Issue 11, 2008
From the journal:

Dalton Transactions

Robust chiral zirconium alkoxide initiators for the room-temperature stereoselective ring-opening polymerisation of rac-lactide†‡§

Amanda J. Chmura,a   David M. Cousins,a   Matthew G. Davidson,*a   Matthew D. Jones,a   Matthew D. Lunnb  and  Mary F. Mahonc  

* Corresponding authors

a Department of Chemistry, University of Bath, Claverton Down, Bath, UK
E-mail: m.g.davidson@bath.ac.uk
Fax: +44 (0)1225 386231
Tel: +44 (0)1225 384467

b Johnson Matthey Catalyst, P.O. Box 1, Belasis Avenue, Billingham, UK

c Bath Chemical Crystallography Unit, Department of Chemistry, University of Bath, Claverton Down, Bath, UK
Fax: +44 (0)1225 386231
Tel: +44 (0)1225 38375

Abstract

Chiral Schiff bases (1H to 4H) and a series of their Group 4 metal alkoxide complexes [(R-1)2Ti(OiPr)2, (R-2)2Ti(OiPr)2, (R-1)2Zr(OiPr)2, (R-2)2Zr(OiPr)2, (R-3)2Zr(OiPr)2, (R-4)2Zr(OiPr)2, (S-1)2Zr(OiPr)2 and (rac-1)2Zr(OiPr)2] have been prepared and characterised by 1H, and 13C NMR spectroscopy. In solution, both Λ and Δ isomers were observed, suggesting a low degree of chiral induction from the ligand. One ligand (R-4H) and three complexes [Δ-(R,R-2)2Ti(OiPr)2, Λ-(R,R-1)2Zr(OiPr)2 and Δ-(R,R-3)2Zr(OiPr)2] have also been characterised by single crystal X-ray diffraction. All complexes were found to have a pseudo-octahedral α-cis geometry. The complexes were tested as initiators for the ring-opening polymerisation of rac-lactide in solution and in the melt. The titanium complexes are inactive in solution and afford atactic polylactide in the melt. Zr(IV) complexes afford heterotactically enriched polylactide both in toluene solution (at 20 °C and 80 °C) and in the melt. Polymerisations were generally found to be well-controlled, giving predictable molecular weights and low molecular weight distributions. Ligand variation (substituents and/or chirality) has little effect on either the activity or selectivity of initiators. Zirconium initiators were found to be unusually robust as they were able to maintain well-controlled polymerisation following addition of water to reactions in solution and when using unpurified monomer for reactions in the melt.

Graphical abstract: Robust chiral zirconium alkoxide initiators for the room-temperature stereoselective ring-opening polymerisation of rac-lactide

About
Cited by
Related
Download options Please wait...

Supplementary files

Article information

DOI
https://doi.org/10.1039/B716304E
Article type
Paper
Submitted
24 Oct 2007
Accepted
17 Dec 2007
First published
23 Jan 2008

Dalton Trans., 2008, 1437-1443

Permissions

Request permissions

Robust chiral zirconium alkoxide initiators for the room-temperature stereoselective ring-opening polymerisation of rac-lactide

A. J. Chmura, D. M. Cousins, M. G. Davidson, M. D. Jones, M. D. Lunn and M. F. Mahon, Dalton Trans., 2008, 1437 DOI: 10.1039/B716304E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements