Copper species

Ullman type coupling occurs between aryl halides and trifluoromethyl copper species generated by the action of copper iodide on sodium tnfluoroacetate [168, 169] or on methyl fluorosulfonyldifluoroacetate [170] (equation 145) Similarly the pentafluoroethyl group can be introduced from potassium pentafluoropropion-ate [171] (equation 146)... 

The copper species formed depends on the solvent, and three different species were detected by F NMR, although the structure of each species was not elucidated [245 This copper reagent undergoes a variety of coupling reactions with aryl, alkenyl, allyl, and acetylenic halides [244, 245 (equation 162)... 

Tliis nietliod can be extended to die preparation of alkenylcoppet conipounds. Tlius, treatment of die iodoalkenyl azide 10 widi iiBuLi at -100 C iSdienie 2.3), followed by transnietaladon witli Znl2 in THF and tlien by a second Iransnieta-lalion widi CuCN-2LiCl, produces die copper species 11. Tliis tlien effects a cis-selective carboctipralion of etliyl propiolate lo ftitnisb tlie f , ) diene 12 in 81%... 

Finally, zinc-copper exchange by treatment of FG RZnI witli Me2CufCN)Li2 provides copper species thal add smootlily lo various alkynes and which can also he used lo perforcn cyclizalion reactions fScheme 2.48) [98]. 

Hie carbocupration of acetyletie takes place smootlily in a cis fasliion, providing a reliable syntlietic route to vinyl copper species iEq. 10.8) [24], Magnesium and zinc. 

As a result, the only stable copper species are insoluble compounds such as CuCN or complex ions such as Cu(CN)2. ... 

The intermediate vinyl copper species react readily with a variety of electrophiles, with retention of stereochemistry. 

Sundararajan et al. [131] in 1999 calculated the slurry film thickness and hydrodynamic pressure in CMP by solving the Re5molds equation. The abrasive particles undergo rotational and linear motion in the shear flow. This motion of the abrasive particles enhances the dissolution rate of the surface by facilitating the liquid phase convective mass transfer of the dissolved copper species away from the wafer surface. It is proposed that the enhancement in the polish rate is directly proportional to the product of abrasive concentration and the shear stress on the wafer surface. Hence, the ratio of the polish rate with abrasive to the polish rate without abrasive can be written as... 

The replacement of vanadia-based catalysts in the reduction of NOx with ammonia is of interest due to the toxicity of vanadium. Tentative investigations on the use of noble metals in the NO + NH3 reaction have been nicely reviewed by Bosch and Janssen [85], More recently, Seker et al. [86] did not completely succeed on Pt/Al203 with a significant formation of N20 according to the temperature and the water composition. Moreover, 25 ppm S02 has a detrimental effect on the selectivity with selectivity towards the oxidation of NH3 into NO enhanced above 300°C. Supported copper-based catalysts have shown to exhibit excellent activity for NOx abatement. Recently Suarez et al and Blanco et al. [87,88] reported high performances of Cu0/Ni0-Al203 monolithic catalysts with NO/NOz = 1 at low temperature. Different oxidic copper species have been previously identified in those catalytic systems with Cu2+, copper aluminate and CuO species [89], Subsequent additions of Ni2+ in octahedral sites of subsurface layers induce a redistribution of Cu2+ with a surface copper enrichment. Such redistribution... 

Mingelgrin U., Biggar J.W. Copper species in aqueous sewage sludge extract. Water Air Soil Pollut 1986 28 351-359. 

The reduction of a solution of a trialkylphosphine copper(I) iodide complex (CuIPR ) with preformed lithium naphthalide (LiNp) in THF or DME under argon was found to give a more reactive copper species, which will undergo oxidative addition with a variety of organic substrates at room... 

In spite of the nominal absence of Bronsted acid sites, it is possible to introduce copper species in the S-l matrix by following an ion-exchange procedure. The unit cell of the S-l can be written as follow [1] ... 

Our data as a whole suggest that upon a thermal treatment at high temperature, the copper species turn mainly into (CuO)n nanoclusters, schematically indicated as... 

The ceramized Cu 13X material showed good catalytic activity and stability in the WHPCO of phenol. The performance of the catalyst (reused without any reactivation treatment) during the 10 consecutive reaction cycles proves an outstanding low leaching of copper species. The catalyst was very efficient in poly-phenol and TOC abatement of a real olive oil mill wastewater. 

The presence of Cu(i) or Cu(n) salts in the aforementioned reactions is critical. It is believed that organozinc reagents undergo transmetallation with copper species to yield more reactive complexes.301 A proposed301 catalytic cycle (Scheme 118) suggests that the alkyl group transferred to the enone from the copper metal in a bimetallic intermediate 207. 

The preparation of the Ni(n) and Cu(n) complexes of the related 18-membered sexadentate ligand (283) has been performed (Hay, Jeragh, Lincoln Searle, 1978). The Ni(n) complex has a structure of type (284). Once again, both complexes are quite labile under acid conditions with the dissociation of the copper species being relatively... 

Cathodic stripping voltammetry has been used to determine copper species in seawater [291,292],... 

Potentiometric stripping analysis has been applied by Sheffrin and Williams [320] to the measurement of copper in seawater at environmental pH. The advantage of this technique is that it can be used to specifically measure the biologically active labile copper species in seawater samples at desired pH values. The method was applied to seawater samples that had passed a 0.45 pm Millipore filter. Samples were studied both at high and at low pH values. 

In seawater, the major chemical species of copper are Cu(OH)Cl and Cu(OH)2 and these account for about 65% of the total copper in seawater (Boyle 1979). The levels of copper hydroxide (Cu(OH)2) increase from about 18% of the total copper at pH 7.0 to 90% at pH 8.6 copper carbonate (CuC03) dropped from 30% at pH 7.0 to less than 0.1% at pH 8.6 (USEPA 1980). The dominant copper species in seawater over the entire ambient pH range are copper hydroxide, copper carbonate, and cupric ion (USEPA 1980). Bioavailability and toxicity of copper in marine ecosystems is promoted by oxine and other lipid soluble synthetic organic chelators (Bryan and Langston 1992). 

Iron(III)-catalyzed autoxidation of ascorbic acid has received considerably less attention than the comparable reactions with copper species. Anaerobic studies confirmed that Fe(III) can easily oxidize ascorbic acid to dehydroascorbic acid. Xu and Jordan reported two-stage kinetics for this system in the presence of an excess of the metal ion, and suggested the fast formation of iron(III) ascorbate complexes which undergo reversible electron transfer steps (21). However, Bansch and coworkers did not find spectral evidence for the formation of ascorbate complexes in excess ascorbic acid (22). On the basis of a combined pH, temperature and pressure dependence study these authors confirmed that the oxidation by Fe(H20)g+ proceeds via an outer-sphere mechanism, while the reaction with Fe(H20)50H2+ is substitution-controlled and follows an inner-sphere electron transfer path. To some extent, these results may contradict with the model proposed by Taqui Khan and Martell (6), because the oxidation by the metal ion may take place before the ternary oxygen complex is actually formed in Eq. (17). 

Reactions with cyclopropene.11 Lithium organocuprates react with the cyclo-propenone ketal 1 (12, 152-154) to form a copper species (a) that behaves as an enolate of a cyclopropanone. Thus it reacts with alkyl halides to form cis-2,3-disubstituted derivatives of 1. 

PhI=NTs in MeCN affords a copper species that is indistinguishable by ultraviolet-visible (UV-vis) spectroscopy from an identical solution derived from Cu(OTf)2. Given the strong oxidizing nature of PhI=NTs, it seems likely that both catalysts proceed through a Cu(II) species. Beyond this, little can be said with certainty. If nitrenoid formation proceeds by a two-electron oxidation of the catalyst, one would need to invoke Cu(IV) as an intermediate in this process (77). This issue is resolved if one invokes the intervention of a bimetallic complex in the catalytic cycle. However, attempted observation of a nonlinear effect revealed a linear relationship between ligand enantiopurity and product ee (77, 78). 

This equilibrium has a buffer-like effect stabilizing the presence of cationic copper species in the structure even in a highly reductive atmosphere. The above scheme of copper oxide-ceria interactions indicates clearly that the catalyst is mutually promoted, i.e., both copper and ceria cooperate in the redox mechanism. 

The rules of stoichiometry also apply in this case. In electrochemical cells, we must consider not only the stoichiometry related to chemical formulas, but also the stoichiometry related to electric currents. The half-reaction under consideration not only involves 1 mol of each of the copper species, but also 2 mol of electrons. We can construct a mole ratio that includes moles of electrons or we could construct a mole ratio using faradays. A faradav (F) is a mole of electrons. Thus, we could use either of the following ratios for the copper half-reaction ... 

The effectiveness of dimethyl sulfide as an additive for the selective formation of anti-product 22 from propargyl epoxide 20 may be due to the formation of stabilized copper species, which are less prone to undergo electron transfer processes. In this respect, other soft ligands which bind strongly to copper, in particular phosphines and phosphites [8h-j, 25, 28], have been used even more frequently. These additives also serve to suppress the formation of a common side product, i.e. an allene containing a hydrogen atom instead of the carbon substituent which should... 

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