Hydrogenation ruthenium chloride

The metal is isolated commercially by a complex chemical process, the final stage of which is the hydrogen reduction of ammonium ruthenium chloride, which yields a powder. The powder is consolidated by powder metallurgy techniques or by argon-arc welding. 

Several other versions of these catalysts have been developed. Arene complexes of monotosyl-l,2-diphenylethylenediamine ruthenium chloride give good results with a,(3-ynones.55 The active catalysts are generated by KOH. These catalysts also function by hydrogen transfer, with isopropanol serving as the hydrogen source. Entries 6 to 8 in Scheme 5.3 are examples. 

Jack Halpern Perhaps I have more reason than anyone else to be disposed to the view that 7r-complexing is an important step of the insertion reaction, because I think that possibly we have the only reasonably clear cut case of an olefin insertion reaction where a complex is clearly implicated. This is the ruthenium chloride-catalyzed hydrogenation of certain olefins, which almost certainly involves the insertion of the olefin into a ruthenium hydrogen bond and where certainly a ruthenium olefin complex is involved as an observable reactant. Nevertheless, I am not at all sure to what extent this is a general or necessary feature of such insertion reactions. The important question is whether one or two coordination positions on the metal ion are involved in the transition state of the insertion reaction. For example, if one considers the insertion of an olefin, say into an M—X bond, then the transition state may look something like ... 

Ruthenium Hydroxide,187192 To an 1% aqueous solution of ruthenium chloride heated to 90-95°C is added an 5% lithium hydroxide solution dropwise under vigorous stirring until the pH of the supernatant liquid becomes 7.5-7.8. Addition of a few drops of the lithium hydroxide solution is usually necessary to prevent the pH of the liquid from becoming more acidic on continued stirring for a further 10-20 min. The black precipitate formed is collected on a filter paper, washed repeatedly with hot distilled water until the filtrate becomes almost neutral, and then dried in vacuo at room temperature. The dried hydroxide is pulverized into fine particles and can be used for hydrogenation at elevated temperatures and pressures without prereduction. 

Nishimura and Kasai studied the hydrogenation of acetophenone in f-butyl alcohol using carefully prepared ruthenium and rhodium blacks.176 The selectivities for the formation of cyclohexyl methyl ketone and 1-phenylethanol as simultaneous products have been determined by application of the equation in Scheme 11.7. The values of K and/as well as the composition of the final products obtained are summarized in Table 11.13. Three ruthenium blacks—Ru (A), Ru (N), and Ru (B)—were prepared from the ruthenium hydroxide precipitated at pH 5,7, and 7.8, respectively, by adding lithium hydroxide solution to an aqueous solution of ruthenium chloride. It is seen that the selectivity for the saturated ketone (see figures in parentheses) was considerably higher over Ru (B) (43%) than over Ru (A) (25%) and Ru (N) (20%). The selectivity over Ru (N) increased markedly to 65% at 100°C and 5.9-7.8 MPa H2. Over rhodium... 

Reactions of Salts of Ruthenium.—A delicate and characteristic reaction of ruthenium chloride consists in formation of an azure-blue tint (possibly due to the formation of dichloride) when hydrogen sulphide is passed through its solution in water. 

The surface areas of a number of commercial palladium blacks were measured using the BET procedure as well as hydrogen chemisorption, electron microscopy and X-ray diffraction analysis. These data showed that these blacks had particle sizes ranging from about 7 to 140 nm and surface areas between 70 and 4 m2/g.20 Ruthenium blacks prepared by the reduction of different samples of ruthenium oxide and ruthenium chloride were found to have surface areas ranging from 3-20 m2/g.21... 

Such polymerization can be avoided by using a catalyst composed of a Group VIII metal or a derivative thereof, e.g., platinum (as platinum black or platinized asbestos or charcoal), hydrogen hexachloroplatinate, or ruthenium chloride then the 1 1 adducts can be obtained in good yield from olefins such as styrene, acrylonitrile, and methacrylic esters with, e.g., dichloro(methyl)-silane 347-349 nevertheless it is advantageous to exclude oxygen and add a polymerization inhibitor such as te/7-butylpyrocatechol or 2,6-di-terf-butyl-4-methylphenol. 

Alumina-supported ruthenium catalysts were prepared by impregnating alumina (Aerosil, 200 m /g) with ruthenium chloride from its aqueous solution. The catalysts composition was Ru Al203 = 2 98 by weight. The catalyst precursors were dried overnight at 120°C in an air oven, and were then calcined at 450 °C for 2 h to form a supported metal oxide [12,13]. The catalysts were reduced in a hydrogen flow at 150°C and 300 °C for 1 h each, and at 400 °C for 2 h in series and then passivated. They were reduced again at 400 °C for 2 h in situ before the catalytic reaction. 

Hydrogenation. The ruthenium chloride complex catalyzes the stereoselective h> drogenation of simple ketones. 

Treating either enantiomer of BINAP with ruthenium chloride forms a complex in which ruthenium is bound as a complex ion in the chiral environment of the larger BINAP molecule. This complex is soluble in dichloromethane, CHjClj/ and can be used as a homogeneous hydrogenation catalyst. 

A method for the electrochemical reduction of D-xylose to 2-deoxy-D-r/rr o-pentitol has been described. The homogeneous hydrogenation of sugars using tris-triphenylphosphine ruthenium chloride is improved in the presence of hydrogen chloride, which inhibits competitive decarbonylation of the sugar. L-(2,3)-Threitol is easily prepared from ( + )tartaric acid by lithium aluminium hydride reduction of the 2,3-0-isopropylidene derivative of diethyl tartrate, followed by acid hydrolysis of the resultant ketal. ... 

Ruthenocene is easily synthesized by the reaction of ruthenium chloride with cyclopentadiene as shown in Scheme 16.1. Ruthenocene is a cream-colored crystal of mp 199-201 °C, stable similar to ferrocene, and it decomposed at ca. 610 C. It is heated at 600 °C under hydrogen atmosphere to yield highly pure filmy ruthenium metal. It is stable to chlorine, hydrogen chloride and sulfuric acid in the absence of oxygen [17]. 

In this paper, we report a direct preparation method of ruthenium-alumina composite by reduction of the mist of a mixed solution of ruthenium chloride and aluminum nitrate. The essential features of the method are as follows. A mist of the mixed solution is generated into a stream of hydrogen by a supersonic atomizer, and treated successively through three furnaces. Temp era-tures of the furnaces are adjusted for evaporation of water, hydrogenolysis of the mixed metal salts, and further reduction of the particles, respectively. 

Thoumazet C, Melaimi M, Ricard L, Mathey F, Le Floch P (2003) A cationic l-(2-methylpyridine)phosphole cymene ruthenium chloride complex as an efficient catalyst in the transfer hydrogenation of ketones. Organometallics 22 1580... 

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