Metals mixtures, interactions

C2H4 Oxidation on Ir02, Ru02 and Ir02-Ti02 Mixtures Equivalence of Metal-Support Interaction and NEMCA... 

Then came the observation that metal electrodes can be electrochemically promoted, but intimate nanocrystalline metal-Ti02 mixtures cannot, as they are already promoted via O2 spillover (Chapter 11). This important experiment, together with several others, established the mechanistic equivalence of NEMCA with YSZ and metal-support interactions with Zr02,... 

Sulphur/metal mixtures form metal sulphides. The reaction can be very violent. This is the case for lithium or magnesium when both the metal and sulphur are in the molten state. This is also true for sodium by heating. The reaction is much less violent when sodium chloride is present. It is also less dangerous if the interaction is made in toluene. 

Mechanism [4] was based on studies involving the direct reaction of antimony metal with DBDPO in the absence of a hydrogen source. The data from these experiments clearly show that if the oxide is reduced to the metal, direct interaction with DBDPO would occur, and that this is a specific and highly exothermic reaction. However, no direct evidence for the presence of metallic antimony in mixtures containing antimony oxide, a polymer substrate and an organohalogen compound was obtained. 

The relative ease with which VpOr can be reduced to V(III) in aluminosilicates indicate the exiirence of weak metal-surface interactions and the inability of the surface to effectively passivate vanadium. Similarly, V on Kaolin (and metakaolin) exist mostly as the "free oxide and can (in part) be reduced to V(III) species. Therefore, DFCC systems containing metakaolin microspheres (or amorphous aluminosilicates (15)) should not be as effective as sepiolite in passivating metals TTke Ni and V. In fact, DCC mixtures loaded with 5000 ppm Ni-equivalents (that is 0.6% V + 0.38% Ni) are not metals resistant when metakaolin is used as a metals scavenger (1) ... 

In a fashion similar to the discussion presented on organic chemicals, Baas et al. (2007) applied the 1-compartment model without TK interactions for the analysis of-time series survival data for the springtail Folsomia Candida exposed to binary mixtures of heavy metals. It must be stressed that no internal concentrations were measured in these experiments instead, the toxicokinetics parameters were solely determined from the survival pattern in time. In this case, the toxicity data were well described without assuming interactions, which stresses that even though we know that interactions on toxicokinetics can occur, this does not mean that they will significantly influence toxicity for every metal mixture in each organism. 

Doyle has put forward arguments against the intermediacy of such complexes in catalytic cyclopropanation . Firstly, metal coordination activates the alkene to nucleophilic attack. Hence, an electrophilic metal carbene would add only reluctantly or not at all. Secondly, the stable PdCl2 complexes of dienes 8 and 428 do not react with ethyl diazoacetate, even if Rh fOAc) or PdCljfPhCbOj is added. The diazoester is decomposed only when it is added to a mixture of the Pd complex and excess diene. These results exclude the metal-carbene-olefin intermediate, but they leave open the possibility of metal carbene interaction with an uncomplexed olefin molecule. The preferred formation of exo-cyclopropanes in the PdCyPhCN) -catalyzed reactions between 8 and N2CHCOOEt or N2CPh2, with exo. endo ratios virtually identical to those observed upon cyclopropanation of monoolefin 429, also rule out coordination of a palladium carbene to the exocyclic double bond of 8 prior to cyclopropanation of the endocyclic double bond. 

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