Presence Of CuCl Research Articles

Mechanistic studies of the catalytic reduction of nitric oxide by carbon monoxide in the presence of platinum(II), copper(I), and copper(II)

A rapid reduction of NO by CO to give N{sub 2}O and CO{sub 2} is catalyzed at low temperatures and pressures by an aqueous system comprised of K{sub 2}PtCl{sub 4}, CuCl{sub 2}, and CuCl, and HCl. Two platinum species , PtCl{sub 3}(CO){sup {minus}} and PtCl{sub 4}{sup 2{minus}}, were observed and characterized spectroscopically. Isotropic labeling studies by using {sup 18}O-enriched water as the solvent for the catalysis show that the CO{sub 2} evolved contains nearly the same {sup 18}O abundance as in the solvent. In contrast, no {sup 18}O from water is incorporated into the product N{sub 2}O. These observations clearly establish that both oxygens in Co{sub 2} strongly implies the presence of a rapid process of oxygen scrambling between coordinated CO and water. Indeed, PtCl{sub 3}(CO){sup {minus}} undergoes oxygen exchange with {sup 18}O-enriched water extremely rapidly without significant decomposition to give CO{sub 2} in the catalyst solution. The reaction of PtCl{sub 3}(CO){sup {minus}} with CO to give CO{sub 2} is also too slow to account for the CO{sub 2} production. However, by reaction with NO, PtCl{sub 3}(CO){sup {minus}} in the CuCl-CuCl{sub 2}-HCl system evolves CO{sub 2} and N{sub 2}O rapidly. The presence of CuCl{sub 2} or CuCl in the solutionmore » is required for the rapid gas production. This reaction is thought to be the process for N{sub 2}O and CO{sub 2} production in the catalysis. Consistent with the observed behavior of the system, the results of kinetic studies may be explained in terms of two kinetically distinguishable processes. One is the carbonylation of PtCl{sub 4}{sup 2{minus}} of which the rate shows first-order dependence on each of (PtCl{sub 4}{sup 2{minus}}), P{sub CO}, and (CuCl). The other process is the reaction of PtCl{sub 3}(CO){sup {minus}} with NO and water. Its rate is first order on (PtCl{sub 3}(CO){sup {minus}}), P{sub NO}, and (CuCl{sub 2}). 30 refs., 4 figs., 6 tabs.« less

Reaction of diazoalkanes with unsaturated compounds. 9 Catalyzed cyclomethylenation of trimethylsilylacetylenes by diazomethane

The catalyzed reaction of methyl-, propyl-, and cyclopropyltrimethylsilylacetylenes with diazomethane in the presence of CuCl leads to the corresponding cyclopropenes and bicyclobutanes with overall yields of up to 70%, and also to the products of incorporation of a methylene group into the C3-H bond of the cyclopropenes formed (2–9%). Partial catalyzed isomerization of the 1-trimethylsilyl-2-cyclopropylcyclopropene formed from trimethylsilylcyclopropylacetylene, into 1-trimethylsilyl-1-cyclopropylallene (yield ∼50%) was discovered to proceed under the reaction conditions.

Lineare Oligophosphaalkane, XXIV Synthese und strukturelle Charakterisierung von Cu8‐Mehrkernkomplexen mit Elektronenmangel‐Phosphidobrücken

Linear Oligophosphaalkanes, XXIV. – Syntheses and Structural Characterisation of Cu8 Complexes with Electron‐Deficient Phosphido BridgesReaction of silylphosphanes (Me3Si)RP–CH2–PR(SiMe3) (R = iPr, tBu, 2,4,6,‐Me3C6H2) with four equivalents of copper(1) halides CuX (X = Cl, Br) or a mixture of two equivalents of CuCl and Cul in the presence of pyridine as an auxiliary ligand affords octanuclear copper(1) complexes of composition Cu8X4(RP–CH2–PR)2(Py)n(CH3CN)m (n = 5, m = 0; n = 4, m = 1; X = Cl, Br, I). Multinuclear compounds of this type may also be obtained by deprotonation of the disecondary phosphanes HRP–CH2–PRH (R = iPr, Ph, 2,4,6‐Me3C6H2) with strong organic bases (DBU) in the presence of CuCl and pyridine. The X‐ray structural analysis of Cu8Cl4(iPr–P–CH2–PiPr)2(Py)5 (3a) (space group P21/c) reveals a Cu4(P–C–P)2 skeleton to which four CuCl(Py)n units (n = 1, 2) are coordinated by Cu–Cl and Cu–P bridges. The phosphorus atoms of the electron‐deficient μ3–PRR′ bridges formed thereby show a distorted trigonal bipyramidal coordination with almost planar PCu3 units. Due to the multiple bridging of the Cu(I) ions in 3a the Cu ⃛Cu distances in the Cu8 complex are relatively short (247.1–276.5 pm).

Vinylcyclopropanation of norbornadiene, norbornene, and dispiroheptadiene by methyl esters of 1-alkylcyclopropene-3-carboxylic acids

Methyl esters of 1-alkylcyclopropene-3-carboxylic acids (I) in the presence of CuCl·P(OPh)3cyclopropanate the intracyclic norbornene double bonds of norbornene, norbornadiene, and dispiroheptadiene to give the corresponding vinylcyclopropane adducts in yields up to 80%. 3,5-Dioxo-4-oxatricyclo[5.2.1. 02,6]dec-8-ene and 5-acetyl-7-oxabicyclo[2.2.1]hept-2-ene, which are heteroanalogs of dicyclopentadiene and norbornene, are inert relative to (I).

Copper-catalyzed conjugate addition of organomagnesium reagents to α,β-ethylenic esters: A simple high yield procedure.

The conjugate addition of organomagnesium reagents to α, β-ethylenic esters is performed in THF, at room temperature (30 min to 1.5 h), in the presence of CuCl (3%) and Me 3SiCl (1.2 eq.). Good yields of 1,4-addition products are obtained according to this very simple procedure.

Polymerization of factor B of the alternative complement pathway via disulfide bond(s) in the presence of Cu 2+ and stimulation by C3b, the major fragment of C3

Factor B (B) of the alternative complement pathway has been found to dimerize via disulfide bond(s) in the presence of CuCl 2. Poly B has no B activity. The Bb fragment was also dimerized, indicating that one free sulfhydryl group on the Bb portion might be involved in polymerization. The Ba fragment was not dimerized. C3b, the major fragment of C3, has the capacity to stimulate polymerization of B. Incubation of C3b, B and factor D in the presence of Mg 2+ and Cu 2+ resulted in the formation of poly B and diminished cleavage of B. These results suggest that polymerization of B due to Cu 2+ might be partly responsible for the impairment of C3 convertase activity of the alternative pathway.

Surface-enhanced Raman scattering observed on chlorinated Cu(111)

Surface-enhanced Raman scattering (SERS) has been observed for the first time on a Cu(111) surface chlorinated in ultra-high vacuum (UHV). The surface obtained preserves its capability to enhance Raman scattering for an indefinitely long time in UHV at sample temperatures T s<420 K. SERS in this case is shown to be associated with the presence of CuCl on the Cu(111) surface. Enhanced Raman spectra of pyridine adsorbed on chlorinated Cu(111) surface have been obtained.

Polymer complexes. VII. Polymerization of acrylonitrile in presence of some transition metal chlorides

AbstractThe polymerization of acrylonitrile was carried out in absence and in presence of CuCl2, CoCl2, NiCl2 and CdCl2. The formed polymer complexes were characterized by elemental analysis, IR and UV‐vis spectroscopy. The rate of polymerization of acrylonitrile increases in presence of CuCl2 and CdCl2, while no effect was observed with CoCl2 and NiCl2‐

Catalytic reaction of methyl diazoacetate with 1-methyl-2-alkenylpyrroles

1. The reaction of 1-methyl-2-alkenylpyrroles with methyl diazoacetate at 20–50°C in the presence of CuCl leads to the formation of both adducts of the carbene at the exocyclic double bond, namely, esters of (1-methyl-2-pyrrolyl)cyclopropanecarboxylic acids, and the products of the insertion of the carbene at the 5- and 4-C-H bonds of the pyrrole ring. 2. The competitive reactions method was used to show that the introduction of one or two methyl groups at the β-position of the vinyl group of 1-methyl-2-alkenylpyrroles reduces its relative activity by factors of 1.8 and 2.7, respectively, and increases the activity of the pyrrole ring by a factor of about 2.

Données complémentaires sur la synthèse, les proprietés spectroscopiques et la chimie du complexe [méthylènechlorophosphine]pentacarbonyltungstène

The thermal decomposition at 110° C of a 7-chloromethyl-7-phosphanorbornadiene PW(CO) 5 complex generates the transient terminal phosphinidene complex (ClCH 2PW(CO) 5] which can be trapped by tolane to give (1-chloromethyl-2,3-diphenylphosphirene) pentacarbonyltungsten. In contrast, in the presence of CuCl at 60° C, the terminal phosphinidene complex rearranges to give (methylenechlorophosphine) pentacarbonyltungsten which has been characterized by 1H, 13C, and 31P NMR spectroscopy. The huge 1 J(CP) coupling constant of 103.8 Hz establishes the presence of a PC double bond. This double bond reacts with HCl and α-enones to give the expected addition and [4 + 2] cycloaddition products. In the presence of AlCl 3, a fast reaction takes place with ferrocene to give the corresponding methyl-ferrocenyl-chlorophosphine complex.

ChemInform Abstract: Palladium Catalyzed Conversion of N,N′‐Diphenylurea into Carbamate Esters.

AbstractThe complex PdCl2(NH2Ph)2 catalyzes the conversion of (I) into (II) under CO/O2 (2:1) pressures at temp. higher than 100 °C. The reaction rate and yields grow with increasing CO and O2 pressures and in the presence of CuCl2(NH2Ph)2 as additional catalyst.

Palladium catalysed conversion of N, N′-diphenylurea into carbamate esters

PdCl 2(PhNH 2) 2 catalyses the conversion of N, N′-diphenylurea into alkyl N-phenylcarbamate under CO and O 2 pressures at temperatures higher than 100 °C. The reaction rate and yields grow with increasing CO and O 2 pressures and in the presence of CuCl 2(PhNH 2) 2. The conversion is accomplished through the following reactions: ▪ Due to a side reaction, some amounts of carbon dioxide are also obtained.

Treatment of diazoalkanes with unsaturated compounds. No. 5. Catalytic cyclopropanation of unsaturated hydrocarbons with diazoethane

The preparative catalytic cyclopropanation of unsaturated hydrocarbons with diazoethane has been achieved for the first time. Addition of the ethylidene fragment to the C=C double bond occurs in a nonstereoselective manner and leads to the formation of the corresponding methylcyclopropanes in 55–70% total yields. In the presence of CuCl, all double bonds of unsaturated hydrocarbons are cyclopropanated with equal facility, whereas in the presence of (PhCN)2PdCl2, preferential regioselective cyclopropanation of strained endocyclic and terminal double bonds is observed, just as was true in the case of reactions with diazomethane.

Amplification of prostaglandin E 2 stimulation of luteinizing hormone-releasing hormone release from median eminence explants: a metal(II)-specific effect of chelated copper

We have previously demonstrated that extracellular copper amplifies prostaglandin (PG) E 2 stimulation of the release of luteinizing hormone-releasing hormone (LH-RH) from explants of the median eminence area(MEA) 1. Two questions were addressed: what is the active form of copper and the metal(II) specificity for copper action? MEA explants were incubated for 5 min in the presence of CuCl 2 (ionic) or copper complexed to histidine (CuHis) at a concentration of 200 μM each and then for 15 min in the presence of 10 μM PGE 2. It was found that chelated copper but not ionic amplified PGE 2 action, and that the magnitude of PGE 2 stimulation of LH-RH release was 3–4 fold in copper-treated than untreated tissue. Moreover, PGE 2-stimulated release was directly related to the dose of CuHis. To test the metal specificity, MEA explants were incubated for 5 min with one of the following metal(II) complexes: CuHis, NiHis, FeHis, ZnHis, CdHis, MnHis, or BaHis (200 μM each) and then for 15 min with 10 μM PGE 2. Controls were incubated with metal(II) complex or PGE 2. Of these complexes, only CuHis and to a lesser extent NiHis stimulated LH-RH release. However, CuHis was the only complex that amplified PGE 2 stimulation of LH-RH release. Thus, amplification is specific for copper. The finding that chelated copper but not ionic copper amplifies PGE 2 is suggestive that the copper-interactive sites on the LH-RH neurons are not exposed to the extracellular space but that they are either embedded in the plasma membrane, facing the intracellular space, or in the cytoplasm. Such an orientation is consistent with copper modulation of the functional state of a postreceptor component involved in the cascade of events initiated by PGE 2 and leading to LH-RH release.

Involvement of prostaglandins in the effect of cupric ions on the human uterus

The effect of cupric ions on the human uterus and the involvement of prostaglandins (PGs) in mediating this effect was studied by recording of isometric contractions of isolated myometrial strips and pieces of uterine arteries, and by intrauterine pressure recordings in women before the onset of menstruation. In vitro , CuCl 2 in concentrations of 10 −4 M and higher caused a significant inhibition of myometrial contractile activity, but no effect on the artery preparations was seen. Furthermore, the contractile response of myometrial strips to PGF 2α and PGE 2 (10 ng/ml) decreased in the presence of CuCl 2 in concentrations of 5 and 50 μmol. In vivo , instillations of 0.3, 1.0 and 2.0 mM of CuCl 2 in 0.7 ml of saline solution into the uterine cavity caused a dose-dependent stimulation of uterine activity, but after pretreatment with naproxen, 500 mg orally, the effect of these substances was abolished. After naproxen treatment, but during infusion of PGF 2α (5 μg/min), the response to the CuCl 2 solutions was partially restored. It is suggested that cupric ions, at high concentrations, have an inhibiting effect on myometrial activity. The stimulatory effect of low doses of CuCl 2 seen after installation into the uterine cavity is largely exerted via initiation of synthesis and release of endometrial PGs.

Dimeric enzyme II mtl of the E. coli phospho enolpyruvate-dependent phosphotransferase system : Cross-linking studies with bifunctional sulfhydryl reagents

The occurrence of intermolecular dithiols on EII mtl has been studied with a number of thiol-specific crosslinking reagents. The reaction of EII mtl with bifunctional maleimide derivatives inactivates the enzyme. At the same time the enzyme is irreversibly cross-linked to a dimeric species. Under optimal conditions 50% of the protein is cross-linked upon reaction with the dimaleimides. The enzyme is also cross-linked under oxidizing conditions in the presence of CuCl 2, presumably by oxidizing an intermolecular dithiol to a disulfide. This oxidation can be reversed by the addition of the reducing agent dithiothreitol. The reaction of phosphorylated EII mtl with the same sulfhydryl-specific bifunctional reagents does not lead to any crosslinked product. The results are discussed in terms of the association state of the purified protein and the distribution of its thiol groups.

ChemInform Abstract: FOLATE ANTAGONISTS. 22. ANTIMALARIAL AND ANTIBACTERIAL EFFECTS OF 2,4‐DIAMINO‐6‐QUINAZOLINESULFONAMIDES

AbstractDie auf zwei Wegen zugänglichen Verbindungen (III) werden auf antibakterielle Aktivität sowie Antimalaria‐Wirkung untersucht.

Cyclization of the hydrazides of vicinal phenylethynyl derivatives of N-methylpyrazole-5-carboxylic and benzoic acids

1. The hydrazides of vicinal phenylethynyl derivatives of N-methylpyrazole-5-carbo-xylic and benzoic acids are respectively cyclized into 6,7-dihydro-6-amino-1-methyl-5-phenylpyrido[3,4-c]pyrazol-7-one and 2-amino-3-benzylideneisoindolin-1-one under the effect of bases. 2. The hydrazide of 4-phenylethynyl-1-methylpyrazole-5-carboxylic acid and the cyclic isomer of tolan-2-carboxylic acid hydrazide, 2-amino-3-benzylideneisoindolin-1-one, are isoraerized in the presence of CuCl with closure of the six-membered pyridazine ring. 3. 6,7-Dihydro-6-amino-1-methyl-5-phenylpyrido[3,4-c]pyrazol-7-one and 2-amino-3-benzylideneisoindolin-1-one are deaminated in oxidation with air in the presence of CuCl.

The solubility of silver chloride in ferric chloride leaching media

The solubility of silver chloride in various FeCl 3-FeCl 2-HCl solutions has been measured over the temperature range 20–100°C; the densities of the associated saturated solutions have also been determined. The solubility increases systematically with either rising temperature or increasing concentrations of the constituent chlorides. The solubility is higher in a ferrous chloride medium than in an equivalent ferric chloride solution. The presence of CuCl 2 systematically raises the AgCl solubility, but increasing ZnCl 2 concentrations cause the solubility to decrease slightly to about 1.5 M ZnCl 2 and subsequently to increase gradually. The addition of NaCl to the iron chloride media substantially increases the AgCl solubility under all conditions. Although the solubility of AgCI is only a few mg/L in cold water, this increases to over 1 g/L in hot, moderately concentrated chloride media. Silver chloride solubilities at elevated temperatures are sufficiently high that silver solubility limitations should not be a problem in most commercial ferric chloride leaching processes.

Is copper effect on glucose incorporation mediated by the insulin receptor in rat adipose tissue?

The insulin receptor is not the site for the stimulatory effect of copper on glucose incorporation into total lipids by adipose tissue; prewashing of adipose tissue of rats fed a stock diet in an insulin-free medium increases the glucose incorporation into total lipids in the presence of 0.1 unit insulin from 220 above control to 430% in the nondiabetic and from 154 to 230% in the streptozotocin-diabetic rat. In contrast, glucose incorporation in the presence of CuCl2 X 2H2O is unaffected by prewashing, being the same in the prewashed as in the unwashed adipose tissue. On the other hand, mild trypsin digestion of adipocytes decreases the glucose incorporation in the presence of 28.5 mU insulin, from 201 to 126% - whereas the effect of copper on glucose incorporation is the same in the trypsin-treated or untreated adipocyte. In order to obtain maximal copper effect the adipocyte has to be preconditioned by insulin; preincubation of diabetic adipose tissue first for one hour with 0.1 unit insulin, and another hour with 100 micrograms CuCl2 X 2H2O added to the medium, results in greater glucose incorporation (230% above control) than when incubated alone with either CuCl2 X 2H2O (125%) or insulin (154%) for two hours. In addition to its previously noted effect on the in vivo insulin release, copper increased the number of the insulin receptor sites in adipocytes.