Substantially Conductive Polymers

Part 03

SYNTHESIS

PossiblePolymerization Mechanism of Acetylene(via the metal-carbene intermediate)

3

HC CHWCl6 / Bu4Sn

polyacetyleneacetylene

WCl6 CH3CH2CH2CH2 WCl5

Bu4Sn Bu3SnCl

Bu4Sn

Bu3SnCl

CH3CH2CH2 C

WCl4

H

H

H3CH2CH2CH2C

CH3CH2CH2CH3

"Metal carbene"

C WCl4CH3CH2CH2

H

HC CH

C WLnH7C3

H

HC CH HC

CH

CH

WLn

H7C3

HC CH

C WLn

C3H7H

HC CH

C

C

H C3H7

H CH

WLnC

CH

HHC C

CH

C3H7

WLn

C

H

CH C3H7

H

CC

C

C3H7

H

H

HHC

HC WLn

HC CH

etc.WLn

H

terminationPolyacetylene

InsolubleInfusibleIntractable

metallocyclemetal-carbene

Solubility Improvement of Polyacetylenes (via incorporation of substituents)

RC CHWCl6 etc. etc.

R R R R RT. Masuda et. al. with improved solubility

WCl6 + C6H5C CH + etc.

PhPhPh

etc.

1 x 200

C. C. Han & T. J. KatzOrganometallics 1982, 1, 1093Organometallics 1985, 4, 2186

Olefin Metathesisring-opening polymerization

WCl6 + PhC CH etc. WLx

PhPhPh

etc.LxW

PhPhPhPhPh Ph

W

etc.

PhPhPh

WLxetc.

PhPhPh

WLx

H

4

Coplanarity is the key for gaining high conductivity

Substituent Effects: Solubility Conductivity

5

full overlaping

Coplanarity gives best overlapingbetween orbitals

Distortion from coplanarityreduces the electron mobility

partial overlaping

no overlaping

90o distortion lead to conjugation defects

doped with I2

R R R R RR = Me, Br, Cl ......... etc.doped with I2; < 0.001 S/cm> 10 S/cm

Steric hindrance effect of substituent is very important

Because,R group destroy the coplanarity of the conjugation systemReduce electron mobility of intrachain and interchain

Alternative Methods for Making Polyacetylenes

17

Cl Cl Cl Cl Cl - HCl¡µ

pyrolytic eliminationPVCpoly(vinylchloride) C. S. Marvel et. al. JACS, 61, 3241 ( 1939 )

Cl2Cl

Cl

Cl

Clpoly(1,4-butadiene)

- HClKNH2 / NH3 (liq)

East German patent 50, 954 ( 1966 )CA 66 : 86117 r

Cl Cl Cl Cl Cl Cl

conjugation defects

Both approaches yield poorly conductive polyacetylenes

Dehydrochlorination

Durham Route (via a processable precursor)

18

X X Ring-openingolefin metahesispolymerization

X X

n

retro-cyclization

X X

n

I2doping 10 S/cm

+

Cyclization

t1/2 ¡Ü 20 h at 20 oC

very unstabledifficult in handling

10-7 S/cm¡î too much " stability gain "

both products form conjugated systems

(X = -CF3, -COOMe)

Cyclooctatetraene

XC CX

Feast et. al.1. Polymer, 21, 595 ( 1980 )2. J. Phys. Colloq. C3, Suppl. 6, 44 : C3 -148 ( 1983 )3. Polymer, 25, 395 ( 1984 )

X

XX

X

19

The Diels–Alder Reaction(1,4-addition reaction; concerted reaction)

8.8

7-45.ppt

+

new bond

new bonddiene dienophile transitionstate

a pericyclic reaction; a [4+2] cycloaddition reaction

3 2σ+ 1

20

ROMP

nn

£G

70 oC

stable at RTeasier in handling " less stability gain "

Resonance Energy (Kcal/mol)

3660

Strategy : Stabilize the prepolymer by reducing the stability gain in the conversion step

X X

n

retro-cyclization

X X

nt1/2 20 h at 20 oC)unstable at RT

For the 2nd ring:24 kcal/mol

Syntheses of Poly(p-phenylene) (PPP)

21

Cl Cl + Nan

+ NaCl Wurtz -Fittig Reaction

G. Gold finger et. al. J. Polym. Sci., 4, 93 ( 1949 )J. Polym. Sci.,16, 589 ( 1955 )

I I

R

+ Cu

R

nUllmann reaction

S. Ozasa et. al. Bull. Chem. Soc. Jpn., 53, 2610 ( 1980 )• Had very low molecular weights or irregular structures

Cl Cl + Na Cl Cl + Na

ClCl Cl + NaCl

NaCl

Cl Cl

or

Cl

Cl Cl

Cl

Reductive polymerization (step-reaction)

22

I I

R

+ Cu I CuI

ROxidativeaddition

I CuI

R

I Cu

R

I

R

+ CuI2

Reductiveelimination

I

R

I

R

etc.

R R

etc.

R RR

23

+ CuCl2 / AlCl3n

P. Kovacic et. al. JACS 85, 454 ( 1963 )

Most successful and economicalOxidizing agent : CuCl2, MnO2, MoCl5, FeCl3Lewis acid catalyst : AlCl3, AlBr3

CuCl2

AlCl3Cl Al

Cl

ClCl + CuCl

Radicalcation

H

HAlCl4

AlCl3CuCl2

- 2H+2 HAlCl4+CuCl

Use of AlCl3 help reduce the following side-reaction

+ Cl ClH

+ CuCl + Cl- H

CuCl2Cl

Oxidative polymerization (step-reaction)

23

24

n n

Ziegler catalyst

MW = 5000 - 10,000poly(1,3-cyclohexadiene)

450- H2

£G

¢J

chloranilxylene

C. S. Marvel et. al.JACS 81, 448 ( 1959 )J. Polym. Sci. A3,1553 ( 1965 )

aromatization

OCl

ClO

Cl

Cl

p-chloranil

( tetrachloro-1,4-benzoquinone )

Oxidant

n n n( Cl2, Br2 )

300 - 380

- 2 HX- H2

n

- H2

X2 ¢J

£G

X X

-2 HX

Catalyzed Chain polymerization

n n

450 ℃chloranil

xylene aromatization

- H2 n n

300 - 380

- 2 HX- H2

℃X X

25

HO OH HO OHpseudomonas putida

Base

C

O

Cl R

O O CC ROO

R

R = OCH3, CH3, Ph

( for improving solubility )

O O CC RROO

n radical chainpolymerization

highly soluble ; easily processibleDP = 600-1000 ( degree of polymerization )

220 ℃n

( t1/2 = 30 sec for R = OMe)

Ballard et. al. JCS, CC 954 ( 1983 )

Lower the aromatization temperature via the decarboxylation

26

Free Radical Chain Reaction

OR

OCORROCO

ROOR

Initiation step

OCORROCOOCORROCO

RO

Propagation steps

RO

R' R' R' R'

( R' = OCOR)

TerminationR' R' R' R'

RO

R' R'n

(X = radical terminator)

X

Syntheses of Polyphenylene Vinylene (PPV)

H3C CO

HCH CH

n

(CH3)3C O K

DMF

G. Kossmehl et. al.Makromol. Chem. 182,3419 ( 1981 )

H2C CO

HH

B

H2C CO

H

H

C C

OH

HH

H n

- H2OCH CH

n

C COH

HH

H

Nu

C COH

HH

HC C

OH

HH

HNu C C

OH

HH

Hetc.

C COH

HH

HC C

OH

HH

HC C

OH

HH

H

C COH

HH

HCH

Hetc. etc.

or

30