Homogeneous palladium catalyst suppressing Pd black formation in air oxidation of alcohols

Tetsuo Iwasawa, Makoto Tokunaga, Yasushi Obora, Yasushi Tsuji

Research output: Contribution to journalArticle

267 Citations (Scopus)

Abstract

In homogeneous catalyst systems, there is the persistent problem that metal aggregation and precipitation cause catalyst decomposition and considerable loss of catalytic activity. Pd black formation is a typical example. Pd catalysts are known to easily aggregate and form Pd black, although they realize a wide variety of useful reactions in organic synthesis. In order to overcome this intrinsic problem of homogeneous Pd catalysis, we explored a new class of Pd catalyst by adopting aerobic oxidation of alcohols as a probe reaction. Herein we report a new catalyst system that suppresses the Pd black formation even under air and with a high substrate to catalyst molar ratio (S/C: more than 1000) in oxidation of alcohols. The novel pyridine derivatives having a 2,3,4,5-tetraphenylphenyl substituent and its higher dendritic unit at the 3-position of the pyridine ring were found to be excellent ligands with Pd(OAc)2 in the palladium-catalyzed air (balloon) oxidation of alcohols in toluene at 80 °C. Comparison with structurally related pyridine ligands revealed that introduction of the 2,3,4,5-tetraphenylphenyl substituent at the 3-position of pyridine ring effectively suppresses the Pd black formation, maintaining the catalytic activity for a long time to give aldehydes or ketones as products in high yields.

Original languageEnglish
Pages (from-to)6554-6555
Number of pages2
JournalJournal of the American Chemical Society
Volume126
Issue number21
DOIs
Publication statusPublished - Jun 2 2004

Fingerprint

Palladium
Alcohols
Air
Pyridine
Oxidation
Catalysts
Ligands
Synthetic Chemistry Techniques
Catalyst activity
Toluene
Ketones
Catalysis
Aldehydes
Metals
Balloons
pyridine
Agglomeration
Derivatives
Decomposition
Substrates

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Homogeneous palladium catalyst suppressing Pd black formation in air oxidation of alcohols. / Iwasawa, Tetsuo; Tokunaga, Makoto; Obora, Yasushi; Tsuji, Yasushi.

In: Journal of the American Chemical Society, Vol. 126, No. 21, 02.06.2004, p. 6554-6555.

Research output: Contribution to journalArticle

Iwasawa, Tetsuo ; Tokunaga, Makoto ; Obora, Yasushi ; Tsuji, Yasushi. / Homogeneous palladium catalyst suppressing Pd black formation in air oxidation of alcohols. In: Journal of the American Chemical Society. 2004 ; Vol. 126, No. 21. pp. 6554-6555.
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