Oxidation by MnO

Metals and Metallic Ions. Under appropriate conditions, ozone oxidizes most metals with the exception of gold and the platinum group. When oxidized by ozone, heavy metal ions, such as Fe and Mn , result in the precipitation of insoluble hydroxides or oxides upon hydrolysis (48—50). Excess ozone oxidizes ferric hydroxide in alkaline media to ferrate, and Mn02 to MnO. ... 

Balance the reaction that occurs when I- is oxidized to I2 by MnO in acid solution, producing Mn+2. 

The slow step of this reaction corresponds to removal of hydride from an anion and finds several counterparts in oxidations of organic compounds by MnO. The anion may have the structure... 

The oxidation by permanganate proceeds readily in acid and neutral solutions (to give MnOz) and in basic solution (to give MnO ). The rate law is ... 

When heated above 330°C, MnO is partially oxidized by CO2, thus the decomposition products also contain Mn02 and CO. 

In 1953 Djerassi and Engle showed that stoich. RuOyCCy oxidised several sulfides to the corresponding sulfones [236]. Sulfilimines (R R S=NR ) were oxidised to sulfoximes R R S(=0)=NR by RuO /aq. Na(IO )/CH2Cl2 [432] oxidation of thianthrene-5-oxide with RuO /aq. Na(IO )/CCyO°C gave thianthrene-5,5-dioxide. Comparisons were made between the behaviour of RuO, CrO Cl and [MnO ] for these reactions, and 0-atom transfer with a possible intermediacy of [RuO ] was postulated [433]. Oxidations of RSPh to the sulfoxides and sulfones by stoich. RuOyaq. CH CN were studied a concerted mechanism may be involved for these and for similar oxidations by [RuO ] and [RuO ] " (Fig. 1.12) [434]. 

Electrocatalytic formation of Me SO from DMSO was effected using cw-[Ru(0) (py)(bpy)2] VPt electrode/water-DMSO cf. mech. Ch. 1 [113], Oxidation of thian-threne-5-oxide by RuO /aq. Na(IO )/CCyO°C gave a mixture of the sulfone and thianthrene-5,5-dioxide with minor amounts of the disulfoxide and also thian-threne-5,5,10-trioxide comparisons were made between the behaviour of RuO, CrOjClj and [MnO ] for these reactions cf. mech. Ch. 1) [114]. 

Oxidations of a number of thiophenes and a wide variety of alkyl- and aryl-substituted thiophenes by RuCyaq. Na(ClO) have been compared with similar oxidations effected stoicheiometrically by [MnO ]", the aim being the destruction of these compounds for environmental reasons. Some were totally oxidised to sulfate, but in many cases end-products were not identified, though 2-ethylthiophene gave 2-acetylthiophene and 2-n-butylthiophene gave 2-butyroylthiophene [115],... 

Both the oxide, MnO, and the hydroxide, Mn(OH)2, are readily oxidized by air. The smooth structural transition going from MnO to MnaO to Mn203 is similar to that described for the corresponding iron compounds (p. 394). 

Treatment of (+)-epoxy-a-dihydroionone with hydrazine hydrate gives as one of the reaction products alcohol 13, which was transformed by oxidation with MnO to (+)-[R >-a-damascone 12 in 65% e. e., t hus estabiishing its absolute con-figuration [22. ... 

In the catalytic cycle of the palladium-benzoquinone-based 1,4-oxidation of 1,3-dienes, benzoquinone is reduced to hydroquinone. The diacetoxylation reaction is conveniently performed with p-benzoquinone in catalytic amounts, employing Mn02 as the stoichiometric oxidant. In this process, the hydroquinone formed in each cycle (cf. Scheme 8-6) is reoxidized to p-benzoquinone by MnO,. For example, the catalytic reaction of cyclohexa-1,3-diene using catalytic amounts of both Pd(OAc)2 and p-benzoquinone with stoichiometric amounts of Mn02 in acetic acid in the presence of lithium acetate afforded a 93% yield of rranj-l,4-diacetoxycyclohex-2-ene (>91% tram) [51b]. The corresponding reaction in the presence of lithium chloride gave ci5-l,4-diacetoxycyclohex-2-ene in 79% yield (>96% cis). 

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