1. Ziegler-Natta Palladium and Nickel Catalysts for the Transformation of Unsaturated Hydrocarbons
G. Myagmarsuren
National Research Laboratory for Environmental Catalysis,
Department of Chemical and Biomolecular Engineering,
Korea Advanced Institute of Science and Technology

2. Catalysis
An acceleration of the rate of a process or reaction, brought about by a catalyst, usually present in small managed quantities and unaffected at the end of the reaction. A catalyst permits reactions or processes to take place more effectively or under milder conditions than would otherwise be possible.

3. The basis for catalysis
A catalyst lower the
activation barrier for a
transformation, by
introducing a new
reaction pathway
– It does not change the
thermodynamics!!

4. Importance of catalysis
Synthetic chemical
Rank*
Catalytic process
Ethene
Sulfuric acid
Propene
1,2-Dichloroethane
Calcium hydroxide
Ammonia
Urea
Phosphoric acid
Chlorine
Ethylbenzene
Sodium carbonate
Sodium hydroxide
Styrene
Nitric acid
Ammonium nitrate
Hydrogene chloride
Acrylonitrile
Ammonium sulfate
Potassium oxide
Titanium oxide 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Hydrocarbon cracking; heterogeneous
SO2 oxidation; heterogeneous
C2H4 + Cl2; heterogeneous
Not catalytic
N2 + H2; heterogeneous
NH3 precursor catalytic
Electrolysis
Alkylation of benzene; homogeneous
Dehydrogenation of ethylbenzene; heterogeneous
NH2 + O2; heterogeneous
Precursors catalytic
HCN + C2H2; homogeneous
- Many major
industrial chemicals
are prepared with
the aid of catalysts
- Many fine chemicals
are also made with
– Reduce cost of
production
– Lead to better
selectivity and less
waste

5. Heterogeneous versus homogeneous
􀂋 A heterogeneous catalyst is material that is in a
different phase from the reactant and product
– For example, Pt/Al2O3 for hydrogenation
» Often used industrially for large scale chemical
manufacture. Can be cheap but catalytically active
species hard to pin down
􀂋A homogeneous catalyst is a substance that is in
the same phase as the reactant and product
– For example, Wilkinson’s catalyst [RhCl(PPh3)]for
hydrogenation

6. Industrial use of homogeneous catalysis

7. C-C bond formation: Polymerization and Oligomerization
Def: the fundamental process by which low molecular weight compounds are converted into high molecular weight compounds.
n=2 – dimerization;
n=3 – trimerization;
n< oligomerization
n>200 up to millions – polymerization.
Low molecular weight material (having two or more reactive groups)
Catalyst
High molecular weight material

8. Brief History (TiCl3) (Al(C2H5)2Cl)
Since the end of 1952, a doctoral candidate, Holzkamp, has been working on growth reaction with ethylene and ethylaluminum in a steel pressure vessel (100°C, 100 atm). In a routine experiment he was surprised to get almost only 1-butene very fast. After a "strenuous investigation“, Holzkamp discovered that the catalytic effect was due to nickel present in the steel reaction vessel.
At the end of October, Breil, another of Ziegler’s collaborators, came to zirconium: a rapid and complete polymerization occurred. Moreover, the infrared spectra demonstrated that the polymer was linear.
Karl Ziegler
    1/2 of the prize
Federal Republic of Germany
Heinz Martin tried the simplest possible conditions: no higher pressure at all and no external heating. The result of the trial was that Martin burst in Ziegler’s office waving a glass flask and crying: "Es geht in Glass!“.
CATALYST: Titanium trichloride + diethylaluminum chloride
(TiCl3) (Al(C2H5)2Cl)

9. Branched/low-density = (LDPE)
Ziegler-Natta Catalyst
most popular plastic.
Grocery bags, shampoo bottles, toys, etc.
Simple structure than all polymers.
Branched/low-density = (LDPE)
Easier to make
Linear/high-density = (HDPE)

10. In Italy, Giulio Natta also recognized that catalysts of the type described by Ziegler were capable of polymerizing 1-alkenes (alpha olefins) to yield stereo-regular polymers. By slightly modifying the catalysts used by Ziegler, Natta was able to prepare highly isotactic linear crystalline polymers from non-polar α-olefins (e.g. propylene).
Giulio Natta
    1/2 of the prize
Italy
CATALYST: Titanium tetrachloride + triethylaluminum
(TiCl4)
(Al(C2H5)3)

11. Automobile and appliance
Polypropylene tacticity
Automobile and appliance
parts, rope, carpeting
Soft n’ sticky…not very good for anything
The way groups are arranged along the backbone chain of a polymer.

12. The Nobel Prize in Chemistry 1963
"for their discoveries in the field of the chemistry and technology of high polymers"
                          
Karl Ziegler
Giulio Natta
1/2 of the prize
Federal Republic of Germany
Italy
Max-Planck-Institut für Kohlenforschung (Max-Planck-Institue for Carbon Research) Mülheim/Ruhr, Federal Republic of Germany
Institute of Technology Milan, Italy
b d. 1973
b d. 1979
Robert L. Banks and J. Paul Hogan
(Phillips Petroleum Company )
Crystallynie polypropylene and
polyethylelene with nickel oxide catalyst

13. Polymerization ApparatusF H2
C3H6 N2
C2H4 P TC
Vacuum

14. Projected demand for catalyzed polyolefins
Polymer
Demand by Year (in tons)
2000
2005
2101
Polyethylene
Polypropylene
Polystyrene
80 000
Cyclic olefins (e.g. PNB)
30 000
60 000

15. Ziegler-Natta Catalysts
Combination of a transition metal compound of an element from groups IV to VIII, and an organometallic compound of a metal from groups I to III.
Catalyst – Transition metal
Co-catalyst – Organometallic Compound, mainly alkyl or alkylhalides of aluminium and boron, or methylaluminoxane.

16. Metal Catalysts for the Transformations of Olefins
Late transition metals
Early transition metals
Early transition metals
Central transition metals

17. Four generations of catalysts for -olefins polymerization  
Innovation
Result
Disciplinary Makeup
Catalyst
Cocatalyst
Support
Activity
Stereo selectivity
Morphology
First generation
1957
TiCl3 purple phases
AlEt2Cl +
Crystal structure analysis
Third component
1964
Lewis bases added –
Coordination chemistry
Second generation
1973
TiCl3 purple phases at lower temperature
Solid state
Third generation
1980
Activated MgCl2 ++
Solid state 
Materials science
Fourth generation
1991
Al-oxane activated metallocene complexes
Silica gel
(–)

18. Important catalyst properties
Activity
– A reasonable rate of reaction is needed
􀂋Selectivity
– Byproducts should be minimized
􀂋Lifetime
– It is costly to replace the catalyst frequently
􀂋Cost
– The acceptable cost depends upon the catalyst
lifetime and product value

19. HOWEVER
Organometallic compounds (alkyl or alkylhalides) are highly reactive and many ignite spontaneously upon exposure to the atmosphere.
Methylaluminoxane is mainly obtained by the partial hydrolysis of trimethylaluminium (TMA) and called as a black box due to the lack of a deep understanding of its structure.
Due to high production costs of MAO and organoborane cocatalysts, it is desirable to find the novel activators which can be used as substitutes for MAO and organoboranes.

20. OBJECTIVES
To develop novel simple catalytic systems for the transformation of unsaturated hydrocarbons:
Catalyst: Palladium and Nickel Complexes
Cocatalyst: Simple Lewis Acid – Boron Trifluorid (BF3) Compounds, e.g. BF3OEt2.

21. Processes Propene dimerization 1-Hexene izomerization
Styrene dimerization
Norbornene and derivative’s polymerization

22. Three different mechanisms
for the C-C bond formation

23. PROPENE DIMERIZATION Octane number Gasoline (80%) Polypropylene
isopropanol, trimers
and tetramers for detergents,
propylene oxide, cumene,
and glycerine
Octane number

24. Alkylation of propene dimers to gasoline

25. Palladium based systems
Catalyst components:
IR, UV, 1H, 13C NMR, elemental analysis: Palladium hydrides
(Pd-H) are responsible for catalytic activity.
Catalytic activity of 2500 mol propene per mol Pd for an hour has been achieved (CPd= mol/l; B/Pd=30; 500C; toluene, contineous supply of propene).
This is 300 times higher than those Ziegler-Natta palladium catalysts described in the literature.

26. Nickel based systems
ESR, NMR, IR spectroscopy

27. Nickel based systems: Catalyst design

28. Efficiency of Nickel Catalysts
Catalyst components:
Ni(PPh3)4 + n BF3OEt2
Astonishing
mol propene per mol
Ni for an hour,
[3-(allyl)Ni(PR3)]+[RAlX3]_
Activity
mol propene per mol Pd for an hour
mol propene per mol Pd for an hour
mol propene per mol Pd for an hour

29. Regioselectivity in Propene Dimerization
Dimerization vs. Double-bond isomerization!!!

30. 1-Hexene isomerization (Pd(acac)2 + 20BF3OEt2 system)
GLC method
Isomerization of 1-hexene is more than 60 times faster than dimerization of propene !!!
The dimerization products can isomerize very fastly during their formation!!!
Profile of isomer distributions versus time for the
isomerization of 1-hexene with Pd(acac)2 + 20BF3OEt2 catalyst.
(CPd=1.47x10-3 mol/dm3, C1-hexene=9.41x10-1 mol/dm3, B/Pd=20, T=100C, aging time 30 min)

31. Styrene dimerization (Pd(acac)2 + 7BF3OEt2 system)
Source:
Importance:
-fine chemicals, e.g. pharmacologically
active Ibuprofen and Naproxen;
-lubricants;
-plasticizers;
-surfactants;
-detergents
Reaction:

32. Results on styrene dimerization
Conversion of mol St per mol Pd for 7 h
Selectivity of 95% to trans-1,3-diphenyl-1-butene
Palladium hydride mechanism
. Kinetic curves: Pd(acac)2 + 7BF3OEt2 system at 600C (1) and 700C (2);
Pd(acac)2 + 1PPh3 + 7BF3OEt2 system at 600C (3) and 700C (4); and
Pd(acac)2 + 2PPh3 + 7BF3OEt2 system at 600C (5) and 700C (6)

33. Norbornene polymerization
What is Norbornene?
CH2 = CH2
DCPD
+ CH2=CH2
Norbornene
Norbornene is a bicyclic olefin.
Norbornene possesses ring strain,
thus the molecule contains a highly
reactive double bond.
Norbornene is manufactured via the
Diels-Alder reaction of
cyclopentadiene and ethylene.
It is a colorless substance which
melts at 460C.

34. Norobornene polymerization routes
Little is known about the cationic and
radical polymerization. The product is
a low molecular weight oligomer with
2,7-enchainity.
The best known polymerization is ROMP.
The polymer contains one double bond in
each repeating unit.
The vinylic polymerization is less developed
than ROMP. The polymer has 2,3-enchainity.

35. Application of norobornene saturated polymers
High optical transparency in the IR region
– data and telecommunication waveguide materials
High optical transparency in the visible ( nm) region
-plastic display substrate
Amorphous nature and subsequent low birefringenece
-optical lenses
High optical transparency in the UV region and
good reactive ion-etch resistance
-photoresist matrix material
Chip fabrication
157 nm photolithgraphy

36. Application (contd.) Low dielectric constant and high Tg
-electronics packaging
Sharp decomposition temperature
and low char yield
-interlayer dielectrics in semiconductors

37. Norbornene polymerization over Pd(acac)2 + 25BF3OEt2 system
Reaction conditions:
[Pd]=5.0x10-6 M; NB/Pd=22 350;
B/Pd=25; 250C
Polymer structure: 2,7-enchainity!!!
13C, 1H NMR, IR
L. Goodall et al. BF Goodrich Co., USA, 1999
Activity – kg NB/(mol Pd  h) !!!
A.Greiner et al kg NB/(mol Pd  h)
MAO/Ni=60 000, 200C: Macromol. Rap. Commun., 20 (1999) 232
Carbocationic mechanism!!!

38. What are Functionalized Norbornenes?
Source: Diels-Alder reactions
Exo isomer is much more reactive than endo.
Exo isomer (more reactive)
(20%)
Common substituents:
Alkyl (R), Acetate (OC(O)R), Alcohol (OH), Aldehyde
(C(O)H), Anhydride (RC(O)O(O)R), Epoxide
CH2C(O)CH), Ester (CO2R), Ether (OR), Nitrile (CN),
Silyl Ether (Si(OR)3), Ketone (C(O)R), Phenyl (Ar)
Endo isomer (less reactive)
80%

39. Polymerization of Alkylnorbornenes over Pd(acac)2 + 25BF3OEt2 Catalyst System
Problem arises:
The conversion is 20% at 250C for 48 h. It means that the only exo-isomer
is reacted. Increase of reaction temperature resulted in drastic drop of activity
due to low thermal stability of the system.
Idea:
Addition of Lewis base PR3 and increase of reaction temperature

40. Pd(acac)2+nPPh3+25BF3OEt2 Catalyst System
And what happened?
Reaction conditions:
[Pd]=5.0x10-6 M; NB/Pd=4500;
B/Pd=25; P/Pd=2; 650C
The activity is 2680 kg BuNb/(mol Pd  h), which is
comparable to that for most active known catalysts !!!;
The introduction of PPh3 switches the carbocationic
polymerization mechanism to the coordination Ziegler-Natta
mechanism !!! Polymer has 2,3-enchainity !!!

41. Switching mechanism
13C NMR spectra
2,7-enchainity
2,3-enchainity

42. Summary
The combinations of readily available Pd and Ni compounds with simple Lewis acid BF3 can lead to industrially important catalytic systems. Activities of these systems are comparable with that of most sophisticated Ziegler-Natta systems.
The switching of catalytic reaction mechanism is much more common phenomenon for transition metal catalysis than it is considered so far.
Those catalysts active in the oligomerization of open chain compounds are presumably active in the polymerization of cyclic compounds.

43. My great dedication to all graduate students – Master and Doctor Candidates, the Real Heroes of the SCIENCE HYSTORY !!!