Copper mercaptide

Mercaptans attack copper to form gel-like copper mercaptide compounds... 

C48H120CICU14N12O14S15.5 20 H2O, Chlorododeca(1,1-dimethyl-2-am-inoethanethiolato)tetradecacopper sulfate eicosa-hydrate, 46B, 1235 C48H120CICU14N12S12 3.5 S04 19 H2O, Copper mercaptide cluster, 42B, 953... 

Halothiophenes, which are not activated through the presence of —I—M-substituents, undergo substitution smoothly under more forcing conditions with copper salts in pyridine or quinoline. Hence 3-cyanothiophene and 5-methyl-2-cyanothiophene have been obtained from the corresponding bromo compounds. 2-Bromothiophene reacts readily with aliphatic cuprous mercaptides in quinoline at 200°C to give thioethers in high yields. The use of the copper-catalyzed Williamson synthesis of alkoxythiophenes from iodo- or bromo-thiophenes and alcoholate has been mentioned before. The reaction of 2-bromothiophene with acetanilide in nitrobenzene in... 

A range of metal catalysts can be employed with peroxygen species for the effective oxidation of sulfur compounds. For example, branched-chain high molecular weight mercaptans are difficult to oxidize with hydrogen peroxide. However, this difficulty is overcome if the reaction is conducted with hydrogen peroxide in the presence of a copper(II) salt.395 The formation of a copper(I) mercaptide followed by its oxidation are believed to be the key steps. 

The metals are bound to the peptide by mercaptide bounds and are arranged in two distinct clusters a four-metal cluster called the a domain and a three-metal cluster called cluster (3, at the C terminal of the protein. The a cluster is an obligate zinc cluster, whereas the zinc in cluster 3 may be replaced by copper or by cadmium. 

Many initiator-accelerator systems that contain accelerators other than amine have been suggested for vinyl pol3rmerization, but only a few have been employed in dental resins. Substitution of p-toluenesulfinic acid, alpha-substituted sulfones and low concentrations of halide and cupric ions for tertiary amine accelerators, yields colorless products (43-48). Most of these compounds have poor shelf-life. They readily oxidize in air to sulfonic acids which do not activate polymerization. Lauroyl peroxide, in conjunction with a metal mercaptide (such as zinc hexadecyl mercaptide) and a trace of copper, has been used to cure monomer-pol3rmer slurries containing methacrylic acid (49-50). Addition of Na salts of saccharine to monomer containing an N,N-dialkylarylamine speeds up pol)rmerization (51). 

Although considerable effort has gone into the preparation and structural determination of sulfur-containing copper complexes, definitive characterization of binuclear complexes containing a mercaptide bridge has proved exceedingly difficult. Two major problems which manifest this difficulty are the tendency for Cu(II) to readily oxidize mercaptans... 

Ethyl diphenylthiophosphinite, (CgH5)2P.SC2Hg, is the condensation product of diphenylchlorophosphine and sodium ethyl mercaptide. It is a liquid, B.pt. 196 5° to 197° C. at 13 mm., density 1-1330. It gives double salts with copper halides. The by-product in... 

Most mercaptides are not available as commercial products, since large-scale applications of these chemical compounds are quite limited (only mercaptides of tin and antimony are used industrially as thermal stabilizers for poly(vinyl chloride) [de Sousa et al., 2000 Qu L. et al., 2002]). However, these compounds can be synthesized in a very simple way. Owing to their low water solubility, mercaptides can precipitate by reacting thiols (or thiophenols) with aqueous solutions of the corresponding metal salts. In addition to the well-known mercaptides of mercury, lead, zinc, and copper, many others, such as mercaptides of silver, gold, platinum, palladium, iridium, nickel, iron, cobalt, antimony, bismuth, and cadmium, have been prepared. 

Copper acetate (Cu(OOCCH3)2, Aldrich) and dodecanethiol (CH3(CH2)nSH, Aldrich) were used to synthesize copper(I) dodecylmercaptide. The salt was dissolved in ethanol and mixed with an alcoholic solution of thiol at room temperature. A green mercaptide precipitate was isolated by vacuum filtration and washed by acetone. Copper(I) dodecylmercaptide was obtained in a similar way, starting from copper(I) chloride (CuCl, Aldrich). 

The formation of a dimer provides a two-electron template on which direct oxidation to the mercaptide can occur. After redox the copper(i) complex is stabilized by further co-ordination of thiol. 

A detailed analysis of the structural effect of thiols on their rate of oxidation is probably unrewarding because of several uncertainties like partition coefficients of the thiols and metal complexes between the aqueous and disulphide phases and, perhaps more important, the degree of contamination of the solutions by other heavy metals due to the well-known ability of metal mercaptides to distil together with thiols . It has to be noticed that the nominal uncatalysed rate is not as small as could be expected in respect to the catalysed rates and that concentration of copper ions of the order of 1 x 10 M is more effective than that of other metals at the nominal concentration of 1 x 10 M. 

Further recent papers concerning metal complexes of thio-analogues of j3-diketones deal with the preparation of the cobalt(n) complex of 1,3-diacetylthioacetone, the synthesis and properties of a series of metal complexes of dithioacetylacetone, the synthesis of the nickel(n) complexes of monothio- and dithio-dibenzoylmethane (67) by the nucleophilic cleavage of 1,2-dithiolium salts by hydroxide or mercaptide ions in the presence of nickel(ii) ions, the bromination of the cobalt(m) complex of monothioacetylacetone (68) with iV-bromosuccinimide to yield (69), and the application of monothiodibenzoylmethane as an analytical reagent for quantitative determination of copper. ... 

Thioesters, Selenoesters, and Thioamides.—Commercially available phenyl dichlorophosphate has been reported to be a superior reagent to MV-dimethyl-phosphoramidic dichloride (4, 244) for the preparation of thioesters directly from carboxylic acids and thiols. Carboxylic acid chlorides can be efficiently converted into thioesters by reaction with adducts formed between thiols and l-methylpyridine-3,5-dicarboxylates. Alternatively, copper(i) mercaptides, formed from thiols and CuaO, or thallous thiophenoxide can be used. The latter method can also be used to prepare selenoesters as well as a-phenylthio-and a-phenylseleno-acids and esters from a-halo-acids and a-halo-esters, respectively. 

Hughey JL, Fawcett TG, Rudich SM, Lalancette RA, Potenza JA, Schugar HJ. 1979. Preparation and characterization of [rac-5,7,7,12,14,14-hexamethyl-l,4,8,ll-tetraazocyclotetradecane]copper(II) o-mercaptobenzoate hydrate, [Cu(tet b)(o-SC6H4C02)] H20, a complex with a C11N4S (mercaptide) chromophore. J Am Chem Soc 101 2617-2623. 

The thiols can act as chelators and bind heavy metal ions through mercaptide formation. The chelation may also involve the amino group. Copper-chelation by penicillamine, changes in copper metabolism and altered concentrations of coppercontaining proteins like ceruloplasmin and altered activity of the copper-dependent superoxide dismutase (an intracellular enzyme for removal of toxic superoxide radicals) may be of importance. Chelation of copper may also increase the prostaglandin E/f ratio, which is assumed to have an anti-inflammatory effect. 

Sodium mercaptides are prepared from the mercaptans and aqueous or alcoholic solutions of sodium hydroxide or alcoholic sodium eth-oxide. The sodium mercaptide reacts with halides, chlorohydrins, esters of sulfonic acid, or alkyl sulfonates [6] to give sulfides in yields of 70% or more. A recent report describes a general procedure for synthesizing aryl thioesters by a nucleophilic displacement of aryl halide with thiolate ion in amide solvents. No copper catalysis is necessary as in an Ullmann-type reaction. 

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