Ziegler-Natta Palladium and Nickel Catalysts for the Transformation of Unsaturated Hydrocarbons

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 -Many major industrial chemicals are prepared with the aid of catalysts - Many fine chemicals are also made with the aid of catalysts – 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< 200 - 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 • 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. • 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. 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). CATALYST: Titanium tetrachloride + triethylaluminum (TiCl4) (Al(C2H5)3)

11. 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" Robert L. Banks and J. Paul Hogan (Phillips Petroleum Company) Crystallynie polypropylene and polyethylelene with nickel oxide catalyst

13. O T O T O T O T M T M T M T M T P Vacuum C3H6 F F F F C2H4 H2 N2 TC PolymerizationApparatus

14. Projected demand for catalyzed polyolefins

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

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 • 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=0.0042 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. Ni(PPh3)4 + n BF3OEt2 Efficiency of Nickel Catalysts • Catalyst components: Astonishing 625 000 mol propene per mol Ni for an hour, [3-(allyl)Ni(PR3)]+[RAlX3]_ • Activity 270 000 mol propene per mol Pd for an hour 200 000 mol propene per mol Pd for an hour 127 000 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) Importance: • Source: -fine chemicals, e.g. pharmacologically active Ibuprofen and Naproxen; -lubricants; -plasticizers; -surfactants; -detergents • Reaction:

32. Results on styrene dimerization Conversion of 75000 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. CH2 = CH2 DCPD + CH2=CH2 Norbornene Norbornene polymerization • What is 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 ofnorobornene saturated polymers High optical transparency in the IR region – data and telecommunication waveguide materials High optical transparency in the visible (400-700 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 overPd(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 – 20 220 kg NB/(mol Pd  h) !!! A.Greiner et al. 20564 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 !!!