Copper complexes sulfides

Phenol-4-sulfonic acid, 2-(2-hydroxynaphthyl-l-azo)-copper complexes, 6, 55 Phenolysis metal sulfides, 2, 342 Phenylalanine... 

The mixture is then chilled in an ice bath for at least 3 hours, and the olive-brown precipitate of the sparingly soluble copper complex of imidazole derivatives is filtered. The product is washed with about 500 ml. of cold water, suspended while moist (Note 4) in 11. of water, and rendered just acid to litmus by the addition of concentrated hydrochloric acid (about 40 ml.). Hydrogen sulfide is then passed into the suspension, with frequent shaking, until precipitation of the copper is complete (2-3 hours). The precipitate is filtered and extracted with 500 ml. of hot water in two or three portions. The clear, light brown to reddish brown filtrate and washings are boiled for 15 minutes, and then 60 g. (0.26 mole) of picric acid is added with stirring heating is continued until solution is complete. 

Harvey, T. J. Yen, W. T. Paterson, J. G. Selective zinc extraction from complex copper-zinc sulfide concentrates by pressure oxidation. Miner. Eng. 1992, 5, 975-992. 

A still more complicated reaction is the chemiluminescent oxidation of sodium hydrogen sulfide, cysteine, and gluthathione by oxygen in the presence of heavy metal catalysts, especially copper ions 60>. When copper is used in the form of the tetrammin complex Cu(NH3) +, the chemiluminescence is due to excited-singlet oxygen when the catalyst is copper flavin mononucleotide (Cu—FMN), additional emission occurs from excited flavin mononucleotide. From absorption spectroscopic measurements J. Stauff and F. Nimmerfall60> concluded that the first reaction step consists in the addition of oxygen to the copper complex ... 

Solubility data (pA sp) for two dozen hexacyanoferrate(II) and hexacyanoferrate(III) salts, and Pourbaix (pe/pH) diagrams for iron-cyanide-water, iron-sulfide-cyanide-(hydr)oxide, iron-arsenate-cyanide-(hydr)oxide, and iron-copper-cyanide-sulfide-(hydr)oxide, are given in a review ostensibly dedicated to hydrometallurgical extraction of gold and silver. " The electrochemistry of Prussian Blue and related complexes, in the form of thin films on electrodes, has been reviewed. ... 

When heated with nitric acid, copper(l) sulfide decomposes forming copper nitrate and hydrogen sulfide. The compound dissolves in aqueous solutions containing cyanide ions forming soluble copper-cyanide complexes. 

Synthesis. The first known thiophene-based metal dithiolenes were reported by Gol dfarb and Kalik in 1968." These consisted of the nickel and copper complexes of 2,3-thiophenedithiolate produced from ethyl 3-thienyl sulfide as shown in Scheme 1. Both complexes were reported as black, high melting solids and were thought to be the neutral bis(2,3-thiophenedithiolate) species. 

V to IX), the copper complexes of the imidazoles also precipitated from the reaction mixture, and were filtered off. Oxalic acid and 4(5)-imidazole (30) were determined in the filtrate.11 40,41 The complex was suspended in hot water,11,29 32-40,41,43 47 50 53,88 dilute sulfuric acid,48,49 or dilute hydrochloric acid,44 the copper was removed as the sulfide, with hydrogen sulfide or sodium sulfide,49 and the excess of hydrogen sulfide was removed with lead acetate.11 40 41,50 The clear... 

Few accounts of the reactions of coordinated ligands have been published. One recent report indicates that the copper complex of S-methylmethionine yields the copper complex of a-amino-y-butyrolactone and dimethyl sulfide upon heating.8 ... 

Silver is widely distributed throughout the world. It rarely occurs in native form, but is found in ore bodies as silver chloride, or more frequently, as simple and complex sulfides. In former years, simple silver and gold-silver ores were processed by amalgamation or cyanidation processes, The availability of ores amenable to treatment by these means has declined. Most silver is now obtained as a byproduct or coproduct from base metal ores, particularly those of copper, lead, and zinc. Although these ores are different in mineral complexity and grade, processing is similar. 

The final step in the reaction involves demetallation of the organic product by H2S with the resultant loss of copper(n) sulfide. The reaction is not quite as simple as it appears, and the intermediate copper(n) complex which is demetallated is not of the expected... 

Figure 4. Concentrations in a model of seawater chemistry including the copper sulfide reactions, a) n = 1 with Kj = 1010 and a value R - 10s for the ratio of organic copper complexes to Cu2+. b) n = 2 with K2 = 1020, R = 105.

In the treatment of complex sulfide concentrates containing copper, nickel, cobalt, lead, and iron, roasting with a moderate excess of sodium chloride at temperatures up to 400°C prior to leaching with hydrochloric acid has been succeasfully used by Kershner and Hoertel (K4) in the recovery of more than 95% of cobalt, nickel, and copper. The chloridized product is treated with steam at 300°C to make most of the iron insoluble before leaching at a pH of 1.0. The advantages of a salt roast prior to... 

Copper-mediated sulfide elimination can lead to ring opening reactions. The hydroxy thioacetal 83, when treated first with n-BuLi and then with CuOTf afforded 84 in 92 % yield via a Grob fragmentation (Sch. 21) [47]. Two equivalents of the Lewis acid were required for the reaction because one equivalent complexes the alk-oxide and a second is necessary to activate the sulfide for elimination. Ring enlargement occurred upon treatment of 85 with CuOTf in benzene through the intermediacy of the thio-substituted epoxide 86 [48]. a-Phenylthiocyclohexanone 87 was obtained in 83 % yield. 

To an ice-cold soln of lysine-Cu(II) complex 5 (5.2 g, 14.9 mmol see Section 2.1.2.2.1.1) in 1 M NaOH (60 mL) and MeOH (60 mL) was added ethyl formate (24 mL, 298 mmol), and the mixture was stirred vigorously for 2 h with ice-cooling. The pH was maintained between 8 and 9 by addition of 5 M NaOH. The organic solvent was removed, and the precipitated copper complex was filtered off and washed with several portions of H2O. The complex was suspended in H2O, H2S was passed through the solution and the copper sulfide was removed by filtration with the aid of Norite and Filter-cel. The filtrate was concentrated to a small volume, and EtOH was added to bring about crystallization. The crystals were collected, dissolved in a small volume of HjO and recrystallized by addition of EtOH yield 1.72 g (33%) mp 214-215 °C (dec) -Hl.l (c 0.91, H2O) -1-15.5 (c 1.4, sat. aq NaHCOs). 

These collectors are effective only under oxidizing conditions, and it is generally accepted that the species that confers hydrophobicity on the mineral surface is either a chemisorbed metal thio compound or the oxidized form of the collector, dithiolate. The amounts of each species formed will depend on the relative stabilities of the metal—sulfur and sulfur—sulfur bonds. The formation of four-membered chelate rings is also possible with soft metal ions such as copper(I) because the largely covalent character of the bond in this instance is able to overcome the strain within the ring by extensive electron delocalization. This could account for the >artial selectivity of some of these reagents for the copper minerals, which has been put to good use in the sequential flotation of copjrer, lead and zinc from complex sulfide ores. ... 

Bleomycin is obtained as an equimolar complex with cupric ion. The copper can be removed by treatment with hydrogen sulfide in methanol solution to give a colorless metal-free BLM, which can be reconverted to the natural copper complex by addition of cupric ion to the aqueous solution, although there are many potential coordination sites in the molecule. Both metal-free and copper-chelated BLMs inhibited growth of microorganisms and mammalian cells, but DNA strand cleavage in vitro was caused only by metal-free BLM, not by the copper-complex. 

---