Issue 34, 2012
From the journal:

Dalton Transactions

New bis(aryloxy)–Ti(iv) complexes and their use for the selective dimerization of ethylene to 1-butene†‡

Fabien Grasset,a   Jean-Benoît Cazaux,a   Lionel Magna,*a   Pierre Braunsteinb  and  Hélène Oliver-Bourbigoua  

* Corresponding authors

a IFPEnergies nouvelles Lyon, Rond point de l’échangeur de Solaize, BP3, 69360 Solaize, France
E-mail: lionel.magna@ifpen.fr
Fax: (+33) 4 37 70 20 66
Tel: (+33) 4 37 70 28 86

b Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Université de Strasbourg, 67081 Strasbourg, France

Abstract

New titanium complexes of general formula [(ArO)nTi(Oi-Pr)(4−n)] were synthesized and used as pre-catalysts for the selective dimerization of ethylene to 1-butene. The complexes were prepared in cyclohexane using [Ti(Oi-Pr)4] and one or two equivalents of the corresponding phenols (ArOH) at room temperature. In this work, both monodentate and chelating phenols were evaluated. For alkyl-substituted phenols, it was demonstrated that large steric hindrance at both ortho and ortho′ positions selectively yielded the mono-substituted complexes [(ArO)Ti(Oi-Pr)3]. Substitution at only one of the ortho positions allowed both the mono- and the di-substituted Ti complexes to be isolated. When a heteroatom was introduced on the phenol backbone, di-substitution systematically occurred except with phenols presenting a hemilabile –CH2NR2 group at the ortho position. Upon activation with 3 equiv. of AlEt3 at 20 bar and 60 °C, all the complexes selectively dimerized ethylene to 1-butene (>86% of butenes among which 99% of 1-butene). An increase of the steric bulk at the ortho position of the ligand or the introduction of a functional group led to decreased activity compared to [Ti(Oi-Pr)4].

Graphical abstract: New bis(aryloxy)–Ti(iv) complexes and their use for the selective dimerization of ethylene to 1-butene

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Article information

DOI
https://doi.org/10.1039/C2DT30991B
Article type
Paper
Submitted
07 May 2012
Accepted
11 Jul 2012
First published
19 Jul 2012

Dalton Trans., 2012,41, 10396-10404

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New bis(aryloxy)–Ti(IV) complexes and their use for the selective dimerization of ethylene to 1-butene

F. Grasset, J. Cazaux, L. Magna, P. Braunstein and H. Oliver-Bourbigou, Dalton Trans., 2012, 41, 10396 DOI: 10.1039/C2DT30991B

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