Alcohols potassium ferrate

Another possible alternative oxidant that has recently been investigated is an Fe(VI) species, potassium ferrate, K2Fe04, supported on montmorillonite clay.14 This reagent gives clean, high-yielding oxidation of benzylic and allylic alcohols, but saturated alcohols are less reactive. 

Potassium ferrate, K2Fe04, is isomorphous with chromates and readily oxidizes alcohols to carbonyl compounds in the presence of alkali.286,287 The purple color of ferrate ion fades with the progress of the reaction. Yields as high as 96% have been reported for the oxidation of cinnamyl alcohol to cinnamaldehyde (equation 111).287... 

Oxidation. Potassium ferrate (VI) is a reagent for selective oxidation of primary alcohols and amines to aldehydes and of secondary alcohols to ketones. Double bonds, aldehyde functions, tertiary hydroxyl groups, and tertiary amino groups are resistant to oxidation. The reaction is carried out at room temperature either in water or in aqueous solvents. In fact water is essential for oxidation. The reaction is carried out at an initial pH of 11.5 the final pH is 13.5. In a typical procedure K.2pe04 (0.(X)2 mole)... 

Potassium ferrate, K2Fe04, which is prepared from ferric nitrate and alkaline hypochlorites [916], is a selective oxidant for the conversion of primary alcohols into aldehydes (not acids), of secondary alcohols into ketones, and of primary amines into aldehydes [917, 918]. 

Sodium ruthenate, Na2Ru04, is prepared in situ from ruthenium tetroxide (in solution in carbon tetrachloride) and 1 M sodium hydroxide by shaking for 2 h at room temperature. The reagent remains in the aqueous layer, which acquires bright-orange color [937]. It oxidizes primary alcohols to carboxylic acids and secondary alcohols to ketones and is comparable with but stronger than potassium ferrate [937]. 

The rarely used potassium ferrate transforms benzylic and allylic alcohols to aldehydes at room temperature in good to high yields. Saturated alcohols give unsatisfactory results [917, 918],... 

Schemes have been devised to substitute less toxic metals for more toxic ones. Potassium ferrate on K10 mont-morillonite clay has been used to replace potassium chromate and potassium permanganate in the oxidation of alcohols to aldehydes and ketones in 54-100% yields.153 The potassium ferrate is made by the action of sodium hypochlorite on iron(III) nitrate or by treatment of iron(III) sulfate with potassium peroxymonosulfate.154 After the oxidation, any excess oxidizing agent, and its reduced form, are easy to recover by filtration or centrifugation. In another case, manganese-containing reagents have been substituted for more toxic ones containing chromium and selenium (4.21).155 Selenium dioxide was used formerly in the first step and pyridinium chlorochromate in the second.

Oxidations. Dramatic improvement has been claimed in handling alumina-supported Mn02 for oxidation. Potassium ferrate deposited on alumina can be used to remove a terminal [CH2O] unit from propargylic alcohols.- ... 

An oxidizing reagent based on potassium ferrate(Vl) has been described [78], This potassium ferrate, when used in conjunction with an appropriate heterogeneous catalyst such as KIO montmorillonite clay, is a strong oxidant which produces cycloalkanols and cycloaUcanones from cycloalkanes, and benzyl alcohol and benzaldehyde from toluene. 

Oxidations. Potassium ferrate(VI) supported on clay has been used in the oxidation of alcohols to carbonyl compounds, of thiols to disulfides, and of organonitrogen compounds. Another method for oxidizing alcohols involves acyl nitrates absorbed in days. ... 

Potassium ferrate(VI) added to benzylamine in water, and shaken 1 min. until the purple color of the ferrate(VI) has disappeared benzaldehyde. Y 70%. -Similarly during 7 min. Cinnamyl alcohol cinnamaldehyde. Y 75%. - Unsaturation in the molecule as well as aldehyde, tert. alcohol, and tert. amine... 

Potassium ferrate, K2pe04, is a mild reagent for the oxidation of primary alcohols and primary alkylamines to aldehydes, and of secondary alcohols to ketones. lodonium nitrate, INO3, is reported to oxidize alcohols to carbonyl compounds electron-withdrawing groups adjacent to the alcohol carbon cause a marked decrease in reactivity olefinic alcohols undergo preferential electrophilic addition to the double bond. ... 

Allylic and benzylic primary and secondary alcohols are more easily oxidized, and a number of reagents selective for these are in use, including freshly precipitated manganese dioxide, silver carbonate, dichlorodicyanoquinone, and potassium ferrate. 4-(Dimethylamino) pyridinium chlorochromate is mild and selective as demonstrated in Equation 6.26 [44]. 

Strontium perferrate, SrFe04, is obtained 4 by double decomposition of the potassium salt and a saturated, neutral solution of strontium bromide. The precipitate is washed with alcohol and ether. Obtained in this manner, the strontium ferrate is not pure, but contains admixed ferric oxide. It is deep red in colour, slightly soluble in water, and readily decomposed by acids. It is useful for preparing aqueous solutions 4 of the perferrates of the less common alkali metals—lithium, rubidium, caesium—of calcium and magnesium. 

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