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Investigation of the Heck reaction and the associated catalytic systems using XAFS and Phosphorus NMR techniques

Investigation of the Heck reaction and the associated catalytic systems using XAFS and Phosphorus NMR techniques
Investigation of the Heck reaction and the associated catalytic systems using XAFS and Phosphorus NMR techniques

The main body of work was conducted on the Heck reaction between 2-methylprop-22-en-1-01 and PhX (X = C1, Br and I) to form 1-phenyl-2-methyl-propanal catalysed by the systems already examined in this thesis (the systems were also extended to include other phosphine ligands (tri(1-napthyl)phosphine and tris(o-methoxyphenyl)phosphine) and 3b as catalyst). The results showed a variety of catalytic properties, from tricyclohexylphosphine which prevents any catalysis, to tri(t-butyl)phosphine which promotes catalysis in all reactions. Reactions catalysed by palladium acetate and tri-o-tolylphosphine, showed that the main phosphorus species present in solution were different, compared with using 1 as catalyst. As the reactions which were catalysed proceeded, the extent of halogenation to the palladium increased. Halogenated species present for reactions catalysed by palladacycles were of the form: (P-C)PdX(solv), ([P-C)PdX2-] and [(P-C)P(m-X)] (where (P-C) is the palladated ring) and Pd(PR3)2(Ph)X, [Pd(Ph)(PR3)(m-X)]2 and [PdX(PR3)(m-X)]2 for reactions catalysed by palladium acetate and phosphine ligand. It was noted for uncatalysed reactions that there was negligible or no coordination of halogen to the metal, which suggests that this is an important early step in the catalytic cycle. Enforced, since heating the catalytic species (1) with PhI led to a stable mixture of species, whilst heating with alcohol led to decomposition of the metal precatalytic complex and liberation of free phosphine. Also, Pd(PtBu3)2 was isolated from the PhBr reaction catalysed by Pd(OAc)2 / PtBu3 and characterised by X-ray crystallography.

University of Southampton
Rayner, Graham
60562524-1437-47ec-a5b2-c2619e855dff
Rayner, Graham
60562524-1437-47ec-a5b2-c2619e855dff

Rayner, Graham (2002) Investigation of the Heck reaction and the associated catalytic systems using XAFS and Phosphorus NMR techniques. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The main body of work was conducted on the Heck reaction between 2-methylprop-22-en-1-01 and PhX (X = C1, Br and I) to form 1-phenyl-2-methyl-propanal catalysed by the systems already examined in this thesis (the systems were also extended to include other phosphine ligands (tri(1-napthyl)phosphine and tris(o-methoxyphenyl)phosphine) and 3b as catalyst). The results showed a variety of catalytic properties, from tricyclohexylphosphine which prevents any catalysis, to tri(t-butyl)phosphine which promotes catalysis in all reactions. Reactions catalysed by palladium acetate and tri-o-tolylphosphine, showed that the main phosphorus species present in solution were different, compared with using 1 as catalyst. As the reactions which were catalysed proceeded, the extent of halogenation to the palladium increased. Halogenated species present for reactions catalysed by palladacycles were of the form: (P-C)PdX(solv), ([P-C)PdX2-] and [(P-C)P(m-X)] (where (P-C) is the palladated ring) and Pd(PR3)2(Ph)X, [Pd(Ph)(PR3)(m-X)]2 and [PdX(PR3)(m-X)]2 for reactions catalysed by palladium acetate and phosphine ligand. It was noted for uncatalysed reactions that there was negligible or no coordination of halogen to the metal, which suggests that this is an important early step in the catalytic cycle. Enforced, since heating the catalytic species (1) with PhI led to a stable mixture of species, whilst heating with alcohol led to decomposition of the metal precatalytic complex and liberation of free phosphine. Also, Pd(PtBu3)2 was isolated from the PhBr reaction catalysed by Pd(OAc)2 / PtBu3 and characterised by X-ray crystallography.

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Published date: 2002

Identifiers

Local EPrints ID: 464820
URI: http://eprints.soton.ac.uk/id/eprint/464820
PURE UUID: 458c3be6-67b9-43d2-bc9e-44d5c93c28fb

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Date deposited: 05 Jul 2022 00:03
Last modified: 05 Jul 2022 03:16

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Author: Graham Rayner

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