3910
D. F. Foster et al. / Tetrahedron 58 ꢀ2002) 3901±3910
2important because of the expense of the ¯uorous ligand)
and at a signi®cantly lower temperature, our system is some
®ve to eight times as productive as the commercial system,
due to a combination of the use of a ¯uorous modi®ed ligand
of lower basicity combined with the much lower phosphine
concentration employed, while giving a linear aldehyde
selectivity that is only slightly less at 80.9% compared
with 83% for the BASF process; the UCC process is
superior in this regard 289.5%). It should be remembered,
however, that propene cannot isomerise, so no loss of
substrate to isomerised alkenes can occur in the commercial
process. The reaction rate is, of course, related to the
[alkene] for these ®rst order reactions. The values quoted
References
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Â
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Â
Â
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Â
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the conditions where he was measuring catalyst leaching.8
His initial [Rh] is much lower than ours, but his [P] is much
higher and his [substrate] lower. Our l/b ratios, linear
selectivities and reaction rates even expressed as turnover
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4. Conclusions
We conclude that by using a system that consists of a
¯uorous solvent in which long chain alkenes are soluble
and a triarylphosphite or triarylphosphine carrying ¯uorous
ponytails on all three aryl groups, hydroformylation can be
successfully carried out in such a way that the product
aldehyde can be obtained in a substantially pure state as a
separate phase at the end of the reaction. Good l/b
selectivities and high rates are obtained even at low rhodium
loadings and with low P/Rh ratios 23±10). The best results,
which compare very well with those obtained using
commercial systems are obtained using Rh
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22.0 mmol dm23)/P24-C6H4C6F13)3 220.0 mmol dm23
) at
708C and 20 bar CO/H2. This gives a linear aldehyde
selectivity of 80.9% and an initial productivity of
8.8 mol dm23 h2l. Rhodium leaching into the aldehyde
phase is limited to 0.05% [0.08 mg Rh 2mol aldehyde)2l]
of the rhodium charged and phosphorus leaching to 3.3%.
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Â
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Acknowledgements
23. Sellin, M. F.; Webb, P. B.; Cole-Hamilton, D. J. Chem.
Commun. 2001, 781±782.
We thank the Royal Society for Personal Fellowships 2E. G.
H. and A. M. S.), the EPSRC for a Postdoctoral Fellowship
2D. J. A.) and funding to use the Catalyst Evaluation and
Optimisation Service 2CATS). We are indebted to Ed
McCurdy, Agilent Technologies UK Ltd for carrying out
the ICPMS analyses.
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