Potassium permanganate-alumina

S.2.4.9 Oxidation of Arenes and Enamines - Potassium Permanganate-Alumina... 

Scheme 6.36 Oxidation of enamines with alumina-supported potassium permanganate.

Preparation of oxidative system Finely ground potassium permanganate (50 g) dissolved in water (100 mL) was added to alumina (acidic or neutral, Merck activity I, 63-200 nm 200 g). After shaking for 15 min, the majority of the water was removed by evaporation under reduced pressure and the obtained powder was dried under microwave irradiation for 5 min. 

Trans -substituted diarylalkenes undergo oxidative cleavage upon treatment by potassium permanganate in the presence of moist alumina as a solid support (equation 32)158. Under the same conditions, cyclic alkenes, with medium-sized rings, give acyclic dialdehydes (equation 33). 

Potassium permanganate adsorbed on either silica or alumina can also be used to cleave double bonds under mild conditions and in good yields. In one procedure the alkene, dissolved in benzene, is passed through a column packed with KMn04 on a silica gel support.The reaction occurs rapidly at room temperature and is equally effective for the cleavage of all types of double bonds, even some that are inert to other traditionid methods. ... 

An even better result is obtained with potassium permanganate in toluene in the presence of neutral alumina. After a mixture of 5 g of alumina, 7.9 g (0.05 mol) of potassium permanganate, and 0.01 mol of cyclododecanol in 50 mL of toluene has been stirred for 30 h at room temperature, a 95% yield of cyclododecanone is obtained [865]. 

Potassium permanganate. 13, 258-259 14, 267 15,273-274 18,301 19,277-278 Oxidations. Well-known oxidation processes have been modified by ultrasound assistance, dispersion of KlVInO on solid supports such as alumina, " zeolite, and kieselguhr. ... 

Potassium permanganate on alumina has been used to oxidize benzylic hydrocarbons to ketones (5.2), often in high yields.21... 

Potassium permanganate impregnated on alumina oxidizes arenes and alkylarenes to ketones under microwave activation [69c]. Potassium perman-ganate-triethylamine is a convenient reagent for the oxidation of benzylic methyl, methylene and methine groups [70a], Aqueous solutions of permanganate oxidize methane at 40-100 °C to produce carbon dioxide as the sole product [70b], Oxidation of hydrocarbons containing weak C-H bonds (9,10-dihydro-... 

Interestingly, 2,5-disubstituted 1,3,4-oxadiazoles have been synthesized by oxidation of l-aroyl-2-arylidene hydrazines with potassium permanganate on silica, alumina, or montmorillonite KIO clay surfaces under MW irradiation conditions [133], KIO clay seemed to be the most appropriate support. 

In order to have convenient product isolation and a better reactivity, a neutral alumina-sup-ported potassium permanganate (NASPP) is used. Solvent-free reactions have received more attention compared to their homogeneous counterparts, due to economical and envi-ronmental demands and simphcity in processes [227]. 

Small amounts (0.02-0.10 mol%) of diphenylamine and hydroquinone were found to inhibit effectively the oxidation by oxygen or peroxides [158]. The latter can be advantageously removed prior to the hydroformylation by several methods (e.g., percolation over neutral alumina, potassium permanganate, silver hydroxide, etc.) [160]. Phosphine oxides are not reduced under common hydroformylation conditions. 

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