Presence Of Cupric Chloride Research Articles

Selenium-binding protein 1 (SELENBP1) is a copper-dependent thiol oxidase

Selenium-binding protein 1 (SELENBP1) was reported to act as a methanethiol oxidase (MTO) in humans, catalyzing the conversion of methanethiol to hydrogen peroxide, hydrogen sulfide and formaldehyde. Here, we identify copper ions as essential to this novel MTO activity. Site-directed mutagenesis of putative copper-binding sites in human SELENBP1 produced as recombinant protein in E. coli resulted in loss of its enzymatic function. On the other hand, the eponymous binding of selenium (as selenite) was no requirement for MTO activity and only moderately increased SELENBP1-catalyzed oxidation of methanethiol. Furthermore, SEMO-1, the SELENBP1 ortholog recently identified in the nematode C. elegans, also requires copper ions, and MTO activity was enhanced or abrogated, respectively, if worms were grown in the presence of cupric chloride or of a Cu chelator. In addition to methanethiol, we identified novel substrates of SELENBP1 from the group of volatile sulfur compounds, ranging from ethanethiol to 1-pentanethiol as well as 2-propene-1-thiol. Gut microbiome-derived methanethiol as well as food-derived volatile sulfur compounds (VSCs) account for malodors that may contribute to extraoral halitosis in humans, if not metabolized properly. As SELENBP1 is particularly abundant in tissues exposed to VSCs, such as colon, liver, and lung, it appears to contribute to copper-dependent VSC degradation.

Performance enhancement of commercial ultrafiltration polysulfone membrane via in situ polymerization of aniline using copper chloride as a catalyst

AbstractBACKGROUNDPolyaniline is well known for enhancing hydrophilicity and antifouling properties, which could be beneficial for protein separation processes in membranes. The development of polyaniline in the presence of cupric chloride as an oxidant was a target for better distribution.RESULTSBiofouling‐resistant hydrophilic membrane surfaces were developed via in situ polymerization of aniline on a polysulfone membrane surface. Membrane surface modifications were made with various percentages of monomer (0.5, 1 and 2%). All the modified membranes exhibited improved membrane surface properties. The modified membrane (Poly(Sulf‐Ani‐2)) containing 2% aniline as a monomer in polymerization solution showed the best hydrophilicity, exceptional permeability and better protein rejection ability as well as enhanced anti‐biofouling property.CONCLUSIONSIn situ polyaniline attachment might be an easy and beneficial technique for the fabrication of hydrophilic membrane surfaces for large‐scale industrial applications. The attachment of polyaniline on polysulfone membrane surfaces through in situ polymerization in the present study proved to be an advanced approach for crafting better membranes with considerable hydrophilicity and fouling control enhancement.

Comparative Analysis of Crystal Structures between 2,2′-Bipyridine and 6,6′-Dimethyl-2,2′-Bipyridine Supported CuSCF3 Complexes: An Unusual Coordination Transition from Mononuclear to Binuclear Mode

We report herein the synthesis of CuSCF3 complex supported by 6,6′-dimethyl-2,2′-bipyridine via the strategy of triphenylphosphine-mediated deoxygenation of CF3SO2Na in the presence of cuprous chloride. The molecular structure of this new cuprous complex was characterized by elemental analysis, 1H (13C, 19F) NMR spectra and verified by X-ray crystallography. Unlike the classical [(2,2′- bipyridine)Cu(SCF3)] complex, 6,6′-dimethyl-2,2′-bipyridine supported cuprous trifluoromethylthiolate complex was dimerized in the form of [{(6,6′-dimethyl-2,2′-bipyridine)Cu(SCF3)}2]. The X-ray crystal structure revealed the Cu2S2 cyclic pattern and sulfur atoms serving as the bridge. The Cu-Cu distance was equal to 3.083 Å which was remarkably longer than the analogous [{(1,10-phenanthroline)Cu(SCF3)}2] (2.5781(9) Å). This interesting phenomenon demonstrated that the substituents on the ligand scaffolds have profound influence on the coordination modes of these N,N-ligand coordinated CuSCF3 complexes.

A combined experimental and theoretical study of the thermal [3+2] cycloaddition of carbonyl ylides with activated alkenes

4-Benzoyl-3,5-diaryltetrahydrofuran-2,2-dicarbonitriles were first synthesized from 2,2-dicyano-3-aryloxiranes and chalcones at toluene reflux; the 4,5-cis products proved to be predominantly formed and were isolated. Whereas shortened reaction times were observed by using microwave irradiation or catalytic cuprous chloride, no significant stereoselectivity change was in general noticed. Reacting 2,2-dicyano-3-aryloxiranes with 2-cyclopentenone next afforded 3-aryl-4-oxohexahydro-1H-cyclopenta[c]furan-1,1-dicarbonitriles, and the endo stereoisomers were isolated. That no stereoselectivity change was noticed in the presence of cuprous chloride rather suggests an impact of the salt on the epoxide ring opening. Finally, treatment of 2,2-dicyano-3-aryloxiranes by 2-morpholinoacrylonitrile yielded 3-cyano-3-morpholino-5-phenyltetrahydrofuran-2,2-dicarbonitriles from which the preponderant trans isomers were isolated. Importantly, the molecular mechanism of the domino reaction between 2,2-dicyano-3-phenyloxirane and 2-cyclopentenone was studied. The rate-determining thermal ring opening of the oxirane is followed by a non-concerted pseudoradical-type reaction of the carbonyl ylide with 2-cyclopentenone. Using the bond evolution theory also allowed the regioselectivity of this non-polar reaction to be explained.

Chalcopyrite dissolution using seawater-based acidic media in the presence of oxidants

Due to water shortages and depletion of both surface water and underground aquifers, seawater is now used increasingly in the mining industry in northern Chile as a main alternative water resource. In this paper, the use of seawater in leaching of the chalcopyrite ore samples with copper grade of 1.6% in acidic media is investigated. Different leach solutions were prepared using different acids (H2SO4, HCl and HNO3) with and without seawater. Cupric chloride and ferric chloride were added as oxidant in the leaching process.Leaching tests were conducted in the agitated leaching reactors with 400 RPM using 100g of the representative ore sample and 1L of leach solution at 45°C, with duration of 7days. The ore was ground to P80 of 62.5μm. The maximum copper extraction of 37.7% was obtained in the test performed using hydrochloric acid in the seawater-based media and in the presence of cupric chloride. In the leaching test conducted using sulfuric acid in the seawater-based media and in the presence of sodium chloride and cupric chloride, the maximum copper recovery of 34.2% obtained. In all of the different designed leaching approaches, the highest copper extraction was obtained in the tests performed with addition of the cupric ions (Cu2+). In general, copper extraction in the leaching tests performed using seawater-based acidic media, were higher than those conducted in the pure water-based leaching media. Only exceptions observed when chloride ions (sodium chloride) were added externally. This indicated the importance of chloride ions presence in the leach solution.

Copper-catalyzed arylation of tetrazole-5-thiones upon convection heating and microwave activation conditions

The arylation of 1-phenyltetrazole-5-thione using a series of iodobenzene derivatives in the presence of cuprous chloride and a ligand such as ethylenediamine. It was shown that the use of microwave activation permitted shortening of the reaction time, increasing yields and simplification of the reaction products isolation.

Oxidative Dimerisation of Isoflavones: Synthesis of Kudzuisoflavone A and Related Compounds

Kudzuisoflavone-A was successfully synthesised via oxidative dimerisation of daidzein in the presence of cuprous chloride. Appropriately substituted isoflavones also undergo regioselective oxidative dimerisation when treated with thallium trifluoroacetate to give novel 6′,6′″-biisoflavones in good yield. A rationale for the regioselectivity is proposed.

Electron Transfer and Aggregate Formation Coinduced Emission Enhancement of 9-Cycloheptatrienylidene Fluorenes in the Presence of Cupric Chloride

A series of 2,7-diaryl-9-cycloheptatrienylidene fluorenes (9-CHFs) were synthesized, and their structures were confirmed by spectroscopic methods. By cooperation with cupric chloride in tetrahydrofuran, 9-CHFs exhibited emission enhancement at locally excited (LE) band and aggregation induced emission at lower energy band when the solution was excited at two different wavelengths. By kinetically tracking the process via absorption, emission, dynamic light scattering, and TEM photography, it could be concluded that electron transfer from 9-CHFs to cupric cation and the aggregate formation coinduced the turn-on luminescence. Based on the study of the fluorescent structure−property relationship, the investigation of anion effect, and the analysis of X-ray diffraction, it was revealed that electrostatic interactions and intermolecular C−H...π interactions resulted in aggregates formation and thereafter restricted the intramolecular free rotation of σ-bonds, which finally increased the quantum yields at two ba...

ChemInform Abstract: Synthesis of Functionalized p-Phenylene Oxide Oligomers

Abstract Oligomers of p-phenylene oxides have been synthesized by coupling of substituted phenols and aryl bromides in the presence of cuprous chloride. The chain length varies from 2 to 5 phenyl rings functionalized at one end by an OH and OMe group and at the other end by an OH, OMe or NO2 functions. The oligomers could be used in material science and as building blocks in supramolecular chemistry. Methods for chemoselective demethylation of methoxy groups were developed.

Synthesis of heterocycles on the basis of arylation products of unsaturated compounds. 19.* Arylation of 2-acetylthio- phene and the synthesis of 2-(5-aryl-2-thien- yl)-4-quinolinecarboxylic acids

The reaction of 2-acetylthiophene with acetylthiophene with arenediazonium chlorides in the presence of cupric chloride as catalyst gives 2-acetyl-5-arylthiophenes. These products react with 5-chloro- and 5-bromoisatins to give 6-chloro- and 6-bromo-substituted 2-(5-aryl-2-thienyl)-4-quinolinecarboxylic acids.

Brush Type Copolymers of Poly(3‐hydroxybutyrate) and Poly(3‐hydroxyoctanoate) with Same Vinyl Monomers via “Grafting From” Technique by Using Atom Transfer Radical Polymerization Method

AbstractBrush type graft copolymers of poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxyoctanoate) (PHO) with methylmethacrylate, (MMA), styrene, (S), and n‐butylmethacrylate, (n‐BuMA) were obtained by using Atom Transfer Radical Polymerization Method, (ATRP), via “grafting from” technique. Firstly PHB and PHO were chlorinated by passing chlorine gas through their solution in CHCl3/CCl4 (75/25 v/v) mixture and CCl4, respectively, in order to prepare chlorinated PHB, PHB‐Cl, and chlorinated PHO, PHO‐Cl, with different chlorine contents. The determination of the chlorine content in chlorinated poly(3‐hydroxyalkanoate) (PHA‐Cl) was performed by the Volhard Method. Then ATRP of vinyl monomers was initiated by using PHA‐Cl as macroinitiators in the presence of cuprous chloride (CuCl)/2,2′‐bipyridine complex as catalyst, at 90 °C in order to obtain brushes containing PHAs. The polymer brushes were fractionated by fractional precipitation methods and the γ values calculated from the ratio of the volume of nonsolvent (methanol) and the volume of solvent (chloroform) of brushes varied between 0.82 and 6.50 depending on the composition of brushes. The polymer products were characterized by gel permeation chromatography (GPC), 1H NMR, FTIR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques.

Preparation of 1H‐1,2,3‐Triazoles by Cuprous Ion Mediated Cycloaddition of Terminal Alkyne and Sodium Azide

Abstract1H‐1,2,3‐triazoles can be prepared in good yield by the reaction of terminal alkyne and sodium azide in the presence of cuprous chloride at a temperature higher than 70°C. The alkyne is unactivated and the reaction has to be carried out under inert gas. At room temperature, the reaction first gives a Cu(I)‐azide complex which is converted to a Cu‐alkyne complex when the temperature is raised to higher than 70°C. The reaction of Cu(I)‐alkyne complex and azide ion dissociated from or coordinated to Cu(I) then gives 1H‐1,2,3‐triazoles.

Palladium‐Catalyzed Enyne Cyclization of 2′‐Alkenyl 2‐Alkynoates in Imidazolium‐Type Ionic Liquids

The use of [bmim][BF4], [bmim][PF6], and [bmim][Cl] ILs as the solvents in Pd(II)‐catalyzed enyne cyclization of 2′‐alkenyl 2‐alkynoates in the presence of cupric chloride has been investigated. The Z/E stereoselectivity of the reaction could range from 90:10 to 4:96 by tuning the amount of LiCl in ILs. After the separation of the product, the IL–catalyst mixture could be recovered by treatment with hydrochloric acid and recycled several times without an obvious loss of catalytic activity.

Synthetic studies on novel benzimidazolopeptides with antimicrobial, cytotoxic and anthelmintic potential

Four substituted benzimidazolyl-benzoic/salicylic acids 5-8 were synthesized by interaction of 5,6-dimethyl-/6-nitrobenzimidazoles with diazotized substituted/unsubstituted aminobenzoic acids in the presence of cupric chloride. The coupling of compounds 5-8 with different amino acid ester hydrochlorides/dipeptide/tripeptide/tetrapeptide methyl esters afforded novel benzimidazolopeptide derivatives 5a-f, 6a-h, 7a-g and 8a-g. The structures of all newly synthesized compounds were established on the basis of analytical, IR, (1)H NMR, (13)C NMR and mass spectral data. Selected peptide ester derivatives were further hydrolyzed by using lithium hydroxide (LiOH) to yield corresponding acid derivatives 5b(a)-d(a), 6e(a)-g(a), 7c(a)-e(a) and 8e(a)-g(a). All peptide derivatives were screened for their antimicrobial, anthelmintic and cytotoxic activities. Almost all newly synthesized benzimidazolopeptides have shown moderate to good anthelmintic activity against all three earthworm species and good antimicrobial activity against pathogenic fungal strains Candida albicans and Aspergillus niger, gram negative bacterial strains Pseudomonas aeruginosa and Escherichia coli. Compounds 8g and 8g(a) possessed significant cytotoxic activity against Dalton's lymphoma ascites (DLA) and Ehrlich's ascites carcinoma (EAC) cell lines.

Glaser Coupling Reaction without Organic Solvents and Bases under Near‐critical Water Conditions

AbstractA Glaser coupling reaction of terminal alkynes in the presence of cupric chloride without organic solvents and bases under near‐critical water has been developed.

Coffee increases levels of urinary 8-hydroxydeoxyguanosine in rats

We examined whether coffee or chlorogenic acid inhibits 8-hydroxydeoxyguanosine (8-OHdG), one of the major forms of oxidative DNA damage, in vivo and in vitro. Forty-eight male Wistar rats were assigned to three treatment groups: a control-diet group ( n=16; coffee-free diet), a 0.62% coffee-diet group ( n=16, dose of coffee consumed 125 mg/day), and a 1.36% coffee-diet group ( n=16, dose of coffee consumed 275 mg/day) and were maintained on an experimental diet for 130 days. The coffee-diet resulted in significantly increased excretion of urinary chlorogenic acid, with the 0.62 and 1.36% coffee-diets resulting in 14.00±0.94 and 15.80±0.41 ng/mg creatinine, respectively, whereas in control rats it was not detected. Using monoclonal antibody to measure 8-OHdG, it was revealed that coffee led to a significant increase in excretion of urinary 8-OHdG on day 130 (46.62±13.42 ng/mg creatinine in 0.62% coffee-diet group and 64.58±20.15 ng/mg creatinine in 1.36% coffee-diet group, P<0.05 vs. control; control group 10.89±2.59 ng/mg creatinine). Furthermore, to clarify the mechanism of 8-OHdG formation by coffee, we investigated the in vitro effect of chlorogenic acid on 8-OHdG formation in human placental DNA. Chlorogenic acid alone did not lead to an increase of 8-OHdG formation, but dramatically increased it in the presence of cupric chloride and H 2O 2. However, chlorogenic acid and cupric chloride decreased the formation of 8-OHdG in the presence of H 2O 2. Based on these results, a possible mechanism of 8-OHdG formation in vivo by chlorogenic acid is discussed.

An improved procedure for N- to C-directed (Inverse) solid-phase peptide synthesis.

A method for solid-phase peptide synthesis in the N- to C-direction that delivers good coupling yields and a low degree of epimerization is reported. The optimized method involves the coupling, without preactivation, of the resin-bound C-terminal amino acid with excess amounts of amino acid tri-tert-butoxysilyl (Sil) esters, using HATU as coupling reagent and 2,4,6-trimethylpyridine (TMP, collidine) as a base. For the amino acids investigated, the degree of epimerization was typically 5%, except for Ser(t-Bu) which was more easily epimerized (ca. 20%). Five tripeptides (AA(1)-AA(2)-AA(3)) with different properties were used as representative model peptides in the development of the synthetic method: Asp-Leu-Glu, Leu-Ala-Phe, Glu-Asp-Val, Asp-Ser-Ile, and Asp-D-Glu-Leu. The study used different combinations of HATU and TBTU as activating agents, N, N-diisopropylethylamine (DIEA) and TMP as bases, DMF and dichloromethane as solvents, and cupric chloride as an epimerization suppressant. The epimerization of AA(2) in the coupling of AA(3) was further reduced in the presence of cupric chloride. However, the use of this reagent also resulted in a decrease in loading onto the resin and significant cleavage between AA(1) and AA(2). Experiments indicated that the observed suppressing effect of cupric chloride on epimerization in the present system merely seemed to be a result of a base-induced cleavage of the oxazolone system, the key intermediate in the epimerization process. Consequently, the cleavages were most pronounced in slow couplings. An improved synthesis of fully characterized amino acid tri-tert-butoxysilyl (Sil) ester hydrochloride building blocks is presented. The amino acid Sil esters were found to be stable as hydrochlorides but not as free bases. Although only a few peptides have been used in this study, we believe that the facile procedure devised herein should provide an attractive alternative for the solid-phase synthesis of short (six residues or less) C-terminally modified peptides, e.g., in library format.

One-pot enantioselective synthesis of optically active homoallylic alcohols from allyl halides.

A one-pot, convenient method for the preparation of optically active homoallylic alcohols from allyl halides was developed. Allyltrichlorosilanes were generated in situ from allyl halides and trichlorosilane in the presence of cuprous chloride and tertiary amine. Without isolation of the allyltrichlorosilanes, benzaldehyde and chiral biquinoline N,N'-dioxide were introduced into the same flask, producing the corresponding homoallylic alcohols with good to high enantioselectivities.

Synthesis of Functionalized p-Phenylene Oxide Oligomers

Oligomers of p-phenylene oxides have been synthesized by coupling of substituted phenols and aryl bromides in the presence of cuprous chloride. The chain length varies from 2 to 5 phenyl rings functionalized at one end by an OH and OMe group and at the other end by an OH, OMe or NO2 functions. The oligomers could be used in material science and as building blocks in supramolecular chemistry. Methods for chemoselective demethylation of methoxy groups were developed.

Antioxidant properties of myricetin and quercetin in oil and emulsions

AbstractThe effect of quercetin and myricetin on the stability of sunflower oil and oil‐in‐water emulsions was studied by storage experiments monitored by measurement of peroxide values, conjugated dienes, and headspace volatile analysis. Myricetin showed strong antioxidant activity in oils stored at 60 or 30°C and in oil‐in‐water emulsions stored at 30°C, whether tocopherols or citric acid were present or not; however, quercetin showed similar antioxidant activity in stripped sunflower oil but no activity in oils that contained tocopherols and citric acid. This showed that myricetin is effective owing to strong radical scavenging and metal‐chelating properties, whereas quercetin has weaker radical scavenging activity, although it is also active by metal‐chelation. The effects of copper and iron salts on the antioxidant activity of myricetin and quercetin were studied in sunflower oil and oil‐in‐water emulsions. Quercetin and myricetin enhanced the prooxidant effect of cupric chloride in oil‐in‐water emulsions (pH 7.4), but this effect was not observed with cupric stearate. The addition of myricetin to emulsions that contained ferric chloride at pH 5.4 also produced a strong prooxidant effect, and small prooxidant effects of flavonols were also detected in the presence of cupric chloride under these conditions. However, myricetin and quercetin reduced the prooxidant effect of ferric palmitate in oils. Myricetin also showed a strong antioxidant effect in oil that contained cupric stearate, although quercetin had no significant effect on the oxidative stability of this system. It therefore appears that flavonols may exert a prooxidant effect in the presence of metal salts, but the nature of the metal salt is important in determining whether a prooxidant effect occurs.