34472-48-5Relevant articles and documents
Synthetic explorations towards sterically crowded 1,2,3-substituted bis(indenyl)zirconium(IV) dichlorides
Moeller, Andreas C.,Blom, Richard,Heyn, Richard H.,Swang, Ole,Goerbitz, Carl-Henrik,Seraidaris, Tanja
, p. 1759 - 1769 (2005)
The systematic synthesis of 1,3-dialkyl-substituted 2-silylindenes and their suitability as zirconocene ligands is discussed. Unexpected reactivities rendered a number of substitution patterns unfeasible, especially for alkyl groups other than methyl in 2-(trimethylsilyl)indene derivatives, and essentially for all derivatives of 2-(dimethylsilyl)indene. The syntheses of rac/meso-bis[1-methyl-2-(trimethylsilyl)indenyljzirconium(IV) dichloride (12) and bis[1,3-dimethyl-2-(trimethylsilyl)indenyl]zirconium(IV) dichloride (13b) are de scribed. The solid-state structure of the latter displays strong deformations within the ligand framework and an unusually large C PcentroidZr-CPcentroid angle. Both, 12/MAO and 13b/MAO, displayed ethene and ethene-co-1-hexene polymerization activity. Curiously, 13b/MAO shows an extraordinary monomer selectivity, which can be rationalized by means of DFT calculations on the active site. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).
Borderline between ElcB and E2 mechanisms. Chlorine isotope effects in base-promoted elimination reactions
Jia, .Zhi Sheng,Rudzinski, Juliusz,Paneth, Piotr,Thibblin, Alf
, p. 177 - 181 (2002)
The chlorine leaving group isotope effect has been measured for the base-promoted elimination reaction of 1-(2-chloro-2-propyl)indene (1-Cl) in methanol at 30 °C: k35/k37 = 1.0086 ± 0.0007 with methoxide as the base and k35/k37 = 1.0101 ± 0.0001 with triethylamine (TEA) as the base. These very large chlorine isotope effects combined with large kinetic deuterium isotope effects of 7.1 and 8.4, respectively, are consistent not with the irreversible ElcB mechanism proposed previously (J. Am. Chem. Soc. 1977, 99, 7926) but with the E2 mechanism with transition states having large amounts of hydron transfer and very extensive cleavage of the bond to chlorine.
Experimental and DFT study on titanium-based half-sandwich metallocene catalysts and their application for production of 1-hexene from ethylene
Ahmadi, Ebrahim,Bahri-Laleh, Naeimeh,Gharajedaghi, Sajjad,Marefat, Mohamadreza,Mohamadnia, Zahra,Pareras, Gerard,Poater, Albert,Simon, Sílvia
, (2021/05/31)
Different types of [Ind-C(R)-Phenyl]TiCl3 catalysts based on pendant arene containing indenyl (Ind) ligand bearing various types of bridges (R=cyclo‐C5H10 (C1), (CH3)2 (C2), 4-tBu-cyclo‐C5H9 (C3), and cyclo‐C6H12 (C4)) have been synthesized, and used in the ethylene trimerization to 1-hexene in the presence of methyl aluminoxane (MAO) as co-catalyst. The reaction conditions were first optimized in C2 catalyst case, where the highest 1-hexene product was achieved at the catalyst concentration, temperature and ethylene pressure of 1.5× 10?3 M, 40 °C, and 8 bar, respectively. During this optimization and under specific reaction conditions, a switching behavior from ethylene trimerization to polymerization was also detected, as an undesired reaction. At the optimized conditions, synthesized catalysts showed the following trend toward both 1-hexene yield and selectivity: C1>C2>C3>C4. Then, to shed light on the possible reaction mechanisms and to confirm the activity trend obtained in experimental section, density functional theory (DFT) calculations were employed. In this line, obtained results for activity trend in the simulation studies fit well with the experiments. According to both experimental and DFT results, the highest catalytic activity was observed in the presence of the catalyst with a cyclohexane middle bridge (C1).
Attempts to prepare an all-carbon indigoid system
Yildizhan, ?eref,Hopf, Henning,Jones, Peter G.
, p. 363 - 372 (2015/06/16)
First attempts are described to prepare a precursor for an all-carbon analog of indigo, the tetracyclic triene 4. Starting from indan-2-one (9) the α-methylene ketone 13 was prepared. Upon subjecting this compound to a McMurry coupling reaction, it dimerized to the bis-indene derivative 17, rather than providing the tetramethyl derivative of 4, the hydrocarbon 14. In a second approach, indan-1-one (18) was dimerized to the conjugated enedione 21 through the bis-1-indene dimer 19. All attempts to methylenate 21 failed, however. When 19 was treated with the Tebbe reagent, the dimer 23 was produced, presumably through a Cope reaction of the intermediately generated isomer 22. The bis-indene derivative 23 can be alkylated with 1,2-dibromoethane to produce a 1:1 mixture of the spiro compounds 24 and 25. Although 9 could be reductively dimerized to 30, the conversion of this olefin to 14 failed.
