Substituent effect of Cp2TiCl2 catalyst for ethylene polymerization: A DFT study

Document Type : Original research

Authors

1 School of Chemistry and Chemical Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China

2 Lanzhou Petrochemical Research Center, Petrochemical Research Institute, PetroChina, Lanzhou 730060, China

3 College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou Gansu 730070, China

Abstract

The substituents on cyclopentadienyl (Cp) can regulate the electronic effect and hindrance of the active center in the metallocene catalyst. This modification can greatly change the catalytic activity of the catalyst and affect some features of the polymer. In order to study the effect of alkyl substituents on Cp in the performance of a typical metallocene catalyst Cp2TiCl2 for ethylene polymerization, two types of catalyst active centers were designed, including non-bridge Cp2(R)TiCH3]+ and bridge [NCP2 (R)TiCH3]+ (R = H, Me, iPr). The effects of alkyl substituent steric hindrance were explored by density functional theory on the complex of catalyst active center with ethylene and the formation of transition state. The results showed that the increase of substituent steric hindrance was unfavorable to complex between ethylene monomer with catalyst active center. Moreover, the bigger alkyl substituent, the greater the activation energy of ethylene insertion into catalyst active center and the more difficult is ethylene polymerization. Therefore, the performance of metallocene catalysts could be regulated by the substituent on Cp.

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References

  1. Breslow DS, Newburg NR (1959) Bis-(cyclopentadienyl)-titanium dichloridealkylaluminum complexes as soluble catalysts for the polymerization of ethylene. J Ame Chem Soc 81: 81-86
  2. Andresen A, Cordes HG, Herwig J, Kaminsky W, Merck A, Mottweiler R, Pein J, Sinn H, Vollmer HJ (1976) Halogen-free soluble Ziegler catalysts for the polymerization of ethylene. Control of molecular weight by choice of temperature. Angew Chem Int Ed Engl 15: 630-632
  3. Sinn H, Kaminsky W, Vollmer H J, Woldt R (1980) “Living polymers” on polymerization with extremely productive Ziegler catalysts. Angew Chem Int Ed Engl 19: 390-392
  4. Kaminsky W (1996) New polymers by metallocene catalysis. Macromol Chem Phys 197: 3907-3945
  5. Koide Y, Bott SG, Barron AR (1996) Alumoxanes as Cocatalysts in the palladiumcatalyzed copolymerization of carbon monoxide and ethylene: Genesis of a structure activity relationship. Organometallics 15: 2213-2226
  6. Zohuri G, Jamjah R, Ahmadjo S (2005) Polymerization of ethylene using Cp2ZrCl2 metallocene and methylaluminoxane homogeneous catalyst system. Iran Polym J 14: 111-116
  7. Yi J, Nakatani N, Tomotsu N, Nomura K, Hada M (2021) Theoretical studies of reaction mechanisms for half-titanocene-catalyzed styrene polymerization, ethylene polymerization, and styrene-ethylene copolymerization: Roles of the neutral Ti(III) and the cationic Ti(IV) species. Organometallics 40: 643-653
  8. Wang YC, Cheng PY, Zhang ZQ, Fan KX, Lu RQ, Zhang S, Wu YX (2021) Highly efficient terpolymerizations of ethylene/propylene/ENB with a half-titanocene catalytic system. Polym Chem 12: 6417-6425
  9. Kitphaitun S, Chaimongkolkunasin S, Manit J, Makino R, Kadota J, Hirano H, Nomura K (2021) Ethylene/myrcene copolymers as new bio-based elastomers prepared by coordination polymerization using titanium catalysts. Macromolecules 54: 10049-10058
  10. Nomura K, Izawa I, Yi J, Nakatani N, Aoki H, Harakawa H, Ina T, Mitsudome T, Tomotsu N, Yamazoe S (2019) Solution XAS analysis for exploring active species in syndiospecific styrene polymerization and 1-hexene polymerization using half-titanocene-MAO catalysts: Significant changes in the oxidation state in the presence of styrene. Organometallics 38: 4497-4507
  11. Ceballos-Torres J, Prashar S, Fajardo M, Chicca A, Gertsch J, Pinar A B, Gómez-Ruiz S (2015) Ether-substituted group 4 metallocene complexes: Cytostatic effects and applications in ethylene polymerization. Organometallics 34: 2522-2532
  12. Rosa CD, Odda R, Auriemma F, Girolamo RD, Scarica C, Giusto G, Esposito S, Guidotti S, Camurati I (2014) Polymorphic behavior and mechanical properties of isotactic 1-butene–ethylene copolymers from metallocene. Catal Macromol 47: 4317-4329
  13. Janeta M, Heidlas J X, Daugulis O, Brookhart M (2021) 2,4,6-Triphenylpyridinium: A bulky, highly electron-withdrawing substituent that enhances properties of nickel (II) ethylene polymerization catalysts. Angew Chem Int Ed 60: 4566-4569
  14. Zhang Y. Wang C, Mecking S, Jian Z (2020) Ultrahigh branching of main-chain-functionalized polyethylenes by inverted insertion selectivity. Angew Chem Int Ed 59: 14296-14302
  15. Talaei A, Taromi FA, Arefazar A, Ahmadjo S, Jazani OM (2014) The influence of bridge type on the activity of supported metallocene catalysts in ethylene polymerization. Chinese J Polym Sci 32: 137-142
  16. Ahmadjo S, Arabi H, Nekoomanesh M Mortazavi SM M, Zohuri G, Ahmadi, Bolandi S (2011) Indirect synthesis of bis(2-PhInd)ZrCl2 metallocene catalyst, kinetic study and modeling of ethylene polymerization. Chem Eng Technol 34: 249-256
  17. Tanja H. R, Helmut G. A (2019) Homogeneous and heterogeneous oligomerization reactions of olefins with unbridged metallocene catalysts. Polyolefins J 6: 107-116
  18. Wondimagegn T, Wang D, Razavi A, Ziegler T (2009) In silico design of C1- and Cs-symmetric fluorenyl-based metallocene catalysts for the synthesis of high-molecular-weight polymers from ethylene/propylene copolymerization. Organometallics 28:1383-1390
  19. Liu JY, Liu SR, Li BX, Li YG, Li YS (2011) Synthesis and characterization of novel halfmetallocene-type group IV complexes containing phosphine oxide–phenolate chelating ligands and their application to ethylene polymerization. Organometallics 30: 4052-4059
  20. Tong ZZ, Huang Y, Xu JT, Fu ZS, Fan ZQ (2015) Chain structure, aggregation state structure, and tensile behavior of segmented ethylene–propylene copolymers produced by an oscillating unbridged metallocene catalyst. J Phys Chem B 119: 6050-6061
  21. Lu L, Hong F, Li BG, Zhu S (2009) Polypropylene and ethylene−propylene copolymer reactor alloys prepared by metallocene/Ziegler−Natta hybrid catalyst. Ind Eng Chem Res 48: 8349-8355
  22. Zhang M, Yuan X, Wang L, Chung T, Huang T, Degroot W (2014) Synthesis and characterization of well-controlled isotactic polypropylene ionomers containing ammonium ion groups. Macromolecules 47: 571-581
  23. Klet RC, Theriault CN, Klosin J, Labinger JA, Bercaw JE (2014) Investigations into asymmetric post-metallocene group 4 complexes for the synthesis of highly regio-irregular polypropylene. Macromolecules 47:3317-3324
  24. Zhang B, Zhang L, Fu Z, Fan Z (2015) Effect of internal electron donor on the active center distribution in MgCl2-supported Ziegler-Natta catalyst. Catal Commun 69: 147-149
  25. Nissinen Ville, Pirinen S, Pakkanen TT (2016) Unexpected cleavage of ether bonds of 1,3-dimethoxypropane in Grignard-Wurtz synthesis of a MgCl2-donor adduct. J Mol Catal-A 413: 94-99
  26. Theurkauff G, Roisnel T, Waassenaar J, Carpentier J, Kirillov E (2014) iPP-sPP Stereoblocks or blends? Studies on the synthesis of isotactic-syndiotactic polypropylene using single C1-symmetric {Ph2C-(Flu)(3-Me3Si-Cp)}ZrR2 metallocene precatalysts. Macromol Chem Phys 215: 2035-2047
  27. Kissin YV, Rishina LA, Lalayan SS, Krasheninnikov VG (2015) A new route to atactic polypropylene: The second life of premetallocene homogeneous polymerization catalyst. J Sci Pol Chem 53: 2124-2131
  28. Nam B, Park OO, Kim S (2015) Properties of isotactic polypropylene/atactic polypropylene blends. Macromol Res 23: 809-813
  29. Chen MC, Roberts J, Marks TJ (2004) Marked counteranion effects on single-site olefin polymerization processes. Correlations of ion pair structure and dynamics with polymerization activity, chain transfer, and syndioselectivity. J Am Chem Soc 126: 4605-4625
  30. Min Y, Hu BW, Li B, Qu JY, Liu BY, Shen XL (2016) Preparation of high molecular weight atactic polypropylene using ansa-metallocenes with doubly hetero-bridges. Acta Polym Sinica 1: 25-30
  31. Xie KF, Xu SY, Hao W, Wang J, Huang AP, Zhang YH (2022) Surface effect of the MgCl2 support in Ziegler-Natta catalyst for ethylene polymerization: A computational study. Appl Surf Sci 589: 153002
  32. Thakur A, Baba R, Wada T, Chammingkwan P, Taniike T (2019) Cooperative catalysis by multiple active centers of a half-titanocene catalyst integrated in polymer random coils. ACS Catal 9: 3648-3656
  33. Thakur A, Baba R, Chammingkwan P, Terano M, Taniike T (2018) Synthesis of aryloxidecontaining half-titanocene catalysts grafted to soluble polynorbornene chains and their application in ethylene polymerization: Integration of multiple active centers in a random coil. J Catal 357: 69-79
  34. Xu X, He G, Wei NN, Hao C, Pan Y (2017) Selective insertion in copolymerization of ethylene and styrene catalyzed by half-titanocene system bearing ketimide ligand: A theoretical study. Chinese J Chem 35: 1731-1738
  35. Varga V, Vecera M, Gyepes R,Pinkas J, Horacek M, Merna J, Lamac M (2017) Effects of the linking of cyclopentadienyl and ketimide ligands in titanium half-sandwich olefin polymerization catalysts. Chem Cat chem 9: 3160-3172
  36. Lee C, Yang W, Parr RG (1988) Development of the colle-salvetti correlation-energy formula into a functional of the electron density. Phys Rev B 37: 785-789
  37. Govind N, Petersen M, Fitzgerald G, King-Smith D, Andzelm J (2003) A generalized synchronous transit method for transition state location. Comput Mater Sci 28: 250-258
  38. Beddie C, Hollink E, Wei PR, Gauld J, Stephan DS (2004) Use of computational and synthetic chemistry in catalyst design: A new family of high-activity ethylene polymerization catalysts based on titanium tris(amino)phosphinimide complexes. Organometallics 23:5240-5251

 

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History

  • Receive Date: 12 September 2022
  • Revise Date: 15 October 2022
  • Accept Date: 24 October 2022

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