Effect of different metals

The experimental data bearing on the question of the effect of different metals and different crystal orientations on the properties of the metal-electrolyte interface have been discussed by Hamelin et al.27 The results of capacitance measurements for seven sp metals (Ag, Au, Cu, Zn, Pb, Sn, and Bi) in aqueous electrolytes are reviewed. The potential of zero charge is derived from the maximum of the capacitance. Subtracting the diffuse-layer capacitance, one derives the inner-layer capacitance, which, when plotted against surface charge, shows a maximum close to qM = 0. This maximum, which is almost independent of crystal orientation, is explained in terms of the reorientation of water molecules adjacent to the metal surface. Interaction of different faces of metal with water, ions, and organic molecules inside the outer Helmholtz plane are discussed, as well as adsorption. 

Dankwardt s vinylidene-mediated reaction apparently operates concurrently with cationic cycloisomerization to give 3-silyl-l-silyloxy naphthalenes (e.g., 13). From his data, a direct comparison can be made of the effect of different metal complexes and silyl groups on selectivity for a vinylidene-mediated reaction pathway (Table 9.2). At least in this instance, Rh(I) is more vinylidene friendly than Pt(II). Iwasawa and coworkers [7], in an isolated related report, also obtained high selectivity for silyl-shifted products in the presence of a Rh(I)-catalyst, albeit one with a substantially different ligand set from that employed by Dankwardt. 

The organic additives have been employed to counteract the harmful effects of different metallic impurities. Such additives act by increasing the induction period, by complexing the harmful impurities, or by suppressing the hydrogen evolution reaction. The additives also increase the current efficiency, reduce the power consumption, and improve the surface morphology. 

Biswas and Mazumdar [49, 50] reported a similar enhancement of thermal stability on metal ion incorporation for the poly-condensate PMDA-BP/BPA/M, (Fig. 2) with the following features of interest (1) With a typical metal ion incorporated in either PMDA-BP or PMDA-BPA, initial decomposition temperature of the metal-loaded polymers does not change significantly PMDA-BP (238 °C) PMDA-BPA (235 °C), PMDA-BP-Fe(III) (280 °C), PMDA-BPA-Fe(III) (290 °C), PMDA-BP-Cu(II) (265 °C), PMDA-BP-Ni(II) (265 °C), PMDA-BP-Ni(II) (263 °C), PMDA-BPA-Ni(II) (280 ° ). (2) With either PMDA-BP or -BPA, the effect of different metal ions on the stability is in the order Fe3+ > Ni2+ > Cu2+ (upto 4% decomposition) in the BPA complex, and upto 25% in the BP complex. (3) Beyond this temperature, the order in stability becomes same in either system Fe3+ > Cu2+ > Ni2+. 

Effects of Different Metal Salicylaldimine Chelates. Varying the central metal profoundly affected catalytic and inhibitory properties. There were only small quantitative variations, however, between N-phenyl- and V-butylsalicylaldimines having the same central metal atom. The only other salicylaldimines where catalyst-inhibitor conversion could be demonstrated were those of copper (II). With copper (II) both the catalytic and the inhibitory effects are much less pronounced than for cobalt (II). Surprisingly nickel (II) complexes behaved like conventional catalysts for hydrocarbon autoxidation—i.e., the rate is proportional to... 

The effects of different metallic promoters (Sn, Ge, Re etc.) and of various basic additives on the performance of the catalyst are discussed. The best catalyst developed is a Pt-Sn/Si02 catalyst p re treated with Ca2+ which is able to catalyze the alkylation of several ortho-disubstituted anilines with high conversions and selectivities. 

The effect of different metals on the stereochemistry was studied149,150,151 in the hydrogenation of 4-ferf-butyhnethylenecyclohexane (9). Whereas Pt, Rh, Ir and Ru yield predominantly the cis isomer, fraws-l-terf-butyl-4-methylcyclohexane is the main product on Pd. The stereochemical behavior of 9 was very similar to that found for the hydrogenation of the isomeric 4-ferf-butyl-l-methylcyclohexene (10) (increasing cis selectivity... 

The effect of different metal atoms or the nuclearity of the complex is not detectable. 

Continuous effort by Righetti et al. was devoted to investigation of the effect of different metal salts on the rate of the Diels-Alder and hetero-Diels-Alder reaction in acetone solution (Sch. 3) [22]. LiClOq, NaC104, Ba(C104)2, and Mg(C104)2 were compared to evaluate the distinctive Lewis acidic nature of each species. When the effect of different cations is compared at the same concentration, Na is 2-3 times less effective than Li, which is 2-3 times less effective than Ba. The outstanding result, however, is that Mg is ca... 

The effects of different metal ions in the nucleic acids can be summarized by considering the action of nickel (II), copper (II), and mercury (II). 

Figure 6.3 shows the effect of different metal deposits (as islands equivalent to a few monolayers with about 90% surface coverage) on the photocurrent ofThe shift of the i-V curve from that of bare material is due to the catalytic effect of the metal on hydrogen evolution. For a metal deposit the photocurrent is parallel to the exchange current density for the dark evolution of H2 Pt, as a catalyst, has the highest exchange current whereas Pb, as an inhibitor, has a very low exchange current. 

The reaction kinetics of hydrogen evolution is particularly sensitive to trace amounts of noble metal impurities in the solution such as Cu and Au, which tend to deposit on the silicon surface [24, 25]. Figure 9 shows the effect of different metal deposits on the photocurrent of p-Si in a H2SO4 solution [26]. There appears to be a correlation between the effect of these metals on photocurrent and the exchange current density of hydrogen evolution on the metals. In addition to metal deposits, hydrogen evolution can also be catalyzed through deposition of a layer of metal... 

The anodic reaction, Hz oxidation, will be discussed in the next section. Here we will devote a few words to the cathodic reaction, Hz evolution, the main aim being to show that the effectiveness of different metals in promoting this reaction can be understood in terms of a classical volcano relationship (see Chapter 3). Generally speaking, the elementary steps in the Hz-evolution reaction are the... 

Table 2 Effect of different metal dithiolates on the photostability (embrittlement time, EMT) of PP processed at 190°C (For structures, see Table 1)...

Oppenheimer and Stern, 1939 Green, 1941 Warburg, 1949 Lehninger, 1950 Vallee, 1951 Williams, 1953). Many of these studies have been concerned purely with the functional characteristics of a given system, using the rate of reaction catalyzed by an enzyme, and the effect of different metal ions upon it, as criteria of the interaction. 

Critical concentrations with respect to soil organisms should be related to a low effect level on the most sensitive species. The effects on the processes of metabolism and other processes within the organisms should be considered and also the diversity of the species, which is most sensitive to heavy metals, has to be accounted. Critical limits must refer to the chronic or accumulated effects. For assessment of the critical concentrations in crops and in drinking water, human-toxicological information is required. In general, for establishing critical loads we should also account the additive effects of different metals and combination effect between the acidification and biogeochemical mobilization of the heavy metals in soils and bottom sediments. 

Yamamoto [86] utilized a similar type ofapparatus, but he examined the effect of different metal and resin surfaces on the friction sensitivity of lead styphnate. 

Eq. (27) and (28) provide an interesting basis to study the electronic effects of different metals on the donor properties of P, S and Se in carbonyl complexes. Anyhow, one of the specific features of work done in this field is, that a major interest has been directed towards an understanding of the different factors determining the stability of a metal ligand bond (e.g. 444>). 

The effect of different metal catalysts upon the oxidation of acetylene has been made the subject of preliminary investigation by Bellamy,102 who observed that the complete oxidation of the substance was progressively accelerated by iron, copper and platinum. He found that a hot spiral of platinum or silver detonated a mixture of acetylene and air but did not become incandescent. A copper spiral, however, when treated in the same way became brilliantly incandescent and eventually ignited the mixture. A spiral of iron acted in the same wav but the incandescence was more difficult to obtain. 

Most of the catalysts studied are Pt/alumina however, studies were also made with one Pd/Al and one Ru/Al in order to get an idea about the effect of different metals on the performance of the catalyst. 

Ribas B (1994) Heterogeneity of metallothionein isoforms by HPLC under the effect of different metals in rabbit kidney, In Bratter P, Ribas B and Schramel P, eds. Trace Elements in Analytical Chemistry and Medicinal Biology, Vol. 6, pp. 303-310. Consejo Superior de Investigaciones Cientificas, Madrid, Spain. 

Effect of Different Metalated Hydrocarbons on Alfin Polymerization of Butadine... 

Allison and Becker have elegantly shown the effect of different metals on the luminescent spectra of porphyrins (7). Their results plainly show that as the metal increases in Z Op decreases as Op increases, and the lifetime of the triplet state decreases. The same is true for paramagnetic metals but to a much greater degree. Therefore it seems that magnesium is perfectly suited for its role in triplet production. 

Su and coworkers examined the effect of different metals like Mn " and Co as well as Fe " on this reactivity. For Fe porphyrins, e.g., Fe(TMPyP), an EC mechanism, encompassing Fe reduction preceding NO coordination, is pro-posed ". Water soluble Mn(TMPyP), Mn(2-TMPyP), Mn(TSS), and Mn(TSPP) illustrate that porphyrins with electron withdrawing groups exhibit higher rates in electrocatalytic NO reduction activity. While the reduction products are similar, the mechanism for Mn is proposed to be via a ECE mechanism, i.e., initial reduction of the Mn to Mn° precedes NO coordination and reduction. The Co(2-TMPyP) illustrated that a two electron couple, Co /, is more efficient than a one electron couple, Fe /, in yielding the N-N coupled product N2O. 

Table 9. Effect of Different Metal Dithiolates on the Photostability (Embrittlement Time, EMT) of PP Processed at 190°C ...

In a subsequent study in the year 2015, the effect of different metals with BIPHEPHOS as a ligand on the same transformation was investigated [59]. Unexpectedly, under nonoptimized hydroformylation conditions, the relevant iridium catalyst exhibited only 5 times lower reactivity than the rhodium system. But the latter allowed slightly better control of the distribution of internal olefins. Ruthenium and palladium catalysts performed significantly worse. 

The last points could be well illustrated by choosing conversion of syngas (CO, CO2, and H2) on perovskites containing one or more metals well known to be active in CO hydrogenation. Thus, the effect of different metals (e.g., Cu for methanol, Rh for ethanol, Co and Cu for higher alcohols, and Co and Fe for hydrocarbons) initially present in the perovskite structure will be successively studied in the present paper. 

Using more effective catalysts. The effect of different metals in the electrode is shown clearly by the fignres in Table 3.1. 

Veses, A., et al., 2015. Catal3dic upgrading of biomass derived pyrolysis vapors over metal-loaded ZSM-5 zeolites effect of different metal cations on the bio-oH final properties. Microporous and Mesoporous Materials 209 (0), 189—196. 

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