyldichloride (3.810

temperature for 3 hours.

ml, 0.0313 mol) in tetrahydrofuran (10 ml) was added

added to SmCl 3 (2.25 g, 8.76 mmol) in tetrahydrofuranwith stirring at 0 °c and kept the mixture under same
condition for 1 hour and at room temperature for 24hours.

After removal of solvent tetrahydrofuran (60 ml)

was added to the residue.

Then the solution was dropwise(80 ml), and the mixture was stirred for 12 hours.
After the solvent was removed in vacuo, the residue was
extracted with hexane (120 ml).

Centrifugation of thesolution followed by recrystallization from hexane gave

Next, to a stirring solution of tert-butylcyclopentadiene (7.06 g, 0.028 mol) in tetrahydrofuran (40ml) was added hexane solution of 1.64 M n-butyllithillm(17 . 5 ml, 0.0287 mol) at 0 °c, and stirred the mixture
for 4 hours at room temperature.

Then to the previous

a yellow crystals of Me 3 Si{4-(tert-butyldimethylsilyl)2-(trimethylsilyl)cyclopentadienyl} {3-trimethylsilylcyclopentadienyl)SmCI 2Li(THF)2.

Yield: 2.78 g (3.47mmol) in one crop, 47.1 %.

tetrahydro-furan solution was added this solution at 0°c and stirred for 14 hours.

The mixture was poured

into a large amount of water (500 ml).

The solution was

extracted with hexane (150 ml, twice) and organic layer
was dried over Na 2S0 4 •Evaporation of the product gave

pale yellow liquid of Me 3 Si{4-(tert-butyldirnethylsilyl)-

Preparation of Me 3 Si{4-(tert-butyldimethylsilyl)-2-(trimethylsilyl)cyclopentadienyl}(3-tertbutylcyclopentadienyl)SmCH(TMS)2.

A ether solutionof 0.67 M LiCH(trimethylsilyl)2 (7.0 mlf 4.69 mmol) was

2-(trirnethylsilyl)cyclopentadiene} (tert-butylcyclo-

added to a solution Me 3 Si{4-(tert-butyldimethylsilyl)-2-pentadiene) (8.46 g, 0.0196 mol).

(trimethylsilyl)cyclopentadienyl} (3-trirnethylsilylcyclo--92-

Yield: 70.3 %.

-93-

Chapter 4

Chapter 4

Polymeri zati on of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Complexes

polymeri zation of Methyl Methacryl ate Cataly z ed by Organo Rare Earth Metal Enalate Canplexes

pentadienyl)SmC1 2Li(THF)2 (2.78 g, 3.47 mol) in toluene

Preparation of Me 2 C(cyclopentadiene) (2,7-di-(100 ml) at 0 °c and the mixture was stirred for 24

tert-butylfluorene).

hours at room temperature.

butyllithium (46 ml, 0.075 mol) was added to a solution

After the removal of

A hexane solution of 1.61 M n-toluene, the residue was extracted with hexane (100 ml).

2,7-di-tert-butylfluorene (18.9 g, 0.068 mol) in tetra-

Centrifugation followed by recrystallizion from hexane

hydrofuran (150 ml) at 0 °C.

gave orange crystals of Me 3 Si{ 4- (tert-butyldimethyl-.

stirred at room temperature for 8 hours, and then after

silyl)-2-(trimethylsilyl)cyclopentadienyl} (3-trimethyl-cooling to -78°C 6,6-dimethylfuluvene (9.0 ml, 0.075

silylcyclopentadienyl)SmCH(TMS)2.

mol) was dropwise added taking over 20 minutes.

Yield: 1.41 g (1.91

The reaction mixture wasThe

mixture was allowed to warm to room temperature withmmol) in one crop, 55.0 %.

stirring.

The solvent was removed in vacuo, and water(500 ml) was added to the residue.

Preparation of 2,7-di-tert-butylfluorene.

After extractingwith ether (200 ml, twice), the ether layer was washed

To a solution of fluorene (34 g, 0.20 mol) and 2,6-di-with water (200 ml, twice) and dried over Na 2 S0 4 •tert-butyl-p-cresol (44 g, 0.30 mol) in nitromethane

the removal of solvent in vacuo, the residue was(300 ml) was added a solution of aluminium chloride (40recrystallized from chloroform/methanol to give pinkg, 0.30 mol) in nitromethane (60 ml) over a period of 30

powder of Me 2C(cyclopentadiene) (2,7-di-tert-butyl-

minutes at room temperature.

fluorene)

The reaction mixture was(8.19 g, 0.021 mol).

After

Yield: 31.4 %.

stirred for 15 minutes and poured into a large amount of
ice water (500 ml).

The solution was extracted withether (150 ml, twice) and washed with 10% NaOH aqueous
solution (100 ml, twice).

Then organic layer was driedover Na 2 S0 4 , and evaporated in vacuo.

The residue wasrecrystallized from ethanol to give green powder of 2,7di-tert-butylfluorene (24.0 g, 0.089 mol).
%•

Yield: 43

Preparation of Me 2 C(cyclopentadienyl) (2,7di-tert-butylfluorenyl)YC1 2Li(THF)2-A

hexanesolution of 1.61 M n-butyllithiurn (17.5 ml, 0.028 mol)
was added to a solution Me 2 C(cyclopentadiene) (2,7-ditert-butylfluorene) (5.07 g, 0.013 mol) in tetrahydrofuran (100 ml) at DoC, and the mixture was stirred atroom temperature for 8 hours.

Then the solution was

dropwise added to YC1 3 (2.83 g, 0.015 mol) in tetra-

-94-

-95-

Chapter 4

Chapter 4

Polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Complexes

polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Canplexeshydrofuran (100 ml), and the mixture was refluxed for 12

with vigorous magnetic stirring.

hours.

continued for 3 hours at 0 °C.

After the solvent was removed in vacuo, thebrown residue was extracted with hexane.

Recrystall-

ization from hexane gave a yellow powder of Me 2C(cyclo-

The stirring was
The reaction mixture wasquenched with 200 ml of methanol, to give white powderof poly(methyl methacrylate).

pentadienyl) (2,7-di-tert-butylfluorenyl)YCI 2Li(THF)2.
Yield: 31.2 %.
polymerization of methyl methacrylate
catalyzed by Me 3 Si{4-(tert-butyldimethylsilyl)-2Preparation of Me 2 C(cyclopentadienyl) (2,7di-tert-butylfluorenyl)YCH(TMS)2.

A ether solutionof 0.75 M LiCH(TMS)2 (6.6 ml, 4.94 rnmol) was added to asolution Me 2C(cyclopentadienyl) (2,7-di-tert-butylfluorenyl)YCI 2Li(THF)2 (2.85 g, 4.12 mol) in toluene (150ml) at 0 °C and stirred for 12 hours under the same
conditions.

After the removal of toluene, the redresidue was extracted with hexane.

Recrystallizationfrom hexane gave red powder of Me 2C(cyclopentadienyl)(2,7-di-tert-butylfluorenyl)YCH(TMS)2.

(trimethylsilyl)cyclopentadienyl} (3-tert-butylcyclopentadienyl) SmCH (TMS)2.

A catalyst Me 3 Si{4-(tert-butyldirnethylsilyl)-2-(trimethylsilyl)cyclopentadienyl} (3-tert-butylcyclopentadienyl)SmCH(TMS) 2 (49.7
mg, 0.67 romol) was dissolved in 10 ml of toluene.

Tothe solution was added 0.85 ml of methyl methacrylate at

o °c with vigorous magnetic stirring.
continued for 12 hours at 0 °C.

The stirring was

The reaction mixture

was quenched with excess of methanol/hexane, and white
powder of poly(methyl methacrylate) was obtained.

Yield: 19.2 %.

polymerization of methyl methacrylate
Polymerization of methyl methacrylate

catalyzed by Me 3 Si{4-(tert-butyldimethylsilyl)-2-catalyzed by Me 2 C(cyclopentadienyl) (2,7-di-tertbutylfluorenyl)YCH(TMS)2.

A catalyst Me 2C(cyclopenta-(trimethylsilyl)cyclopentadienyl} (3-tert-butylcyclopentadieny l) SmH.

A catalyst Me 3 Si { 4- (tert-

dienyl)(2,7-di-tert-butylfluorenyl)YCH(TMS)2 (23.3 mg,

butyldirnethylsilyl)-2-(trirnethylsilyl)cyclopentadienyl}

0.0365 romol) was dissolved in 19 ml of toluene.

(3-tert-butylcyclopentadienyl)SmCH(TMS) 2 (30.0 mg, 0.41

To thesolution was added 1.0 ml of methyl methacrylate at 0 °C

-96-romol) was dissolved in 10 ml of toluene.

-97-

The solution

Chapter 4

Chapter 4

Polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal Enolate Complexes

polymerization of Methyl Methacrylate Catalyzed by Organo Rare Earth Metal ETIolate Complexes

was degassed and charged with H2 , and stirred there for
1 hour.

The color of the solution changed from orrulge

to yellow.

References

The solution was added to 0.85 ml of methyl

methacrylate at 0 °C with vigorous magnetic stirring.

1) (a)Yasuda, H.; Yamamoto, H.; Yokota, K.; Miyake, S.;

The stirring was continued for 12 hours at DoC.

Nakamura, A. J. Am. Chern. Soc., 1992, 114, 4908.

Finally, the reaction mixture was quenched wi th eXCE~SS(b)Yasuda, H.; Yamamoto, H.; Yamashita, M.; Yokota,of methanol/hexane to provide white powder of poly-K.; Nakamura, A.; Miyake, S.; Kai, Y.; Kanehisa, N.

(methyl methacrylate).

Macromolecules, 1993, 26, 7134. (c)Yasuda, H.;
Yamamoto, H.; Takemoto, Y.; Yamashita, M.; Yokota, K.;
Miyake, S.; Nakamura, A. Macromol. Chem. Macromol.

Symp. 1993, 67, 187. (d)Yasuda, H.; Tamai, H. Prog.
Polym. Sci., 1993, 18, 1097.
2) It should be noted that such an eight membered ringintermediate was proposed for isotactic polymerizationof methyl methacrylate.;(a)Bawn, C. E. H.; Leadwith,
A. Q. Rev. Chern. Soc. 1962, 16, 361.

(b)Cram, D. J.;

Kopecky, K. R. J. Am. Chern. Soc. 1959, 81, 2748.
3)Evans, W. J.;Dominguez, R.;Hanysa, T. P.

Organometallics 1986, 5, 1291.
4) (a)Hatada, K.; ute, K.; Tanaka, K.;Kitayama, T.;Okamoto, Y. Polym. J., 1985, 17, 977. (b)Hatada, K.;
Ute, K.; Tanaka, K.; Okamoto, Y.;Kitayama, T. Polym.
J., 1986, 18, 1037. (c)Kitayama, T.; Shinozaki, T.;

Masuda, E.; Yamamoto, M.; Hatada, K. Polym. Bull.,
1988, 20, 505.

(8)Kitayarna, T.; Shinozaki, T.;

Sakamoto, T.; Yamamoto, M.; Hatada, K. Makromol. chern.

Suppl., 1989, 15, 167.

-98-

-99-

Chapter 5
Living Polymerization of Trimethylsilyl Substituted Methacrylate
Catalyzed by Organo Rare Earth Metal Complexes

Chapter 5protected methacrylate monomers stereoselectively.
Physical properties of stereoregulated water soluble
Living Polymerization of Trimethylsilyl

polymers thus obtained may be interesting from an

Substituted Methacrylate Catalyzed by Organo Rare

industrial point of view.
In this chapter, rare earth metal complexes were

Earth Metal Complexes

applied to the polymerization of various protected
methacrylate monomers.
Introduction

In 1982, Nakahama et ale found the anionic living
polymerization of tert-butyldimethylsilyl substituted 4vinylphenol.

In this case, monodispersed poly(4-vinylphenol)(M.,/~ <1.1) was obtained quantitatively

upon hydrolysis of silyl group.

This is the firstexample of anionic living polymerization of thefunctional monomer, which is generally very difficult by
conventional method 1 ).
In a similar manner, poly(methacrylic acid) andpoly(hydroxyethyl methacrylate) have been prepared by
the polymerization of their protected monomer (CH 2 =CMeCOOSiMe 3 and CH 2 =CMeCOOCH 2 CH 2 0SiMe 3 ) followed byhydrolysis (deprotection).

However, stereoselective

polymerization of these monomers has not been achieved
so far.

Judging from the result of methyl methacrylate

polymerization by rare earth metal complexes 2 ), theinitiating system would be expected to polymerize the

-100-

-101-

Ch apter 5
Living Polymerization of Trimethylsilyl Subs tituted Methacrylate
Catalyzed by Organo Rare Earth Metal Canplexes

Results and Discussion

Rare Earth Metal Initiated Polymerizationof Trimethylsilyl Methacrylate.

Polymerization oftrimethylsilyl methacrylate (TM8MA) was examined first.
Tab l e 1 shows the result of the polymerization catalyzed

L1)oby SmMe (CsMe s ) 2 (THF ) and [8mH ( CsMe s ) 2 ] 2 •

rl
rl

o(V)

Lf)

0

""

0

The product was

obtained as a water soluble poly(methacrylic acid) by
the treatment with methanol.

...

s::
o
-.-I

Both the initiators

afforded poly(methacrylic acid) with narrow molecularweight distribution in good yield.

+l
cd
H
+l

""I

o

Figure 2 shows ·therelationship between ~ and ~/~ against conversion.

o

s::

rl

(l)
C)

s::

~

o

C)

increases linearly with the conversion retaining ~/~

H

o

L.{)

value below 1.10.

These results indicated that theo
4--1

Furthermore, TMSMA was

N

cd
-.-I

+l

polymerization of TMSMA by rare earth metal initiators
proceeded in a living manner.

+l

rl

-.-I

H
H

s::

o H

-.-I

polymerized stereoselectively affording highly syndio(rr ~ 90%).

tactic poly(methacrylic acid)The

stereoselectivity was calculated from the peak intensityNratio in carbonyl region of

13

C_ NMR spectrum (Figure 3).

,.......,
('oJ

U"I

From the above results, it 1S obvious that the

(l)

::8

U"I

mechanism of polymerization here is quite similar tothat of methyl methacrylate polymerization.

U

As sho~ffl in..--..

cd

Figure 1, the reaction is estimated to proceed throughan 8 membered cyclic intermediate, which is the ori9inof the high stereoselectivity.

-102-- 103-

..-a:~(f)c~

I-....-

o
o

Q)

+J
reS

o

rl
~

~

0

reS

~

}

+J

;;

~[_HH

mHH __ H_H Hm H_~m

H m H H QH HQ

1

1.0S[
J
8 .-----------------------------~

Q)

I

8
rl

I

J

J

~

rl

I

~

(j}

~
~

a:

l{)

0

0
T""-

c

(f)
N

::J

o
+-'

U

II

+J

C

4--1

c3

I

Q)

.0.

Q)

T""-

~~

Q)

+J

8
.r-!

,,~

0

Cat . Concn . : 1.0 mol%

~

..;t

0
0
E

6

rl

I

IT:

Cat. : CpT 2SmH

'r-!

2

0

c
0

.r-!

+J
reS

20

N

40

60

80

100

Conversion (%)

.r-!
~
Q)

~

............
C")

rl

Q)

0

~

~

(f)

---I

0

C")

0

I

o

..-I

'"o

0

Fig. 2

Conversion vs. Mn and Mw/Mn of poly(methacrylic acid) generated by polymerization of trimethylsilyl methacrylate.

t})

.r-!
Ii4

/

II

N

I

o

-104-

-105-

Chapter 5

Living Polymerization of Trimethylsilyl Substituted Methacrylate
Catalyzed by Organo Rare Earth Metal Complexes

Block and Random Copolymerization of Tri-

E

if)
if)

o

0..
0..
-

-

methylsilyl Methacrylate and Methyl Methacrylate
Catalyzed by SmMe(C SMe S )2(THF).

--t

Since polymer-

izations of both TMSMA and methyl methacrylate by rareoo - - - - - - - -- -- -=.zNearth metal complexes proceeded through the similar
metal enolate intermediate, copolymerization of thesemonomers was expected to occur smoothly.
Random copolymerization was examined firs t .

o

When

1:10 to 1:3 (TMSMA:MMA) mixture of the monomers wasillreacted with SmMe(C SMe s ) 2(THF), only homopolymer ofI\ comethyl methacrylate was obtained.

o

u
.0

o

Higher TMSMA r atio

than 1:3 resulted in no reaction (Table 2).
rrOoTable 3 shows the result of block copolymerization.
In both the order of the monomer addition (MMA-TMSMA andTMSMA-MMA), 2nd stage polymerization did not start at
all.
To get further insight into the inefficiency of theblock copolymerization, I demonstrated the stoichiometric reaction at -78°C between SmMe(C sMe s ) 2(THF) andboth rnethacrylates (TMSMA, MMA).

o

o
u

r~
l

Each sequential

addition of the monomers in the order of TMSMA-MMA and
MMA-TMSMA resulted in the formation of Sm(TMSMA) (MMA)Meand Sm(MMA) (TMSMA)Me, which decomposed upon hydrolysis
to afford CH 3 CH(COOH)CH 2C(CH 3 ) (CH 2Me) (COOCH 3 ) and CH 3 CH
(COOCH 3 )CH 2C(CH 3 ) (CH 2Me) (COOH) , respectively (Figure 4,
5).

Thus, the addition of TMSMA to the active end of

Sm-(MMA)Me and the addition of MMA to the Sm(TMSMA)Me

-106-

-107-

Table 2. Random Copolymerization of Trimethylsilyl Methacrylate and Methyl Methacrylate Initiated bySmMe(C 5 Me 5 )2(THF)a)

I
f-I

10-4~

M."/~

5

7.73

1.17

58.3

0

liS

5

3.31

1.11

75.2

0

1/10

5

2.12

1.21

96.2

0

TMSMA/MMA ratiotime(h)

III

15

1/2

15

1/3

conversion, % MA content,%

0

co
I

a)Reaction conditions: initiator concentration, 1.0 mol%of monomer; polymn. temp., -78°C; solvent, toluene.

Table 3. Block Copolymerization of Trimethylsilyl Methacrylate(TMSMA) with Methyl Methacrylate(MMA)a)
A-B
A
A-B
AlB
monomer
10-4~(M."I ~)
10-4~
(M."I ~)
ratio
I
f-I

MMA-TMSMA

1.14(1.05)

1.14(1.04)

2.27(1.04)

2.31(1.03)

5.69(1.04)

5.65(1.03)

3.72(1.21)

3.75(1.20)

3.84(1.18)

3.80(1.19)

0'"I
TMSMA-MMAa)Reaction conditions: initiator, SmMe(C 5Me 5 )2(THF);
initiator concentration, 1.0 mol% of monomer;[premonomer] I [comonomer] = Ill, solvent, toluene.

Cp*28mMe(THF) + MMAj" p==C
'"8m
\C-Me
/

\

OMe
"'- /O-C~ /Me
8m
Y-CH 2 Me/ \, Me\:,,
C==CH 2/O=C
O-(TM8)
/

/OMe
TM8MA

II

Me-- CH 2.......
.-1

o
I

H+

oII

0

CH 3 IIc"OMe
HO /C""CH/CH21~
~
~

CH 3

Fig. 4

CH 2MeStoichiometric reaction of SmMe(C sMeS)2(THF) with methyl methacrylate
and trimethylsilyl methacrylate.

Cp*28mMe(THF) + TM8MA

j/O-(TM8)
,O==C
,
'"8m
\C-Me
/

\

O-(TM8)
O-C, Me
/

"'- /

MMA

II

"'-" /

8m
Y-CH 2 Me/ \ Me\:,,
C==CH 2
/
O=C
OMe
\

Me-- CH 2\

I.......

.......
.......
I

H+

oII

0

CH 3 IIC" OH
MeO /C""CH /CH21~
~

~

CH 3

Fig. 5

CH 2MeStoichiometric reaction of SmMe(C SMeS)2(THF) with trimethylsilyl
methacrylate and methyl methacrylate.

Chapter 5
Living Polymerization of Trimethylsilyl Substituted Methacrylate
Catalyzed by Organo Rare Earth Metal Complexes

end occurred in the stoichiometric reaction, though
copolymerization between these monomers did not occur.

0)

I

E
l{)

o--- 0-0(f)
I

Rare Earth Metals Initiated Polymerization

I

f'...

~

The polymer-oN(j)1..()

ization of trimethylsiloxyethyl substituted methacrylate

0-00..
I..0of Trimethylsiloxyethyl Methacrylate.

I

0
0

C'?

could occur by using organo rare earth metal complexes
as initiator.

The polymerization provided high

I

I..()

I

0

~

([ c

II

~

I

0

N

Ct)
Ct)'::!2.

N

G

o

I

o
o
-+---0

~ .~

u..>-

N

I

~

I

o

methacrylate) which was not available by conventionalo~Io, , /0 0N NtooN-omolecular weight monodispersed poly(trimethylsiloxyethyl

anionic polymerization (Figure 6).

I

0

~

o
~

I

.,..,ooTable 4 shows theQ)

result of polymerization of trimethylsiloxyethyl0..--..

methacrylate catalyzed by [SmH(C SMe S)2]2.

(f)

The polymer-

~

E Q)
(f) C

LL

2

I

Q)

~

NQ)

- ~
Z

concentration and at 0 °C of polymerization temperature.

m.,..,N

I

C'?
Q)

ization occurred only in 1.0 mol% of catalyst

+l

2

-I<

r-I

::J

0.. 0
..--..~

o

C'?

+-'

W

--o

These polymerizations gave poly(trimethylsiloxyethyl

([

(Mw/~

= 1.20).

o

I

I

o
I

I

siloxyethyl methacrylate bearing the stronger si-o bondwas demonstrated.

However, polymerization of thismonomer was not initiated by [SmH ( CsMe s ) 2 ] 2' which might

0

C'?

0

I

I

0" /0

o

\I

N

I

o

be ascribed to the steric effect of the bulky tertbutyldimethylsilyl group.

-112-

0

N

G
I

-+---0otrimethylsiloxy group of the obtained polymer.

~

o
o

N

polydispersity may be caused by slow decomposition of

Accordingly, the polymerization of tert-butyldimethyl-

N

o

N

The broad

C

~I

I

I

rather broad polydispersity

~

I

T"'""

methacrylate) with high molecular weight (> 10 4 ) and

o

-113-

'0
~

•

Q)

m+l

m

.,..,U)r-I

~

U)

Q)

~

U

..c m
+l..c
~+J
~Q)

(/) E:

Chapter 5

Living Pol ymerization of Trimethylsilyl Substituted Methacrylate
Catalyzed by Organo Rare Earth Metal Canplexes

Experimental Section

..

~

o

. .--1

General.

Ul

H

Q)
~

r-i

0

00

00

molecular weight distribution o f hydrophilic polymer s~owere determined by gel permeation chromatography (GPC)

o

..

H
H

Number averaged molecular weight andon a Tosoh SC-8010 high-speed liquid chromatograph
N

(Y)

r-I
OO

rr-

equipped with a differential refractometer detector,
using acetonitrile/phosphate buffer (4/1) as a eluent a t
40.0 °C.

The columns are consisted of four columns:

TSK-GEL G3000PWXL, TSK-GEL G4000PWXL, TSK-GEL GSOOOPWXL
and TSK-GEL G6000PWXL (Tosoh Manufacturing Co., Ltd.)was used.
N

L.{')

r-i

m

N

N

•

The flow rate was 1.0 ml IDln

- 1.

The molecularweight calibration curve was obtained by using TSK
standard Poly(ethylene oxide)s : 2.6 x 101.20), 4.6 x 10 4 (~/~ = 1.10), 9.5 x 1044(~/~ =(~/~ = 1.04),

1.7 x 105 (~/~ = 1.04), 2.S x 105 (~/~ = 1.04), S.l x
105 (~/~ = 1.0S) and 9.13 x 10 5 (~/~ = 1.08) (Tosoh
Manufacturing Co., Ltd.).

,-...

The complex,

cO[SmH (CsMe s ) 2] 2 was prepared in the same procedure as
described in chapter 2.

-114-

-llS-

Chapter 5

Chapter 5

Living Polymerization of Trimethylsilyl Substituted Methacrylate
Catalyzed by Organo Rare Earth Metal Canplexes

Preparation of SmMe (CsMe s ) 2 (THF) 4) •The

Living Polymerization of Trimethylsilyl Substituted Methacrylate
Catalyzed by Organo Rare Earth Metal Canplexes

hours and stirred at room temperature for 8 hours.

The

complex, SrnMe(C sMe s )2(THF) was prepared in the same

mixture was quenched by water and then extracted byprocedure as described in chapter 2.

hexane.

The solution was concentrated in vacuo to givetert-butyldimethylsiloxyethyl methacrylate in 65.6%
yield [bp. 60.7-61.7 °C/0.3 mrnHg].
Preparation of trimethylsiloxyethyl methacrylate.

Hydroxyethyl methacrylate (24.3 ml, 200

romol) was added with stirring to a solution of triethyl

Polymerization of trimethylsilyl meth-

A toluene

amlne (55.8 ml, 400 mmol) in THF (150 ml) at room

acrylate catalyzed by SmMe(C S Me S )2(THF).

temperature under Ar.

solution of SmMe(C s Me s )2(THF) (0.051 g, 0.1 mmol) was

Stirring was continued for 10

minutes under the same conditions.

Trimethylsilyl

added to a toluene solution of 100 equivalent trimethyl-chloride (38.1 ml, 300 mmol) was added with stirring atsilyl methacrylate (1.79 ml, 10 mmol) at -78°C.

O°C and the mixture was stirred for 24 hours at room

stirring for several hours the solution was quenchedtemperature.

with excess methanol.

The mixture was quenched by water and thenextracted by hexane.

After

The solution was concentrated invacuo to produce trimethylsiloxyethyl methacrylate in
Polymerization of trimethylsiloxyethyl79.1 % yield [bp. 57.5 °C/1.0 mmHg].

methacrylate catalyzed by SmMe (CsMe s ) 2 (THF) •A

toluene solution of [SmH(C S Me S )2]2 (0.042 g, 0.05 romol)
Preparation of tert-butyldimethylsiloxyethyl methacrylate.

Hydroxyethyl methacrylate (36.5

was added to a toluene solution of 100 equivalent
trimethylsilyl methacrylate (1.79 ml, 10 mmol) at -78°C.

ml, 300 romol) was added with stirring to a solution of

After stirring for several hours the solution wastriethyl amine (55.8 ml, 400 mmol) in THF (180 ml) a.t

quenched with excess methanol.

room temperature under Ar.

Stirring was continued for

10 minutes under the same conditions.

Tert-butyl-

dimethylsilyl chloride (50 g, 331 mmol) was added withstirring at 0 °C and the mixture was refluxed for 7-116-

Polymerization of tert-butyldimethylsiloxyethyl methacrylate catalyzed by [SmH(C sMe s )2]2.

-117-

A

Chapte r 5
Methac ryla t e
Living Polym erizati on of Trime thylsil yl S ubstit uted
xe s
Ccmple
Metal
Earth
Rare
Cataly zed by Organo

t o lue ne sol u tion o f[ SmH(C s Me s ) 2] 2 was adde d to a tolu ene

xye't hyl
so l u tion o f 200 equi vale nt tert- buty ldim ethy lsilo
Afte r stir ring for 3,
meth a cryl ate at -78, 0 and 60°C .
ss
6, and 24 hour s the solu tion was quen ched by exce
meth anol .

Chapte r 5thylsil yl Substi tuted Metha crylate
Tr.imeof
Living Polym erizati on
Earth Metal Canple xes
Rare
OrganobyCataly zed(1.0 ml) of SrnMe(C s Me s ) 2(TH F)(0.0 51 g, 0.1 romo l) was

adde d to a mixt ure of meth yl met hacr y l a te and, 10: 1
trim ethy lsily l meth acry late (1: 1, 2: 1 , 3: 1, 5 : 1
l ved i nmola r rati o, amou nts of mono mer: 20 romo l) d i sso
Thetolu ene (20 ml) with vigo rous stir r i ng at -78° C.
o r 15stir ring was cont inue d for seve ral hour s (5, 6exce sshour s), and the reac tion mixt ure was pour ed into

Bloc k cop olym eriz atio n of met hyl
met hac ryla te with trim ethy lsil yl met hac ryla tecata lyze d by SmMe(C S Me S )2(T HF).

The resu lting poly mer was drie d unde r redu cedpres sure .

Meth yl meth acry latetion (20(2.14 ml, 20 mmo l) was adde d to the tolu ene solu
O°C withml) of SmMe(C s Me s ) 2(TH F) (0.02 5 g, 0.05 romo l) at
vigo rous mag netic stir ring .

meth anol .

The stir ring was cont inue d

A half of the reac tion mixt ure was take n
poly
out and pour ed into meth anol . The prec ipita tedfor 2 hour s.

n ruld(Met hyl meth acry late) was coll ecte d by filtr atio
adde ddrie d in vacu um. To the rest of the mixt ure wasat O°C.
trirn ethy lsily l meth acry late (1.79 ml, 10 mmo l)reac tion
The stir ring was cont inue d for 4 hour s, and theinto
was term inate d by pour ing the reac tion mixt ure
r redu ced
meth anol . The reSU lting poly mer was drie d undepres sure .

Equ imo lar Rea ctio n of SmM e(C S Me S )2(T HF) withmet hyl met hac ryla te and trim ethy lsil yl
Meth yl meth acry late (0.07 1 ml, 0.66
Me ) 2romo l) was adde d to a stir red solu tion of SmMe(C s s

met hac ryla te.

ofur an at(THF ) (0.42 g, 0.83 romo l) in 20 ml of tetra hydr
8 ml,
-78° C and then trirn ethy lsily l meth acry late (0.14to0.83 mmo l) was adde d and the mixt ure was allow ed
10reac t at room temp eratu re. Afte r stir ring foryel lowminu tes the colo r of the solu tion chan ged from
HCI
oran ge to pale yello w. A few drop s of aque ous
f thesolu tion was adde d to the solu tion (the colo r oa t e wassolu tion chan ged pale -yel low) and whit e prec ipit
Afte r extr acti on with chlo rofo rm and
uct wasconc entr atio n of the prod uct, the reSU lt i ng prod

gene rated .

Rand om cop olym eriz atio n of met hyl
met hac ryla te with trim ethy lsil yl met hac ryla tecata lyze d by SmMe(C SMe S )2(T HF).

-118 -

sepe rate d by gas chro mato grap h.

A tolu ene solu tion

-119 -

Chapter 5

Living Polymerization of Trimethylsilyl Substituted Meth acryla t e
Catalyzed by Organo Rare Earth Met al Canpl exes

Chapter 5
Living Polymerization of Trimethylsilyl Substituted Methacrylate
Catalyzed by Organo Rare Earth Metal Cccoplexes

Equimolar Reaction of SmMe(C SMe S )2(THF) withtrimethylsilyl methacrylate and methyl
methacrylate.

Trimethylsilyl methacrylate (0.11 ml,

0.61 romol) was added to a stirred solution of SmMe(C s Me s ) 2(THF)

References(0.390 g, 0.767 rnmol) in 20 ml of tetra-hydrofuran at -78°C and then methyl methacrylate (0.082
ml, 0.76 romol) was added and the mixture was allowed toreact at room temperature.

After stirring for 10l)Hirao, A.; Yamaguchi, K.; Takenaka, K.; Su z uki, K.;
Nakahama,

S.; Yamazaki, N. Makromol. Chern., Rapid

Commun., 1982, 3, 94 1 .
2)(a)Yasuda, H.; Yamamoto, H.; Yokota, K.i Miyake,
S.;Nakarnura, A. J. Am. Chern. Soc., 1992, 114, 4908.

minutes the color of the solution changed from yellow-(b)Yasuda, H.; Yamamoto, H.; Yamashita, M.; Yokota ,orange to pale yellow.

K.; Nakamura, A.; Miyake, S.; Kai, Y.; Kanehisa, N.

A few drops of HCl aqueous

solution was added to the solution (the color of theMacromolecules, 1993, 26, 7134. (c)Yasuda, H. ;solution changed pale-yellow) and white precipitate was

Yarnamoto, H.; Takemoto, Y.; Yamashita, M. ; Yokot a, K.;

generated.

Miyake, S.; Nakamura, A. Macromol. Chern . Macr omol .

After extraction with chloroform andconcentration of the product, the resulting product was

Symp. 1993, 67, 187. (d)Yasuda, H.; Tarnai , H. Pro g.

seperated by gas chromatograph.

Polym. Sci., 1993, 18, 1097.
3)Evans, W.

J.; Chamberlain, L. R.; Ulibarr i , T . A.;

Ziller, J. W. J. Am. Chern. Soc., 1988, 110, 6432.
4)Evans, W. J.; Bloom, l.; Hunter, W. E.;Atwood, J. L.

J. Am. Chern. Soc., 1983, 105, 1401.

-120-

-121-

LIST OF PUBLICATIONS

1.Novel Synthesis of High Molecular Weight Polymers with
Extremely Low Polydispersity by the Unique Initiation
Properties of Organolanthanide Complexes
Yasuda, H.; Yamamoto, H.; Takemoto, Y.; Yamashita, M.;
Yokota, K.; Miyake, S.; Nakamura, A.

Macramal. Chern., Macramal. Symp. 1993, 67, 187-201.

2.Synthesis of High Molecular Weight Poly(methyl
methacrylate) with Extremely Low Polydispersity by the
Unique Function of Organolanthanide(III) Complexes
Yasuda, H.; Yamamoto, H.; Yamashita, M.; Yokota, K.;
Nakamura, A.; Miyake, S.; Kai, Y; Kanehisa, N.

Macromolecules

1993, 26, 7134-7143.

3.High Molecular Weight Monodisperse Polymers
Synthesized by Rare Earth Metal Complexes
YASUDA, H.; IHARA E.; YOSHIOKA, S.; NODONO, M.;
MORIMOTO, M.,; YAMASHITA, M.

Catalyst Design for Tailor-made Polyolefins

1994,237-248.

4.0rganolanthanide Initiated Living Polymerization of £Caprolactone,

o-Valerolactone, and~-Propiolactone

Yamashita M.; Takemoto, Y.; Ihara, E.; Yasuda, H.
submitted for pUblication.