Compared with a conventional organic solvent system,25 the
ionic liquid microemulsion containing Pd nanoparticles can
obviously shorten the reaction time as shown in Table 2 (Entry
1 and Entry 2). In order to extend the application of the ionic
liquid microemulsion containing Pd nanoparticles, we examined
other Heck reactions in the system (Entry 3, Entry 4 and Entry
5). It can be seen that the system has good performance for the
cross coupling reaction.
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In conclusion, Pd nanoparticles were successfully prepared in
situ in a H2O/TX-100/[BMIM]PF6 microemulsion. Thereinto,
surfactant TX-100 served as the reductant and stabilized the Pd
nanoparticles together with the ionic liquid [BMIM]PF6. The
average size of the monodispersed Pd nanoparticles was about
3 nm. The H2O/TX-100/[BMIM]PF6 microemulsion contain-
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system for the ligand-free Heck reaction. It was consistent with
the requirements of green chemistry. The catalytic system could
be cycled for four times at least. Investigations of other C–C
coupling reactions catalyzed by this green medium are currently
underway in our laboratory.
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Acknowledgements
We gratefully acknowledge the support of this study by the
National Natural Science Foundation of China 20673036,
J0830415.
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Notes and references
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1432 | Green Chem., 2009, 11, 1428–1432
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