Potassium tetroxide

The tetroxides of the alkali metals.—The highest oxide formed by lithium is the dioxide, and with sodium the trioxide potassium, rubidium, and csesium form tetroxides. A. V. Harcourt38 showed that the indications of the higher oxides of potassium observed by J. L. Gay Lussac and L. J. Thenard, and by H. Davy, about 1810, probably represented the formation of potassium tetroxide. The... 

Phosphorus tribromide Potassium, ruthenium tetroxide, sodium, water... 

Potassium osmate (VI) dibydrate [19718-36-6] M 368.4. Hygroscopic POISONOUS crystals which are soluble in H2O but insol in EtOH and Et20. It decomposes slowly in H2O to form the tetroxide which attacks the eyes. The solid should be kept dry and in this form it is relatively safe. [Synthesis 610 1972.]... 

Ammonia can also react violently with a large selection of chemicals including ethylene oxide, halogens, heavy metals, and oxidants such as chromium trioxide, dichlorine oxide, dinitrogen tetroxide, hydrogen peroxide, nitric acid, liquid oxygen, and potassium chlorate. 

Since osmium tetroxide is expensive and toxic, alternate reagents were also explored. This has led to the use of potassium permanganate by two different groups. ... 

Oxidation of a mixture of perfluorononene isomers to a mixture of per-fluorocarboxylic acids is accomplished with two agents, potassium permanganate and ruthenium tetroxide. Oxidation with potassium permanganate is slower and gives lower yields than oxidation with ruthenium tetroxide [40] (equation 32). 

The actual catalyst is a complex formed from osmium tetroxide and a chiral ligand, e.g. dihydroquinine (DHQ) 9, dihydroquinidine (DHQD), Zj -dihydroqui-nine-phthalazine 10 or the respective dihydroquinidine derivative. The expensive and toxic osmium tetroxide is employed in small amounts only, together with a less expensive co-oxidant, e.g. potassium hexacyanoferrate(lll), which is used in stoichiometric quantities. The chiral ligand is also required in small amounts only. For the bench chemist, the procedure for the asymmetric fihydroxylation has been simplified with commercially available mixtures of reagents, e.g. AD-mix-a or AD-mix-/3, ° containing the appropriate cinchona alkaloid derivative ... 

To a solution of 6.36 parts of 17(3-hydroxy-17a-methyl-5o -androst-Ten-3-one in 95 parts of acetic acid and 12 parts of water is added 40 parts of lead tetracetate and 0.6 part of osmium tetroxide. This mixture is stored at room temperature for about 24 hours, then is treated with 2 parts of lead tetracetate. Evaporation to dryness at reduced pressure affords a residue, which is extracted with benzene. The benzene extract is washed with water, and extracted with aqueous potassium bicarbonate. The aqueous extract is washed with ether, acidified with dilute sulfuric acid, then extracted with ethyl acetate-benzene. This organic extract is washed with water, dried over anhydrous sodium sulfate, and concentrated to dryness in vacuo. To a solution of the residual crude product in 20 parts of pyridine is added 10 parts of 20% aqueous sodium bisulfite and the mixture is stirred for about 20 minutes at room temperature. 

Determine the correct chemical formulas of potassium permanganate, dinitrogen tetroxide, nickel(II) chloride hexahydrate, sodium hydrogen phosphate, and iron(Itl) oxide. 

Berberinephenolbetaine (121) was first obtained by Pyman and designated as neoxyberberine (79). Acetoneberberine (119) was oxidized with potassium permanganate in aqueous acetone to give neoxyberberine acetone (120), the structure of which was established by Iwasa and Naruto (80). On treatment with hydrochloric acid followed by sodium hydroxide, 120 gave 121 (79-81), which was also obtained directly from 119 by oxidation with potassium permanganate or osmium tetroxide (Scheme 26) (80). 

Potassium permanganate or osmium tetroxide oxidize alkenes to furnish 1,2-diols (glycols). 

The osmium-catalyzed dihydroxylation reaction, that is, the addition of osmium tetr-oxide to alkenes producing a vicinal diol, is one of the most selective and reliable of organic transformations. Work by Sharpless, Fokin, and coworkers has revealed that electron-deficient alkenes can be converted to the corresponding diols much more efficiently when the pH of the reaction medium is maintained on the acidic side [199]. One of the most useful additives in this context has proved to be citric acid (2 equivalents), which, in combination with 4-methylmorpholine N-oxide (NMO) as a reoxidant for osmium(VI) and potassium osmate [K20s02(0H)4] (0.2 mol%) as a stable, non-volatile substitute for osmium tetroxide, allows the conversion of many olefinic substrates to their corresponding diols at ambient temperatures. In specific cases, such as with extremely electron-deficient alkenes (Scheme 6.96), the reaction has to be carried out under microwave irradiation at 120 °C, to produce in the illustrated case an 81% isolated yield of the pure diol [199]. 

Phosphorus pentafluoride Phosphorus pentasulfide Phosphorus pentoxide Phosphorus, red Phosphorus tribromide Phosphorus bichloride Water or steam Air, alcohols, water Formic acid, HF, inorganic bases, metals, oxidants, water Organic materials Potassium, ruthenium tetroxide, sodium, water Acetic acid, aluminum, chromyl dichloride, dimethylsulfoxide, hydroxylamine, lead dioxide, nitric acid, nitrous acid, organic matter, potassium, sodium water... 

Quinoline Salicylic acid Silicon Dinitrogen tetroxide, linseed oil, maleic anhydride, thionyl chloride Iodine, iron salts, lead acetate Alkali carbonates, calcium, chlorine, cobalt(II) fluoride, manganese trifluoride, oxidants, silver fluoride, sodium-potassium alloy... 

Sulfides Sulfur Sulfur dioxide Sulfuric acid Sulfuryl dichloride Acids, powerful oxidizers, moisture Oxidizing materials, halogens Halogens, metal oxides, polymeric tubing, potassium chlorate, sodium hydride Chlorates, metals, HC1, organic materials, perchlorates, permanganates, water Alkalis, diethyl ether, dimethylsulfoxide, dinitrogen tetroxide, lead dioxide, phosphorus... 

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. 

In summary, the reaction of osmium tetroxide with alkenes is a reliable and selective transformation. Chiral diamines and cinchona alkakoid are most frequently used as chiral auxiliaries. Complexes derived from osmium tetroxide with diamines do not undergo catalytic turnover, whereas dihydroquinidine and dihydroquinine derivatives have been found to be very effective catalysts for the oxidation of a variety of alkenes. OsC>4 can be used catalytically in the presence of a secondary oxygen donor (e.g., H202, TBHP, A -methylmorpholine-/V-oxide, sodium periodate, 02, sodium hypochlorite, potassium ferricyanide). Furthermore, a remarkable rate enhancement occurs with the addition of a nucleophilic ligand such as pyridine or a tertiary amine. Table 4-11 lists the preferred chiral ligands for the dihydroxylation of a variety of olefins.61 Table 4-12 lists the recommended ligands for each class of olefins. 

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