10 Telomerization of Conjugated Diolefins with Aromatics and Olefins Using Chelated Organosodium Catalysts
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WILLIAM BUNTING and ARTHUR W. LANGER, JR. Corporate Research Laboratories, Esso Research and Engineering C o . , L i n d e n , N . J . 07060
Telomerization of butadiene and isoprene with aromatics and olefins proceeds rapidly at 0°-100°C using organosodium catalysts in combination with aliphatic tertiary chelating polyamines containing two to six nitrogens. The products range from monoadduct up to tacky semisolids. Chain transfer increased with increasing complexing ability of the chelating agent, increasing chelating agent concentration, increasing acidity of the telogen, increasing temperature, and decreasing monomer concentration. More than 74 mole % selectivity to pentenylbenzene was obtained from butadiene and toluene. The ratio of alpha/internal unsaturation in the monoadduct varied from 0.5 to 1.7, and it decreased at the higher temperatures because of the double bond isomerization activity of the catalyst. Catalyst efficiencies greater than 1300 grams/gram benzylsodium were obtained.
A nionic telomerizations of conjugated diolefins with hydrocarbon acids are known but suffer from very low catalytic efficiencies. Morton et al. (1) and, later, Pappas et al. (2) used unchelated organosodium compounds to telomerize conjugated diolefins with weak hydrocarbon acids but obtained very low catalyst efficiencies (about 5 grams/gram catalyst). More recently, the anionic telomerization of butadiene and toluene by sodium on oxide supports (3) and sodium in tetrahydrofuran (4) was studied;, also, a potassium amide/lithiated alumina catalyst was used to telomerize butadiene (5). Common organosodium compounds are generally insoluble in inert solvents, and this causes considerable difficulty in their preparation and 201 Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
202
POLYAMINE-CHELATED
ALKALI
M E T A L
COMPOUNDS
p u r i f i c a t i o n as w e l l as i n t h e i r use as catalysts a n d reagents.
I n earlier
w o r k w i t h o r g a n o l i t h i u m catalysts i t w a s f o u n d t h a t c h e l a t i n g t e r t i a r y diamines and higher polyamines formed e n h a n c e d reactivities. T h e prospects organosodium compounds this p a p e r .
s o l u b l e complexes
(6)
with
of o b t a i n i n g s i m i l a r results w i t h
s t i m u l a t e d the research t h a t is t h e subject of
S u b s t a n t i a l differences
between
l i t h i u m systems w e r e e x p e c t e d a n d f o u n d . amines a n d s o d i u m c o m p o u n d s
the chelated sodium
and
F o r example, chelating d i -
form only weak, unstable
a l t h o u g h t h e d i a m i n e s s h o w some effect o n o r g a n o s o d i u m
complexes catalysts i n
solution. Downloaded by AUBURN UNIV on November 15, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0130.ch010
T h i s r e p o r t covers the use of c h e l a t e d o r g a n o s o d i u m c o m p o u n d s n o v e l catalysts for t e l o m e r i z i n g c o n j u g a t e d
diolefins w i t h w e a k
c a r b o n acids s u c h as aromatics a n d olefins ( 7 ) .
T h e factors affecting the
c h a i n - t r a n s f e r r e a c t i o n w e r e of p a r t i c u l a r interest b e c a u s e one of objectives
as
hydro-
w a s to increase s e l e c t i v i t y t o l o w - m o l e c u l a r - w e i g h t
T h e p r o d u c t s are u s e f u l i n s y n t h e s i z i n g p l a s t i c i z e r alcohols,
our
species. flame
re-
tardants, a n d surface coatings. Discussion Chelated Organosodium
Compounds.
T h e chelated
organosodium
c o m p o u n d s u s e d i n the t e l o m e r i z a t i o n process consist of those by
aliphatic, tertiary, chelating polyamines.
complexed
I n general, any
organo-
s o d i u m c o m p o u n d s m a y b e u s e d that, w h e n c h e l a t e d , c a n i n i t i a t e p o l y m e r i z a t i o n of the diolefin. T h i s relates to c a r b a n i o n b a s i c i t y i n that the i n i t i a t i n g c a r b a n i o n m u s t h a v e c o m p a r a b l e or greater b a s i c i t y t h a n the a l l y l c a r b a n i o n f o r m e d f r o m t h e d i o l e f i n . P h e n y l s o d i u m a n d b e n z y l s o d i u m are t h e most u s e f u l .
A l k y l sodium compounds
are too r e a c t i v e to p e r m i t
p r e f o r m i n g the c o m p l e x w i t h o u t d e c o m p o s i n g the c h e l a t i n g agent.
How-
ever, t h e y c a n b e u s e d w h e n the c o m p l e x is f o r m e d i n the presence
of
m o n o m e r or a s u i t a b l e h y d r o c a r b o n a c i d to c o n v e r t the a l k y l a n i o n to a c a r b a n i o n of l o w e r a c t i v i t y . T h e p r e f e r r e d c h e l a t i n g agents are d e r i v a t i v e s of e t h y l e n e d i a m i n e , h i g h e r p o l y a m i n e s , a n d isomers.
T h e particular tertiary chelating poly-
a m i n e s d i s c u s s e d here together w i t h t h e i r a b b r e v i a t i o n s are ( t h e y are a l l permethylated polyamines ) : TMED:
tetramethylethylenediamine
PMDT:
pentamethyldiethylenetriamine
i s o - H M T T : tris- ( ^ - d i m e t h y l a m i n o e t h y l ) a m i n e H M T P : heptamethy ltetraethylenepentamine OMPH :
octamethylpentaethylenehexamine
T w o examples of c h e l a t e d o r g a n o s o d i u m c o m p o u n d s
are s h o w n i n F i g -
u r e 1.
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
10.
BUNTING A N D LANGER
k
Me Me \ /
(
v%
\J
NMe2
N — -Na —
Na
Me
Ph
,NMe2 NMe2
M e
iso-HMTT*PhNa
PMDT*BzNa Figure 1.
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203
Telomerization of Olefins
Two chelated organosodium compounds
Telomerization. T h e t e l o m e r i z a t i o n is r u n b y i n t r o d u c i n g gaseous b u t a d i e n e i n t o t h e a t m o s p h e r e a b o v e a s o l u t i o n o f catalyst i n t h e h y d r o c a r b o n a c i d u n d e r c o n d i t i o n s r i g o r o u s l y e x c l u d i n g a i r or w a t e r . T h e gaseous b u t a d i e n e m a y b e d i l u t e d w i t h a n i n e r t gas a n d b u b b l e d t h r o u g h the reactant s o l u t i o n . T o m a x i m i z e c o n v e r s i o n to l o w m o l e c u l a r - w e i g h t p r o d u c t s , efficient m i x i n g o f reagents is necessary. T h e r e a c t i o n p r o d u c t is i s o l a t e d b y w a s h i n g w i t h w a t e r a n d d i s t i l l i n g . T h e process is r e p r e sented i n F i g u r e 2 b y t h e t e l o m e r i z a t i o n o f toluenes a n d b u t a d i e n e . T h e i n i t i a l step i n v o l v e s attack of t h e c h e l a t e d o r g a n o s o d i u m o n t h e conjugated
d i o l e f i n to g i v e a n a l l y l a n i o n .
T h e a l l y l a n i o n c a n either
abstract a p r o t o n f r o m t h e h y d r o c a r b o n telogen
( t o l u e n e ) to g i v e t h e
m o n o a d d u c t o r a d d to another m o l e c u l e of d i o l e f i n to g i v e a n e w a l l y l Θ Na#Chel
Figure 2.
Telomerization of toluene and butadiene
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
204
POLYAMINE-CHELATED
ALKALI
M E T A L
COMPOUNDS
a n i o n . F u r t h e r , p r o t o n a b s t r a c t i o n o r d i o l e f i n attack c a n o c c u r at either t h e 1- or 3 - c a r b o n of t h e a l l y l a n i o n . T h e r e seems to b e a p o s i t i v e c o r r e l a t i o n b e t w e e n t h e r e l a t i v e r e a c t i v i t i e s of the 1- a n d 3-carbons i n p r o t o n a b s t r a c t i o n a n d i n p o l y m e r i z a t i o n . It is possible to v a r y the r a t i o of m o n o a d d u c t s I : I I (see F i g u r e 2 ) as w e l l as the average d e g r e e of p o l y m e r i z a t i o n of the r e a c t i o n b y v a r y i n g t h e r e a c t i o n c o n d i t i o n s a n d catalyst. R e m e t a l a t i o n of p r o d u c t s c a n o c c u r at b o t h b e n z y l i c a n d a l l y l i c positions to p r o d u c e a d d i t i o n a l b r a n c h e d t e l o m e r structures. A l t h o u g h t h e y w e r e not a l l i d e n t i f i e d , the n u m b e r of gas c h r o m a t o g r a p h i c
(GC)
peaks i n the d i a d d u c t f r a c t i o n i n d i c a t e d t h a t a l l e x p e c t e d s t r u c t u r a l a n d Downloaded by AUBURN UNIV on November 15, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0130.ch010
d o u b l e - b o n d isomers w e r e o b t a i n e d . N a t u r e of the Catalyst.
T h e effect of v a r y i n g t h e c h e l a t i n g agent
i n t o l u e n e - b u t a d i e n e t e l o m e r i z a t i o n is s h o w n i n T a b l e s I a n d I I .
The
use of t r i g l y m e ( a t e t r a e t h e r ) as a c h e l a t i n g agent gave a n i n a c t i v e Table I. Chelating Agent None TMED PMDT iso-HMTT HMTP OMPH triglyme
Effect of Chelating Agent,
Total Product (grams)
Selectivity to monoadduct, %
6.0 15.8 11.5 13.3 17.5 15.8 no reaction
34 32 26 45 60 59
40°C
e
Alpha/Internal Unsaturation 0.5 0.5 1.2 1.6 1.4 1.5
T o 2.63 mmoles benzylsodium were added 2.63 mmoles chelating agent and 50 ml toluene. The reaction was heated to 40°C and maintained at 40°C while 22 cc/min gaseous butadiene were introduced into the atmosphere above the reaction for 2 hrs. A t the end of that time 5 ml of water were added, and the organic layer separated and dried (K2CO3). Toluene was removed at water-aspirator pressure, and the residue was distilled (140°C/0.05 mm). The distillate was analyzed by G C . α
Table II. Chelating Agent None TMED PMDT iso-HMTT HMTP α
Effect of Chelating Agent,
Total Product (grams)
Selectivity to Monoadduct, %
50 m g ( w a x y solid) 11.8 9.5 8.6 11.2
0 41.5 18 6.2 22.5
5°C
e
Alpha/Internal Unsaturation — 0.21 0.85 1.72 1.5
Same reaction conditions as in Table I except the reaction temperature was 5°C.
catalyst.
P r e s u m a b l y t h e c a t a l y s t d e c o m p o s e d via m e t a l a t i o n of
the
c h e l a t i n g agent. I n terms of s e l e c t i v i t y to m o n o a d d u c t a n d a l p h a / i n t e r n a l u n s a t u r a t i o n at 4 0 ° C , the T M E D - B z N a gives results s i m i l a r to b e n z y l s o d i u m a l o n e whereas complexes c o n t a i n i n g the h i g h e r c h e l a t i n g agents
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
10.
BUNTING
AND
LANGER
205
Τ elomenzation of Olefins
differ m a r k e d l y f r o m b e n z y l s o d i u m
alone.
T h i s is a reflection of
the
r e l a t i v e s t a b i l i t y of the complexes. A t 4 0 ° C , T M E D - B z N a is a r e l a t i v e l y weak
complex
while
PMDT-BzNa
and
the
complexes
with
higher
c h e l a t i n g agents are r e l a t i v e l y strong complexes. As shown i n Tables I and II, unchelated less r e a c t i v e t h a n is the c h e l a t e d
benzylsodium
benzylsodium.
Ignoring
is
much
colligative
properties there are several g e n e r a l explanations for the n a t u r e of
the
catalyst. C e r t a i n l y the i n s o l u b i l i t y of o r g a n o s o d i u m c o m p o u n d s i n h y d r o c a r b o n m e d i a a n d t h e r e l a t i v e l y h i g h s o l u b i l i t y of c h e l a t e d
organosodium
c o m p o u n d s is p a r t of a n y e x p l a n a t i o n c o m p a r i n g c h e l a t e d w i t h u n c h e l a t e d Downloaded by AUBURN UNIV on November 15, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0130.ch010
s o d i u m c o m p o u n d s . M o r e o v e r , s u r r o u n d i n g the s o d i u m c a t i o n b y a L e w i s base ( t h e c h e l a t i n g a g e n t ) m i g h t b e e x p e c t e d to increase the
electron
d e n s i t y o n the a n i o n , m a k i n g the a n i o n i n a chelated, s o d i u m c o m p o u n d a stronger base r e l a t i v e to t h e a n i o n i n a n u n c h e l a t e d s o d i u m c o m p o u n d (8, 9 ) .
T h e m o r e c h e l a t i n g g r o u p s s u r r o u n d i n g the c a t i o n , the greater
s h o u l d be the c h a r g e p o l a r i z a t i o n of the c a r b o n - s o d i u m
bond.
A s the
c h a r g e d e n s i t y o n the i n t e r m e d i a t e a l l y l a n i o n i n v o l v e d i n the t e l o m e r i z a t i o n ( F i g u r e 3 ) increases, the r e l a t i v e reactivities of the 1- a n d 3-carbons i n p r o t o n a b s t r a c t i o n a n d p o l y m e r i z a t i o n w o u l d b e e x p e c t e d to c h a n g e i n a d i r e c t i o n i n c r e a s i n g t h e r e l a t i v e r e a c t i v i t y of the 3 - c a r b o n , w h i c h f u n d a m e n t a l l y agrees w i t h the d a t a g i v e n i n T a b l e s I a n d I I .
Figure 3.
Allyl anion intermediate in toluene-butadiene telomerization
U n d o u b t e d l y , greater c h a r g e p o l a r i z a t i o n i n the m e t a l - c a r b o n occurs i n the c h e l a t e d c o m p o u n d s .
However,
how
bond
significant this i n
creased c h a r g e p o l a r i z a t i o n is w i t h a n a l r e a d y h i g h l y i o n i c species is a moot question.
W h e r e a s the o r g a n o l i t h i u m c o m p o u n d s are u s u a l l y c o n
s i d e r e d to b e f a i r l y covalent
i n nature, the organosodium
are u s u a l l y t h o u g h t of as h i g h l y i o n i c species
compounds
(10).
A n o t h e r possible e x p l a n a t i o n of the results invokes steric effects i n the i n t e r m e d i a t e a l l y l a n i o n ( F i g u r e 3 ) .
T h e steric i n t e r a c t i o n b e t w e e n
the b u l k y c h e l a t e d c a t i o n a n d the b e n z y l g r o u p p r o b a b l y
pushes
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
the
206
POLYAMINE-CHELATED
ALKALI
M E T A L
COMPOUNDS
c h e l a t e d c a t i o n t o w a r d the 1-carbon, i n c r e a s i n g the steric s h i e l d i n g a b o u t t h e 1-carbon r e l a t i v e to the 3 - c a r b o n .
C o n s e q u e n t l y , i n g o i n g to h i g h e r
c h e l a t i n g agents t h e c h e l a t e d c a t i o n b e c o m e s i n c r e a s i n g l y b u l k y a n d t h e 3 - c a r b o n b e c o m e s m o r e r e a c t i v e r e l a t i v e to t h e 1-carbon i n p r o t o n a b straction (manifested b y increasing a l p h a / i n t e r n a l unsaturation i n Tables I a n d I I ) . M o r e o v e r , t h e steric r e q u i r e m e n t s f o r r e a c t i o n w i t h b u t a d i e n e ( p o l y m e r i z a t i o n ) s h o u l d b e greater t h a n p r o t o n e x t r a c t i o n f r o m toluene (chain transfer).
C o n s e q u e n t l y , s e l e c t i v i t y to m o n o a d d u c t
should i n -
crease w i t h h i g h e r c h e l a t i n g agents. T h e d a t a i n T a b l e s I a n d I I are f o l l o w e d q u i t e w e l l w i t h a l p h a / Downloaded by AUBURN UNIV on November 15, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0130.ch010
i n t e r n a l u n s a t u r a t i o n a n d w i t h s e l e c t i v i t y to m o n o a d d u c t
(Table
C o n v e r s i o n to m o n o a d d u c t , t h o u g h , is n o t w e l l f o l l o w e d at 5 ° C
I).
(Table
I I ) . T h i s m a y b e because of a t e m p e r a t u r e - d e p e n d e n t c h a n g e i n c o l l i g a t i v e p r o p e r t i e s , l o w e r t e m p e r a t u r e f a v o r i n g h i g h e r states of a g g r e g a t i o n . W e h a v e n o m o l e c u l a r - w e i g h t d a t a for c h e l a t e d o r g a n o s o d i u m
com-
p o u n d s i n s o l u t i o n . H o w e v e r , L a n g e r has m e a s u r e d the m o l e c u l a r w e i g h t s of s e v e r a l 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 o u n d s i n h y d r o c a r b o n s o l u t i o n (II).
H e f o u n d T M E D - n - B u L i to b e m o n o m e r i c at 0 . 1 M a n d
LiCHPh
2
TMED-
to v a r y c o n s i d e r a b l y i n a g g r e g a t i o n state w i t h c h a n g e i n c o n -
c e n t r a t i o n , b e i n g m o n o m e r i c o n l y at l o w c o n c e n t r a t i o n ( 0 . 0 5 M ) .
The
chelated organosodium compounds probably behave like the h i g h l y ionic c h e l a t e d d i p h e n y l m e t h y l l i t h i u m . C o n s e q u e n t l y , a g g r e g a t i o n states greater t h a n one are p r o b a b l y i m p o r t a n t i n catalysis of the t e l o m e r i z a t i o n , p a r t i c u l a r l y at l o w temperatures a n d h i g h catalyst concentrations. A m o d e l f o r the c a t a l y s t s t r u c t u r e i n v o l v i n g c o l l i g a t i v e p r o p e r t i e s , i o n i c c h a r a c t e r , a n d steric effects is p r o b a b l y necessary b e f o r e w e c a n k n o w t h e i n t i m a t e details of the m e c h a n i s m of the t e l o m e r i z a t i o n r e a c t i o n . Nonstoichiometric Catalyst.
B e n e f i c i a l results i n o p t i m i z i n g selec-
t i v i t y to l o w - m o l e c u l a r - w e i g h t t e l o m e r c a n be o b t a i n e d b y d e v i a t i n g f r o m the 1:1 s t o i c h i o m e t r y of o r g a n o s o d i u m c o m p o u n d s to c h e l a t i n g agent. Table III. Mmoles iso-HMTT 2.63 5.26 5.26 10.52 10.52 2.63
Nonstoichiometric Catalyst Total Product, grams
Mmoles BzNa 2.63 2.63 5.26 2.63 5.26 10.52
1 2 1 4 2 0.25
29.3 38.8 39.8 40.3 40.1 39.7
Compositions
a
Selectivity Alpha/ Internal to Monoadduct, % Unsaturation 1.2 50 1.52 65.8 73.2 1.25 1.41 66.8 74.4 1.16 0.61 63.8
Butadiene 50 cc/min, was bubbled for 2 hr into 250 ml toluene containing the catalyst at 40°C. The reaction was quenched with 5 ml of water. Yields are distilled yields. Molar ratio of chelating agent to benzylsodium a
6
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
10.
BUNTING
AND
207
Telomerization of Olefins
LANGER
D a t a for n o n s t o c h i o m e t r i c c a t a l y s t c o m p o s i t i o n s are s h o w n i n T a b l e I I I . I n t h e p r e c e d i n g section the l a r g e differences b e t w e e n T M E D - B z N a at 5 ° C ( T a b l e I I ) a n d 4 0 ° C ( T a b l e I ) are b r i e f l y discussed i n terms of the s t r e n g t h of the c o m p l e x .
A t 40°C T M E D - B z N a
behaves
much
u n c h e l a t e d b e n z y l s o d i u m i n the t e l o m e r i z a t i o n whereas at 5 ° C
like
TMED-
B z N a differs m a r k e d l y f r o m b e n z y l s o d i u m . A t h i g h e r t e m p e r a t u r e s the c o m p l e x b e t w e e n c h e l a t i n g agent a n d s o d i u m c o m p o u n d is m o r e disso ciated.
T h i s e q u i l i b r i u m c a n be forced
to the r i g h t b y a d d i n g m o r e
c h e l a t i n g agent o r m o r e s o d i u m c o m p o u n d :
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Chel + N a X
chel-NaX
K
e q
. =
^
ίΐ^Γ^ν! [chel] [N a A J
U n f o r t u n a t e l y , b o t h excess s o d i u m c o m p o u n d a n d c h e l a t e d s o d i u m compound
c a t a l y z e the t e l o m e r i z a t i o n , e v e n w h e n the f o r m e r is less
effective, a n d i t is difficult to separate these t w o reactions. W i t h excess c h e l a t i n g agent, h o w e v e r , the e q u i l i b r i u m shift is clear.
T h e data i n
T a b l e I I I for excess c h e l a t i n g agent s u p p o r t t h e c o n c e p t of a c h e l a t e d s o d i u m c o m p o u n d i n e q u i l i b r i u m w i t h free c h e l a t i n g agent a n d s o d i u m compound.
It is also possible, p a r t i c u l a r l y b e l o w 25 ° C , that c a t a l y t i c
species of s t o i c h i o m e t r y c h e l N a X or c h e l ( N a X ) 2
2
are i n v o l v e d i n a d d i t i o n
to c h e l - N a X i n the t e l o m e r i z a t i o n r e a c t i o n . Effect of Temperature and Butadiene Concentration. I n c r e a s i n g t h e r e a c t i o n t e m p e r a t u r e increases the c h a i n - t r a n s f e r rate faster t h a n the p o l y m e r i z a t i o n rate ( T a b l e I V ) . A c t i v a t i o n e n e r g y for c h a i n transfer is p r o b a b l y h i g h e r t h a n that f o r p o l y m e r i z a t i o n a l t h o u g h the l o w e r s o l u b i l i t y of b u t a d i e n e at the h i g h e r temperatures w o u l d also c o n t r i b u t e to the same result. Table IV. Temperature
°C
5 40 70
Effect of Reaction Temperature
Telomer Yield, grams
Selectivity to Monoadduct, %
8.6 13.3 15.0
6.2 45 67
Alpha/Internal Unsaturation 1.7 1.6 0.9
I n c r e a s i n g the r e a c t i o n t e m p e r a t u r e n o t o n l y increases
conversions
to m o n o a d d u c t b u t also decreases catalyst l i f e t i m e a n d isomerizes the product.
U n d e r f a v o r a b l e c o n d i t i o n s , m o r e t h a n 1300 grams
gram B z N a were 110°C
obtained.
product/
A g i n g the catalyst, i s o - H M T T - B z N a ,
for f o u r h o u r s results i n a n i n a c t i v e catalyst.
at
P r e s u m a b l y the
catalyst s l o w l y decomposes via m e t a l a t i o n a n d d e c o m p o s i t i o n
of
the
c h e l a t i n g agent as w a s s h o w n for the c h e l a t e d a l k y l l i t h i u m catalysts. T h a t t h e decrease i n a l p h a / i n t e r n a l u n s a t u r a t i o n w i t h i n c r e a s i n g tern-
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
208
P O LYA M I N E - C H E L A T E D
4
M E T A L
COMPOUNDS
Effect of Butadiene Addition Rate
Table V . C # Rate (cc/min)
ALKALI
Selectivity to Monoadduct, %
6
Time
22 44 66 110
(min)
Alpha/Internal Unsaturation 0.88 0.91 1.03 1.35
67 63 59 57
120 60 40 24
p e r a t u r e results i n p a r t f r o m p r o d u c t i s o m e r i z a t i o n a n d n o t o n l y f r o m some f u n d a m e n t a l c h a n g e i n t h e n a t u r e of t h e c a t a l y s t ( d i s s o c i a t i o n ) is s h o w n i n T a b l e V . A d d i n g a constant a m o u n t o f b u t a d i e n e , b u t i n Downloaded by AUBURN UNIV on November 15, 2016 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0130.ch010
shorter r e a c t i o n t i m e s , increases a l p h a / i n t e r n a l u n s a t u r a t i o n . A l s o , i n c r e a s i n g t h e effective
b u t a d i e n e c o n c e n t r a t i o n decreases s e l e c t i v i t y to
m o n o a d d u c t as expected. Scope of the Reaction. Isoprene also has b e e n successfully u s e d ; i t gives
s l i g h t l y h i g h e r s e l e c t i v i t y to m o n o a d d u c t
t h a n does
butadiene
u n d e r i d e n t i c a l r e a c t i o n c o n d i t i o n s , reflecting t h e s l i g h t l y l o w e r r e a c t i v i t y of i s o p r e n e i n t h e t e l o m e r i z a t i o n . B e n z e n e a n d octene h a v e b e e n u s e d to r e p l a c e toluene. T h e y give h i g h e r m o l e c u l a r w e i g h t telomers, r e f l e c t i n g a s l o w e r c h a i n - t r a n s f e r step b e c a u s e o f t h e l o w e r a c i d i t y o f a l l y l i c a n d a r o m a t i c protons r e l a t i v e to t h e b e n z y l i c protons o n toluene (12).
Also,
the o r g a n o s o d i u m c o m p o n e n t of t h e catalyst has b e e n r e p l a c e d e n t i r e l y o r i n p a r t b y t h e analogous o r g a n o l i t h i u m c o m p o u n d .
I n general the
presence of o r g a n o l i t h i u m c o m p o u n d s i n t h e t e l o m e r i z a t i o n process gives t e l o m e r o f m a r k e d l y h i g h e r m o l e c u l a r w e i g h t because o r g a n o l i t h i u m c o m p o u n d s u n d e r g o c h a i n - t r a n s f e r t y p e reactions m u c h s l o w e r t h a n d o organosodium compounds.
T h e s e reactions are s u m m a r i z e d i n T a b l e V I .
Preparation of O x o Alcohols. A t e l o m e r p r o d u c t c o n t a i n i n g a b o u t e q u a l a m o u n t s o f a l p h a a n d i n t e r n a l olefin m o n o a d d u c t s
was hydro-
f o r m y l a t e d u s i n g c o b a l t o c t a c a r b o n y l at 120 °C a n d 3000 p s i g , y i e l d i n g a 6 0 % c o n v e r s i o n to a l d e h y d e s . Table V I . Taxogen Telogen RM
isoprene toluene BzLi
C h e l a t i n g agent P M D T Temperature, °C Time, min Selectivity to monoadduct, % M n
T h e aldehydes were reduced to their
Miscellaneous
C4H6
1-octene C HnNa 5
isoHMTT
40 120
40 120
trace 2549
trace 2422
Telomerizations
C4H6
toluene BzLi/ BzNa TMED
40 120
8.6
isoprene toluene BzNa
C4H6
benzene C H Na 6
5
isoHMTT
iso-HMTT
70 80
70 120
64
low 998
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
10.
BUNTING
AND
209
Telomerization of Olefins
LANGER
c o r r e s p o n d i n g alcohols w i t h T M E D - L i A l H
4
i n benzene
(13).
three alcohols p r o d u c e d a b o u t 6 0 % w a s 6 - p h e n y l - l - h e x a n o l .
Of
the
T h e other
t w o alcohols are p r o b a b l y 5 - p h e n y l - 2 - m e t h y l - l - p e n t a n o l a n d 4 - p h e n y l - 2 ethyl-l-butanol.
B y c o n v e r t i n g these alcohols to p h t h a l a t e esters,
low
v o l a t i l i t y p l a s t i c i z e r s are o b t a i n e d .
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Experimental R e a c t i o n s w e r e r u n u n d e r c o n d i t i o n s r i g o r o u s l y e x c l u d i n g a i r or moisture. H y d r o c a r b o n solvents w e r e p u r i f i e d b y passage t h r o u g h a n a l u m i n a c o l u m n a n d storage over s o d i u m r i b b o n b e f o r e use. C h e l a t i n g agents w e r e d r i e d ( s o d i u m r i b b o n ) , f r a c t i o n a l l y d i s t i l l e d , a n d stored over calcium hydride. Organosodium compounds were obtained from Orgmet (Hampstead, N . H . ) a n d used without further purification. General Telomerization. O r g a n o m e t a l l i c c o m p o u n d a n d solvent w e r e a d d e d to a d r i e d flask e q u i p p e d w i t h a s t i r r i n g b a r i n a d r y box. T h e r e a c t i o n flask w a s s t o p p e r e d or fitted w i t h a t h e r m o m e t e r a n d r e m o v e d f r o m the d r y box. T h e r e a c t i o n w a s p l a c e d u n d e r n i t r o g e n a n d h e a t e d ( o r c o o l e d ) to the d e s i r e d t e m p e r a t u r e . T h e c o n j u g a t e d d i o l e f i n w a s t h e n a d d e d b y i n t r o d u c i n g it i n t o t h e atmosphere a b o v e t h e s o l u t i o n , b u b b l i n g t h r o u g h the r e a c t i o n s o l u t i o n , o r d i s s o l v i n g i n a n a p p r o p r i a t e solvent, a n d a d d i n g the r e s u l t a n t s o l u t i o n d r o p w i s e . A t the e n d of t h e d e s i r e d r e a c t i o n p e r i o d , 5-10 m l of w a t e r w e r e a d d e d w i t h s t i r r i n g . T h e o r g a n i c l a y e r w a s d r i e d ( K C 0 ) a n d either f r a c t i o n a l l y d i s t i l l e d at w a t e r - a s p i r a t o r pressure ( b p of m o n o a d d u c t is a b o u t 1 1 5 - 1 2 0 ° C / 1 5 m m , d i a d d u c t a b o u t 1 7 5 ° C ) or b u l b - t o - b u l b d i s t i l l e d ( 1 4 0 ° C / 0 . 0 2 m m ) . D i s t i l l a t e s w e r e a n a l y z e d o n a C a r b o w a x - 2 0 M c o l u m n at a b o u t 1 8 0 ° C . T h e monoadducts were characterized b y N M R and IR. Chelated Organolithium Catalyst. T o 1.6 m l of 1.6N n - b u t y l l i t h i u m i n hexane w e r e a d d e d 50 m l toluene a n d 0.6 m l P M D T , g e n e r a t i n g P M D T - B z L i in situ. T h e r e a c t i o n was k e p t at 4 0 ° C w h i l e b u t a d i e n e w a s i n t r o d u c e d i n t o the a t m o s p h e r e a b o v e the r e a c t i o n (22 c c / m i n ) for 2 hrs. T h e r e a c t i o n w a s t h e n q u e n c h e d w i t h 5 m l of w a t e r . T h e o r g a n i c l a y e r w a s separated, d r i e d ( K C 0 ) , a n d the solvent w a s r e m o v e d u n d e r v a c u u m to give 5 grams of p r o d u c t h a v i n g M = 2549. Chelated Organolithium/Organosodium Catalyst. T o 0.95 m l of 1.62V n - b u t y l l i t h i u m (1.5 m m o l e s ) w e r e a d d e d 50 m l t o l u e n e , 0.17 grams (1.5 m m o l e s ) b e n z y l s o d i u m , a n d 0.45 m l (— 3 m m o l e s ) T M E D . T h e r e a c t i o n w a s h e a t e d to 40 ° C a n d k e p t at that t e m p e r a t u r e w h i l e gaseous b u t a d i e n e was i n t r o d u c e d (22 c c / m i n ) i n t o the a t m o s p h e r e a b o v e the r e a c t i o n for 2 h r . T h e r e a c t i o n w a s t h e n q u e n c h e d w i t h 5 m l of w a t e r , a n d the o r g a n i c l a y e r s e p a r a t e d a n d d r i e d ( K C 0 ) . T h e toluene w a s r e m o v e d at w a t e r - a s p i r a t o r pressure, a n d the r e s i d u e was d i s t i l l e d ( 1 4 0 ° C / 0 . 0 5 m m ) . T h e d i s t i l l a t e was a n a l y z e d b y G C . T o t a l p r o d u c t w e i g h t was 6.1 grams. S e l e c t i v i t y to m o n o a d d u c t w a s 8 . 6 % . T h e r a t i o of a l p h a - t o - i n t e r n a l u n s a t u r a t i o n w a s 1.25. Telomerization of Toluene and Isoprene. T o 0.3 g r a m b e n z y l s o d i u m w e r e a d d e d 50 m l of t o l u e n e a n d 0.7 m l of i s o - H M T T . A s o l u t i o n of 20 m l isoprene i n 25 m l toluene w a s a d d e d d r o p w i s e to this r e a c t i o n m i x t u r e at 70 ° C over 80 m i n . A w o r k - u p s i m i l a r to the p r e c e d i n g e x a m p l e w a s 2
3
P
2
3
n
2
3
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.
210
POLYAMINE-CHELATED
ALKALI
M E T A L
COMPOUNDS
used. T h e t o l u e n e - i s o p r e n e t e l o m e r w e i g h e d 23.8 grams. S e l e c t i v i t y t o m o n a d d u c t w a s 6 4 % b a s e d o n G C analysis. Telomerization of Benzene and Butadiene. T o 0.26 g r a m ( 2 . 6 3 m m o l e s ) o f p h e n y l s o d i u m w e r e a d d e d 5 0 m l o f b e n z e n e a n d 0.7 m l of i s o - H M T T . T h e r e a c t i o n w a s k e p t at 70 ° C w h i l e b u t a d i e n e w a s i n t r o d u c e d i n t o t h e a t m o s p h e r e a b o v e t h e r e a c t i o n f o r 2 hrs at 2 2 c c / m i n . A w o r k - u p s i m i l a r t o t h a t g i v e n u n d e r c h e l a t e d o r g a n o l i t h i u m catalyst gave 7 grams o f b e n z e n e b u t a d i e n e t e l o m e r w i t h M = 998. Telomerization of 1-Octene and Butadiene. T o 0.3 g r a m o f n - a m y l s o d i u m w e r e a d d e d 50 m l o f 1-octene a n d 0.7 m l o f i s o - H M T T . B u t a d i e n e gas w a s a d d e d t o this r e a c t i o n m i x t u r e a t 40 ° C at 2 2 c c / m i n f o r 2 h r . A w o r k - u p s i m i l a r t o t h a t g i v e n u n d e r c h e l a t e d o r g a n o l i t h i u m catalyst gave 4.6 grams o f o c t e n e - b u t a d i e n e t e l o m e r w i t h M = 2422. n
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n
Literature Cited 1. Morton, Α., Patterson, G. H., Donovan, J. P., Little, E . L., J. Amer. Chem. Soc. (1946) 68, 93. 2. Pappas, J. J., Schriesheim, Α., U.S. Patent 3,189,660 (1965). 3. Eberhardt, G. G., Peterson, H . J., J. Org. Chem. (1965) 30, 82. 4. Kume, S., et al., Makromol. Chem. (1966) 98, 109; Kume, S., Makromol. Chem. (1966) 98, 120. 5. Bloch, H . S., U.S. Patent 3,355,484 (1967). 6. Langer, A. W., U.S. Patent 3,541,149 (1970); U.S. Patent 3,451,988 (1969). 7. Bunting, W., Langer, A W., U.S. Patent 3,750,200 (1972); U.S. Patent 3,742,057 (1973). 8. Originally proposed to account for the unusual reactivity of TMED-n-BuLi: Langer, A. W., Am. Chem. Soc. Div. Polymer Chem. Preprints (1966) 137. 9. Langer, A. W., Trans. Ν.Y. Acad. Sci. (1965) 27, 746. 10. Cotton, F. Α., Wilkinson, G., "Advanced Inorganic Chemistry," Interscience, New York, 1962. 11. Langer, A. W., unpublished results. 12. Cram, D. J., "Fundamentals of Carbanion Chemistry," p. 19, Academic, New York. 1965. 13. Langer, A. W., Whitney, Τ. Α., Chem. Abstr. (1971) 75, 38572Z; U.S. Patent 3,734,963 (1973). RECEIVED March 13, 1973.
Langer; Polyamine-Chelated Alkali Metal Compounds Advances in Chemistry; American Chemical Society: Washington, DC, 1974.