Controlled geometry catalyst

Dow Insite LLDPE, VLDPE solution controlled geometry catalyst (single site) Octene-1 may be used as comonomer... 

Control of Catalyst Location in a CMR - From the previous section, it can be seen that the optimal location or distribution of a catalyst in a membrane can strongly influence results. This question was studied theoretically by Keller et for an isothermal, irreversible first-order reaction in a homogeneous membrane with slab geometry. They enumerated some different criteria of optimality maximize the reaction rate per membrane area minimize the flux of reactant leaving the membrane and maximize the purity at the output side, expressed as the ratio (flux of product)/(flux of reactant). The first optimality... 

Hanaoka, Oda, and coworkers report [23] that single-site polymerization catalysts are of considerable interest industrially today, because they afford highly controllable polymerization performances based on precise design of catalyst architecmre and their industrial applications. Among them, they point to constrained geometry catalyst and phenoxy-induced complex, they call phenics-Ti, that are used together with methyl aluminoxane... 

Miilhaupt and coworkers studied homo- and copolymerizations of 1,5-HD with ethylene and styrene using the MAO-activated constrained geometry catalyst 8. This catalyst system afforded very high 1,5-HD incorporation (reaching 52 mol%) with randomly distributed cis- and transcyclopentane rings in the homo- and copolymer backbones. The ratio of vinyl side chains to cyclic rings was controlled by the 1,5-HD concentration, where low concentrations of 1,5-HD promoted cyclopolymerization. 

ELITE resins are produced via INSITE Technology, a constrained geometry catalyst and process technology developed by The Dow Chemical Company that provides extraordinary control over polymer arehiteeture. 

The asymmetric reduction of enamides using hydrogenation conditions is a well documented reaction with a number of groups reporting excellent results [14]. Syn delivery of hydrogen from the same face of the molecule ensures that the enamide geometry defines the relative stereochemistry obtained, and a range of chiral catalysts have been developed to control the absolute stereochemistry. However, a... 

The course of stereospecific olefin polymerization was studied by using the molecular mechanics programs, MM-2 and Biograph, based on the optimized geometries of the ethylene complex and the transition state [13,203]. Interestingly, the steric interaction at the transition state mainly controls the stereochemistry in polymerization, which proceeds specifically isotactic or syndiotactic depending on the kind of catalyst. 

As described, an FI catalyst potentially possesses five isomers arising from the coordination modes of ligands in an octahedral geometry, suggesting that an FI catalyst has the ability to form well-defined multimodal polymers that are expected to possess an excellent combination of material properties and processability. In fact, on activation with MAO, Zr-FT catalyst 32 furnishes uni-, bi- and tri-modal PEs in a controlled manner, simply by varying the polymerization temperatures (Fig. 19) [24, 25],... 

Beyond palladium, it has recently been shown that isoelectronic metal complexes based on nickel and platinum are active catalysts for diyne reductive cyclization. While the stoichiometric reaction of nickel(O) complexes with non-conjugated diynes represents a robust area of research,8 only one example of nickel-catalyzed diyne reductive cyclization, which involves the hydrosilylative cyclization of 1,7-diynes to afford 1,2-dialkylidenecyclohexanes appears in the literature.7 The reductive cyclization of unsubstituted 1,7-diyne 53a illustrates the ability of this catalyst system to deliver cyclic Z-vinylsilanes in good yield with excellent control of alkene geometry. Cationic platinum catalysts, generated in situ from (phen)Pt(Me)2 and B(C6F5)3, are also excellent catalysts for highly Z-selective reductive cyclization of 1,6-diynes, as demonstrated by the cyclization of 1,6-diyne 54a.72 The related platinum bis(imine) complex [PhN=C(Me)C(Me)N=Ph]2Pt(Me)2 also catalyzes diyne hydrosilylation-cyclization (Scheme 35).72a... 

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