Glycine Complexes Research Articles

Recovery of copper from alkaline glycine leach solution using solvent extraction

Abstract Glycine solutions in an alkaline environment have been shown to be able to leach copper from its oxide, native and sulfide minerals as a copper glycinate complex. This paper explores the recovery of copper from its aqueous glycinate complexes at alkaline pH through solvent extraction. Solvent extraction of copper from synthetic glycinate liquor (with background sulfate anions) containing 2 g/L Cu has been studied using Mextral 84H (2-hydroxy-5-nonylacetophenone oxime) and Mextral 54–100 (1-benzoyl-2-nonyl ketone) extractants with a kerosene diluent. The effect of different parameters such as pH of aqueous phase, glycine and extractant concentrations, equilibrium time, temperature, extractant loading capacity as well as the concentration of sulphuric acid as stripping reagent were investigated. Over 99.9% Cu was extracted with 5% Mextral 84 H at room temperature at an Aqueous-to-Organic (A:O) ratio of 2:1. Under similar conditions, 95.87% Cu was extracted by 10% Mextral 54–100. HPLC analysis for free glycine indicated that neither extractants take up glycine during the extraction process. Stripping experiments with spent electrolyte solution showed that copper loaded on Mextral 54–100 can be completely stripped in single stage at an O:A ratio of 10:1 while only 79.95% Cu can be stripped from Mextral 84H with same conditions applied. Copper extraction from leachates of malachite and chalcopyrite ore samples was performed in order to validate extraction results from the synthetic solutions. Over 99% copper was extracted from the malachite leachate (containing 2620 mg/L Cu) in a single stage by both 10% Mextral 54–100 (raffinate pH of 9.76) and 5% Mextral 84H (raffinate pH of 10.0) at an O:A of 2:1; with no impurity elements picked up by either extractants. At an O:A ratio of 2:1, single stage copper extraction from chalcopyrite leachate by 10% Mextral 54–100 (raffinate pH of 9.87) was 93.20% and 95.57% by 5% Mextral 84H (raffinate pH of 9.91) with the rejection of all impurity elements other than Zn in the aqueous raffinate. From the chalcopyrite leachate containing 2288 mg/L Cu and 699 mg/L Zn, the Zn co-extraction into the organic phase at an O:A ratio of 1 was found to be 16.5% for Mextral 54–100 whilst Zn co-extraction was not noted with Mextral 84H under the alkaline conditions.

Asymmetric Synthesis of Chiral α‐Substituted Mercaptoglycine Derivatives via α‐Sulfenylation of Ni(II) Complex of Glycine and S‐Substituted 4‐Methylbenzenesulfonothioate

The asymmetric α‐sulfenylation of Ni(II) complex of glycine with S‐substituted 4‐methylbenzenesulfonothioate is reported. Due to the mild and simple reaction conditions, this asymmetric reaction is compatible with various functional groups.

Thermodynamics of reactions of complex formation for Ce3+ and Er3+ ions with glycine in an aqueous solution

Enthalpies of complex formation for glycine (HL±) with Ce3+ and Er3+ ions at 298.15 K and the value of the ionic strength of 0.5 (KNO3) are determined by calorimetric means using two independent procedures. Thermodynamic characteristics of the reactions of formation for complexes of glycine with Ce3+ and Er3+ ions at various [metal]: [ligand] molar ratios are calculated.

Alterations in intestinal and liver histomorphology and basal hematological and biochemical parameters in relation to different sources of dietary copper in adult rats

Abstract Copper (Cu) is required for all basic biochemical and physiological processes. The aim of this study was to evaluate the effects of different sources of dietary Cu on the histomorphometry of liver and jejunal epithelium in adult rats. Male 12-week-old rats were used in a 12-week experiment. The control diet provided the required Cu level from sulfate, and other two diets were supplemented with Cu as a glycine complex at 75% and 100% of daily requirement. Basal hematological and plasma biochemical analyses were also performed. There was no effect of Cu supplementation on the liver weight and the plasma and liver Cu concentration. Histomorphometric analysis of liver tissue showed an increase in the collagen amount and intracellular space in the group supplemented with Cu amino acid. Cu given in the organic form at 100% of daily requirement decreased the muscular and submucosa layer and the crypt depth. In turn, organic copper given at 75% of daily requirement did not influence the intestinal morphology. Dietary Cu given to adult rats as copper sulfate or a glycine complex meeting 100% of the daily requirement appears to be less harmful with regard to intestinal epithelium than when given as a glycine complex at 100% of daily requirement.

Вплив хелатних сполук мікроелементів і β-каротину на морфологічний та хімічний склад яєць перепелів

<p>The quail chickens took feeding complex of glycine chelated microelements and microbial β-carotene during 90-day growing period. The inorganic compounds of copper, zinc, iron, manganese and cobalt were replaced by their glycine forms in a dose corresponding to the physiological daily norm in these elements.</p><p>We fixed increasing the thickness of shell eggs by 5.2 % compared with the control group, and by 11 % compared to quails, which took feeding complex of glycinate microelements and microbial β-carotene in a dose equal to half physiological norm.</p><p>Replacement of inorganic sources of microelements with their glycinate in doses of norm and half norm did not affect the weight of the eggs, yolks and shell of egg; nevertheless, the quail that treated of glycinate microelements in half norm doses, increased weight protein eggs by 3.3 % compared to quail, that feeding by glycinate microelements in norm dose.</p><p>Feeding of quail of glycinate microelements and microbial β-carotene in a half norm dose caused the egg shell thickness reduction by 5l6 % compared to the control group.</p><p>The introduction of glycinate microelements and microbial β-carotene in a daily norm dose contributed to the accumulation of dry matter in eggs by 3% due to the increase of organic matter, including 1.6 per cent of crude protein, 0.6 per cent of nitrogen free extract, and 0.17 per cent of ash.</p><p>We registered strong increase of nitrogen free extract in the eggs of Group II by 0.88 % compared to the control. </p>

Validity of Generalized Standard Addition Method for a Mixture of Amino Acid Analysis

A Modified version of the Generlized standard addition method ( GSAM) was developed. This modified version was used for the quantitative determination of arginine (Arg) and glycine ( Gly) in arginine acetyl salicylate – glycine complex . According to this method two linear equations were solved to obtain the amounts of (Arg) and (Gly). The first equation was obtained by spectrophotometic measurement of the total absorbance of (Arg) and (Gly) colored complex with ninhydrin . The second equation was obtained by measuring the total acid consumed by total amino groups of (Arg) and ( Gly). The titration was carried out in non- aqueous media using perchloric acid in glacial acetic acid as a titrant. The developed method is accurate, precise, and free from interferences and may provide a useful approach to calibrate in the direct analysis of solid sample and it is suitable method to be used as a quality control procedure.
 Key words: GSAM , amino acid analysis

Prediction of the rotational spectra of microsolvated complexes with low cost DFT methods

Some of the most used DFT methods together with MP2 have been tested using 6-311++G(d,p) and TZVP basis sets to probe their usefulness in prediction of the rotational spectra of several microsolvated complexes of formamide, t-N-methylformamide, glycine and β-propiolactone. Results obtained for the rotational parameters and the prediction of the spectra have been compared to experimental data previously measured by Fourier Transform Microwave Spectroscopy. Analysis of the standard deviation of the predicted rotational spectra for all the levels tested indicates that the methods which better approach to the MP2 results are mPW91LYP and B3LYP-D3.

Enhanced aerobic exercise performance in women by a combination of three mineral Chelates plus two conditionally essential nutrients

BackgroundCertain essential and conditionally essential nutrients (CENs) perform functions involved in aerobic exercise performance. However, increased intake of such nutrient combinations has not actually been shown to improve such performance.MethodsFor 1 mo, aerobically fit, young adult women took either a combination of 3 mineral glycinate complexes (daily dose: 36 mg iron, 15 mg zinc, and 2 mg copper) + 2 CENs (daily dose: 2 g carnitine and 400 mg phosphatidylserine), or the same combination with generic mineral complexes, or placebo (n = 14/group). In Trial 1, before and after 1 mo, subjects were tested for 3 mile run time (primary outcome), followed by distance covered in 25 min on a stationary bike (secondary outcome), followed by a 90 s step test (secondary outcome). To test reproducibility of the run results, and to examine a lower dose of carnitine, a second trial was done. New subjects took either mineral glycinates + CENs (1 g carnitine) or placebo (n = 17/group); subjects were tested for pre- and post-treatment 3 mile run time (primary outcome).ResultsIn Trial 1, the mineral glycinates + CENs decreased 3 mile run time (25.6 ± 2.4 vs 26.5 ± 2.3 min, p < 0.05, paired t-test) increased stationary bike distance after 25 min (6.5 ± 0.6 vs 6.0 ± 0.8 miles, p < 0.05, paired t-test), and increased steps in the step test (43.8 ± 4.8 vs 40.3 ± 6.4 steps, p < 0.05, paired t-test). The placebo significantly affected only the biking distance, but it was less than for the glycinates-CENs treatment (0.2 ± 0.4. vs 0.5 ± 0.1 miles, p < 0.05, ANOVA + Tukey). The generic minerals + CENs only significantly affected the step test (44.1 ± 5.2 vs 41.0 ± 5.9 steps, p < 0.05, paired t-test) In Trial 2, 3 mile run time was decreased for the mineral glycinates + CENs (23.9 ± 3.1 vs 24.7 ± 2.5, p < 0.005, paired t-test), but not by the placebo. All changes for Test Formula II or III were high compared to placebo (1.9 to 4.9, Cohen’s D), and high for Test Formula II vs I for running and biking (3.2 & 3.5, Cohen’s D).ConclusionIn summary, a combination of certain mineral complexes plus two CENs improved aerobic exercise performance in fit young adult women.

Achieving Reversible H2/H+ Interconversion at Room Temperature with Enzyme-Inspired Molecular Complexes: A Mechanistic Study

Inspired by the contribution of the protein scaffold to the efficiency with which enzymes function, we used outer coordination sphere features to develop a molecular electrocatalyst for the reversible production/oxidation of H2 at 25 °C: [Ni(PCy2NPhe2)2]2+ (CyPhe; PR2NR′2 = 1,5-diaza-3,7-diphosphacyclooctane, Cy = cyclohexyl, Phe = phenylalanine). Electrocatalytic reversibility is observed in aqueous, acidic methanol. The aromatic rings in the peripheral phenylalanine groups appear to be essential to achieving reversibility based on the observation that reversibility for arginine (CyArg) or glycine (CyGly) complexes is only achieved with elevated temperature (>50 °C) in 100% water. A complex with a hydroxyl group in the para-position of the aromatic ring, R′ = tyrosine (CyTyr), shows similar reversible behavior. NMR spectroscopy and molecular dynamics studies suggest that interactions between the aromatic groups as well as between the carboxylic acid groups limit conformational flexibility, contributing t...

Glycine adsorption on a mercury electrode modified by neodymium

Ranges of neodymium reduction potentials in aqueous solutions of potassium chloride at pH = 2 and in solutions containing glycine were determined by differential pulse polarography. The glycine complex with neodymium is not formed in the range of the amino acid concentration 0.001–0.12 M. Glycine adsorption on a mercury electrode and on an electrode modified with neodymium was studied by the cyclic voltammetry method.

Site-resolved multiple-quantum filtered correlations and distance measurements by magic-angle spinning NMR: Theory and applications to spins with weak to vanishing quadrupolar couplings

We discuss and analyze four magic-angle spinning solid-state NMR methods that can be used to measure internuclear distances and to obtain correlation spectra between a spin I = 1/2 and a half-integer spin S > 1/2 having a small quadrupolar coupling constant. Three of the methods are based on the heteronuclear multiple-quantum and single-quantum correlation experiments, that is, high rank tensors that involve the half spin and the quadrupolar spin are generated. Here, both zero and single-quantum coherence of the half spins are allowed and various coherence orders of the quadrupolar spin are generated, and filtered, via active recoupling of the dipolar interaction. As a result of generating coherence orders larger than one, the spectral resolution for the quadrupolar nucleus increases linearly with the coherence order. Since the formation of high rank tensors is independent of the existence of a finite quadrupolar interaction, these experiments are also suitable to materials in which there is high symmetry around the quadrupolar spin. A fourth experiment is based on the initial quadrupolar-driven excitation of symmetric high order coherences (up to p = 2S, where S is the spin number) and subsequently generating by the heteronuclear dipolar interaction higher rank (l + 1 or higher) tensors that involve also the half spins. Due to the nature of this technique, it also provides information on the relative orientations of the quadrupolar and dipolar interaction tensors. For the ideal case in which the pulses are sufficiently strong with respect to other interactions, we derive analytical expressions for all experiments as well as for the transferred echo double resonance experiment involving a quadrupolar spin. We show by comparison of the fitting of simulations and the analytical expressions to experimental data that the analytical expressions are sufficiently accurate to provide experimental (7)Li-(13)C distances in a complex of lithium, glycine, and water. Discussion of the regime for which such an approach is valid is given.

Standard thermodynamic functions of Co2+ complexation with glycine and L-histidine in aqueous solution

The enthalpies of the reactions between solutions of Co(NO3)2 and solutions of glycine (Gly) and L-histidine (His) are determined via direct calorimetry at different pH values and metal: ligand ratios using KNO3 as a background electrolyte (T = 298.15 K, I = 0.2–1.0). The enthalpy changes upon the formation of cobalt glycinate complexes and Co2+ mixed-ligand complex, viz., glycine–L-histidine, were calculated. The standard thermodynamic parameters (ΔrH°, ΔrG°, ΔrS°) of complexation are determined. The CoGlyHis complex is shown to be stable toward decomposition into homogeneous complexes.

ChemInform Abstract: Stereoselective Synthesis of Arylglycine Derivatives via Palladium‐Catalyzed α‐Arylation of a Chiral Nickel(II) Glycinate.

AbstractStructurally diverse aryl bromides are well tolerated in the α‐arylation reaction with a chiral nickel(II) glycinate complex.

Stereoselective Synthesis of Arylglycine Derivatives via Palladium-Catalyzed α-Arylation of a Chiral Nickel(II) Glycinate.

A practical and efficient stereoselective synthesis of arylglycine derivatives was realized via palladium-catalyzed α-arylation of a chiral nickel(II) glycinate complex with aryl bromides. The structurally diverse arylglycine products were obtained in excellent isolated yields and with good diastereoselectivity. A simple acidic hydrolysis furnished optically pure arylglycines in high yield, and the chiral ligand (S)-BPB could be efficiently recovered and reused.

Cyclic voltabsorptometry of copper nanofoil in aqueous glycine solutions

Real time detection of the electrode products as a function of potential during the electrolysis is desirable for fundamental analyses of the electrode processes. In the present work, cyclic voltabsorptometry was used to investigate the electrochemical behavior of copper in glycine solutions at acidic, neutral and alkaline pH levels. A long-optical-path thin-layer cell was used for the spectroelectrochemical measurements. Electro-oxidation of the deposited copper nanofoil leads to formation of Cu(I)–glycine complex with high electrochemical stability. At a high concentration of glycine, all the deposited copper can be directly converted into soluble Cu(I)–glycine complex in the KCl-containing solutions without accumulation of the intermediate CuClads. The Cu(I)–glycine complex is also evidenced to be an intermediate in the cupric complex reduction to copper. This Cu(I) complex can be destroyed at relatively positive potentials where the evolution of chlorine occurs, especially in acidic and neutral solutions. This work proves that cyclic voltabsorptometry is adaptable for the analysis of the potential-dependent formation and conversion of the light-absorbing metal complexes.

Towards an understanding of the CO2-philicity in glycine: Deepening into the CO2:Aminoacid interactions

The potential energy surface (PES) for the CO2:glycine complexes were thoroughly examined by means of the MP2/aug-cc-pVDZ computational level. Heterodimers exhibit non-covalent interactions holding monomers together primarily by Xlp···CO2 (X=O, N) tetrel bonds and, in some binary complexes, by additional OCOlp···HY (Y=O, N) H-bonds. Non-classical CH···O H-bonds are also present in some cases as secondary interactions. Binding energies are between −3.00 and up to −5.29kcal/mol, being for the most stable complexes comparable with the one obtained for the paradigmatic water dimer. Partitioning of the interaction energy points to electrostatic as the prime contribution to the stability with an important dose of dispersion. Electron density shifts reveal a gain of electron density associated to the tetrel bond acceptor, whereas the donor moiety experiences a loss.

ChemInform Abstract: Asymmetric Synthesis of Chiral Heterocyclic Amino Acids via the Alkylation of the Ni(II) Complex of Glycine and Alkyl Halides.

AbstractOptimized conditions including the molar ratio of the reactants are applied to the synthesis of title compounds such as (V) and (IX), synthons of natural products and pharmaceutical drugs.

The leaching of gold, silver and their alloys in alkaline glycine–peroxide solutions and their adsorption on carbon

The leaching of gold and silver in a pH modified glycine solution in the presence of hydrogen peroxide was investigated. It was found that this lixiviant system can dissolve gold and/or silver under neutral and alkaline conditions at ambient to moderately elevated temperatures (23–60°C). The gold leaching rate in solutions containing 0.5M glycine and 1% peroxide at pH11 after 48h of leaching was found to be 0.322μmol/m2s, which is comparable to gold leaching rate after six days in thiosulphate–EDTA or thiosulphate–oxalate systems in the presence of thiourea (0.22–0.25μmol/m2s). In alkaline glycine–hydrogen peroxide solutions, it has been found that gold leach rate from gold–silver (50% Ag) alloy is about 6 times higher than rate from pure gold and the silver leach rate was 0.247μmol/m2s. An induction period of 48h was noted for rolled precious metal foils, after which leaching rapidly accelerated. The reaction rate sensitivity to temperature can be explained by a mechanism that is chemical reaction controlling rather than mass transfer controlling as found for cyanide leaching. Precious metal dissolution rates increased with increased glycine concentration, increased silver content, and increasing pH (up to pH11). The gold–glycinate complex was found to effectively load on activated carbon up to 13.2gAu/kgcarbon in 4h.

ChemInform Abstract: A Convenient Method for the Asymmetric Synthesis of Fluorinated α‐Amino Acids from Alcohols.

AbstractThe presented method provides access to a broad scope of enantioenriched aliphatic, benzylic, and pyridinyl‐substituted fluorinated α‐amino acids in a Mitsunobu‐Tsunoda reaction from a readily synthesized Belokon complex of glycine and fluorinated alcohols.

ChemInform Abstract: A Highly Efficient Catalyst of a Nitrogen‐Based Ligand for the Suzuki Coupling Reaction at Room Temperature under Air in Neat Water.

AbstractAn air‐stable and water‐soluble PdCl2—glycine complex exhibits excellent catalytic activity in the reaction of aryl halides (I) containing a carboxyl group with various boronic acids (II) (24 examples).