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Regioselectivity in aqueous palladium catalysed hydroxycarbonylation of styrene: a catalytic and mechanistic study

Ionescu, Adriana LU ; Laurenczy, Gabor and Wendt, Ola LU (2006) In Dalton Transactions p.3934-3940
Abstract
Regioselectivity control was studied in palladium catalysed hydroxycarbonylation of styrene in neat water with water-soluble phosphines, mostly trisulfonated triphenylphosphine, TPPTS, but also N-bis(N', N'-diethyl-2-aminoethyl)-4-aminomethylphenyl-diphenylphosphine, N3P. The factor giving the highest changes in regioselectivity in the TPPTS system, under similar reaction conditions, is the temperature. In the N3P case, only a minor variation in the n/i ratio as a function of temperature is observed. In situ normal- and high-pressure NMR experiments were performed to obtain further information about the catalytic cycle and the reaction intermediates. Two palladium hydride intermediates, a palladium eta(3)-benzylic complex and both the... (More)
Regioselectivity control was studied in palladium catalysed hydroxycarbonylation of styrene in neat water with water-soluble phosphines, mostly trisulfonated triphenylphosphine, TPPTS, but also N-bis(N', N'-diethyl-2-aminoethyl)-4-aminomethylphenyl-diphenylphosphine, N3P. The factor giving the highest changes in regioselectivity in the TPPTS system, under similar reaction conditions, is the temperature. In the N3P case, only a minor variation in the n/i ratio as a function of temperature is observed. In situ normal- and high-pressure NMR experiments were performed to obtain further information about the catalytic cycle and the reaction intermediates. Two palladium hydride intermediates, a palladium eta(3)-benzylic complex and both the branched and linear palladium acyl complexes were identified in the HP NMR experiments. The hydroxycarbonylation in water using styrene as a substrate operates using a hydride mechanism for pathways leading to both linear and branched product. Insertion of styrene in the palladium - hydride bond gives an eta(3)-benzyl compound. A high CO pressure gives a kinetic preference for the iso-acyl in the next step. In the TPPTS system, at moderate temperatures, the hydrolysis of the iso-acyl is faster than its conversion to the thermodynamically more stable n-acyl. A low n/i therefore requires high pressures and reasonably low temperatures. The N3P ligand always favours the linear product since isomerisation of the iso-acyl to the n-acyl in this system is fast under all conditions investigated. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Dalton Transactions
issue
32
pages
3934 - 3940
publisher
Royal Society of Chemistry
external identifiers
  • wos:000239605300013
  • scopus:33746916477
ISSN
1477-9234
DOI
10.1039/b607331j
language
English
LU publication?
yes
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The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Organic chemistry (S/LTH) (011001240), Department of Chemistry (011001220)
id
55a64aed-2ea6-4ad4-a032-c5a46dcf1537 (old id 399203)
date added to LUP
2016-04-01 12:23:14
date last changed
2020-02-19 02:02:18
@article{55a64aed-2ea6-4ad4-a032-c5a46dcf1537,
  abstract     = {Regioselectivity control was studied in palladium catalysed hydroxycarbonylation of styrene in neat water with water-soluble phosphines, mostly trisulfonated triphenylphosphine, TPPTS, but also N-bis(N', N'-diethyl-2-aminoethyl)-4-aminomethylphenyl-diphenylphosphine, N3P. The factor giving the highest changes in regioselectivity in the TPPTS system, under similar reaction conditions, is the temperature. In the N3P case, only a minor variation in the n/i ratio as a function of temperature is observed. In situ normal- and high-pressure NMR experiments were performed to obtain further information about the catalytic cycle and the reaction intermediates. Two palladium hydride intermediates, a palladium eta(3)-benzylic complex and both the branched and linear palladium acyl complexes were identified in the HP NMR experiments. The hydroxycarbonylation in water using styrene as a substrate operates using a hydride mechanism for pathways leading to both linear and branched product. Insertion of styrene in the palladium - hydride bond gives an eta(3)-benzyl compound. A high CO pressure gives a kinetic preference for the iso-acyl in the next step. In the TPPTS system, at moderate temperatures, the hydrolysis of the iso-acyl is faster than its conversion to the thermodynamically more stable n-acyl. A low n/i therefore requires high pressures and reasonably low temperatures. The N3P ligand always favours the linear product since isomerisation of the iso-acyl to the n-acyl in this system is fast under all conditions investigated.},
  author       = {Ionescu, Adriana and Laurenczy, Gabor and Wendt, Ola},
  issn         = {1477-9234},
  language     = {eng},
  number       = {32},
  pages        = {3934--3940},
  publisher    = {Royal Society of Chemistry},
  series       = {Dalton Transactions},
  title        = {Regioselectivity in aqueous palladium catalysed hydroxycarbonylation of styrene: a catalytic and mechanistic study},
  url          = {http://dx.doi.org/10.1039/b607331j},
  doi          = {10.1039/b607331j},
  year         = {2006},
}