Chelated Organolithium Catalysis

1 Some Mechanistic Aspects of N-Chelated Organolithium Catalysis A. W. LANGER, JR.

Downloaded by RMIT UNIV on July 19, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0130.ch001

Corporate Research Laboratories, Esso Research and Engineering Co., Linden, N.J. 07036 Chelating tertiary polyamines have a dramatic effect on the reactivity and properties of organolithium compounds. The unusual properties of the chelates have led to their extensive use as unique catalysts and chemical reagents. Some general aspects related to structure and properties are discussed including the nature of the chelating agent, chelate/LiR ratio, aggregation, and metalation. These are examined as they relate to ion pairing of the lithium-carbon bond, reactivity, and some aspects of polymerization. Metalations produce kinetically favored products with very slow rearrangement to the thermodynamically more stable products. The effects of ion pair structure and steric hindrance in the chelating agent are illustrated in butadiene polymerization. Chain transfer mechanisms in ethylene polymerization are presented to explain cyclopentane rings in the product. " D e f o r e 1964 there w a s extensive l i t e r a t u r e o n the effects of m o n o f u n c t i o n a l L e w i s bases o n the r e a c t i v i t y of o r g a n o h t h i u m particularly i n the polymerization

field

(I).

However

no

compounds, information

was a v a i l a b l e o n the effects of c h e l a t i n g bases. S i n c e c h e l a t i n g polyethers w e r e i n w i d e use, one c a n o n l y speculate t h a t t h e y h a d b e e n t r i e d a n d w e r e d i s c a r d e d b e c a u s e t h e y r a p i d l y d e c o m p o s e d the a l k y l l i t h i u m . C h e l a t i n g t e r t i a r y p o l y a m i n e s h a v e a d r a m a t i c effect o n the r e a c t i v i t y a n d properties of o r g a n o l i t h i u m c o m p o u n d s . T h e chelates are n e w c o m positions w h i c h are r a p i d l y

finding

w i d e use as u n i q u e catalysts

and

c h e m i c a l reagents. N - c h e l a t e d a l k a l i m e t a l c o m p o u n d s w e r e d i s c o v e r e d i n 1960 at E s s o Research and Engineering C o . w h e n b u t y l l i t h i u m was complexed w i t h TMED

(NjNjN^JV'-tetramethylethylenediamine)

polymerization (2).

for

use

in

ethylene

A t that t i m e t h e o b j e c t i v e w a s to m a k e n e w 1

Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.

non-

2

P O L Y A M I N E - C H E L A T E D A L K A L I M E T A L COMPOUNDS

t r a n s i t i o n m e t a l p o l y m e r i z a t i o n catalysts, a n d the q u e s t i o n w a s

raised

whether t r i e t h y l a l u m i n u m c o u l d be simulated b y complexing an a l k y l l i t h i u m w i t h a chelating tertiary diamine. AlEt adds

3

Z i e g l e r (3)

h a d s h o w n that

d i m e r dissociates to a n e l e c t r o n deficient m o n o m e r i c species w h i c h to e t h y l e n e

reaction).

to f o r m l o n g e r

chain a l u m i n u m alkyls (the

growth

P r e s u m a b l y the ethylene coordinates w e a k l y w i t h the a l u m i

n u m a n d is p o l a r i z e d b y

the p a r t i a l l y i o n i c A l - C b o n d

to

facilitate

a d d i t i o n , s h o w n at the top of F i g u r e 1.


Al

Al

8l-N

/R,

^ Ν η

/\

^

/\

Figure 1.

Γ Ν

χ

β

/\

Λ δ-

Trialkylaluminum simulation with an organolithium chelate

B u t y l l i t h i u m w a s also k n o w n to p o l y m e r i z e e t h y l e n e (4, 5, 6 ) ,

but

it was less a c t i v e t h a n t r i e t h y l a l u m i n u m . C o n c e p t u a l l y it was felt that B u L i s h o u l d b e m o r e a c t i v e because of the s m a l l e r c a t i o n a n d m o r e i o n i c m e t a l - c a r b o n b o n d , b u t the l o w p o l y m e r i z a t i o n a c t i v i t y c o u l d b e b y greater d i f f i c u l t y i n b r e a k i n g d o w n the strong aggregates.

caused

Solvation

b y T M E D w a s v i s u a l i z e d to g i v e d i m e r a n d m o n o m e r structures w h i c h w e r e d i r e c t l y r e l a t e d to A l E t , s h o w n at the b o t t o m of F i g u r e 1. A t the 3

same t i m e , s o l v a t i o n of l i t h i u m b y T M E D w a s e x p e c t e d to f u r t h e r increase t h e i o n i c c h a r a c t e r of t h e L i - C b o n d . T M E D w a s u s e d r a t h e r t h a n ethers b e c a u s e i t was e x p e c t e d to b e less r e a c t i v e t o w a r d B u L i . T h e s e expectations w e r e r e a l i z e d b y the p r e p a r a t i o n of h i g h m o l e c u l a r w e i g h t p o l y e t h y l e n e at 2 5 ° - 5 0 ° C whereas A l E t b e l o w a b o u t 90 ° C .

3

a c t i v i t y is n e g l i g i b l e

T h e i n c r e a s e d i o n i c c h a r a c t e r of the catalyst c a u s e d

a n increase i n m e t a l a t i o n c a p a b i l i t y a n d l e d to the d i s c o v e r y of t e l o m e r i z a t i o n reactions

(7)

a n d n e w o r g a n o m e t a l l i c syntheses

(8).

T h e extra

o r d i n a r y r e a c t i v i t y of the N - c h e l a t e d o r g a n o l i t h i u m complexes s t i m u l a t e d extensive

r e s e a r c h d i r e c t e d t o w a r d d e f i n i n g the s c o p e of

the

catalyst

system, finding n e w a p p l i c a t i o n s , a n d e x a m i n i n g the r e l a t i o n s h i p of s t r u c t u r e to chelate p r o p e r t i e s

(9,10,11).

I n 1962 a n d 1963 t h e c h e l a t e d o r g a n o l i t h i u m c o m p l e x e s a n d t h e i r a p p l i c a t i o n i n ethylene t e l o m e r i z a t i o n w e r e d i s c o v e r e d i n d e p e n d e n t l y e a c h o t h e r b y E b e r h a r d t (12) patents (13,

14)

at S u n O i l C o .

of

T h i s r e s e a r c h l e d to t w o

i n w h i c h the c l a i m s i n v o l v i n g c h e l a t e d catalysts w e r e


1.

3

N-Chelated Organolithium Catalysis

LANGER

o v e r t u r n e d b y interference p r o c e d u r e s (2, 7,15,16). p u b l i s h e d (12, 17, 18)

S e v e r a l papers w e r e

w h i c h h e l p e d s t i m u l a t e interest i n the catalysts.

In addition Eberhardt discovered

t h e i r use for the t e l o m e r i z a t i o n of

e t h y l e n e w i t h h i g h e r olefins c o n t a i n i n g a l l y l i c h y d r o g e n s

(19).

Eber-

hardt's a n d his c o - w o r k e r s ' research r e s u l t e d i n patents of c h e l a t e d o r g a n o l i t h i u m catalysts u s e d for i s o m e r i z a t i o n of olefins (20), ethylene w i t h b e n z y l d i a l k y l a m i n e s (21), 100 ° C (22),

t e l o m e r i z a t i o n of

ethylene polymerization above

a n d p r e p a r a t i o n of t e l o m e r waxes

(23).

T h e scope of t h e c h e l a t e d a l k a l i m e t a l system a n d the m a n y uses for these n e w complexes are c o v e r e d t h o r o u g h l y i n this v o l u m e .

T h e r e are

several g e n e r a l aspects r e l a t e d to s t r u c t u r e a n d properties w h i c h are


i m p o r t a n t i n a l l p r e p a r a t i o n s a n d a p p l i c a t i o n s . T h e s e i n c l u d e the r a t i o of c h e l a t i n g agent to the o r g a n o l i t h i u m c o m p o u n d , the n a t u r e of

the

c h e l a t i n g agent, a g g r e g a t i o n o f t h e complexes, a n d the s h a r p l y i n c r e a s e d metalation reactivity compared w i t h uncomplexed organolithium com pounds.

T h i s p a p e r discusses these features i n r e l a t i o n to the l i t h i u m -

c a r b o n b o n d , the c h e m i c a l r e a c t i v i t y of the complexes, a n d some aspects of p o l y m e r i z a t i o n . Structure

of Lithium

Chelates

Alkyllithium compounds

exist as tetramers or hexamers i n h y d r o

c a r b o n solvents d e p e n d i n g p r i m a r i l y u p o n the b u l k i n e s s a n d size of the a l k y l groups (24, 25).

O t h e r l a r g e l y covalent o r g a n o l i t h i u m c o m p o u n d s

p r o b a b l y h a v e s i m i l a r degrees of association a l t h o u g h one m i g h t expect h i g h e r aggregates f r o m d i p o l e interactions for those h a v i n g m o r e i o n i c L i - C bonds.

S u p p o r t for this i d e a c a n b e f o u n d i n w o r k b y M a k o w s k i

a n d L y n n (26)

w h o s h o w e d that l o w m o l e c u l a r w e i g h t p o l y b u t a d i e n y l -

l i t h i u m has a degree of association c o n s i d e r a b l y greater t h a n six i n the absence of solvent.

T h e y also s h o w e d that association t h e n decreases

w i t h i n c r e a s i n g m o l e c u l a r w e i g h t to a l i m i t i n g v a l u e of t w o . h y d r o f u r a n b o t h p o l y i s o p r e n y l l i t h i u m (27)

I n tetra-

a n d p o l y s t y r y l l i t h i u m (28)

w e r e r e p o r t e d to b e m o n o m e r i c a l t h o u g h t h e y are d i m e r i c i n h y d r o c a r b o n solvents

(29).

n - B u t y l l i t h i u m is h e x a m e r i c i n b e n z e n e a n d c y c l o h e x a n e (30)

a n d at t h e i r f r e e z i n g points (31),

but no cryoscopic

h a v e b e e n r e p o r t e d i n paraffinic solvents.

at 25 ° C

measurements

In our laboratory

cryoscopic

studies i n b e n z e n e , toluene, a n d η-heptane s h o w e d that it w a s a h e x a m e r i n b e n z e n e a n d t o l u e n e b u t a tetramer i n η-heptane at concentrations b e t w e e n 0 . 2 M a n d 1 . 0 M (32).

T h e h e p t a n e result m i g h t b e a t t r i b u t e d

to stronger s o l v a t i o n of the b u t y l groups at t h e f r e e z i n g p o i n t ( — 9 0 . 7 ° C ) , t h e r e b y s t a b i l i z i n g a s m a l l e r aggregate. M a n y chelated organolithium compounds

c a n b e o b t a i n e d as

1:1

complexes, b u t o n l y c e r t a i n l i t h i u m aggregates a p p e a r to f o r m i n s o l u b l e


4

POL Y A M I N E - C H E L A T E D A L K A L I M E T A L COMPOUNDS

c o m p l e x e s ( 8 , 10).

T M E D , irarw-^N^^N'-tetramethyl-l^-cyclohexane-

diamine ( f r a r w - T M C H D ) and tetramethyl-l,3-propanediamine

(TMPD)

formed

tetramer.

c r y s t a l l i n e complexes w i t h b u t y l l i t h i u m d i m e r

and

A t t e m p t s to isolate complexes h a v i n g 3 : 1 , 5 : 1 , or 6:1 B u L i : c h e l a t e ratios w e r e unsuccessful.

T h u s the stable aggregate structures i n b u t y l l i t h i u m

persist i n c o m p l e x e s f o r m e d w i t h b i d e n t a t e c h e l a t i n g agents.

However

a n e q u i m o l a r a m o u n t of a strong c h e l a t i n g agent w i l l p r o d u c e 1:1 c o m plexes i n d i l u t e solutions. tions at b o t h 1:1

B u L i : T M E D is m o n o m e r i c at l o w

(10, 32, 33)

a n d 1:2

concentra-

B u L i / T M E D ratios a n d

(33)

d i m e r i c at 1:1 r a t i o at h i g h concentrations. T M E D p r o d u c e s a c r y s t a l l i n e c o m p l e x w i t h m e t h y l l i t h i u m tetramer,


b u t e v e n a large excess of T M E D does not b r e a k d o w n t h e tetramer to d i m e r or m o n o m e r ( 8 ) .

T h i s result shows that m e t h y l b r i d g e s are stronger

t h a n t e r t i a r y a m i n e c o m p l e x a t i o n to l i t h i u m . complexes w i t h b i d e n t a t e

chelating

agents also c o n t a i n e d l i t h i u m d i m e r a n d tetramer species ( 8 ) .

V a r i o u s other

organolithium

However

p r e l i m i n a r y attempts to p r e p a r e ( C H L i ) 6

5

4

· T M E D f r o m solutions

con-

t a i n i n g 4:1 a n d 6:1 m o l a r ratios y i e l d e d o n l y crystals h a v i n g the u n u s u a l r a t i o of t h r e e p h e n y l h t h i u m p e r T M E D ( 8 ) .

A t r i m e r i c l i t h i u m species

has b e e n r e p o r t e d for l i t h i u m bis ( t r i m e t h y l s i l y l ) a m i d e i n x-ray studies (34)

a l t h o u g h K i m u r a a n d B r o w n (35)

i n t e r p r e t e d the s o l u t i o n b e h a v i o r

as a n e q u i l i b r i u m b e t w e e n d i m e r a n d tetramer.

It w o u l d be i n t e r e s t i n g

to d e t e r m i n e w h e t h e r the p h e n y l anions b r i d g e i n a s i m i l a r m a n n e r to a m i d e ions or w h e t h e r a c h e l a t i n g agent p r o d u c e s a different aggregate structure.

Molecular weight

(C H Li) 6

5

3

d a t a are n e e d e d to d i s t i n g u i s h b e t w e e n

· T M E D and ( C H 5 L i ) · 2 T M E D . 6

6

W i t h the u n u s u a l r a t i o ,

this w o r k m u s t be c o n s i d e r e d tentative u n t i l it is repeated. T h e r e w a s also e v i d e n c e for c o m p l e x f o r m a t i o n w i t h p h e n y l h t h i u m d i m e r w h i c h w o u l d b e analogous to the p h e n y l h t h i u m d i m e r complexes i n ether reported b y West and W a a c k W i t h the exception

of

c o m p o u n d s h a v e y i e l d e d 1:1

solvents

(36). m e t h y l l i t h i u m , a l l types

of

organolithium

complexes w i t h b i d e n t a t e , t r i d e n t a t e , or

tetradentate c h e l a t i n g t e r t i a r y p o l y a m i n e s (16).

M o s t are c r y s t a l l i n e b u t

B u L i · T M E D is a n o i l . Stable complexes c o n t a i n i n g t w o molecules

of c h e l a t i n g agent per

o r g a n o h t h i u m are o b t a i n e d o n l y w h e n solvent separated i o n p a i r f o r m a t i o n is f a v o r a b l e .

T h i s occurs w i t h i o n i c l i t h i u m c o m p o u n d s h a v i n g a

large, soft a n i o n . F o r e x a m p l e c r y s t a l l i n e complexes have b e e n i s o l a t e d having

the

compositions

(C H )2CHLi · ( T M E D ) , 6

5

2

(C H )sCLi· e

6

( T M E D ) , a n d ( C H ) C H L i · H M T T , w h e r e H M T T is h e x a m e t h y l t r i 2

e

5

ethylenetetramine ( 8 ) .

2

S u c h structures s h o u l d b e g e n e r a l for a l l l i t h i u m

c o m p o u n d s i n w h i c h t h e negative c h a r g e o n t h e a n i o n is m o r e t h a n i n the b e n z y l a n i o n .


diffuse

1.

5

Ν-Chelated Organolithium Catalysis

LANGER

I n o r d e r to a v o i d chelate d e c o m p o s i t i o n t h e c a r b a n i o n m u s t b e less r e a c t i v e t h a n b e n z y l a n i o n , o r i t w i l l metalate t h e c h e l a t i n g agent w i t h subsequent d e c o m p o s i t i o n .

F i g u r e 2 illustrates c r y s t a l l i n e complexes of

b e n z y l l i t h i u m w i t h b i - , t r i - , a n d tetradentate c h e l a t i n g agents.

While

the first t w o a r e stable, t h e t e t r a m i n e c o m p l e x decomposes extensively i n 24 hours. I n contrast, a l l three complexes w i t h d i p h e n y l m e t h y l l i t h i u m a r e stable. F o r t h e first t w o complexes w i t h b e n z y l h t h i u m , t h e U V s p e c t r u m i n b e n z e n e shows o n l y o n e a b s o r p t i o n a t 3 3 0 n m f o r t h e contact i o n p a i r . T h e t e t r a m i n e c o m p l e x also shows a s m a l l a b s o r p t i o n at 3 6 7 n m , p r e s u m a b l y f r o m a loose or separated i o n p a i r structure. I n t h e c r y s t a l lattice where

i o n pair separation should be more

favorable,

decomposition


o c c u r r e d r a p i d l y via b e n z y l i o n attack o n a n Ν — C H (C H )2CHLi · H M T T 6

5

3

group. F o r

c o m p l e x t h e U V a b s o r p t i o n at 4 6 0 n m f o r t h e

separated i o n p a i r is l a r g e r t h a n that at 4 2 0 n m f o r t h e contact i o n p a i r , i n d i c a t i n g a h i g h e r p r o p o r t i o n of separated i o n pairs t h a n i n t h e b e n z y l l i t h i u m complex.

T h i s is consistent w i t h t h e greater resonance s t a b i l i z a

t i o n o f d i p h e n y l m e t h y l c o m p a r e d w i t h b e n z y l a n i o n . I n this case, h o w ever, t h e c o m p l e x is stable to d e c o m p o s i t i o n because t h e less r e a c t i v e c a r b a n i o n cannot m e t a l a t e the c h e l a t i n g agent despite the greater c o n c e n t r a t i o n of separated i o n p a i r s . T h e s e results i n d i c a t e that t h e t e t r a m i n e complexes exist i n t w o forms : ( a ) a contact i o n p a i r i n w h i c h o n l y three nitrogens solvate l i t h i u m a n d the f o u r t h is u n c o o r d i n a t e d a n d ( b ) a sepa r a t e d i o n p a i r i n w h i c h t h e f o u r t h n i t r o g e n displaces t h e c a r b a n i o n to t h e outer sphere. TMED \/ r- Ν

Ν

PMDT

HMTT

\ /

YELLOW STABLE

λ max 330 nm

YELLOW STABLE

YELLOW-ORANGE D E C / 2 4 HRS.

330 nm

330 ; 367 nm

STABLE

STABLE

λ max 420 nm

420 nm

Figure 2.

STABLE 420

460 nm

Organolithium chelates.

Top: Crystalline benzyllithium complexes. Bottom: Crystalline diphenyl methyllithium complexes.


6


#

X - r a y structures for v a r i o u s c r y s t a l l i n e o r g a n o l i t h i u m complexes are

c o v e r e d i n C h a p t e r 3 w h i c h p r o v i d e s p r o o f for chelate r i n g structures as o p p o s e d to o p e n c h a i n p o l y m e r i c structures. It also supports the N M R finding

of i n c r e a s e d i o n i c c h a r a c t e r i n the L i - C b o n d u p o n s o l v a t i o n of

the l i t h i u m

(10).

T h e resistance of o r g a n o l i t h i u m aggregates to d i s s o c i a t i o n b y d o n o r solvents or c h e l a t i n g L e w i s bases is u n d o u b t e d l y r e l a t e d to the lattice e n e r g y of the aggregates just as was f o u n d for the c o m p l e x a t i o n of i n o r g a n i c salts (see C h a p t e r 6, K l e m a n n et ah).

A s s t a b i l i t y increases, m o r e

p o w e r f u l s o l v a t i n g agents are r e q u i r e d to o v e r c o m e this lattice energy. I f s t a b i l i t y is too h i g h for 1:1 c o m p l e x a t i o n b y p e r m e t h y l a t e d p o l y e t h y l -


enetetramines, the l a t t i c e energy of the aggregate is a b o v e a b o u t kcals/mole

at 25 ° C .

Methyllithium

tetramer appears

to

be

200

i n this

category. A l l of the a b o v e d i s c u s s i o n deals w i t h the r a t i o of c h e l a t i n g agent to o r g a n o l i t h i u m c o m p o u n d i n v a r i o u s complexes.

I n most cases m o l e c u -

lar w e i g h t has either not b e e n d e t e r m i n e d or i t w a s d e t e r m i n e d at a single c o n c e n t r a t i o n i n a single solvent. It s h o u l d be u n d e r s t o o d that a l l of the chelates h a v e a strong t e n d e n c y to aggregate because of t h e i r i n c r e a s e d i o n i c character.

T h e d i p o l e - d i p o l e interactions are d e p e n d e n t o n t e m -

p e r a t u r e , c o n c e n t r a t i o n , solvent, etc. T h u s the degree of a g g r e g a t i o n for a n y specific system s h o u l d b e d e t e r m i n e d w h e n e v e r i t is suspected i n f l u e n c i n g properties.

of

I n d i l u t e solutions, as i n catalysis, t h e chelates

are b e l i e v e d to be m o n o m e r i c .

W h e r e c o n c e n t r a t i o n studies w e r e m a d e

( T M E D · LiCH ο -I

ο >

20

/

800 μ

12

n-HEPTANE, 25°C. Φ 0.1M BuLi, 820 mm H

8

2

A 0.5M BuLi

400

1 0.5

1 1.0

CO

4 1

1

1.5

2.0

0

TMED/BuLi MOLE RATIO

Figure 3.

Parallel between BuLi hydrogenolysis rate and α-methylene proton chemical shift


8

POL Y A M I N E - C H E L A T E D A L K A L I M E T A L COMPOUNDS

h y d r o g e n a n d 25 ° C i n η-heptane, the 1:1 c o m p l e x r e a c t e d a p p r o x i m a t e l y 7000 times faster t h a n u n c o m p l e x e d B u L i to p r o d u c e b u t a n e a n d l i t h i u m hydride.

G i l m a n r e p o r t e d that b u t y l l i t h i u m r e a c t e d c o m p l e t e l y

h y d r o g e n o n l y after 61 h o u r s at 100 p s i g (40).

with

F u r t h e r m o r e the r e a c t i v i

ties of p h e n y l h t h i u m a n d p h e n y l p o t a s s i u m t o w a r d h y d r o g e n o l y s i s benzene were compared.

in

P h e n y l h t h i u m c o m p l e t e l y r e a c t e d i n 32.2 hrs

at 100 p s i g whereas the r e a c t i o n w i t h p h e n y l p o t a s s i u m was 9 0 % i n 0.54 hrs at s l i g h t l y a b o v e a t m o s p h e r i c pressure (40).

complete

A n increased

r a t e of h y d r o g e n o l y s i s of p h e n y l h t h i u m has also b e e n r e p o r t e d a d d i t i o n of ether solvents (41).

upon

T h e a b o v e facts t a k e n together p r o v i d e

a d d i t i o n a l e v i d e n c e that c h e l a t i o n increases the i o n i c c h a r a c t e r of the


M-C

bond. R e a c t i v i t y of b u t y l l i t h i u m f u r t h e r increases w h e n T M E D is r e p l a c e d

b y a t r i d e n t a t e ( P M D T ) or a tetradentate ( H M T T ) c h e l a t i n g agent. I n these complexes r e a c t i v i t y is excessively h i g h a n d leads to r a p i d m e t a l a t i o n of the c h e l a t i n g agent.

T h u s , m o r e effective

or m o r e

extensive

s o l v a t i o n of l i t h i u m b y n i t r o g e n bases gives the L i - C b o n d i o n p a i r p r o p e r t i e s s i m i l a r to u n c o m p l e x e d a l k y l s o d i u m or a l k y l p o t a s s i u m . H o w ever the l i t h i u m chelates h a v e advantages i n s o l u b i l i t y a n d m u c h l o w e r a g g r e g a t i o n i n h y d r o c a r b o n solvents. T h i s r e l a t i o n s h i p to i o n i c character a p p l i e s o n l y to a g i v e n o r g a n o l i t h i u m c o m p o u n d , h o w e v e r , a n d not to a c o m p a r i s o n of different c a r banions.

F o r e x a m p l e h y d r o g e n o l y s i s of 1:1 complexes of T M E D

with

butyllithium, benzyllithium, diphenylmethyllithium, and triphenylmethyll i t h i u m gives s h a r p l y d e c r e a s i n g rates i n the o r d e r s h o w n (42). butyllithium complex

Y e t the

a l m o s t c e r t a i n l y has s o m e c o v a l e n t c o n t r i b u t i o n

whereas the t r i p h e n y l m e t h y l l i t h i u m c o m p l e x is a n i o n p a i r . H e r e w e are c o n c e r n e d w i t h t h e i n t r i n s i c r e a c t i v i t y of the c a r b a n i o n ; i n this r e a c t i o n it is the n u c l e o p h i l i c i t y of the c a r b a n i o n t o w a r d h y d r o g e n w h i c h correlates w i t h r e a c t i o n rates. T h e b e n z y l i c c a r b a n i o n s are w e a k e r n u c l e o p h i l e s to the extent that the n e g a t i v e charge is d e l o c a l i z e d i n t o the a r o m a t i c rings. A t the same t i m e this resonance s t a b i l i z a t i o n also favors i o n p a i r i n g r a t h e r than covalent bonding.

F o r the r e a c t i o n w i t h h y d r o g e n there w i l l b e a

b a s i c i t y cut-off p o i n t b e l o w w h i c h a c a r b a n i o n w i l l not react at a p r a c t i c a l rate. T h i s p r i n c i p l e also a p p l i e s to the a d d i t i o n of e t h y l e n e to organo l i t h i u m reagents. (43)

F a i l u r e to r e c o g n i z e this l e a d B a r t l e t t a n d c o w o r k e r s

to c o n c l u d e t h a t i o n i c c h a r a c t e r i n the L i - C b o n d is u n f a v o r a b l e

a l t h o u g h the opposite c o n c l u s i o n w a s d r a w n for T M E D complexes

(44).

O t h e r factors w h i c h m u s t b e c o n s i d e r e d i n c l u d e t h e i n t r i n s i c r e a c t i v i t y of the c a r b a n i o n , a g g r e g a t i o n , c o o r d i n a t i v e u n s a t u r a t i o n , a n d p o l a r i z i n g a b i l i t y of the m e t a l c a t i o n . Q u a l i t a t i v e l y this cut-off p o i n t appears to b e s l i g h t l y b e l o w t r i p h e n y l m e t h y l c a r b a n i o n , at a b o u t a pK

b

M S A D scale (45).

T h i s places the p K

f f

of 30-31 o n the

of h y d r o g e n at a b o u t 29-31 ( s a m e


1.

scale).

9

N-Chelated Organolithium Catalysis

LANGER

C h e l a t e d a l k y l l i t h i u m c a n metalate a n y c o m p o u n d h a v i n g a n

a c i d i t y greater t h a n m e t h a n e (less t h a n a b o u t 40 p K ) . t t

A g g r e g a t i o n adversely affects m e t a l a t i o n r e a c t i v i t y . W i t h f o r m e d c o m p a r e d w i t h 9 0 % Li at e q u i l i b r i u m . T h e s e results s h o w the r e m a r k a b l y h i g h k i n e t i c a c i d i t y of t e t r a m e t h y l s i l a n e a n d also i n d i c a t e that its t h e r m o d y n a m i c a c i d i t y falls b e t w e e n that of b e n z e n e and T M E D .

T h i s latter o b s e r v a t i o n is c o n t r a r y to p r e d i c t i o n s b a s e d

on

e l e c t r o n e g a t i v i t y a n d suggest c a r b a n i o n s t a b i l i z a t i o n b y ρττ-άπ o v e r l a p . Table I.

Kinetic and Thermodynamic Product Yields from Metalation Reactions W i t h T M E D · Ser-BuLi Chelated Products

Reactants TMED-sec-BuLi

+ TMS

Li-TMS Initial

>95%

Li—CtH*

-C-C-N^

C

> 750

300

550

230

420

145

290

80

260

40

65

30

C-C ^N-C-C-N^ C

C

C-C ^N-C-C-N" "C-C

C

C-C >-C-C-N' C-C ^C-C

C

C-C

/C-C N-C-C-N

C-C" NONE

Figure 5.

2

is b e l i e v e d to b e u n f a v o r a b l e

C-C

Effect of diamine substituents on polymerization rates, 0.002M BuLi-Diamine, n - C , 25°C 7


1.

N-Chetoted Organolithium Catalysis

LANGER

15

I n the p r e c e d i n g section a

Steric Effects of the Chelating Agent.

t r i a m i n e chelate w a s s h o w n to h a v e l o w a c t i v i t y i n b u t a d i e n e p o l y m e r i z a t i o n c o m p a r e d w i t h t h e d i a m i n e chelate.

T h e effects of m o r e g r a d u a l

changes i n chelate s t r u c t u r e o n the rates of p o l y m e r i z a t i o n f o r b u t a d i e n e a n d styrene are s h o w n i n F i g u r e 5. T h e steric b u l k of t e t r a m e t h y l e t h y l e n e d i a m i n e w a s s y s t e m a t i c a l l y i n c r e a s e d b y successive r e p l a c e m e n t of m e t h y l groups b y e t h y l groups, a n d a c t i v i t y decreased a c c o r d i n g l y .

W i t h both

m o n o m e r s , h o w e v e r , the a c t i v i t y of b u t y l l i t h i u m alone w a s l o w e r t h a n that w i t h the most h i n d e r e d c h e l a t i n g agent, t e t r a e t h y l e t h y l e n e d i a m i n e (TEED). Instead of steric h i n d r a n c e to p r o p a g a t i o n , a n a l t e r n a t i v e e x p l a n a t i o n


is dissociation of the c h e l a t i n g agent f r o m the l i t h i u m c a u s e d b y i n c r e a s i n g h i n d r a n c e to c o m p l e x a t i o n .

the

D i s s o c i a t i o n definitely is a c o n -

t r i b u t i n g factor w i t h c h e l a t i n g agents h a v i n g larger a l k y l substituents l i k e t e t r a p r o p y l e t h y l e n e d i a m i n e , p a r t i c u l a r l y at h i g h e r p o l y m e r i z a t i o n t e m peratures because the p e r cent 1,2-polybutadiene structure decreases s u b stantially.

H o w e v e r T E E D a n d T M E D p r o d u c e d n e a r l y the same p e r

cent 1,2-polybutadiene structure at 25 ° C i n d i c a t i n g that the p o l y m e r w a s p r o d u c e d at a c h e l a t e d l i t h i u m site. T h e s e d a t a a n d the d a t a f r o m P M D T ( a t r i a m i n e ) suggest that m o n o m e r a p p r o a c h to the i o n p a i r site is h i n d e r e d b y substituents o n the c h e l a t i n g agents. A q u a n t i t a t i v e measure of the steric factor o n p o l y m e r i z a t i o n rates can b e o b t a i n e d w i t h o u t a s t u d y of chelate dissociation e q u i l i b r i a u n d e r p o l y m e r i z a t i o n c o n d i t i o n s a n d a knowledge

of the specific p r o p a g a t i o n rate constants for the

covalent,

contact i o n p a i r a n d separated i o n p a i r species. T h e results are easily r a t i o n a l i z e d b y a s s u m i n g p r o p a g a t i o n

takes

p l a c e at a T M E D · L i R " contact i o n p a i r site w h e r e the b u l k i e r c h e l a t i n g f

agents c o u l d h i n d e r m o n o m e r a p p r o a c h to the i o n p a i r . H o w e v e r H a y c o n c l u d e d that the a c t i v e site is ( T M E D ) L i R ~ e v e n at a 1:1 m o l e r a t i o 2

of B u L i / T M E D ( 3 3 ) .

+

O n e w o u l d not expect steric h i n d r a n c e to m o n o m e r

j u d g i n g f r o m the b u l k i n e s s of the c h e l a t i n g agents i n s u c h a

chelate

separated i o n p a i r unless the a l l y l a n i o n is b u r i e d i n the chelate h y d r o c a r b o n s h e l l or s t r o n g l y h y d r o g e n b o n d e d to the shell. M o r e l i k e l y , the h i n d e r e d c h e l a t i n g agents w o u l d h a v e greater difficulty f o r m i n g the active d i c h e l a t e d l i t h i u m species. L o w e r a c t i v i t y w i t h h i n d e r e d c h e l a t i n g agents is also consistent w i t h p o o r e r a b i l i t y to b r e a k the l i t h i u m d i m e r a n d f o r m the a c t i v e 1:1

complex.

Increased steric b u l k i n the c h e l a t i n g agent a d v e r s e l y affects catalyst a c t i v i t y . H o w e v e r there are several m e c h a n i s m s b y w h i c h steric h i n d r a n c e c o u l d affect a c t i v i t y , b u t w e cannot d i s t i n g u i s h t h e m at present. Chain Transfer Mechanisms.

C h e l a t e d a l k a l i m e t a l catalysts c a n

u n d e r g o a v a r i e t y of c h a i n transfer reactions d e p e n d i n g p r i m a r i l y u p o n the i o n i c character of t h e m e t a l - c a r b o n b o n d a n d the n a t u r e of the c a r -


POLY A M I N E - C H E L A T E D A L K A L I M E T A L COMPOUNDS

16

b a n i o n . I n g e n e r a l , c h a i n transfer reactions increase w i t h catalyst s t r u c t u r a l changes i n the o r d e r covalent
LiC H

4

2

5

= CHR

2

+

>LiCH = C H

4

R'H

>LiR' +

CH 2

+

2

(1)

= CHR

(2)

RH

(3)

RH

(4)

B o t h R e a c t i o n 1 a n d R e a c t i o n 2 are w e l l k n o w n w i t h other a l k y l metals l i k e AIR3 whereas

R e a c t i o n 3 a n d R e a c t i o n 4 are e x p e c t e d of

strong

c a r b a n i o n catalysts. R e a c t i o n 1 appears to result solely i n t e r m i n a t i o n . I n h y d r o g e n o l y s i s experiments

w i t h v a r i o u s chelates

we

have observed

l i t h i u m h y d r i d e i n a l l cases at r o o m t e m p e r a t u r e .

precipitation

A t t e m p t s to

of

generate

c h e l a t e d L i H in situ b y a d d i n g h y d r o g e n d u r i n g e t h y l e n e p o l y m e r i z a t i o n also c a u s e d a r a p i d , i r r e v e r s i b l e loss of a c t i v i t y . S i n c e there is n o e v i d e n c e that l i t h i u m h y d r i d e c a n a d d to e t h y l e n e u n d e r m o d e r a t e p o l y m e r i z a t i o n c o n d i t i o n s , i t is u n l i k e l y that a n y significant c h a i n transfer occurs via this mechanism.

P o t a s s i u m a l k y l s r e a d i l y e l i m i n a t e olefin w i t h the f o r m a t i o n

of m e t a l h y d r i d e , a n d s o d i u m a l k y l s d o so at e l e v a t e d temperatures

(56).

It w a s n o t e d earlier that c h e l a t i o n of l i t h i u m a l k y l s makes t h e m m o r e l i k e s o d i u m or p o t a s s i u m c o m p o u n d s ,

so i t is q u i t e p r o b a b l e that some

t e r m i n a t i o n occurs b y e l i m i n a t i n g L i H . It is c o n c e i v a b l e that this c o u l d be a c h a i n transfer m e c h a n i s m w i t h m o r e r e a c t i v e m o n o m e r s t h a n e t h y l ene b e c a u s e a d d i t i o n to l i t h i u m h y d r i d e w o u l d b e m o r e f a v o r a b l e . E b e r h a r d t (57)

r e p o r t e d that olefins w e r e o b t a i n e d u s i n g c h e l a t e d

b u t y l l i t h i u m catalysts a n d assumed t h a t t h e y w e r e p r o d u c e d b y R e a c t i o n 2. H o w e v e r olefins are p o t e n t i a l l y a v a i l a b l e f r o m three different reactions. T h e a m o u n t of olefin p r o d u c e d b y E b e r h a r d t is n o t k n o w n to b e i n excess of that f r o m the catalyst so R e a c t i o n 1 c a n n o t b e e x c l u d e d .

Reaction 2

must be considered plausible b y analogy w i t h a l u m i n u m alkyls. B r o a d d u s (49)

has s h o w n that B u L i · T M E D c a n m e t a l a t e a n a l p h a

olefin at the v i n y l i c h y d r o g e n s as w e l l as at t h e a l l y l i c positions.

This

r e a c t i o n m u s t also take p l a c e w i t h ethylene as s h o w n i n R e a c t i o n 3.


If

1.

17

N-Chehted Organolithium Catalysis

LANGER

t h e v i n y l l i t h i u m a d d e d t o ethylene a n d t h e n c h a i n t r a n s f e r r e d via t r a n s m e t a l a t i o n , o n e w o u l d a g a i n o b t a i n l i n e a r a l p h a olefins.

However we

h a v e i d e n t i f i e d allcylcyclopentanes as t h e m a j o r p r o d u c t t y p e ( o v e r 9 5 % ) i n e t h y l e n e p o l y m e r i z a t i o n studies w i t h B u L i / 2 T M E D i n it-heptane at 100 ° C a n d 1000 p s i g ethylene. T h e s e c y c l i c structures a r e p r o d u c e d a t t h e h e x e n y l l i t h i u m stage d u r i n g p o l y m e r i z a t i o n i n i t i a t e d b y v i n y l l i t h i u m : LiCH CH . C H CH =CHCH 2

LiCH=CH

+ 2C H —

2

2

4

2

2

LiCH CH | CH

CH2 | CH

2

_

2

^

2

2

2


^ C H

Li (CH CH ) CH CH 2

2

n

CH

2

" 2 4 , * C

I CH

H

I CH

2

/ CH

H (CH CH ) CH CH 2

2

n

CH

2

CH*5

2

2

C H 2

4 |

LiCH=CHo +

2

2

2

CHo CH

2

If t h e r i n g s t r u c t u r e w e r e p r o d u c e d b y m e t a l a t i o n o f olefinic p r o d u c t s a n d c y c l i z a t i o n after a d d i t i o n o f t w o molecules o f ethylene, t h e y w o u l d be cyclohexane derivatives: ^ C H LiR + RCH CH=CH -»-RH + RCH -CH

2C H

N

2

2

j©

RCH I CH, I CH 2

2

2

4

-RCHCH=CH

2

CH CH CH CH Li 2

2

2

2

CHCH,Li I CH I CH ά

2

2

M a s s spectroscopic analysis o f s e p a r a t e d p r o d u c t s i n t h e Ce-50 r a n g e s h o w e d o n l y c y c l o p e n t a n e rings. T h e r e f o r e t h e m a j o r c y c l i z a t i o n r e a c t i o n



18

m u s t p r o c e e d via v i n y l l i t h i u m a n d the major c h a i n transfer process i n the absence of a c i d i c solvents m u s t be R e a c t i o n 3.

A previously

proposed

c y c l i c e l i m i n a t i o n m e c h a n i s m (53, 58) m u s t b e c o n s i d e r e d less p r o b a b l e because one

w o u l d expect b o t h

five

a n d six m e m b e r e d

r i n g s to

be

produced. W h e n c o m p o u n d s are present w h i c h are m o r e a c i d i c t h a n ethylene, R e a c t i o n 4 is the p r e f e r r e d c h a i n transfer r e a c t i o n . T h i s is c l e a r l y the case when

aromatic

solvents

are

used

to

obtain

alkylaromatic

telomers.

A l t h o u g h a l k y l a r o m a t i c s w e r e the major p r o d u c t s , some a l k y l c y c l o p e n t a n e p r o d u c t s w e r e also p r o d u c e d .

T h i s is consistent w i t h a s l i g h t l y l o w e r

a c i d i t y for ethylene c o m p a r e d w i t h b e n z e n e

(about 1ρΚ

α

unit)

(59).


R e p l a c i n g p a r t of the a r o m a t i c solvent b y a n inert saturated solvent l i k e heptane decreased the rate of c h a i n transfer to a r o m a t i c a n d i n c r e a s e d t h e p r o p o r t i o n of a l k y l c y c l o p e n t a n e s i n the p r o d u c t ( 6 0 ) . M a s s spectro s c o p i c analysis of

these

products

also

indicated small quantities

of

molecules h a v i n g t w o n a p h t h e n i c rings a n d some h a v i n g a n a r o m a t i c r i n g a n d a n a p h t h e n e r i n g . S u c h molecules i n d i c a t e that a s m a l l a m o u n t of c y c l i z a t i o n occurs either i n a c h a i n transfer step, s u c h as c y c l i c e l i m i n a t i o n , or via m e t a l a t i o n of olefinic p r o d u c t s .

T h e latter seems m o r e p r o b

a b l e since there are three reactions w h i c h c o u l d p r o d u c e olefins. I f one naphthene ring i n each two ring molecule

c o u l d b e s h o w n to b e six

m e m b e r e d , i t w o u l d a d d strong s u p p o r t for the m e c h a n i s m i n v o l v i n g olefins i n the f o r m a t i o n of the second r i n g . Appendix Bibliography of U.S. Patents on N-Chelated A l k a l i Metal

Compounds

3,206,519° E b e r h a r d t , G . G . 3,257,364 3,321,479

6

T e l o m e r i z a t i o n of ethylene w i t h aromatics Eberhardt, G . G . T e l o m e r i z a t i o n of ethylene w i t h olefins E b e r h a r d t , G . G . a n d B u t t e , W . Α., J r . P r e p a r a t i o n of o r g a n o l i t h i u m a m i n e complexes

3,329,736 3,402,144

B u t t e , W . Α., J r . a n d M o r r i s , J . W . , I l l I s o m e r i z a t i o n of Olefins Hay, A S . L i t h i a t i o n of p o l y p h e n y l e n e ethers

3,404,042

Langer, A . W . and Forster, E . O. O r g a n i c b a t t e r y electrolytes

3,450,795 3,451,988

Langer, A W . P r e p a r a t i o n of b l o c k c o p o l y m e r s Langer, A W . C o m p o s i t i o n s a n d uses for p o l y m e r i z a t i o n

3,458,586

Langer, A . W . T e l o m e r i z a t i o n of ethylene w i t h aromatics


1.

LANGER


3,474,143

B u t t e , W . Α., J r . T e l o m e r i z a t i o n of ethylene w i t h C6H5CH2NR2

3,498,960

Woiford, C. F.

3,502,731

Peterson, D . J .

19

R a n d o m c o p o l y m e r i z a t i o n of dienes a n d styrenes L i t h i a t i o n of methylsulfides 3,509,188

c

Halasa, A . F . and Tate, D . P. P o l y l i t h i a t i o n of f errocenes

3,511,865

Peterson, D . J .

3,517,042

Peterson, D . J .

3,522,326

B o s t i c k , Ε. E . , H a y , A . S. a n d C h a l k , A . J .

L i t h i a t i o n of methylsilanes


L i t h i a t e d methylsilanes G r a f t i n g o n l i t h i a t e d p o l y p h e n y l e n e ethers 3,532,772

de l a M a r e , H . a n d N e u m a n n , F . E . Polymerizations using chelated L i P R

3,536,679 3,541,149 3,567,703 3,579,492 3,584,056

2

Langer, A . W . L i t h i a t e d c h e l a t i n g agents Langer, A W . C r y s t a l l i n e o r g a n o l i t h i u m chelates Eberhardt, G . G . E t h y l e n e p o l y m e r i z a t i o n at 101-150 ° C Smith, W . N . , Jr. N a r r o w m o l e c u l a r w e i g h t d i s t r i b u t i o n p o l y e t h y l e n e at 0-75 ° C Peterson, D . J . Uses for l i t h i a t e d methylsulfides

3,594,396

Langer, A . W . L i t h i a t e d m e t h y l s i l a n e chelates

3,597,463

Peterson, D . J . Uses for l i t h i a t e d methylsulfides

3,598,793

K o c h , R. W . P r e p a r a t i o n of c a r b o x y l a t e d r u b b e r s

3,624,260


3,626,019

Black, E . P. E t h y l e n e - p s e u d o c u m e n e telomer w a x

3,627,837

Webb,F.J. P r e p a r a t i o n of graft c o p o l y m e r s

3,632,658

Halasa, A . F. P o l y l i t h i a t i o n of aromatics

3,634,548

H a r w e l l , Κ. E . a n d G a l i a n o , F . R . P r e p a r a t i o n of graft c o p o l y m e r s

3,646,219


3,647,803

Schlott, R . F . , H o e g , D . W . a n d P e n d l e t o n , J . F . P r e p a r a t i o n of o r g a n o s o d i u m chelates


20


3,652,696 3,657,373

H o n e y c u t t , S. C . E t h y l e n e - a r o m a t i c telomer w a x Peterson, D . J . O l e f i n p r e p a r a t i o n u s i n g l i t h i a t e d methylsilanes

3,658,925

E r m a n , W . F . and Broaddus, C. D . L i t h i a t i o n of l i m o n e n e

3,663,585 3,666,618

Langer, A . W . L i t h i a t i o n of ferrocene Black, E . P. Uses for telomer l a m i n a t i n g w a x

3,666,744

Black, E . P.


Process for p r e p a r i n g telomer l a m i n a t i n g w a x 3,674,895

Gaeth, R. H . a n d Farrar, R. C . Polymerizations using m u l t i l i t h i u m initiators

3,678,088

Hedberg, F . L . and Rosenberg, H . L i t h i a t i o n of metallocenes

3,678,121

3,679,650

M c E l r o y , B. J . and Merkley, H . N a r r o w molecular weight distribution polydienes using d i l i t h i u m initiators Schott, H . a n d H e r w i g , W . P o l y m e r i z a t i o n of

3,691,241

alpha-methylstyrene

Kamienski, C. W . and Merkley, J. H . Uses for a l k a l i m e t a l m a g n e s i u m

3,734,963 3,737,458 3,742,057

organohydrides

Langer, A . W . and Whitney, T. A . I n o r g a n i c l i t h i u m chelates Langer, A W . G r i g n a r d reactions of l i t h i a t e d c h e l a t i n g agents Bunting, W . M . and Langer, A . W . Chelated organosodium compositions

3,755,484

Langer, A . W . T e l o m e r w a x finishing process

3,755,447

Klemann, L . P., Whitney, T. A . and Langer, A . W . S e p a r a t i o n a n d p u r i f i c a t i o n of c h e l a t i n g p o l y a m i n e s

3,755,533 3.751.384 3,758,580 3,758,585 3,763,131 3.764.385 3,767,763

Langer, A . W . and Whitney, T. A . S e p a r a t i o n a n d r e c o v e r y of l i t h i u m salts Langer, A . W . Chelated organolithium compositions Langer, A . W . , Whitney, T. A . and Klemann, L . P. S e p a r a t i o n a n d p u r i f i c a t i o n of t e r t i a r y p o l y a m i n e s Bunting, W . M . and Langer, A . W . I n o r g a n i c s o d i u m chelates Langer, A . W . T e l o m e r w a x process a n d c o m p o s i t i o n Langer, A . W., Whitney, T. A . E l e c t r i c b a t t e r y u s i n g c h e l a t e d i n o r g a n i c l i t h i u m salts Bunting, W . B., Langer, A . W . S e p a r a t i o n a n d r e c o v e r y of s o d i u m c o m p o u n d s


1.

LANGER


3,769,345

Langer, A . W . P r e p a r a t i o n o f o r g a n o l i t h i u m a m i n e complexes

3,770,827

Langer, A . W., Whitney, T. A . Separation of chelating tertiary polyamines

a

6

c

21

Claims lost to 3,451,988 and 3,458,586. Claims lost to 3,769,345. Claims lost to 3,663,585.


Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39.

Bywater, S., Advan. Polym. Sci. (1965) 4, 66. Langer, A. W., Jr., U.S. Patent 3,451,988. Ziegler, K., Angew. Chem. (1959) 71, 623. Ziegler, K., Gellert, H., Ann. (1950) 567, 195. Bartlett, P. D., Friedman, S., Stiles, M., J. Amer. Chem. Soc. (1953) 75, 1771. Hanford, W. E., Roland, J. R., Young, H. S., U.S. Patent 2,377,779. Langer, A. W., Jr., U.S. Patent 3,458,586. Langer, A. W., Jr., U.S. Patent 3,541,149. Langer, A. W., Jr., Trans. Ν.Y. Acad. Sci. (1965) 27, 741. Langer, A. W., Jr., Polym. Prepr., Amer. Chem. Soc., Div. Polym. Chem. (1966) 7 (1), 132. Langer, A. W., Jr., Gordon Conf. (Polym.), July, 1965. Eberhardt, G. G., Butte, W. Α., J. Org. Chem. (1964) 29, 2928. Eberhardt, G. G., U.S. Patent 3,206,519. Eberhardt, G. G., U.S. Patent 3,321,479. Langer, A. W., Jr., U.S. Patent 3,541,149. Langer, A. W., Jr., U.S. Patent 3,769,345. Eberhardt, G. G., Davis, W. R., J. Polym. Sci. (1965) A3, 3753. Butte, W. Α., Hydrocarbon Process. (1966) 45 (9), 277. Eberhardt, G. G., U.S. Patent 3,257,364. Butte, W. Α., Morris, J. W., III, U.S. Patent 3,329,736. Butte, W. Α., U.S. Patent 3,474,143. Eberhardt, G. G., U.S. Patent 3,567,703. Black, E. P., U.S. Patents 3,626,019; 3,666,618; 3,666,744. Brown, T. L., Pure Appl. Chem. (1971) 23, 447. Margerison, D., Pont, J. D., Trans. Faraday Soc. (1971) 67, 353. Makowski, H. S., Lynn, M., J. Macromol. Chem. (1966) 1 (3), 443. Morton, M., Bostick, Ε. E., Livigni, R. Α., J. Polym. Sci., PartA-1(1963) 1, 1735. Bywater, S., Worsfold, D. J., Can. J. Chem. (1962) 40, 1564. Morton, M., Fetters, L. J., J. Polym. Sci., Part A-2 (1964 ) 2, 3311. Margerison, D., Newport, J. P., Trans. Faraday Soc. (1963) 59, 2058. Lewis, H. L., Brown, T. L., J. Amer. Chem. Soc. (1970) 92, 4664. Findeis, A. F., Langer, A. W., Jr., unpublished data. Hay, J. N., McCabe, J. F., Robb, J. C., Trans. Faraday Soc. (1972) 68, 1. Mootz, V. D., Zinnius, Α., Boettcher, B., Angew. Chem. (1969) 81, 398. Kimura, Β. Y., Brown, T. L., J. Organometal. Chem. (1971) 26, 57. West, P., Waack, R., J. Amer. Chem. Soc., (1967) 89, 4395. Melchior, M. T., Klemann, L. P., Langer, A. W., Jr., Int. Congr. Organo metal. Chem., 6th, Aug. 1973, Prepr. Forster, E. O., Langer, A. W., Jr., U.S. Patent 3,404,042. Klemann, L. P., Melchior, M. T., Langer, A. W., Jr., Int. Congr. Organo metal. Chem., 6th, Aug. 1973, Prepr.



22

POLYAMINE-CHELATED ALKALI METAL COMPOUNDS

40. Gilman, H., Jacoby, A. L., Ludeman, H., J. Amer. Chem. Soc. (1938) 60, 2336. 41. CIauss,V. K., Bestian, H., Ann. (1962) 654, 8. 42. Langer, A. W., Jr., unpublished data. 43. Bartlett, P. D., Tauber, S. J., Weber, W. P., J. Amer. Chem. Soc. (1969) 91, 6362. 44. Bartlett, P. D., Goebel, C. V., Weber, W. P., J. Amer. Chem. Soc. (1969) 91, 7425. 45. Cram, D. J., "Fundamentals of Carbanion Chemistry," p. 19, Academic, New York, 1965. 46. Langer, A. W., Jr., unpublished data. 47. Melchior, M. T., Klemann, L. P., Whitney, T. Α., Langer, A. W., Jr., Polym. Prepr., Amer. Chem. Soc., Div. Polym. Chem. (1972) 13 (2), 649. 48. Broaddus, C. D., J. Org. Chem. (1970) 35, 10. 49. Broaddus, C. D., Amer. Chem. Soc., Div. Petrol. Chem. Prepr. (1970) 15 (2), E82. 50. Langer, A. W., Jr., U.S. Patent 3,737,458. 51. Langer, A. W., Jr., U.S. Patent 3,536,679. 52. Morton, M., Sanderson, R. D., Sakata, R., J. Polym. Sci., Part C (1971) 9, 61. 53. Langer, A. W., Jr., Akron Summit Polym. Conf., 1st, June 1970. 54. Hay, J. Ν., McCabe, J. F., J. Polym. Sci., PartA-1(1972) 10, 3451. 55. Shimomura, T., Toile, Κ. J., Smid, J., Szwarc, M., J. Amer. Chem. Soc. (1967) 89, 796. 56. Finnegan, R. Α., Trans. Ν.Ύ. Acad. Sci. (1965) 27 (7), 730. 57. Eberhardt, G. G., Organometal. Chem. Rev. (1966) 1, 491. 58. Langer, A. W., Jr., Sixth Middle Atlantic Meeting, Amer. Chem. Soc., Feb., 1971. 59. Maskornick, M. J., Streitweiser, Α., Tetrahedron Lett. (1972) (17), 1625. 60. Langer, A. W., Jr., U.S. Patent 3,763,131. RECEIVED September 4, 1973.


Chelated Organolithium Catalysis

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