Tetrapropylammonium perruthenate

Tetrapropylammonium perruthenate (TPAP or TPAPR) is the chemical compound described by the formula N(C3H7)4RuO4. Sometimes known as the Ley–Griffith reagent, this ruthenium compound is used as a reagent in organic synthesis. This salt consists of the tetrapropylammonium cation and the perruthenate, RuO4− anion. Ruthenium tetroxide is a highly aggressive oxidant, but its one-electron reduced derivative is a mild oxidizing agent for the conversion of alcohols to aldehydes (the Ley oxidation).[1] This oxidizing agent can also be used to oxidize primary alcohols all the way to the carboxylic acid. Use of a higher catalyst loading, larger amount of the co-oxidant, and addition of two equivalents of water. In this situation, the aldehyde reacts with water to form the geminal-diol hydrate, which is then oxidized again.[2]

Tetrapropylammonium perruthenate
Names
IUPAC name
Tetrapropylammonium perruthenate
Identifiers
3D model (JSmol)
Abbreviations TPAP
TPAPR
ChemSpider
ECHA InfoCard 100.156.687
UNII
Properties
C12H28NRuO4
Molar mass 351.43 g/mol
Appearance Green solid
Melting point 160 °C (320 °F; 433 K) (decomposition)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

The oxidation generates water that can be removed by adding molecular sieves. TPAP is expensive, but it can be used in catalytic amounts. The catalytic cycle is maintained by adding a stoichiometric amount of a co-oxidant such as N-methylmorpholine N-oxide[3] or molecular oxygen.[4]

Oxidation of alcohol to aldehyde with TPAP (0.06 eq.) and N-methylmorpholine N-oxide (1.7 eq.) with molecular sieves in dichloromethane.[5]

References
  1. Ley, Steven V.; Norman, Joanne; Griffith, William P.; Marsden, Stephen P. (1994). "Tetrapropylammonium perruthenate, Pr4N+RuO4−, TPAP: A catalytic oxidant for organic synthesis". Synthesis. 1994 (7): 639–666. doi:10.1055/s-1994-25538. (review article)
  2. Xu, Z.; Johannes, C. W.; Houri, A. F.; La, D. S.; Cogan, D. A.; Hofilena, G. E.; Hoveyda, A. H. (1997). "Applications of Zr-catalyzed carbomagnesation and Mo-catalyzed macrocyclic ring closing metathesis in asymmetric synthesis. Enantioselective total synthesis of Sch 38516 (Fluvirucin B1)". J. Am. Chem. Soc. 119 (43): 10302–10316. doi:10.1021/ja972191k.
  3. Griffith, William P.; Ley, Steven V.; Whitcombe, Gwynne P.; White, Andrew D. (1987). "Preparation and use of tetra-n-butylammonium per-ruthenate (TBAP reagent) and tetra-n-propylammonium per-ruthenate (TPAP reagent) as new catalytic oxidants for alcohols". J. Chem. Soc., Chem. Commun. (21): 1625–1627. doi:10.1039/C39870001625.
  4. Lenz, Roman; Ley, Steven V. (1997). "Tetra-n-propylammonium perruthenate (TPAP)-catalysed oxidations of alcohols using molecular oxygen as a co-oxidant". J. Chem. Soc., Perkin Trans. 1 (22): 3291–3292. doi:10.1039/A707339I.
  5. Hadfield, John A.; McGown, Alan T.; Butler, John (2000). "A high-yielding synthesis of the naturally occurring antitumour agent irisquinone" (PDF). Molecules. 5 (12): 82–88. doi:10.3390/50100082.
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