Permanganic anion

Primary, secondary and tertiary aliphatic amines are efficiently converted to nitro compounds in 80-90 % yield with dimethyldioxirane, a reagent prepared from the reaction of oxone (2KHSO5-KHSO4-K2SO4) with buffered acetone. Dimethyldioxirane (DMDO) has been used for the synthesis of 1,3,5,7-tetranitroadamantane (71) from the corresponding tetraamine as the tetrahydrochloride salt (70) and is an improvement over the initial synthesis using permanganate anion (Table 1.7). ° Oxone is able to directly convert some aromatic amines into nitro compounds. 

The key to the oxidation-number method of balancing redox equations is to realize that the net change in the total of all oxidation numbers must be zero. That is, any increase in oxidation number for the oxidized atoms must be matched by a corresponding decrease in oxidation number for the reduced atoms. Take the reaction of potassium permanganate (KMn04) with sodium bromide in aqueous acid, for example. An aqueous acidic solution of the purple permanganate anion (Mn04 ) is reduced by Br- to yield the nearly colorless Mn2+ ion, while Br- is oxidized to Br2. The unbalanced net ionic equation for the process is... 

Although the effect of increasing pH, already mentioned, is to increase the susceptibility of the substrate to oxidation, this increase generally decreases the effectiveness of the electrophilic oxidant at the same time. Permanganic acid is more effective than the permanganate anion as an oxidant.16 Wet... 

An exciting addition to the armoury of asymmetric phase transfer catalysed reactions has been the oxidative cyclisation of 1,5-dienes (Scheme 13) [21]. This tandem reaction process leads to the formation of tetrahydrofurans such as 35 in a single step from the open chain dienes 34. The step which determines the sense of asymmetry is the initial attack of permanganate anion, and this chiral information is efficiently relayed in the cyclisation to give products with three new stereogenic centres. For example, oxidation of the di-enone 34 with potassium permanganate, catalysed by the salt 36, gave the tetrahydrofuran 35 in 72% ee. 

Aliphatic and cyclic polyfluorinated alkencs are readily oxidized by potassium permanganate. Polylluoroalkenes whose C = C bonds are deficient in electrons are readily attacked by the permanganate anion. Depending on the substitution of the C = ( bond, the resulting products are acids or ketones. 

Oxidation of heterocyclic compounds with permanganate anion 04KGS643. 

The permanganate anion MnC)4 has a tetrahedral geometry with a Td point group symmetry, Fig. 1. At each oxygen atom, we have a core like 2s orbital as well as two 2-pn and one 2pffvalance orbitals. The total number of valence electrons is 32 of which 8 are in core type 2s levels and the remaining 24 in molecular orbitals spanned by 2pn, 2pa and 3d. We show in Fig. 2 the levels represented by orbitals made up of 2pn, 2pa and 3d. 

Two common oxidizing agents are potassium dichromate (K2Cr207) and potassium permanganate (KMn04). As Figure 4.22 shows, the colors of the dichromate and permanganate anions are distinctly different from those of the reduced species ... 

Manganese has a rich history within the field of organic synthesis (363, 364). For example, the permanganate anion has long been used as an oxidant to produce a variety of products (363). Manganese111 acetate also has been extensive explored over the years for the initiation of free radical reactions that lead to carbon-carbon bond formation. These topics have been reviewed and will not be presented further here (363, 364). Manganese chemistry, however, has made an impact in other areas as well, notably the asymmetric epoxidation of alkenes. 

In 1997, Marko and co-workers (423) followed up on their initial report of the KMn04 and oxalyl chloride system. This new system consists of KMn04, MesSiCl, benzytriethylammonium chloride with dichloromethane as the solvent. It gives good delds of dichlorinated alkenes. The permanganate anion is brought into solution by the ben-... 

Permanganate anion oxidizes alkanes at room temperature in trifluoroacetic acid solution [68a], The cation MnOs is apparently the active species. The selectivity of the reaction corresponds to 1° 2° 3° = 1 60 2100. In CFjCOOH-HiO solution, the active species are possibly Mn04, HMn04, or OsMnOCOCFs [68b], The oxidation of benzene proceeds via either cation VIII-17 or oxenoid VIII-18. 

Scheme 6.9. A cartoon depiction of a possible path by which permanganate anion (Mn04") inbasicaqneonsmedinm yields (Z)-orcw-l,2-dihydroxycyclohexane(cis-l,2-cyclohexanediol). Note that the oxidation at carbon is accompanied by a redaction at manganese.

The color of the complex anion is similar to that of the permanganate anion. Quantities of the [Mn(P04)2] ion too small to be discerned by their color can be detected by adding diphenylcarbazide. A violet color lesults, similar to that produced by the chromate-diphenylcarbazide reaction (see page 188). 

---