Ruthenium chloride reactions

Dr. Halpern I don t know whether this is relevant to the first reaction or not, but we have also been struggling with the study of various reactions of ruthenium chlorides including ruthenium(II) chloride for a long time. Among the reactions studied is the formation of olefin and carbonyl complexes of ruthenium(II). These form readily in aqueous solution, and are fairly stable. James and Kemp, working on these systems in my laboratory have studied in some detail the kinetics of the reactions ... 

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 ... 

In aqueous 5M HC1, solutions of ruthenium chloride catalyze the hydration of acetylene, giving acetaldehyde (equation 166).614 Propyne reacted to give acetone. The reaction is inhibited by high or low chloride concentrations. The mechanism proposed is given in Scheme 60. 

A relatively inexpensive route to [Os(NH3)6]3+ has been found using the commercially available (NH4)2[OsC16] as starting material (equation 21)."° It is interesting that a similar reaction with ruthenium chloride is known100 to yield instead the... 

A bis(cyclophane)ruthenium(II) complex has been prepared by using Bennett s procedure reaction of diene 265, obtained by Birch reduction of 4,5,7,8-tetramethyl[22](l,4)cyclophane 266, with ruthenium chloride gives the dimeric chloride complex 267 (Scheme 27, p. 223). Treatment of the solvated complex 268 with 266 in the presence of trifluoroacetic acid leads to 269 (163). The structures of complexes 267, 268, and 269 are based on ... 

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. 

Ruthenium chloride complexes, such as dichlorotris(triphenylphosphane)ruthenium(II), effectively catalyze the addition of polyhalocarbons to double bonds5 13 18. In a mechanistic and stereochemical study, carbohalogenation of cyclohexene with carbon tetrachloride in the presence of dichlorotris(triphenyIphosphane)rulhenium(II) gave l-chloro-2-(trichloromethyl)cyclohexane (2) in 77% yield and a diastereomeric ratio (transjeis) of 96 419. In comparison, the same conversion promoted by dibenzoyl peroxide is considerably less selective and gives the same product in only 10% yield with a 53 47 ratio of the trans, cis-isomets. This striking difference led to the conclusion that the ruthenium-catalyzed version does not proceed via a free-radical mechanism, as assumed in the peroxide-mediated reaction. 

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. 

The metathesis of vinyltri(alkoxy,methyl)silanes, reaction (17), proceeds smoothly at 60-130°C in the presence of ruthenium chloride complexes such as RuCl2(PPh3)3, or in some cases rhodium chloride complexes such as RhCl(PPh3)3,... 

Ruthenium In one of the earliest examples of a transition metal-catalyzed hydroalkoxylation reaction from 1998, the cyclization of 2-allylphenols to benzo-dihydrofurans was catalyzed by a cocktail of ruthenium chloride, silver- and copper triflates, and a phosphane ligand (Scheme 8a) [44]. A control experiment implied that triflic acid alone was ineffective as catalyst, but this experiment is at variance with a later report where 2-allylphenol was cyclized using only 5 mol% of triflic acid as catalyst (CH2CI2, 40°C, 3 h) [45]. 

Basifiska and Domka in 1993 reported [21] Fe-Ru catalysts for the WGS reaction. They took a, p, y or 5 iron hydroxide and impregnated with Rh followed by calcination at 400 or 600 °C. The catalysts were prepared by ruthenium chloride. The catalytic activity results are presented in Table 2.1. 

Y. Doi, S. Tamura, Homogeneous catalysis of the water gas shift reaction using ruthenium chloride in aqueous alkaline solution, hrm-g. Chim. Acta 54 (1981) L235-L236. 

In the 1960s, ring-opening metathesis polymerization was first developed, and simple ruthenium chloride was used for this reaction. " In the 1970s and 80s, the mechanism of this reaction involving sequential [2-i2] steps was suggested by Chauvin and Katz. ° The first alkylidene complexes that underwent the [2 -i 2] reactions of this proposed mechanism were prepared by Schrock, Casey, and Grubbs. These mechanistic data led to the... 

The monomer is made by the Diels-Alder reaction of dicyclopentadiene with ethylene. The catalyst for ROMP is ruthenium chloride in butanol. The process is relatively simple as the two liquids (ruthenium chloride in butanol and norbornene) are directly mixed in the extruder, in air. The norbornene to ruthenium ratio is very high (c.a. 25000) and the conversion reaches 50%. As the process operates in air, a small amount of norbornene is oxidized into epoxynorbornane (the epoxide to ruthenium ratio is c.a. 5) which can accelerate the polymerization. Indeed, mechanistic studies have shown that the catalytic reaction passes through a ruthenium hydride (formed by substitution of chlorine by butoxy ligands and further p-H abstraction) or through a ruthenium oxametallacyclobutane (formed by reaction of the ruthenium complex with epoxynorbornane) [33]. 

TEA or trioctylamine, and vinyl acetate as the acyl donor, led to the corresponding chiral acetate in yields above 68% and enantioselectivities of 80-97% ee. In 2006, Wolfson et al. reported the DKR of 1-phenylethanol by hydrated ruthenium chloride in an aqueous medium using Novozym 435 as the lipase. ° This novel process, involving phenyl acetate as the acyl donor, led to the formation of the corresponding chiral acetate in 82% yield and 98% ee. Besides its low price and ideal environmental impact, performing the reaction in an... 

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