Monomeric Ti(IV) homopiperazine complexes and their exploitation for the ring opening polymerisation of rac-lactide

Chemistry Central Journal

Stuart L Hancock¹  Mary F Mahon¹  Matthew D Jones¹ 

[1] Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK

关键词: Catalysis;    Lactide;    Polymerisation;    Titanium;   

Others  :  787858
DOI  :  10.1186/1752-153X-7-135

 received in 2013-06-20, accepted in 2013-07-29,  发布年份 2013

【 摘 要 】

Background

The area of biodegradable/sustainable polymers is one of increasing importance in the 21st Century due to their positive environmental characteristics. Lewis acidic metal centres are currently one of the most popular choices for the initiator for the polymerisation. Thus, in this paper we report the synthesis and characterisation of a series of monometallic homopiperazine Ti(IV) complexes where we have systematically varied the sterics of the phenol moieties.

Results

When the ortho substituent of the ligand is either a Me, tBu or amyl then the β-cis isomer is isolated exclusively in the solid-state. Nevertheless, in solution multiple isomers are clearly observed from analysis of the NMR spectra. However, when the ortho substituent is an H-atom then the trans-isomer is formed in the solid-state and solely in solution. The complexes have been screened for the polymerisation of rac-lactide in solution and under the industrially preferred melt conditions. Narrow molecular weight material (PDI 1.07 – 1.23) is formed under melt conditions with controlled molecular weights.

Conclusions

Six new Ti(IV) complexes are presented which are highly active for the polymerisation. In all cases atactic polymer is prepared with predictable molecular weight control. This shows the potential applicability of Ti(IV) to initiate the polymerisations.

【 授权许可】

   
2013 Hancock et al.; licensee Chemistry Central Ltd.

【 图 表 】

Figure 1.

Scheme 1

Figure 2.

Figure 3.

Figure 4.

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