Propylene complexes with silver

The stability of the propylene complexes of various silver salts is very dependent upon the nature of the anion. The data of Table III in conjunction with the recorded (223) stability of the propylene complex of AgNOs establish that the order of increasing stability is NOg < CIO 4- <... 

The composition and formation constants of silver complexes with 6-phenyl-2,2 -bipyridine (bpp, 197), in propylene carbonate solution (198), were determined poten-tiometrically. Cyclic voltametry and galvanostatic coulometry were used to determine the normal potential of the reduction processes of Ag(II) to Ag(I), as depicted in reactions 28 and 29265. 

Copper (I) complexes of olefins have been less widely studied but have been found to be analogous to silver(I) complexes in several ways. It was shown 54>, that solid cuprous chloride absorbed ethylene, propylene and isobutylene and solid cuprous bromide absorbed ethylene to give 1 1 complexes, while diole-fms (butadiene and isoprene) and acetylenes were reported S6> to form complexes with a 2 I copper olefin (or acetylene) stoichiometry. Andrews and... 

Copper, silver, and gold form complexes with olefins of the following composition [CuX(olefin)] (X = C1, Br olefin = ethylene, propylene, butenes, COT, NBD, etc. dienes in these complexes are monodentate ligands), [Cu2X2(COD)2],... 

The gas-phase oxidation of ethylene to ethylene oxide over a supported silver catalyst was discovered in 1933 and is a commercially important industrial process. Using either air or oxygen, the ethylene oxide is produced with 75% selectivity at elevated temperatures (ca. 250 °C). Low yields of epoxides are obtained with propylene and higher alkenes so that other metal-based catalysts are used. A silver-dioxygen complex of ethylene has been implicated as the active reagent.222... 

A simple dynamic model is discussed as a first attempt to explain the experimentally observed oscillations in the rate of propylene oxide oxidation on porous silver films in a CSTR. The model assumes that the periodic phenomena originate from formation and fast combustion of surface polymeric structures of propylene oxide. The numerical simulations are generally in qualitative agreement with the experimental results. However, this is a zeroth order model and further experimental and theoretical work is required to improve the understanding of this complex system. The in situ use of IR Spectroscopy could elucidate some of the underlying chemistry on the catalyst surface and provide useful information about surface coverages. This information could then be used to either extract some of the surface kinetic parameters of... 

Silver(i).-Group VII Donor Ligands. AW-Dimethylthioformamide complexes AgCl,-2DMTF, AgBr,2DMTF, and AgI,DMTF have been characterized in solution and in the solid state, and the dissociation constant for reaction (26) was determined from conductivity measurements. Complex solubilities of AgX (X = Cl, Br, or I) have been determined in benzonitrile and trichloroacetonitrile mixtures with propylene-carbonate.The results were compared with previous work in acetonitrile and propionitrile. 

The direct oxidation of propylene by molecular oxygen is a low-selective reaction. The propylene oxide yield can be raised by limiting the conversion rate to a low value, about 10 to 15 per cent, by using more selective catalysts, or by achieving co-oxidation with a more oxidizable compound than propylene (acetaldehyde, isobutyraldehyde etc.). Many patents have been Hied concerning this process, but without any industrial implementation. Among them is the liquid phase oxidation of propylene on a rare earth oxide catalyst deposited on silica gel (USSR), or in the presence of molybdenum complexes in chlorobenzene or benzene (JFP Instiiut Francois du Petrole. Jefferson ChemicalX vapor phase oxidation on modified silver catalysts (BP British Petroleum IFP, or on ... 

Olefin epoxidation is not only important in the manufacture of bulk chemicals, e. g. ethylene and propylene oxides, but is also a widely used transformation in the fine-chemicals industry [1], Ethylene oxide is manufactured by vapor-phase oxidation of ethylene, with air or oxygen, over a supported silver catalyst [2], This method is not generally applicable as olefins containing allylic or other reactive C-H bonds give complex mixtures of products with low epoxide selectivity. The method has recently been extended to some other olefins that do not contain reactive allylic C-H bonds, e. g. butadiene, styrene, norbornene, and tert-butyl ethylene [3]. Some of these products, e. g. butadiene monoepoxide and styrene oxide, have potential applications as fine chemicals/intermediates. 

This method for the separation of deuterated olefin isomers has been used successfully by Ache and Wolf [66]. Fig. 6.2C shows the separation of ethylene (1), ethylene-d, (2) and ethylene-dj (3) by circular chromatography. The separation obtained at the ninth cycle took about 100 min. Successful separation of the deuterated olefins on columns containing a complexing stationary phase, i.e., silver nitrate solution in ethylene glycol, gave the possibility of separating isotopic olefin position isomers labelled also with tritium. Lee and Rowland [65] demonstrated the possibility of this separation. Fig. 6.2D shows the separation of ethylene (1), ethylene-t, (2) and propylenes CHj H—CH=CH2... 

When small molecules, such as olefins, come into contact with a metal complex in macromolecules, such as silver-polymer complexes, a significant amount of olefins are absorbed by the silver-polymer complexes. The propylene solubilities in Ag-POZ complex films ([Ag ] in AgBp4 [C=0] in POZ = 1 1, ca. 80 wt.% of AgBp4 in the polymer matrix) were plotted against the propylene pressure, as shown in Fig. 9-4 [15]. The propylene solubility in pure POZ was very small. However, the propylene solubilities in a 1 1 AgBp4-POZ complex (190 and 240 cm (STP)of propylene per 1 cm of silver-polymer complex at 50 and 190 kPa, respectively) significantly increased 100 times compared to those in pure POZ because of the chemically specific binding of propylene into silver ions. 

The olefin solubility in a silver-PEO complex has been also reported. AgBp4-PEO absorbed 45 cm (STP) of propylene per 1 g of silver-PEO complex, at 30 °C and 93 kPa [17]. The relationship between the olefin solubility and the structure can be understood by an ab initio calculation based on the density functional theory of the model system. The theoretical calculation shows that the bond length between the silver ion and the closest anion atom in the AgBp4-PEO film changes from 2.309 to 2.506 A with the addition of ethylene, and the free energy for the formation of an ethylene adduct with AgBF4 is favorable for an ethylene-silver complex in PEO [15, 18-19] (Fig. 9-5). 

Valuable products are produced from the oxidation of both ethylene and propylene (Figs. 1 and 2). Ethylene is epoxidized with oxygen in the vapor phase over a silver catalyst, and propylene is epoxidized with an alkyl hydroperoxide in the liquid phase using a molybdeniim catalyst system. Vinylic oxidation products or their stable isomers, including acetaldehyde, acetone, and vinyl acetate, have been manufactured by a series of related catalytic reactions. These reactions occur either in solutions of palladium complexes or on the surfaces of supported palladium catalysts. Bismuth molybdate is an effective catalyst for allylic oxidations of propylene, which are of paramount importance to the chemical industry. Propylene is oxidized in the vapor phase to give acrolein for acrylic acid manufacture or, in the presence of ammonia, to give acrylonitrile. Second- and third-generation catalysts,... 

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