The alcoholysis of the heteroscorpionate methyl aluminum complex (bpzmp)AlMe2 (1) (bpzmp = 2,4-di-tert-butyl-6- (bis-(3,5-dimethylpyrazol-1-yl)methyl)phenoxo), promoted both by phenol and isopropanol, has been investigated. The reaction of 1 with phenol afforded the dimeric mono(phenoxo) derivative 2, whereas the alcoholysis of 1 with the less acidic isopropanol involved the coordinated heteroscorpionate ligand and led to the tetrahedral complex 3 in which the aluminum atom is surrounded by one h2-N,O coordinated bpzmp ligand and one h1-O coordinated ppzmp ligand (ppzmp = 2,4-di-tert-butyl-6-(i-propoxy-(3,5-dimethylpyrazol-1-yl)methyl)phenoxo). Complexes 1–3 have been tested in the ring opening polymerization (ROP) of L-lactide. The dimeric mono(phenoxo) derivative 2 was inactive in the ROP of Llactide. Quite surprisingly, complex 3 was found to be active in ROP of L- and rac-lactide, showing a good molar-mass control.

Ring Opening Polymerization of Lactide promoted by Alcoholyzed Heteroscorpionate Aluminum Complexes

GRISI, Fabia;MILIONE, Stefano
2010-01-01

Abstract

The alcoholysis of the heteroscorpionate methyl aluminum complex (bpzmp)AlMe2 (1) (bpzmp = 2,4-di-tert-butyl-6- (bis-(3,5-dimethylpyrazol-1-yl)methyl)phenoxo), promoted both by phenol and isopropanol, has been investigated. The reaction of 1 with phenol afforded the dimeric mono(phenoxo) derivative 2, whereas the alcoholysis of 1 with the less acidic isopropanol involved the coordinated heteroscorpionate ligand and led to the tetrahedral complex 3 in which the aluminum atom is surrounded by one h2-N,O coordinated bpzmp ligand and one h1-O coordinated ppzmp ligand (ppzmp = 2,4-di-tert-butyl-6-(i-propoxy-(3,5-dimethylpyrazol-1-yl)methyl)phenoxo). Complexes 1–3 have been tested in the ring opening polymerization (ROP) of L-lactide. The dimeric mono(phenoxo) derivative 2 was inactive in the ROP of Llactide. Quite surprisingly, complex 3 was found to be active in ROP of L- and rac-lactide, showing a good molar-mass control.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/3014650
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