Versatile organoaluminium catalysts based on heteroscorpionate ligands for the preparation of polyesters
A series of alkyl aluminium complexes based on heteroscorpionate ligands were designed as catalysts for the ring-opening polymerisation of cyclic esters and ring-opening copolymerisation of epoxides and anhydrides. Treatment of AlX 3 (X = Me, Et) with ligands bpzbe H [bpzbe = 1,1-bis(3,5-dimethylpyr...
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Veröffentlicht in: | Dalton transactions : an international journal of inorganic chemistry 2018-06, Vol.47 (22), p.7471-7479 |
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Sprache: | eng |
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Zusammenfassung: | A series of alkyl aluminium complexes based on heteroscorpionate ligands were designed as catalysts for the ring-opening polymerisation of cyclic esters and ring-opening copolymerisation of epoxides and anhydrides. Treatment of AlX
3
(X = Me, Et) with ligands bpzbe
H
[bpzbe = 1,1-bis(3,5-dimethylpyrazol-1-yl)-3,3-dimethyl-2-butoxide], bpzte
H
[bpzte = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-
para
-tolylethoxide], and (
R
,
R
)-bpzmm
H
[(
R
,
R
)-bpzmm = (1
R
)-1-{(1
R
)-6,6-dimethyl-bicyclo[3.1.1]-2-hepten-2-yl}-2,2-bis(3,5-dimethylpyrazol-1-yl)ethoxide] for 2 hours at 0 °C afforded the mononuclear dialkyl aluminium complexes [AlMe
2
{κ
2
-bpzbe}] (
1
), [AlEt
2
{κ
2
-bpzbe}] (
2
), [AlMe
2
{κ
2
-(
R
,
R
)-bpzmm}] (
3
) and [AlEt
2
{κ
2
-(
R
,
R
)-bpzmm}] (
4
), and the dinuclear dialkyl complexes [AlMe
2
{κ
2
-bpzte}]
2
(
5
) and [AlEt
2
{κ
2
-bpzte}]
2
(
6
). The molecular structures of the new complexes were determined by spectroscopic methods and confirmed by X-ray crystallography. The alkyl-containing aluminium complexes can act as highly efficient single-component initiators for the ring-opening polymerisation of -caprolactone and
l
-lactide and for the ring-opening copolymerisation of cyclohexene oxide and phthalic anhydride to give a range of biodegradable polyesters.
Aluminium complexes have been developed as versatile catalysts for the preparation of polyesters. |
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ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/c8dt01553h |