Ruthenium preparation

Dissolution of a zinc-ruthenium alloy in hydrochloric acid leaves an explosive residue of finely divided ruthenium [1], More probably this is the hydride, which may decompose on slight stimulus, the evolved hydrogen probably igniting because of the catalytic activity of the metal. Ruthenium prepared from its compounds by borohydride reduction is especially dangerous in this respect [2],... 

Ooourrenoe and History of Ruthenium—Preparation—Properties—Colloidal Ruthenium—Atomio Weight—Alloys. 

Asymmetric hydrogenation has been achieved with dissolved Wilkinson type catalysts (A. J. Birch, 1976 D. Valentine, Jr., 1978 H.B. Kagan, 1978). The (R)- and (S)-[l,l -binaph-thalene]-2,2 -diylblsCdiphenylphosphine] (= binap ) complexes of ruthenium (A. Miyashita, 1980) and rhodium (A. Miyashita, 1984 R. Noyori, 1987) have been prepared as pure atrop-isomers and used for the stereoselective Noyori hydrogenation of a-(acylamino) acrylic acids and, more significantly, -keto carboxylic esters. In the latter reaction enantiomeric excesses of more than 99% are often achieved (see also M. Nakatsuka, 1990, p. 5586). 

Ruthenium (III) chloride (2H2O) (P-form) [14898-67-0] M 207.4 + HjO, m >500 (dec), d 3.11, pK 3.40 (for aquo Rh hydrolysis). Dissolve in H2O, filter and concentrate to crystallise in the absence of air to avoid oxidation. Evaporate the solution in a stream of HCl gas while being heated just below it boiling point until a syrup is formed and finally to dryness at 80-100 and dried in a vacuum over H2SO4. When heated at 700° in the presence of CI2 the insoluble a-form is obtained [Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Vol II 1598 1965 J Org Chem 46 3936 1981]. 

The crude, but essentially pure, dibenzo-18-crown-6 obtained from the Organic Syntheses preparation described above (Eq. 3.11) may be hydrogenated in M-butanol solution over 5% ruthenium on alumina, in a stainless steel autoclave at 1,000 p.s.i.. Di-cyclohexano-18-crown-6 is obtained from this treatment in 58—69% yield as a mixture of crystalline diastereomers having a melting range of 38-54°. 

Preparation of Ruthenium Tetroxide Solution. Ruthenium dioxide (0.4 g) is suspended in 50 ml carbon tetrachloride. A solution of 3.2 g sodium metaperiodate in 50 ml water is added and the mixture stirred 1 hr at 0°. The black ruthenium dioxide gradually dissolves. 

Ruthenium and osmium have no oxides comparable to those of iron and, indeed, the lowest oxidation state in which they form oxides is -t-4. RUO2 is a blue to black solid, obtained by direct action of the elements at 1000°C, and has the rutile (p. 961) structure. The intense colour has been suggested as arising from the presence of small amounts of Ru in another oxidation state, possibly - -3. 0s02 is a yellowish-brown solid, usually prepared by heating the metal at 650°C in NO. It, too, has the rutile structure. 

Rapoport s findings have been confirmed in the authors laboratory where the actions of carbon-supported catalysts (5% metal) derived from ruthenium, rhodium, palladium, osmium, iridium, and platinum, on pyridine, have been examined. At atmospheric pressure, at the boiling point of pyridine, and at a pyridine-to-catalyst ratio of 8 1, only palladium was active in bringing about the formation of 2,2 -bipyridine. It w as also found that different preparations of palladium-on-carbon varied widely in efficiency (yield 0.05-0.39 gm of 2,2 -bipyridine per gram of catalyst), but the factors responsible for this variation are not knowm. Palladium-on-alumina was found to be inferior to the carbon-supported preparations and gave only traces of bipyridine,... 

Rhodium-on-carbon has also been found to bring about the formation of 2,2 -biquinoline from quinoline, the yield and the percentage conversion being similar to that obtained with palladium-on-carbon. On the other hand, rhodium-on-carbon failed to produce 2,2 -bipyridine from pyridine, and it has not yet been tried with other bases. Experiments with carbon-supported catalysts prepared from ruthenium, osmium, iridium, and platinum have shown that none of these metals is capable of bringing about the formation of 2,2 -biquinoline from quinoline under the conditions used with palladium and rhodium. ... 

Preparation of Ruthenium Tetroxide (/5) In a 250-ml flask equipped with a magnetic stirrer and cooled in an ice-salt bath is placed a mixture of 0.4 g of ruthenium dioxide and 50 ml of carbon tetrachloride. A solution of 3.2 g of sodium metaperiodate in 50 ml of water is added and the mixture is stirred 1 hour at 0°. The black ruthenium dioxide gradually dissolves. The clear yellow carbon tetrachloride layer is separated and filtered through glass wool to remove insoluble materials. The solution may be used immediately or stored in the cold in the presence of 50 ml of sodium metaperiodate solution (1 g/50 ml). As prepared above, the solution is about 0.037 M in ruthenium tetroxide and contains 0.3 g/50 ml. 

The2-aminophenethyl alcohols resulting from condensation of orr/ici-nitrotoliienes are good precursors for preparation of indoles. Watanabe and co workers have developed ruthenium-catalyzed dehydrogenadveiV-heterocyclizadon for synthesis of indoles and other hereto cycles from 2-aminophenethyl alcohols or 2-nitrophenylethyl alcohols fEq. 10.52. The oxidadve cycli-zadon of 2-aminophenethyl alcohols are also catalyzed by Pd-based catalysts. ... 

Selective conversion of l,4-androstadiene-3,l7-dione to 4-androsten-3,17-dione was achieved with (Ph Pi RuClj (SI), prepared by refluxing ruthenium... 

The sequence has been applied to the synthesis of 1,4-cyclohexanedione from hydroquinone 10), using W-7 Raney nickel as prepared by Billica and Adkins 6), except that the catalyst was stored under water. The use of water as solvent permitted, after hltration of the catalyst, direct oxidation of the reaction mixture with ruthenium trichloride and sodium hypochlorite via ruthenium tetroxide 78). Hydroquinone can be reduced to the diol over /o Rh-on-C at ambient conditions quantitatively (20). 

Chloro-2-(3-methyl-4H-1,2,4-triazol-4-yDbenzophenone (Oxidation of 7solution prepared by adding sodium periodate (2 g) to a stirred suspension of ruthenium dioxide (200 mg) in water (35 ml). The mixture became dark. Additional sodium periodate 18 g) was added during the next 15 minutes. The ice-bath was removed and the mixture was stirred for 45 minutes. Additional sodium periodate (4 g) was added and the mixture was stirred at ambient temperature for 18 hours and filtered. The solid was washed with acetone and the combined filtrate was concentrated in vacuo. The residue was suspended in water and extracted with methylene chloride. The extract was dried over anhydrous potassium carbonate and concentrated. The residue was chromatographed on silica... 

The main use of acrolein is to produce acrylic acid and its esters. Acrolein is also an intermediate in the synthesis of pharmaceuticals and herhicides. It may also he used to produce glycerol hy reaction with isopropanol (discussed later in this chapter). 2-Hexanedial, which could he a precursor for adipic acid and hexamethylene-diamine, may he prepared from acrolein Tail to tail dimenization of acrolein using ruthenium catalyst produces trans-2-hexanedial. The trimer, trans-6-hydroxy-5-formyl-2,7-octadienal is coproduced. Acrolein, may also he a precursor for 1,3-propanediol. Hydrolysis of acrolein produces 3-hydroxypropionalde-hyde which could he hydrogenated to 1,3-propanediol. ... 

At one stage in our project we were surprised to learn that some workers had found difficulties in preparing the tetroxide from the dioxide, until we experienced the same trouble. This problem has now been resolved (3). Ruthenium dioxide is available commercially in both anhydrous and hydrated forms, the former being obtained by direct oxidation of ruthenium metal and the latter by a precipitation process. Only the hydrated form is oxidizable under the mild conditions (2,3) that we use and this form must be specified when purchasing the dioxide. It is noteworthy that the dioxide recovered from carbohydrate oxidations is always easily re-oxidized to the tetroxide. The stoichiometry has been determined of both the oxidation of the dioxide by periodate and reduction of the tetroxide which results on oxidation of an alcohol. 

From the reaction of 5-0-benzoyl-l,2-0-isopropylidene-o -D-en/t/iro-pentofuranos-3-ulose (prepared in 80% yield by oxidation of 5-0-benzoyl-l,2-0-isopropylidene- -D-xylofuranose (35,36) with ruthenium tetroxide) with an excess of diazomethane in methanol-ether, two main products (m.p. 44°-45°C. and 76°-77°C.), both epoxides, could be isolated by chromatography of the product on a silica column. An... 

High-valent ruthenium oxides (e. g., Ru04) are powerful oxidants and react readily with olefins, mostly resulting in cleavage of the double bond [132]. If reactions are performed with very short reaction times (0.5 min.) at 0 °C it is possible to control the reactivity better and thereby to obtain ds-diols. On the other hand, the use of less reactive, low-valent ruthenium complexes in combination with various terminal oxidants for the preparation of epoxides from simple olefins has been described [133]. In the more successful earlier cases, ruthenium porphyrins were used as catalysts, especially in combination with N-oxides as terminal oxidants [134, 135, 136]. Two examples are shown in Scheme 6.20, terminal olefins being oxidized in the presence of catalytic amounts of Ru-porphyrins 25 and 26 with the sterically hindered 2,6-dichloropyridine N-oxide (2,6-DCPNO) as oxidant. The use... 

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