A Kinetic Investigation of the Initialization of Catalyzed Chain Growth of Styrene: The Reaction of Cp*2 ZrCl 2 with Dibenzylmagnesium

作者：Primpke Sebastian; Deinert Adrian; Ehlers Florian; Vana Philipp^*

来源：Macromolecular Chemistry and Physics, 2014, 215(6): 544-554.

DOI：10.1002/macp.201300710

• catalysts
• catalyzed chain growth (CCG)
• kinetics (polym
• )
• metal-organic catalysts
• organometallic catalysts
• NMR spectroscopy

The system Cp*2ZrCl2 and dibenzyl magnesium in toluene, which is a model system for initialization in the catalyzed chain growth (CCG) of styrene using a bifunctional organometallic chain transfer agent, is studied via time-resolved NMR spectroscopy. Based on these data, a mechanism of initialization is proposed. The experimental concentration profiles of the individual species can successfully be modeled to the proposed kinetic scheme. Refined kinetic coefficients of high significance can be obtained by applying analytical methods using pseudo-first-order rate approximations. It is found that the adduct of the Zr catalyst and the Mg compound only slowly transforms via a ligand exchange reaction, yielding the alkylated Zr species. The temperature dependence of these reactions indicates a high reaction barrier of this type of rearrangement, which constitutes the core reaction of CCG in terms of molecular-weight control. <boxed-text content-type="graphic" position="anchor"> <graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="urn:x-wiley:10221352:media:macp201300710:macp201300710-abs-0001">image</graphic

• 出版日期2014-3