Sodium molybdate -Hydrogen

U- C]glucose from H2 C03 by Scenedesmus obtusiusculus. A 50-70% yield was obtained in 0.5 h at 30 °C. A 44% yield of D-[U- C]arabinose has been obtained by treatment of D-[ glucose 2-nitrophenylhydrazone with ammoni-acal sodium molybdate-hydrogen peroxide mixtures. D-[5- H]Mannose and L-[5- H]gulose have been prepared by the route shown in Scheme 1. ... 

Aubry, J. M. and S. Bouttemy, S. 1997. Preparative oxidation of organic compounds in microemulsions with singlet oxygen generated chemically by the sodium molybdate/ hydrogen peroxide system. J Am Chem Soc, 119, 5286-5294. 

Oxidation. Maleic and fumaric acids are oxidized in aqueous solution by ozone [10028-15-6] (qv) (85). Products of the reaction include glyoxyhc acid [298-12-4], oxalic acid [144-62-7], and formic acid [64-18-6], Catalytic oxidation of aqueous maleic acid occurs with hydrogen peroxide [7722-84-1] in the presence of sodium tungstate(VI) [13472-45-2] (86) and sodium molybdate(VI) [7631-95-0] (87). Both catalyst systems avoid formation of tartaric acid [133-37-9] and produce i j -epoxysuccinic acid [16533-72-5] at pH values above 5. The reaction of maleic anhydride and hydrogen peroxide in an inert solvent (methylene chloride [75-09-2]) gives permaleic acid [4565-24-6], HOOC—CH=CH—CO H (88) which is useful in Baeyer-ViUiger reactions. Both maleate and fumarate [142-42-7] are hydroxylated to tartaric acid using an osmium tetroxide [20816-12-0]/io 2LX.e [15454-31 -6] catalyst system (89). 

The use of molybdenum catalysts in combination with hydrogen peroxide is not so common. Nevertheless, there are a number of systems in which molybdates have been employed for the activation of hydrogen peroxide. A catalytic amount of sodium molybdate in combination with monodentate ligands (e.g., hexaalkyl phosphorus triamides or pyridine-N-oxides), and sulfuric acid allowed the epoxidation of simple linear or cyclic olefins [46]. The selectivity obtained by this method was quite low, and significant amounts of diol were formed, even though highly concentrated hydrogen peroxide (>70%) was employed. 

Olas and Wachowicz (2002) investigated the effects of tranx-resveratrol and vitamin C on oxidative stress in blood platelets. The level of 02 in control blood platelets and platelets incubated with resveratrol or vitamin C was recorded using a chemiluminescence method. On the other hand, Oh and others (2006) reported the x02 quenching activities of various freshly squeezed fruit and vegetable juices by measuring their inhibitory effects on the rubrene oxidation induced by x02 from disproportionation of hydrogen peroxide by sodium molybdate in a microemulsion system. 

Molybdenum salts used as catalysts include cobalt molybdate for hydrogen treatment of petroleum stocks for desulfurization, and phospho-molybdates to promote oxidation. Compounds used for dyes are sodium, potassium, and ammonium molybdates. With basic dyes, phosphomolyb-dic acid is employed. The pigment known as molybdenum orange is a mixed crystal of lead chromate and lead molybdate. Sodium molybdate, or molybdic oxide, is added to fertilizers as a beneficial trace element. Zinc and calcium molybdate serve as inhibitory pigments in protective coatings arid paint for metals subjected to a corrosive atmosphere. Compounds used to produce better adherence of enamels are molybdenum trioxide and ammonium, sodium, calcium, barium, and lead molybdates. 

Sodium molybdate(VI)-Hydrogen peroxide, Na2Mo04-H202. 

Sodium Thiomolybdates.—Two are knowm the normal salt, NajMoS, prepared as dark reddish crystals by the action of hydrogen sulphide upon a solution of sodium molybdate, and the acid salt, NagMogSy, obtained as a dark grey mass by treatment of the normal salt with a deficiency of acid. Oxythiomolybdates are obtained by the action of sodium hydrosulphide upon sodium tri- and para-molybdates. 

Oxidation of the Schiff bases (19) made from the monoamide of DAMN (derived from DAMN by hydration of one of the nitrile functions) gives 4-cyanoimidazole-5-carboxamides (20) in good yields ( 70% or more) (Scheme 2.1.7). Such oxidations can be readily accomplished using hydrogen peroxide with a catalytic amount of sodium molybdate fSl]. 

No reaction took place with hydrogen peroxide and tri-n-butylamine in the absence of sodium molybdate. The observation that tri-n-butylamine is an effective catalyst led us to evaluate the reaction with a range of structurally different amines. The results are reported in Table 3. 

Scheme 1 Representation of the oxidation of thioethers with hydrogen peroxide catalysed by sodium molybdate and tri-n-butylamine...

The phase-transfer-assisted permanganate oxidation of alkynes and alkenes has been reviewed. Terminal and internal alkynes are oxidized to 1,2-dicarbonyl compounds by the combined action of diphenyl disulphide, ammonium peroxidisulphate and water or by sodium periodate in the presence of ruthenium dioxide (equation 34). Other reagents for the conversion of acetylenes into 1,2-dicarbonyl compounds are hydrogen peroxide in the presence of (2,6-dicarboxylatopyridine)iron(II), the complex oxo(A, A -ethylenebissalicylideneiminato)chromium(V) trifluoromethanesulphonate (216)and ruthenium tetroxide as a mediator in electrooxidation. l-Acetoxyalkan-2-ones 217 are obtained by the oxidation of terminal acetylenes with sodium perborate and mercury(II) acetate in acetic acid ". Terminal alkynes give a-ketoaldehydes 218 on treatment with dilute hydrogen peroxide, combined with mercury(II) acetate and sodium molybdate or sodium tungstate under phase-transfer conditions. ... 

Figure 22.5 Schematic representation of the dark singlet oxygenation of a substrate S in a water-in-oii singie-phase jem water/surfactant/cosurfactant/solvent by the chemical source hydrogen peroxide/sodium molybdate.

A thiourea such as (311) was oxidized with sodium molybdate and hydrogen peroxide to an amidine sulphonic acid (312). The sulphonic acid group was replaced by an amine to give the guanidine Scheme 5.70.) [374]. The avoidance of methyl mercaptan as a by-product was a considerable advantage. 

Moroxydine (512) was first synthesized by introducing morpholine to dicyanodiamidine [667], but an improved method is the oxidation of amidinothiourea (510) with hydrogen peroxide and sodium molybdate dihydrate to give (511) followed by reaction with morpholine [374] Scheme 5.120.). This avoids the evolution of methyl mercaptan. The drug has antibiotic properties and some action as an influenza suppressant [668]. 

Preparative Methods by the oxidation of thiourea or amino-iminomethanesulfinic acid (formamidinesulfinic acid) with peracetic acid. Many substituted aminoiminomethanesulfonic acids can be prepared in the same way. 2 Others have utilized hydrogen peroxide with sodium molybdate as a catalyst to oxidize the corresponding thioureas to a variety of monosubsUtuted aminoiminomethanesulfonic acids the substituents include phenyl, 2-methylphenyl, 4-fluorophenyl, / -propyl, cyclohexylmethyl, S-a-methylbenzyl, cyclooctyl, and benzhydiyl. ... 

Hydrogen sulfide has been produced in commercial quantities by the direct combination of the elements. The reaction of hydrogen and sulfur vapor proceeds at ca 500°C in the presence of a catalyst, eg, bauxite, an aluminosihcate, or cobalt molybdate. This process yields hydrogen sulfide that is of good purity and is suitable for preparation of sodium sulfide and sodium hydrosulfide (see Sodium compounds). Most hydrogen sulfide used commercially is either a by-product or is obtained from sour natural gas. 

Better results are obtained by transferring 25.0 mL of the diluted hydrogen peroxide solution to a conical flask, and adding 100 mL 1M(1 20) sulphuric acid. Pass a slow stream of carbon dioxide or nitrogen through the flask, add 10 mL of 10 per cent potassium iodide solution, followed by three drops of 3 per cent ammonium molybdate solution. Titrate the liberated iodine immediately with standard 0.1M sodium thiosulphate in the usual way. 

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