Sodium ruthenate

The treatment of this insoluble residue may vary. In one typical process, residue is subjected to fusion with sodium peroxide. Ruthenium and osmium are converted to water-soluble sodium ruthenate and osmate, which are leached with water. The aqueous solution is treated with chlorine gas and heated. The ruthenate and the osmate are converted to their tetroxides. Ruthenium tetroxide is distilled out and collected in hydrochloric acid. The tetroxide is converted into ruthenium chloride. Traces of osmium are removed from ruthenium chloride solution by boiling with nitric acid. 

The residue, which contains Ir, Ru, and Os, is fused with sodium peroxide at 500°C, forming soluble sodium ruthenate and sodium osmate. Reaction of these salts with chlorine produces volatile tetroxides, which are separated from the reaction medium by distillation and absorbed into hydrochloric acid. The osmium can then be separated from the ruthenium by boiling the chloride solution with nitric acid. Osmium forms volatile osmium tetroxide ruthenium remains in solution. Ruthenium and osmium can thus be separately purified and reduced to give the metals. 

Polymer supported sodium ruthenate is able to catalyze the oxidation of alcohols with iodosobenzene or tetrabutylammonium periodate in CH2CI2.8 It is not clear whether the primary oxidant is ruthenate or perruthenate. 

An aqueous solution of soditun ruthenate is able to oxidize cyclohexanol. These reaction conditions are hardly appropriate for routine employment in the laboratory because of the high price of Na2Ru04 that is used stoichiometrically and of the need to perform the reaction in aqueous 1M NaOH in order to avoid the dismutation of sodium ruthenate. Some mechanistic studies suggest that the real oxidant could be perruthenate,9 present in very small amounts and in equilibrium with ruthenate regardless of... 

Oxidation. This reagent effects the oxidation of primary alcohols to carboxylic acids under alkaline conditions. Exposure of the hydroxy carboxylate salt derived from 1 to sodium ruthenate in 1 (V sodium hydroxide solution afforded the diacid 2, in which the substituent at Ce had epimerized to the thermodynamically favored 8-configuration. ... 

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]. 

Sodium ruthenate [957] and potassium ruthenate [196 oxidize allylic and benzylic alcohols to carboxylic acids at room temperature. Cinnamyl alcohol is transformed into cinnamic acid with sodium ruthenate in 1 M sodium hydroxide at 10 °C after 1 h in 70% yield [957]. In oxidations with potassium ruthenate, only catalytic amounts can be used in the presence of a persulfate, which reoxidizes the reduced ruthenium salt [196. ... 

High yields of ketones result from the gentle oxidation of alcohols with compounds of ruthenium. Ruthenium tetroxide oxidizes cyclohexanol to cyclohexanone in carbon tetrachloride at room temperature in 93% yield [940], Instead of the rather expensive ruthenium tetroxide, which is required in stoichiometric amounts, catalytic amounts of ruthenium trichloride may be used in the presence of sodium hypochlorite as a reoxidant with the same results [701]. Sodium ruthenate [937] and potassium ruth-enate [196], which are prepared from ruthenium dioxide and sodium periodate in sodium hydroxide and from ruthenium trichloride and potassium persulfate, respectively, also effect oxidations to ketones at room temperature. 

Oxidations. By using Phl=0 (in presence of KBr) as an oxidant, alcohols are oxidized to acids and ketones in water in excellent yields. When catalyzed by either poly(4-vinylpyridine)-supported sodium ruthenate or a (salen)chromium complex chemoselective oxidation of alcohols (e.g., allylic alcohols to alkenoic acids) occurs, which is contrary to the effect of (salen)manganese and (porphyrin)iron complexes (giving epoxy alcohols). ... 

Oxidations with sodium ruthenate Carboxylic acids from alcohols... 

---