Copper thiourea salts

Localized deposits containing copper and copper oxides demand a high local concentration of thiourea, and if an inadequate excess of thiourea is present to complex the cuprous ion, precipitation of the insoluble, white copper-thiourea monochloride salt may occur. 

There also exists a considerable number of ionic tris(thiourea) complexes. Thiourea is capable of reducing copper(II) salts to copper(I) complexes in acid solution to form [Cu(thiourea)3] salts. The following have been isolated chloride (194, 195), nitrate (194), oxalate (194, 195, 298), monohydrogen arsenate, and phosphate (298). 

Aquothiourea complexes are produced by hydrolysis of thiourea-copper(I) salts, e.g., [Cu(SC(NH2)2 2H20]X (X = NO3, HSO4, CIO4, iC204) (195). 

Recently copper(i) salts including thiolates have been studied as nucleophiles. Copper(i)butanethiolate and copper(i)cyanide in DMF did not react with t-butyl chloride or benzyl chloride, but halogenoaromatic compounds react under similar conditions. When the reactions were repeated in the presence of thiourea or quinoline, the expected products, di-t-butyl sulphide, valeronitrile and phenylacetonitrile, were obtained. The thiourea or quinoline probably act as ligands and bind strongly to the copper, forming the ion (CuL4)+, leaving the counterion (e.g. BuS from CuSBu) available for normal nucleophilic attack . 

Protein-Based Adhesives. Proteia-based adhesives are aormaHy used as stmctural adhesives they are all polyamino acids that are derived from blood, fish skin, caseia [9000-71 -9] soybeans, or animal hides, bones, and connective tissue (coUagen). Setting or cross-linking methods typically used are iasolubilization by means of hydrated lime and denaturation. Denaturation methods require energy which can come from heat, pressure, or radiation, as well as chemical denaturants such as carbon disulfide [75-15-0] or thiourea [62-56-6]. Complexiag salts such as those based upon cobalt, copper, or chromium have also been used. Formaldehyde and formaldehyde donors such as h exam ethyl en etetra am in e can be used to form cross-links. Removal of water from a proteia will also often denature the material. 

Antongst other confounds which function as accelerators with diazonium salts are thiourea dioxide (formamldine sulfinic acid), and p-tolylhydrazine. whilst copper is the most efficient of the metal ions, catalytic qviantities giving a large Increase in R, some other transition metals have a marked effect. These include titanic sulfate and vanadyl sulfate. 

Interesting cases of deposition concern compounds where the oxidation state of the metal can take different values, such as copper or tin. Several reports concern the formation of CuxS with x between 1 and 2 [18, 47-50]. Varkey et al. [48] show that cuprous sulfide (CU2S) is formed in TU solutions, using a Cu(I) precursor (CuCl). However it can be obtained also when starting from a cupric salt (Cu(II)) due to the reducing properties of thiourea (and other sulfur precursors) as shown by Nair et al. 

Copper salts are reasonably soluble over a wide pH range, but In and Ga salts only exhibit solubilities above ImM at pH < 3 for In and at pH < 1.5 for Ga (82). Rotating disk electrode experiments show that Cu deposits under mass transfer-controlled conditions on Mo, whereas In deposits under kinetic control at room temperature. There are a few reports on electrodeposition of Cu/In or In/Cu stacks for the realization of CIS semiconductor compounds [83, 84). One technologically interesting report from Penndorf et al. [83] describes the use of copper tape as both the substrate and source of Cu for the formation of CuInS2. Indium was electrode-posited on the copper tape in a roll-to-roU process with remarkably high current densities of 150-200 mAcm with the help of thiourea. CeU efficiencies of up to 6% were reported with this approach. 

Quite recently, Guibal and his research team (Butewicz et al., 2010) have irrrmo-bilized thiourea onto chitosan the new polymer was employed for the sorption and recovery of platinum and palladitrm from acidic solutions (up to 1-2 M HCl concentrations). The kinetics of the sorption process was investigated and the pseudo-second rate equation was used for modehng the uptake kinetics. Similarly, Chanthateyanonth et al. (2010) reported the successful immobilization of vinyl sirlfonic acid sodium salt onto dendritic hyper branched chitosan. The new chitosan derivatives displayed improved water solrrbility as compared to the starting material. In addition, the new material showed better antimicrobial activity and chelating behavior with cadmium(II), copper(II), and nickel(II) than chitosan itself. 

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