Bis(pyridine)silver(I) Permanganate

[82503-38-6]  · C10H10AgMnN2O4  · Bis(pyridine)silver(I) Permanganate  · (MW 385.01)

(oxidant, useful for the oxidation of polycyclic aromatics and alkynes to diketones,1 primary benzylic alcohols to aldehydes,2 secondary alcohols to ketones;2 for the oxidative coupling of amines;3 and the deoximation of oximes3)

Physical Data: purple solid, decomposes at 104-105 °C.2

Solubility: sol acetone, chloroform and dichloromethane; sparingly sol benzene and pyridine.2

Analysis of Reagent Purity: elemental analysis.2

Preparative Method: pyridine (3 mol) is added to KMnO4 (1 mol) dissolved in a minimum of distilled water followed by AgNO3 (1 mol) in 1.7 L of distilled water. The purple precipitate (90%) is washed with water and then benzene. After drying over CaCl2 it is recrystallized from acetone/benzene.2 The visible spectrum resembles that of potassium permanganate and the IR displays a strong band at 900 cm-1.

Handling, Storage, and Precautions: slowly reduced by polar solvents such as acetone, chloroform, and dichloromethane; less soluble, but more stable in benzene and pyridine;2 insensitive to hammer blows, but ignites above 80 °C;2 store small amounts (10-50 g) in glass vessels at or below rt.

Oxidation of Polycyclic Aromatic Hydrocarbons.1

Polycyclic aromatic hydrocarbons such as naphthalene, anthracene, and phenanthrene are converted into diketones when oxidized by bis(pyridine)silver permanganate as illustrated in eqs 1 and 2. The conditions employed are mild (rt in CH2Cl2) and the yields are uniformly high.

Oxidation of Alkynes.2

Nonterminal alkynes are also oxidized to diketones, while terminal alkynes undergo coupling, as illustrated in eqs 3 and 4. The conversion of benzocyclobutadienes into diketones is accompanied by carbon-carbon bond cleavage (eq 5).2

Oxidation of Primary Alcohols.2

Primary benzylic alcohols are converted into the corresponding aldehydes in good yield when oxidized by bis(pyridine)silver permanganate in benzene (eqs 6 and 7).

Oxidation of Secondary Alcohols.2

Secondary alcohols are converted into the corresponding ketones by use of this reagent (eqs 8 and 9).

Oxidative Coupling of Amines.2

When treated with this oxidant, substituted anilines undergo a coupling reaction (eqs 10 and 11). Other primary amines are oxidized to aldehydes. For example, benzylamine gives benzaldehyde in 95% yield.

Oxidation of Oximes.3

Oximes are converted by bis(pyridine)silver permanganate into the corresponding aldehydes or ketones (eqs 12 and 13).

In most respects the reactions of bis(pyridine)silver permanganate are very similar to those of Bis(2,2-bipyridyl)copper(II) Permanganate. The latter has, however, been reported to be more stable and easier to handle.4

1. Firouzabadi, H.; Sardarian, A. R. S 1986, 946.
2. Firouzabadi, H.; Vessal, B.; Naderi, M. TL 1982, 23, 1847.
3. Firouzabadi, H.; Sardarian, A. SC 1983, 13, 863.
4. Firouzabadi, H.; Sardarian, A. R.; Naderi, M.; Vessal, B. T 1984, 40, 5001.

Donald G. Lee

University of Regina, SK, Canada

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