Water-soluble catalyst RuCl2

The same reaction was investigated in a reverse experimental setup, i.e. having the water-soluble catalyst [ RuCl2(TPPMS)2 2] + excess TPPMS, and the hydrogen donor HCOONa in the aqueous phase and the substrate aldehyde together with the products in the organic (chlorobenzene) phase [249,250], Unsaturated aldehydes, such as cinnamaldehyde (Scheme 3.18)... 

Diphenylacetylene and 1-phenyl-1-propyne were hydrogenated to the corresponding 1,2-disubstituted alkenes in aqueous-organic biphasic media at 50°C and 0.1 MPa H2, using the water-soluble catalyst [RuCl2(TPPMS)2]2 and an excess of TPPMS. The stereoselectivity of the reaction strongly depended on the pH of the catalyst-containing aqueous phase under acidic conditions, Z-alkenes could be obtained with selectivity close to 100% (81). The role of water was clari-fled by theoretical studies (82). 

The water soluble tertiary phosphine complex of ruthenium(II), [RuCl2(PTA)4], (PTA=l,3,5-triaza-7-phosphaadamantane) was used as catalyst precursor for the hydrogenation of CO2 and bicarbonate in aqueous solution [51]. For this relatively... 

Sodium or ammonium formates are also suitable as hydride donors for the hydrogenation of a, 0-unsaturated and aromatic aldehydes with water-soluble Ru complexes [88, 93], With [RuCl2(TPPMS)2], both the catalyst and the formate are in the aqueous phase the phase-transfer problem associated with catalysts not soluble in water and aqueous formate solutions does not arise [93, 94]. These systems olfer interesting theoretical aspects [87, 95, 186]. 

Water-soluble ruthenium complexes RuHCl(tppts)3, RuCl2(tppts)3, RUH2 (tppts)3, or the rhodium complex RhCl(PTA)3, are also effective catalysts for the hydrogenation of the carbonyl function of aldehydes [16], carbohydrates [17], and keto acids [13], provided that the iodide salt Nal is added for ruthenium complexes. 

Formic acid and formates were among the most effective donors used for the reduction of olefins with [RuCl2(PPhj)j] or [RhCl(PPh3)3] catalysts in non-aqueous systems [239-241], No wonder, the water soluble analogues of these catalysts became widely used in aqueous solutions. In a series of investigations [242-245] with Ru/IPPMS and Rh/TPPMS catalysts olefins (such as 1-heptene) were hydrogenated in mixtures of HCOOH/HCOONa. Crotonaldehyde was selectively reduced to butyraldehyde by the [RhCl(TPPMS)3] catalyst [245], It was also established that (unfiltered) ultraviolet irradiation accelerated the reactions [245],... 

More recently, catalytic hydrogenations of alkenes by other catalysts in water have been explored. For example, water-soluble ruthenium complex RuCl2(TPPTS)3 has been used for the catalytic hydrogenation of unsaturated alkenes (and benzene). Hydrogenation of nonactivated alkenes catalyzed by water-soluble ruthenium carbonyl clusters was reported in a biphasic system. The tri-nuclear clusters undergo transformation during reaction but can be reused repeatedly without loss of activity. The organometallic aqua complex [Cp Ir (H20)3] " ... 

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