¹⁹F NMR Investigations of the Reaction of B(C₆F₅)₃ with Different Tri(alkyl)aluminum Compounds

Abstract

Business strategy publications about decision‐making have provided a large amount of information on decision‐making relating to market share, competitive advantage, managing change and achieving quality. Nevertheless, little research has been carried out on strategic environmental management. Four in‐depth case studies of environmental strategy formation and implementation in chemical/pharmaceutical companies in Ireland are presented here. A continuum describing the differing levels of strategic environmental management among the companies is developed. The dimensions for the continuum include attitude towards environmental management, compliance record, level of environmental training, environmental department structure and community relationship, among others. The findings suggest that environmentally proactive companies follow a decentralized or holistic approach to environmental management. Furthermore, these companies have developed an environmental philosophy which has been adopted throughout the organization. This philosophy is identified as environmental caring

Metal catalysts for the vinyl/addition polymerization of norbornene

“…The addition sequence of the cocatalytic compounds influenced the polymerization activity. Higher activities are obtained using the addition sequence "Cr-4 → AlEt 3 → B(C 6 F 5 ) 3 " compared to "Cr-4 → B(C 6 F 5 ) 3 → AlEt 3 " (5.1 × 10 6 vs. 8.2 × 10 5 g polymer /mol metal h) which may be reasoned by differences in C 6 F 5 ↔ ethyl exchange [98]. When AlEt 3 is added first such ligand exchange reaction can take place rapidly upon the subsequent addition of B(C 6 F 5 ) 3 to the catalyst mixture and the metal complexes will then be activated with the stronger Lewis acid Al(C 6 F 5 ) 3 .…”

“…At equimolar ratio the equilibrium lies on the side of the unchanged borane together with its boranate [B(C 6 F 5 ) 3 R] − anion. For tri(noctyl)aluminum even at large Al(n-C 8 H 17 ) 3 excess no C 6 F 5 ↔ alkyl exchange can be observed, but boranate anions form [98].…”

“…Importantly, the combination of B(C 6 F 5 ) 3 and AlMe 3 leads to a facile aryl/alkyl group exchange and for an equimolar ratio results in the formation of BMe 3 and Al(C 6 F 5 ) 3 [96,97]. Accordingly, B(C 6 F 5 ) 3 and AlEt 3 undergo an analogous ligand exchange reaction [98] The reaction between B(C 6 F 5 ) 3 and the higher aluminum alkyls tri(iso-butyl)aluminum and tri(n-hexyl)aluminum (AlR 3 with R = i-Bu, n-C 6 H 13 ) is slower and requires excess AlR 3 to shift the C 6 F 5 ↔ R exchange equilibria to almost complete formation of Al(C 6 F 5 )R 2 and BR 3 . At equimolar ratio the equilibrium lies on the side of the unchanged borane together with its boranate [B(C 6 F 5 ) 3 R] − anion.…”

“…When B(C 6 F 5 ) 3 is added first to the metal complex the boron atom may coordinate to the donor atom of a ligand to increase its coordination number to four [118], which completes the coordination sphere of the small boron atom and slows down the C 6 F 5 /Et-ligand exchange with the subsequently added AlEt 3 [98,119] Also, the borane B(C 6 F 5 ) 3 alone could be used as an effective activator (tested for Cr-4 and Fe-5) leading to similar activities of 3.1 × 10 5 g polymer /mol metal h.…”

Controlled ring‐opening polymerization of l‐lactide and ε‐caprolactone catalyzed by aluminum‐based Lewis pairs or Lewis acid alone

“…A solution of AlMe 3 in toluene (2 mL, 2.1 mmol) was added to a solution of B(C 6 F 5 ) 3 (11 mL, 2.1 mmol) in toluene at room temperature . The mixture was stirred for 2 h, and evaporated to dryness in vacuo to give a greenish white solid (0.94 g, 1.8 mmol).…”