Rubidium catalysts yields

A unique feature of azoles amongst five membered heterocycles is that they can act both as the carbon or the heteroatom donor during the bond formation. This possibility is frequently exploited in synthetic transformations. Pyrrole, for example, coupled effectively with bromoarenes in the presence of palladium based catalysts (6.67.), The use of PBuj as ligand and rubidium carbonate as base allowed for the reduction of catalyst loading to 1% without significant deterioration of the yield"... 

The reaction was carried out in dioxane, HMPA, and sulfolane as well as in mixtures of dioxane-DMSO (5 1 by volume) and water-DMSO (1 2) at 100-140°C with alkali metal (Li, Na, K, Rb, Cs) hydroxides, tetrabu-tylammonium hydroxide, and rubidium chloride examined as catalysts. All tests were run in an autoclave (1 L) at an initial acetylenic pressure of 12 atm. The most significant effect on the yield of 1-ethynylcyclo-hexanol (110) is that of the catalyst and the solvent. According to their diminishing efficiency, the catalysts examined are arranged as follows KOH RbOH > (Bu4)NOH > LiOH RbCl failed to catalyze the reaction and in the presence of CsOH, resinification was observed. The alcohol 110 is formed most readily in aqueous DMSO, dioxane being next in efficiency (with account for the yield based on the oxime consumed). Addition of DMSO to dioxane does not improve the yield of 110, and only trace amounts of this compound were obtained in HMPA and sulfolane. 

Finally, it has recently been reported that irradiation of a solution of [Ru(bipy)3] containing colloidal K[Fe(FeCN)6] (Prussian blue, PB) produces hydrogen and oxygen continuously. It is necessary for both PB (A ax=700nm) and [Ru(bipy)3T (A ax = 452) to be irradiated and for potassium or rubidium ions to be present in the solution (the reaction is inhibited by Na", Li" or Ca ). Evidently, PB performs a variety of different functions in this reaction. Control experiments show that it can act as an electron transfer catalyst from [Ru(bipy)3] , as a chromophore for H2 production from strong electron donors, and as a catalyst for O2 production from [Ru(bipy)3] at pH as low as 2. Quantum yields in this system are 0.1 X10 but it does appear to be a genuine example of simultaneous H2 and O2 production. 

We have studied the synthesis of fatty acids by the closed Fischer-Tropsch process, using various carbonates as promoters and meteoritic iron as catalyst. The conditions used were D2/CO mole ratio = 1 1, temperature == 400°C, and time = 24-48 hr. Sodium, calcium, magnesium, potassium, and rubidium carbonates were tested as promoters but only potassium carbonate and rubidium carbonate produced fatty acids. These compounds are normal saturated fatty adds ranging from C5 to Cis, showing a unimodal Gaussian distribution without predominance of odd over even carbon-numbered aliphatic chains. The yields in general exceed the yields of aliphatic hydrocarbons obtained under the same conditions. The fatty acids may be derived from aldehydes and alcohols produced under the influence of the promoter and subsequently oxidized to the acids. 

Fatty acids in relatively high yields (usually in excess of the yields of aliphatic hydrocarbons) can be produced in a closed-system Fischer-Tropsch process using meteoritic iron as a catalyst, provided potassium carbonate or rubidium carbonate is used as a promoter. Aldehydes and alcohols or oxygenated intermediate complexes attached to the catalyst may be the source of the fatty acids. 

For the group I metals, it was found that stable complexes beween dicyclohexyl-18-crown-6 and sodium, potassium, rubidium and cesium metals have been obtained in benzene. These new complexes demonstrated the ability to act as active catalysts for the polymerization of butadiene and isoprene. Such catalysts increased the yield and rate of polymerization as compared with conventional alkali metal anionic systems. In addition, the microstructure of the polymer is different from that of the same polymer prepared by metals alone. 

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