Non‐Hydrolytic Route to Aluminoxane‐Type Derivative for Metallocene Activation towards Olefin Polymerisation

Abstract

Summary: Access to methylaluminoxane‐type derivatives by a non‐hydrolytic route is described. The procedure involves the reaction between trimethylaluminium (TMA) and benzoic acid (BA) at temperatures comprised from 20 to 100 °C in toluene. The structure of the different aluminic derivatives formed for different ratios R = TMA/BA as well as the reaction pathways leading to these products were investigated by 1H NMR spectroscopy at different temperatures. The monomeric and/or oligomeric “Me2AlOAlMe2” species issued from the reaction between BA and TMA were found to methylate and then activate (cationize) rac‐Et(Ind)2ZrCl2 as shown by UV/visible spectroscopy analysis. This is further confirmed by successful hex‐1‐ene polymerisations carried out in the presence of such activators.

Novel Organic Activators for Single Site Iron Catalysts

“…For [TMA]/[AA] ratio equal to 4, the 1 H NMR spectrum (see Figure 1) shows the presence of two series of signals at 1.2-1.6 ppm and À0.4 to À1.0 ppm that can be attributed, respectively, to the methyl groups of various products derived from AA (II to IV, see Scheme 1) and to the methyl groups of -OAlMe 2 structures, on the basis of previous investigations with BA and TMA. [13] The different AA derivatives that can successively form at 25 8C through the reaction with TMA as well as the reaction pathways are shown in Scheme 1. Contrarily to BA, it is only in the presence of a large excess of TMA (ten times), that a single methyl signal is observed at 1.4 ppm in agreement with a complete conversion of AA into dimethylaluminum tert-butylalkoxide (IV) and Alox structures.…”

“…However, as indicated by the small activity observed at ratio 4, in the absence of any free TMA, products issued by the reaction between AA and TMA may also exhibit some activating capacity, although it is very low compared to BA/TMA systems. [13] In the light of these observations, a new series of activating systems based on the reaction of TMA with aromatic carboxylic acids, i.e, BA and naphthoic acid (NA) was prepared and investigated, see Table 2.…”

“…It was also shown by UV-spectroscopy that the compounds containing -Al-O-Al-moieties (MAO-like) are the only species able to activate the metallocene rac-Et(Ind) 2 ZrCl 2 . [13] Following this route, we explored the reaction of other carboxyl containing compounds (such as acetic acid (AA) and BA derivatives) with several trialkylaluminum compounds (without the use of any additional commercial MAO as co-catalyst). The capacity of the reaction products formed to activate a single-site catalyst toward ethylene polymerization was then checked.…”

“…[11][12][13] It was shown that the main products formed depend on the temperature and on the TMA/BA initial ratio. At room temperature and using a 1:1 ratio, a dimethyl aluminum carboxylate, Ph(CO)OAl(CH 3 ) 2 , is first formed.…”

Functional Star‐Like Polystyrenes as Organic Supports of MeDIP(2,6‐iPrPh)2FeCl2 Catalyst Toward Ethylene Polymerization

“…[24,25] The reaction between either benzophenone (BZ) or benzoic acid (BA) with TMA has been thoroughly investigated at the laboratory, demonstrating that some of the alkoxide aluminum-based species formed in these reactions, can readily activate iron complexes toward ethylene polymerization. [26,27] On the basis of these results, we have extended our approach toward novel organic supports, by designing functional star-like PS bearing either a BZ moiety or a BA function at each PS branch-end. [28] The latter were then reacted with TMA to directly form alkoxide aluminum-based species at the periphery of the star-like microgel.…”