Osmium tetroxide potassium chlorate

Potassium permanganate. Dimethyl sulfide-Chlorine. Dimethyl sulfoxide. Dimethyl sulfoxide-Chlorine. Dimethylsulf-oxide Sulfur trioxide. Dipyridine chro-mium(VI) oxide. Iodine. Iodine-Potassium iodide. Iodine tris(trifluoroacetate). Iodosobenzene diacetate. Isoamyl nitrite. Lead tetraacetate. Manganese dioxide. Mercuric acetate. Mercuric oxide. Osmium tetroxide—Potassium chlorate. Ozone. Periodic acid. Pertrifluoroacetic acid. Potassium ferrate. Potassium ferricyanide. Potassium nitrosodisulfonate. Ruthenium tetroxide. Selenium dioxide. Silver carbonate. Silver carbonate-Celite. Silver nitrate. Silver oxide. Silver(II) oxide. Sodium hypochlorite. Sulfur trioxide. Thalli-um(III) nitrate. Thallium sulfate. Thalli-um(III) trifluoroacetate. Triphenyl phosphite ozonide. Triphenylphosphine dibromide. Trityl fluoroborate. 

Octene-l-al, 38,62 2-Octenes, 303 2-Octylamine, 554 4-Octyne, 96 2-Octyne-l-ol, 62 4-Octyne-3-one, 96 Olefin inversion, 303-304 Olefin methathesis, 570 Orcinol dimethyl ether, 465 Orcinol monomethyl ether, 465 Osmium tetroxide, 31,575,576 Osmium tetroxide-Potassium chlorate, 361... 

Hydroxylation Boric acid (see Diborane). Hydrogen peroxide. Hydrogen peroxide-Osmium tetroxide. Hydrogen peroxide-Selenium dioxide. Osmium tetroxide. Osmium tetroxide-Barium chlorate. Peracetic acid. Perbenroic acid. Persucdnic acid. Pertrifluoroacetic acid. Potassium permanganate. Potassium persulfate. Selenium dioxide. Silver acetate. Silver chlorate. 

The history of asymmetric dihydroxylation51 dates back 1912 when Hoffmann showed, for the first time, that osmium tetroxide could be used catalytically in the presence of a secondary oxygen donor such as sodium or potassium chlorate for the cA-dihydroxylation of olefins.52 About 30 years later, Criegee et al.53 discovered a dramatic rate enhancement in the osmylation of alkene induced by tertiary amines, and this finding paved the way for asymmetric dihydroxylation of olefins. 

Butyl hydroperoxide,37 barium chlorate,38 or potassium ferricyanide39 can also be used as oxidants in catalytic procedures. Scheme 12.6 provides some examples of oxidations of alkenes to glycols by permanganate and by osmium tetroxide. 

The oxidizing action of potassium chlorate in neutral or slightly acid soln. is greatly facilitated by the presence of traces of osmium tetroxide, 0s04. 

Inclusion in the reaction of a cooxidant serves to return the osmium to the osmium tetroxide level of oxidation and allows for the use of osmium in catalytic amounts. Various cooxidants have been used for this purpose historically, the application of sodium or potassium chlorate in this regard was first reported by Hofmann [7]. Milas and co-workers [8,9] introduced the use of hydrogen peroxide in f-butyl alcohol as an alternative to the metal chlorates. Although catalytic cis dihydroxylation by using perchlorates or hydrogen peroxide usually gives good yields of diols, it is difficult to avoid overoxidation, which with some types of olefins becomes a serious limitation to the method. Superior cooxidants that minimize overoxidation are alkaline t-butylhydroperoxide, introduced by Sharpless and Akashi [10], and tertiary amine oxides such as A - rn e t h y I rn o r p h o I i n e - A - o x i d e (NMO), introduced by VanRheenen, Kelly, and Cha (the Upjohn process) [11], A new, important addition to this list of cooxidants is potassium ferricyanide, introduced by Minato, Yamamoto, and Tsuji in 1990 [12]. 

Osmium tetroxide catalytically assists the oxidation of certain oxidisable substances. For example,8 a mixture of 15 grams of arsenic with 10 grams of potassium chlorate in 50 e.c. of water remains unaltered even after addition of a few drops of dilute sulphuric acid. Upon introducing a trace of osmium tetroxide (c. 0-015 gram) in solution, the temperature immediately rises, the arsenic being rapidly oxidised to... 

From the mechanism shown in Scheme 7.23, we would expect the dihydroxylation with syn-selectivity. The cyclic intermediate may be isolated in the osmium reaction, which is formed by the cycloaddition of OSO4 to the alkene. Since osmium tetroxide is highly toxic and very expensive, the reaction is performed using a catalytic amount of osmium tetroxide and an oxidizing agent such as TBHP, sodium chlorate, potassium ferricyanide or NMO, which regenerates osmium tetroxide. For example, Upjohn dihydroxylation allows the syn-selective preparation of 1,2-diols from alkenes by the use of catalytic amount of OSO4 and a stoichiometric amount of an oxidant such as NMO. 

Osmium tetroxide is also a catalyst in the oxidation of the double bond by chlorates. Cis addition of hydroxyl groups takes place as is shown by the preparation of cis-l,2-cyclohexanediol from cyclohexene and the formation of the proper diastereoisomeric dihydroxy derivatives of maleic, fumaric, and 4-halocrotonic acids. Silver chlorate is preferred to potassium chlorate in the hydroxylation of crotonic acid. ... 

Oxidation. As one step in the synthesis of furaneol (3, a flavor principle of pineapples and strawberries), Buchi et a . wished to effect hydroxylation of 2,5-dimethyl-2,5-dimethoxy-2,5-dihydrofurane (1). They tried oxidation of(1 15.8 mmole) with potassium chlorate (22.8 mmole) and osmium tetroxide (0.3 mmole) in aqueous letrahydro-furane containing sodium bicarbonate at 30° for 63 hr. however, the expected diol... 

Sodium chlorate, NaC103 potassium chlorate, KCI03 silver chlorate, AgCIOj and barium chlorate, Ba(CIOj)2, oxidize organic compounds only in the presence of catalysts, usually osmium tetroxide [310, 714, 715, 716, 718] or vanadium pentoxide [716, 718]. Because such oxidations do not occur without catalysts, it is likely that the real oxidants are osmium tetroxide and vanadium pentoxide, respectively, and that the function of the chlorates is reoxidation. 

Diarylacetylenes are converted in 55-90% yields into a-diketones by refluxing for 2-7 h with thallium trinitrate in glyme solutions containing perchloric acid [413. Other oxidants capable of achieving the same oxidation are ozone [84], selenium dioxide [509], zinc dichromate [660], molybdenum peroxo complex with HMPA [534], potassium permanganate in buffered solutions [848, 856, 864,1117], zinc permanganate [898], osmium tetroxide with potassium chlorate [717], ruthenium tetroxide and sodium hypochlorite or periodate [938], dimethyl sulfoxide and iV-bromosuccin-imide [997], and iodosobenzene in the presence of a ruthenium catalyst [787] (equation 143). 

Hydroxylation at double bonds of unsaturated carboxylic acids is accomplished stereoselectively by the same reagents as those used to hy-droxylate alkenes. syn Hydroxylation is carried out with potassium permanganate [101] or osmium tetroxide with hydrogen peroxide [130], sodium chlorate [310, 715], potassium chlorate [715], or silver chlorate [310] as reoxidant, anti Hydroxylation is achieved with peroxyacids, such as peroxybenzoic acid [310] or peroxyformic acid, prepared in situ from hydrogen peroxide and formic acid [101] (equation 472). 

Olefins can be oxidized stereospecifically to cz,y-a>glycols by aqueous potassium chlorate solutions118 or, better, silver chlorate solutions119 if a little osmium tetroxide is added (Hofmann). The method is suitable mainly for conversion of water-soluble olefins into glycols and cannot be used for water-insoluble olefins.120,121... 

Procedure. A drop of potassium chlorate-potassium iodide solution, acidified with a drop of dilute (1 1,000) sulfuric acid, is placed on a spot plate. A drop of 1 % starch solution and a drop of the neutral test solution are added. According to the osmium and ruthenium content, blue starch-iodine is formed, either at once or in a short time. A blank test should be carried out for small amounts of osmium tetroxide. 

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