New Pre-Catalysts for Olefin Polymerisation and Ring-Opening Polymerisation of Lactides/Lactones

Walton, Mark (2014) New Pre-Catalysts for Olefin Polymerisation and Ring-Opening Polymerisation of Lactides/Lactones. Doctoral thesis, University of East Anglia.

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A number of pre-catalysts featuring phenoxyimine, phenolate and calixarene ligand systems have
been synthesized, characterised and screened for their ability to polymerize α-olefins or ring open
polymerize (ROP) cyclic esters.
The treatment of a number of related phenoxyimine ligands (L1H – L3H, L6H – L14H) and bridged
phenoxyimines (L4H2 and L5H2) with vanadium trichloride (VCl3), vanadium oxytrichloride (VOCl3) or
vanadium oxytripropoxide (VO(OnPr)3) afforded the compounds 1 – 20. Compounds 21, 22 and 23
were isolated from the reaction between VO(OnPr)3 and diphenolate ligand (L15H2) or bridged
diphenolates (L16H4 or L17H4) respectively. Treatment of the alkali vanadium compound
(LiVO(OtBu)4) with tert-butylcalix[6]arene (L18H6) afforded compound 24, while on a number of
syntheses, the minor 1D polymeric compound 25 was also obtained. Whilst the reaction between
tert-butylcalix[8]arene (L19H8) and NaVO(OtBu)4 led to the formation of compound 26, the use of the
alkali free VO(OtBu)3 resulted in the formation of two solvates of compound 27.
Imidazole (L20H), oxazole (L21H), α-diimine (L22), iminopyridine (L23, L24) and phenoxyimine (L25H –
L29H) ligand sets have been treated with group 5 (Nb or Ta) chlorides or oxytrichlorides to afford
compounds 28 – 50, which have been fully characterised. The screening of group 5 compounds 1 – 50
for the polymerisation of α-olefins revealed high activity, significantly in the case of the niobium precatalysts
which were two orders of magnitude above the previously reported compounds.
The reactions between 1,3-dipropoxy-p-tert-butyl-calix[4]arene (L30H2), hexahomotrioxacalix[3]arene
(L31H3) or tripropoxy-p-tert-butylcalix[4]arene (L32H) with zinc or magnesium alkyls has been
explored, resulting in the isolation of compounds 51 – 58, which includes a number of
heterobimetallic compounds. While all of the zinc and magnesium compounds screened were found
to be active for the ring opening polymerisation of either ε-caprolactone or rac-lactide, compound 58,
featuring a tripropoxy-p-tert-butylcalix[4]arene (L32H) ligand with a magnesium n-butyl group was
found to exhibit exceptional activity and immortal character.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Users 2259 not found.
Date Deposited: 17 Oct 2014 11:38
Last Modified: 17 Oct 2014 11:38


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