coacervation. The resulting mixture was left at room temperature
overnight and the supernatant liquid was removed by decantation.
The residual dark brown solid was heated at 120 ◦C for 2 h,
washed with THF, and dried in vacuo to afford PI Pt (996 mg).
Pt loading amount was 0.142 mmol g−1 determined by XRF after
decomposition of the catalyst with sulfuric acid and nitric acid at
180 ◦C for 2 h. The loading yield of Pt was 71%.
Notes and references
1 (a) R. Akiyama and S. Kobayashi, J. Am. Chem. Soc., 2003, 125, 3412;
(b) K. Okamoto, R. Akiyama and S. Kobayashi, J. Org. Chem., 2004,
69, 2871; (c) K. Okamoto, R. Akiyama and S. Kobayashi, Org. Lett.,
2004, 6, 1987; (d) R. Nishio, M. Sugiura and S. Kobayashi, Org. Lett.,
2005, 7, 4831; (e) H. Hagio, M. Sugiura and S. Kobayashi, Org. Lett.,
2006, 8, 375; (f) K. Okamoto, R. Akiyama, H. Yoshida, T. Yoshida and
S. Kobayashi, J. Am. Chem. Soc., 2005, 127, 2125.
2 H. Hagio, M. Sugiura and S. Kobayashi, Synlett, 2005, 813.
3 Recently hydrogenation using polymer supported platinum catalyst has
been reported. See: (a) X.-X. Han, R.-X. Zhou, G.-H. Lai, B.-H. Yue and
X.-M. Zheng, React. Kinet. Catal. Lett., 2004, 81, 41; (b) J. Aumo, J. Lilja,
P. Maki-Arvela, T. Salmi, M. Sundell, H. Vanio and D. Y. Murzin, Catal.
Lett., 2002, 84, 219; (c) Z. M. Michalska, B. Ostaszewski, J. Zientarska
and J. M. Rynkowski, J. Mol. Catal. A: Chem., 2002, 185, 279; (d) L. M.
Bronstein, D. M. Cherynylshov, I. O. Volkov, M. G. Ezernitskaya, P. M.
Valetsky, V. G. Matveeva and E. M. Sulman, J. Catal., 2000, 196, 302;
(e) C. Lange, D. D. Caro, A. Gamez, S. Storck, J. S. Bradley and W. F.
Maier, Langmuir, 1999, 15, 5333; (f) Z. Yu, S. Liao, Y. Xu, B. Yang
and D. Yu, J. Mol. Catal. A: Chem., 1997, 120, 247; (g) D. G. Duff,
T. Mallat, M. Schneider and A. Baiker, Appl. Catal. A, 1995, 133, 133;
(h) E. Tronconi, C. Crisafulli, S. Galvagno, A. Donato, G. Neri and
R. Pietropaolo, Ind. Eng. Chem. Res., 1990, 29, 1766; (i) H. C. Clark,
C. A. Fyfe, P. J. Hayes, I. McMahon, J. A. Davies and R. E. Wasylishen,
J. Organomet. Chem., 1987, 322, 393.
Typical procedure for hydrogenation catalyzed by the
PI Pt
Nitrobenzene (131 mg, 1.07 mmol) was dissolved in THF (5 cm3)
and hydrogenated with PI Pt (75 mg, 0.0107 mmol Pt, 1 mol%) at
room temperature under atmospheric pressure of hydrogen. The
reaction was monitored by TLC. After completion of the reaction,
the mixture was filtered and the PI Pt was recovered (69 mg,
92%).7 The filtrate was concentrated in vacuo and Pt leaching was
measured by XRF. The crude product was purified by silica gel
column chromatography eluted with chloroform–methanol–25%
aqueous ammonia = 190 : 9 : 1 to give aniline as colorless oil
(99 mg, quant.).8
4 With a less amount of PI Pt or with PI Pt prepared from PtCl2(COD),
the yield of the desired compounds was not satisfactory.
5 (a) P. N. Rylander, in Catalytic Hydrogenation over Platinum Metals,
Academic Press, New York, 1967; (b) R. L. Augustine, in Catalytic
Hydrogenation, Marcel Dekker Inc., New York, 1965.
Acknowledgements
6 A. P. Gray and H. Kraus, J. Org. Chem., 1961, 26, 3368.
7 Due to handling problems, a small amount of the used PI Pt was not
recovered.
8 The crude product after filtration and concentration was almost pure.
Purification was not necessarily required.
This work was partially supported by Grant-in-Aid for Scientific
Research from the Japan Society of the Promotion of Sciences
(JSPS).
This journal is
The Royal Society of Chemistry 2006
Org. Biomol. Chem., 2006, 4, 2529–2531 | 2531
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