Ziegler-Natta Polymerization of Olefins

Ziegler-Natta polymerization is used extensively for the polymerization of simple olefins (e.g. ethene, propene and 1-butene) and is the focus of much academic attention, as even small improvements to a commercial process operated on this scale can be important. Ziegler-Natta catalyst systems, which in general are early transition metal compounds used in conjunction vyith alkylaluminum compounds, lend themselves to study in the chloroaluminate(iii) ionic liquids, especially those with an acidic composition. 

Late Transition Metal atalyzed Polymerization oTOlefins 

Poly(phenylethene) has been prepared in high yield in [BMIM][BF4] and [BUPY][BF4] ionic liquids using rhodium(i) catalysts with EtsN as a co-catalyst [40]. It was shown that the catalysts could be recycled without significant loss of activity. Subsequently [41], it was shown that the amine co-catalyst was uimecessary in these ionic liquids. It was not clear whether this was due to the inherent basicity of the [BF4] ion or the presence of F . When a range ofionic liquids were used for this polymerization the yield and molecular weight of the polymer were found to depend on the ionic liquid used [42], The use of alcohol co-solvents was also found to increase the molecular weights of the products. 

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Mejzlik, J., Lesna, M. and Kratochvila, J. Determination of the Number of Active Centers in Ziegler-Natta Polymerizations of Olefins. Vol. 81, pp. 83 — 120. 

The mechanistic similarity between Ziegler-Natta polymerization of olefins and the alkene cyclization reactions described above suggested that early transition metal catalysts would be effective catalysts for the coupling of... 

An example is provided by the structures of Group IV metallacycles, LL MCl2, where ligands L and L are cyclopentadienyl based and M is Ti or Zr. As a class, these compounds act as catalyst precursors in homogenous (Ziegler-Natta) polymerization of olefins, e.g. 

The methods developed for the determination of the number of active centers are classified into three main categories, based on (i) labelling of the macromolecules, (ii) consumption data of an effective catalyst poison, and (iii) other principles. The methods are characterized and their advantages, shortcomings and pitfalls are specified. Examples of procedures used to obtain the number of active centers employing various methods are presented. The importance of the data obtainedfor understanding Ziegler-Natta polymerizations of olefins is outlined. 

Kinetic Features of Ziegler-Natta Polymerization of Olefins. 84... 

MWD control in Ziegler-Natta polymerization of olefins will be dealt with in this chapter, by sub-dividing the topic into the two following general headings ... 

The )9-alkyl elimination step can considered as analogous to the more familiar f-hydride elimination in which a C-C bond is broken instead of a C-H bond. Note that this reaction is the microscopic reverse of the propagation step in the mechanism of the Ziegler-Natta polymerization of olefins (eq. (I)). 

Polymerization can be classified according to the main phase in which the reaction occurs as liquid (most polymerizations), vapor (e.g., Ziegler Natta polymerization of olefins), and solid phase (e.g., finishing of melt step polymerization). Polymerization reactions occur in liquid phase and can be further subclassified into... 

Porous polyethylene with Ziegler-Natta Polymerization of olefins j... 

The insertion of alkenes into M-H or M-C bonds is one of the common methods used for the generation of metal alkyl complexes and is a crucial step in a variety of catalytic processes, most importantly the Ziegler-Natta polymerization of olefins. In these intramolecular reactions, a coordinated alkene undergoes a concerted 1,2-insertion via a planar... 

Electrophiles do not have to be cations tris(pentafluorophenyl)borane B(C6Fs)3 and related Lewis acids are very efficient hydride and alkyl anion abstractors and have found important applications as co-catalysts in the homogeneous Ziegler-Natta polymerization of olefins.The quest for better activators with potential... 

Uses Catalyst for Ziegler-Natta polymerization of olefins and dienes reactant in prod, of transition metal catalysts organic synthesis... 

Uses Catalyst for Ziegler-Natta polymerization of olefins and dienes reactant in prod, of transition metal catalysts alkylating agent for prod, of organotin compds. and organophosphorus derivs. organic synthesis Manuf./Distrib. Akzo Nobel http //WWW. akzonobei. com Diethylaluminum chloride CAS 96-10-6 EINECS/ELINCS 202-477-2 UN UN 3052... 

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