96-14-0Relevant articles and documents
TRANSFORMATIONS OF 1-VINYLCYCLOBUTENE
Vdovin, V. M.,Finkel'shtein, E. Sh.,Shelkov, A. V.,Yatsenko, M. S.
, p. 2364 - 2366 (1986)
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Mercaptosilane-assisted synthesis of highly dispersed and stable Pt nanoparticles on HL zeolites for enhancing hydroisomerization of n-hexane
Liu, Cun,Liu, Haiou,Wang, Jinshan,Zhang, Xiongfu,Zhu, Peng
, p. 3482 - 3492 (2022/02/21)
The synergistic effect between metal and acid sites has been considered to be of great importance to n-alkane hydroisomerization catalyzed by bifunctional catalysts. Herein, we report a facile mercaptosilane-assisted in situ synthesis approach to achieve stable and highly dispersed small Pt nanoparticles supported on HL zeolite catalysts (Pt/HL-SH) for n-hexane hydroisomerization. In comparison with the catalysts (Pt/HL-C) synthesized by a traditional ion-exchange method, the Pt/HL-SH catalysts show both high activity and excellent catalytic stability and also no obvious sintering of Pt nanoparticles is observed during the reaction due to the fact that the Pt/HL-SH catalysts possess both higher dispersion of Pt particles within the HL nanocrystals and more mesopores produced by mercaptosilane. Moreover, the regeneration stability of n-hexane hydroisomerization over Pt/HL-SH catalysts was also examined by five continuous cycles, demonstrating excellent regeneration properties. Thus, the mercaptosilane-assisted in situ synthesis approach is a promising way to prepare bifunctional catalysts for enhancing their catalytic performance in n-alkane hydroisomerization.
Boosting homogeneous chemoselective hydrogenation of olefins mediated by a bis(silylenyl)terphenyl-nickel(0) pre-catalyst
Lücke, Marcel-Philip,Yao, Shenglai,Driess, Matthias
, p. 2909 - 2915 (2021/03/14)
The isolable chelating bis(N-heterocyclic silylenyl)-substituted terphenyl ligand [SiII(Terp)SiII] as well as its bis(phosphine) analogue [PIII(Terp)PIII] have been synthesised and fully characterised. Their reaction with Ni(cod)2(cod = cycloocta-1,5-diene) affords the corresponding 16 VE nickel(0) complexes with an intramolecularη2-arene coordination of Ni, [E(Terp)E]Ni(η2-arene) (E = PIII, SiII; arene = phenylene spacer). Due to a strong cooperativity of the Si and Ni sites in H2activation and H atom transfer, [SiII(Terp)SiII]Ni(η2-arene) mediates very effectively and chemoselectively the homogeneously catalysed hydrogenation of olefins bearing functional groups at 1 bar H2pressure and room temperature; in contrast, the bis(phosphine) analogous complex shows only poor activity. Catalytic and stoichiometric experiments revealed the important role of the η2-coordination of the Ni(0) site by the intramolecular phenylene with respect to the hydrogenation activity of [SiII(Terp)SiII]Ni(η2-arene). The mechanism has been established by kinetic measurements, including kinetic isotope effect (KIE) and Hammet-plot correlation. With this system, the currently highest performance of a homogeneous nickel-based hydrogenation catalyst of olefins (TON = 9800, TOF = 6800 h?1) could be realised.
Highly Active Superbulky Alkaline Earth Metal Amide Catalysts for Hydrogenation of Challenging Alkenes and Aromatic Rings
Eyselein, Jonathan,F?rber, Christian,Grams, Samuel,Harder, Sjoerd,Knüpfer, Christian,Langer, Jens,Martin, Johannes,Thum, Katharina,Wiesinger, Michael
supporting information, p. 9102 - 9112 (2020/03/30)
Two series of bulky alkaline earth (Ae) metal amide complexes have been prepared: Ae[N(TRIP)2]2 (1-Ae) and Ae[N(TRIP)(DIPP)]2 (2-Ae) (Ae=Mg, Ca, Sr, Ba; TRIP=SiiPr3, DIPP=2,6-diisopropylphenyl). While monomeric 1-Ca was already known, the new complexes have been structurally characterized. Monomers 1-Ae are highly linear while the monomers 2-Ae are slightly bent. The bulkier amide complexes 1-Ae are by far the most active catalysts in alkene hydrogenation with activities increasing from Mg to Ba. Catalyst 1-Ba can reduce internal alkenes like cyclohexene or 3-hexene and highly challenging substrates like 1-Me-cyclohexene or tetraphenylethylene. It is also active in arene hydrogenation reducing anthracene and naphthalene (even when substituted with an alkyl) as well as biphenyl. Benzene could be reduced to cyclohexane but full conversion was not reached. The first step in catalytic hydrogenation is formation of an (amide)AeH species, which can form larger aggregates. Increasing the bulk of the amide ligand decreases aggregate size but it is unclear what the true catalyst(s) is (are). DFT calculations suggest that amide bulk also has a noticeable influence on the thermodynamics for formation of the (amide)AeH species. Complex 1-Ba is currently the most powerful Ae metal hydrogenation catalyst. Due to tremendously increased activities in comparison to those of previously reported catalysts, the substrate scope in hydrogenation catalysis could be extended to challenging multi-substituted unactivated alkenes and even to arenes among which benzene.
