Oxalate Salts Research Articles

Photocatalyst‐Free Synthesis of Oxindoles and Isoquinolinediones via the Radical Reaction of N‐Arylacrylamides with Monoalkyl Cesium Oxalate Salts by Visible Light Catalysis

AbstractA photocatalyst‐free cascade reaction of N‐alkyl‐N‐arylmethacrylamides with monoalkyl cesium oxalate salts is described. In the presence of visible light and (NH4)2S2O8, monoalkyl cesium oxalate salts undergo single‐electron oxidation/CO2 extrusion to generate alkyl radicals, followed by the addition and subsequent cyclization to give alkylated oxindoles. In addition, N‐alkyl‐N‐methacryloylbenzamides could be applied for the cascade reaction, providing a series of alkylated isoquinolinediones, which are completely different from the products obtained with monoalkyl oxalates as substrates.

Current Trends and Technological Advancements in the Use of Oxalate-Degrading Bacteria as Starters in Fermented Foods—A Review

Nephrolithiasis is a medical condition characterized by the existence or development of calculi, commonly referred to as stones within the renal system, and poses significant health challenges. Calcium phosphate and calcium oxalate are the predominant constituents of renal calculi and are introduced into the human body primarily via dietary sources. The presence of oxalates can become particularly problematic when the delicate balance of the normal flora residing within the gastrointestinal tract is disrupted. Within the human gut, species of Oxalobacter, Lactobacillus, and Bifidobacterium coexist in a symbiotic relationship. They play a pivotal role in mitigating the risk of stone formation by modulating certain biochemical pathways and producing specific enzymes that can facilitate the breakdown and degradation of oxalate salts. The probiotic potential exhibited by these bacteria is noteworthy, as it underscores their possible utility in the prevention of nephrolithiasis. Investigating the mechanisms by which these beneficial microorganisms exert their effects could lead to novel therapeutic strategies aimed at reducing the incidence of kidney stones. The implications of utilizing probiotics as a preventive measure against kidney stone formation represent an intriguing frontier in both nephrology and microbiome research, meriting further investigation to unlock their full potential.

Synthesis, characterization, and molecular docking studies of novel hippuric acid anhydrides as potential antiurolithic, analgesic and free radical scavenging agents

Hippuric acid is a biotransformation product in humans which is excreted through urine. Dietary intake of phenolic compounds increases its concentration in urine. Hippuric acid is experimentally proved to be a regulator of calcium oxalate super saturation in human urine and has a solvent effect on oxalate salts. Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used analgesics employed in associated renal colic of urolithiasis. The objective of the present study was to chemically link hippuric acid through anhydride linkage to various NSAIDs to synthesize potential mutual prodrugs for urolithiasis and associated renal colic. Hippuric acid was linked to eleven NSAIDs through anhydride linkage by first synthesizing hippuryl chloride using oxalyl chloride as chlorinating agent, followed by its reaction with sodium salts of NSAIDs. Structures of obtained compounds were elucidated using UV spectrophotometry, FTIR spectrometry, 1H NMR and C-13 NMR spectrometry. Synthesized compounds were evaluated for in vitro antioxidant, in vivo acute toxicity, in vivo antiurolithic, in vivo analgesic and in vitro hydrolysis studies. Molecular docking analysis on TNF-α and COX-2 was carried out to determine target protein binding. Synthesized compounds showed stability at acidic pH which indicate potential gastro protective effect of synthesized conjugates. Compounds P9 an P6 showed maximum in vivo antiurolithic activity while P9 and P8 showed maximum in vitro antioxidant activity. All the conjugates except P2 showed significant analgesic activity which show that conjugation of hippuric acid to NSAIDs did not result in loss of analgesic potential. Docking studies showed better affinity with TNF-α as compared to COX-2.

Recent Advances of Oxalate Decarboxylase: Biochemical Characteristics, Catalysis Mechanisms, and Gene Expression and Regulation.

Oxalate decarboxylase (OXDC) is a typical Mn2+/Mn3+ dependent metal enzyme and splits oxalate to formate and CO2 without any organic cofactors. Fungi and bacteria are the main organisms expressing the OXDC gene, but with a significantly different mechanism of gene expression and regulation. Many articles reported its potential applications in the clinical treatment of hyperoxaluria, low-oxalate food processing, degradation of oxalate salt deposits, oxalate acid diagnostics, biocontrol, biodemulsifier, and electrochemical oxidation. However, some questions still remain to be clarified about the role of substrate binding and/or protein environment in modulating the redox properties of enzyme-bound Mn(II)/Mn(III), the nature of dioxygen involved in the catalytic mechanism, and how OXDC acquires Mn(II) /Mn(III). This review mainly summarizes its biochemical and structure characteristics, gene expression and regulation, and catalysis mechanism. We also deep-mined oxalate decarboxylase gene data from National Center for Biotechnology Information to give some insights to explore new OXDC with diverse biochemical properties.

Efficient Quantification of Soluble and Insoluble Oxalates in Clay Mineral Mixtures

ABSTRACT Quantification of oxalate salts in soil clay minerals is necessary to study oxalate biogeochemistry, but existing analytical techniques are expensive and time-consuming. We aim to develop an efficient attenuated total reflectance mid-infrared (MIR) spectroscopic technique to quantify oxalate salts in a clay mineral matrix. We calibrated MIR models for analysis of oxalate anion concentrations in standard solutions (0–0.01 M) by using a partial least-squares regression algorithm. MIR models were also developed for analysis of sodium oxalate (NaOx) and calcium oxalate (CaOx) content in clay mineral mixtures with composition like soils of a semi-arid region and with contrasting concentrations (0–1.0 g g−1 for both oxalate salts) to test sensitivity of analyses. Validation plots (true vs predicted values) showed excellent model fit (R2 ≥ 0.96) and accuracy (normalized root mean squared error of prediction ≤ 0.06) for CaOx, NaOx and oxalic acid components. Once predictive models are stored in analytical software, MIR spectroscopic analyses of samples are much more efficient than chemical techniques. Our MIR spectral-based models are suitable for direct quantification of oxalate salts in clay mineral mixtures for samples like those used for model calibration.

Insight into the Structure and Property Diversity of Four Nicorandil Oxalate Salt Polymorphs Based on Experiments and Quantum Chemistry Study

Insight into the Structure and Property Diversity of Four Nicorandil Oxalate Salt Polymorphs Based on Experiments and Quantum Chemistry Study

Hydrothermal conversion of cerium oxalate to CeO2: a parade of oxalate and water coordination modes

Hydrothemal conversion of lanthanide/actinide oxalate salts to nanocrystalline oxide has gained technological importance in the chemistry of f-elements.

Synthesis and characterization of four diastereomers of β-lactamase inhibitor drug intermediate

A short and efficient stereo-specific synthesis of three stereoisomers (two diastereomer and one enantiomer) of Oxalate salt of benzyl (2S,5R)-5-(benzyloxyamino)piperidine-2-carboxylate (8) has been described. Compound 8 is a key intermediate in the synthesis of β-lactamase inhibitors, was synthesized in high diastereomeric excess using chirally pure L-pyroglutamic acid. In this report, we also describe a chiral high performance liquid chromatography (CHPLC) method to separate these isomers. The developed CHPLC method was validated for the accurate determination of the diastereomeric purity of compound 8.

Lithium Carbonate and Oxalate Salts as Corrosion Inhibitors for Magnesium Alloy AZ31B in NaCl Solution

The corrosion inhibition effectiveness of dissolved Li2CO3 and Li2C2O4 was studied for Mg alloy AZ31B in 0.1 M NaCl solution. The electrochemical and corrosion inhibition properties of Li salts were studied using potentiodynamic polarization, linear polarization resistance, electrochemical impedance spectroscopy, and H2 evolution measurement methods. The corrosion inhibition efficiency as a function of immersion time was also investigated. The morphology and chemical composition of AZ31B surfaces after 24 h immersion in 0.1 M NaCl with and without the addition of dissolved Li salts revealed considerable differences in corrosion properties. The role of Li+ ions, ions, and on corrosion inhibition of AZ31B was focused and their role in corrosion inhibition was discussed. Li2CO3 had better corrosion inhibition efficiency compared to Li2C2O4 in 0.1 M NaCl solution at ambient temperature. The optimum concentration of Li2CO3 was 50 mM to provide the highest corrosion inhibition efficiency of 96.75%, while the optimum concentration and inhibition efficiency for Li2C2O4 were 3 mM and 82.84%, respectively. Surface characterization of the Li2CO3-inhibited AZ31B revealed that the enhanced corrosion protection was due to formation of a protective layer mainly composed of MgCO3. Corrosion studies over time showed that Li2CO3 could effectively provide corrosion protection for 48 h, while Li2C2O4 became ineffective after 12 h of immersion in 0.1 M NaCl.

Dual functional behaviour of dicationic ionic liquid as extractant and hydrophobic biphasic solvent for extraction of Pb(II) in water

Herein, it was aimed to investigate the extraction ability of hydrophobic di-cationic imidazolium-based ionic liquid with inbuilt carboxylic acid functionalities for one of the heavy metals, Pb(II) from aqueous solution. Two dicationic ionic liquids, IL-1 named 1,1′(butane-1,4-diyl)bis(3-(4carboxyphenyl)-2-methyl-1H-imidazol-3-ium) chloride and IL-2 named 1,1′(dodecane-1,12-diyl)bis(3-(4carboxyphenyl)-2-methyl-1H-imidazol-3-ium)chloride tailored with (CH2)n bridging spacer chains, n = 4 and n = 12 respectively were synthesized. The Pb(II) displayed extraction percentages greater than 90% with both the aqueous biphasic system of IL-1 and IL-2. An efficient back-stripping of the Pb(II) metal ion was done using with aqueous solution of oxalic acid. Calcination of lead oxalate salt obtained showed highest purity of PbO confirmed by PXRD and EDX data. The established experimental condition with the synthesized ionic liquids is a distinguished one as no salting out agent, no extra extracting agents other than the synthesized ionic liquids were used. Moreover, the regeneration of the ionic liquid (IL-2), and back stripping of Pb(II) as oxalate salt makes this system an efficient one with negligible loss of the ionic liquid (IL-2) into the aqueous medium thus obliging the standards of environment-friendly sustainable development.

Recovery of nickel oxide nanorods from a laterite-originated intermediate product by ammonia leach-deammoniation method

Extraction of nickel from laterites, especially low-grade limonitic ores has been facing challenges related to the lack of an effective beneficiation method. A chemo-physical laterite ore processing comprising oxalic acid leaching followed by size separation of the leach residue was recently introduced by the authors as a novel method to collect small amounts of nickel values dispersed in the ore matrix into distinct oxalate particles to form an intermediate product. In the present work, the ammonia leaching of such intermediate product containing about 12 wt% NiC2O4·2H2O was accomplished. Factors such as initial ammonia concentration (NH3: 2.5–25 wt%), temperature (T: 20–50 °C), pulp density (S/L: 50–200 g/L), and sonication were examined in a series of agitated leaching tests. It was found that under the conditions of 25% NH3, T = 50 °C, S/L = 200 g/L, and 15 min of sonication, about 93% of nickel is dissolved resulting in a pregnant leach solution (PLS) with a nickel content of 7.4 g/L. Besides, the activation energy for dissolution of nickel oxalate in ammonia solution was found to be about 71 kJ mol–1 from a kinetic analysis of leaching data. The PLS was subsequently deammoniated by either boiling or vacuum-assisted gentle heating to reclaim the nickel as an oxalate salt. Electron microscopic analysis of nickel oxalate precipitates formed from ammonia solutions exhibited rod-like morphology with high aspect ratio. Deammoniation under boiling led to well-shaped and distinct particles (∼150 nm width), while the precipitates obtained under partial vacuum were splintered and finer (∼40 nm width). The pyrolysis at 400 °C in an air atmosphere of the nickel oxalate particles from the boiling and the vacuum-assisted deammoniation methods generated mesoporous NiO nanorods with average widths of about 100 and 30 nm, and specific surface areas of about 45 and 70 m2 g−1, respectively.

Comparative study of artificial intelligence based multi‐modelling approach and optimization of photoreactor

AbstractThis study presents a generic methodology for modelling and optimizing a reactor with complex and poorly understood kinetics. Here, a photoreactor is considered which performs photodegradation of sodium oxalate salt in spent Bayer liquor. Multiple data‐driven modelling methods, including artificial neural networks (ANN), genetic programming (GP), hybrid genetic programming‐grey wolf optimization (GP‐GWO), and multi‐gene genetic programming (MGGP), were used to model the reactor's performance based on experimental data. The input parameters considered for modelling were initial solution pH, power of the lamp, total organic carbon, and catalyst loading. The models were evaluated based on their predictability, explainability, complexity, and adherence to the reactor's phenomenology. The MGGP model was found to be the most effective and was used to generate surface plots showing the parity between experimental results and model predictions. Additionally, the MGGP model was optimized using GWO to determine the process conditions that maximize the reaction rate.

Cu and As containing pigments in Zhejiang architecture polychrome paintings: a case study of degradation products of emerald green

The discoloration of pigments caused by deterioration may significantly alter an artifact's original pattern and design, which could have an impact on its intended meaning. The green pigments containing copper (Cu) and arsenate (As) in paintings are usually recognized as Emerald green or Scheele’s green and are also infrequently reported as cornwallite and lavendulan. Recent studies point out that lavendulan may be the degradation product of Emerald green but not a natural mineral. Overall, there are still relatively few cases of current studies on green pigment with Cu and As. The elemental composition and molecular structure of green minerals containing Cu and As are similar, so it is difficult to identify by Raman spectroscopy. The green pigment samples used in this investigation were taken from architectural paintings in the Wenchang palace and traditional Ziweishan dwellings. The composition of the paint samples was investigated comprehensively by Raman spectroscopy, scanning electron microscope observation, micro-X-ray diffraction (μ-XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) analysis. From the results of elemental distribution, the pigments mainly contain Cu, As, and Cl. The morphological results illustrated that the particles in these three pigments are rounded and granular, indicating the synthetic pigment is possibly emerald green. The characteristic vibrational peaks of the As–O, Cu–O and Cu–Cl bond were detected by Raman spectroscopy, and infrared spectroscopy found the presence of oxalate salt. The XPS and XANES analysis results show that As valence is + 5. This study found that the green pigment samples are a degradation product of emerald green. The formation of this product is related to the preservation environment. The results of this work will provide information to understand the degradation processes of emerald green and be a reference for the identification of pigments containing Cu and As elements.

Improved Process for the Preparation of Naloxegol Oxalate, an Opiod Receptor Antagonist.

The present article discloses an improved and robust commercial process of the modern medicine naloxegol oxalate, which is used to treat opioid-induced constipation. The synthesis originates from the easily available key starting material, viz., naloxone, and ends with the oxalate salt of naloxegol (a pharmaceutically acceptable salt). This novel route has a very high yield and purity greater than 99.5%, substantially free from impurities (less than 1%).

A quaternary solid-form of ritonavir: an oxalate salt oxalic acid co-crystal acetone solvate

Solid-state analysis of a new quaternary solid-form of ritonavir: an oxalate salt oxalic acid co-crystal acetone solvate.

Evolved Gas Analyses of Sedimentary Rocks From the Glen Torridon Clay‐Bearing Unit, Gale Crater, Mars: Results From the Mars Science Laboratory Sample Analysis at Mars Instrument Suite

AbstractEvolved gas analysis (EGA) data from the Sample Analysis at Mars (SAM) instrument suite indicated Fe‐rich smectite, carbonate, oxidized organics, Fe/Mg sulfate, and chloride in sedimentary rocks from the Glen Torridon (GT) region of Gale crater that displayed phyllosilicate spectral signatures from orbit. SAM evolved H2O data indicated that the primary phyllosilicate in all GT samples was an Fe‐rich dioctahedral smectite (e.g., nontronite) with lesser amounts of a phyllosilicate such as mixed layer talc‐serpentine or greenalite‐minnesotaite. CO2 data supported the identification of siderite in several samples, and CO2 and CO data was also consistent with trace oxidized organic compounds such as oxalate salts. SO2 data indicated trace and/or amorphous Fe sulfates in all samples and one sample may contain Fe sulfides. SO2 data points to significant Mg sulfates in two samples, and lesser amounts in several other samples. A lack of evolved O2 indicated the absence of oxychlorine salts and Mn3+/Mn4+ oxides. The lack of, or very minor, evolved NO revealed absent or very trace nitrate/nitrite salts. HCl data suggested chloride salts in GT samples. Constraints from EGA data on mineralogy and chemistry indicated that the environmental history of GT involved alteration with fluids of variable redox potential, chemistry and pH under a range of fluid‐to‐rock ratio conditions. Several of the fluid episodes could have provided habitable environmental conditions and carbon would have been available to any past microbes though the lack of significant N could have been a limiting factor for microbial habitability in the GT region.

Using micro computed tomographic imaging for analyzing kidney stones.

Stone analysis is a critical part of the clinical characterization of urolithiasis. This article reviews the strengths and limitations of micro CT in the analysis of stones. Using micro CT alone in a series of 757 stone specimens, micro CT identified the 458 majority calcium oxalate specimens with a sensitivity of 99.6% and specificity of 95.3%. Micro CT alone was also successful in identifying majority apatite, brushite, uric acid, and struvite stones. For some minor minerals-such as apatite in calcium oxalate or calcium salts in uric acid stones-micro CT enables the detection of minute quantities well below 1%. The addition of a standard for calibrating X-ray attenuation values improves the ability of micro CT to identify common stone minerals. The three-dimensional nature of micro CT also allows for the visualization of surface features in stones, which is valuable for the study of stone formation.

Physiotherapy in the rehabilitation of patients with urolithiasis with ureteral stones after extracorporeal shock wave lithotripsy

Urolithiasis currently occupies a leading position among all urological pathologies, accounting for 26 % to 37 %, which elevates this problem to the rank of socially significant issues and determines the high relevance of finding new approaches to the development of rehabilitation programs to use in the early postoperative period after shock wave lithotripsy for the prevention of postoperative complications and relapses of the disease. Objective. To study the features of the influence of combined vacuum interferential therapy and mono-influences with interferential currents on nitrogen metabolism and excretory function of the kidneys in patients with urolithiasis with ureteral stones after extracorporeal shock wave lithotripsy. Material and methods of treatment. The study included 105 male patients with urolithiasis and ureteral stones after extracorporeal shock wave lithotripsy, whose mean age was 47.6 ± 3.8 years. The patients were divided by simple randomization into 3 groups comparable in terms of age, clinical and functional characteristics, and instrumental data: from the 2nd day after ESWL against the background of drug treatment, the patients of the main group 1 (n = 35) were prescribed vacuum interferential therapy on the lumbosacral region and the projection of the ureters with a carrier frequency of 5 kHz, in the frequency range of 80–150 Hz, with a vacuum of 0.3–0.4 bar, 15 min per unit, 6–8 procedures per course; from the 2nd day after ESWL against the background of drug treatment, the patients of the comparison group (n = 35) were prescribed mono-impacts of interferential currents on the lumbosacral region and the projection of the ureters with a carrier frequency of 5 kHz, in the frequency range of 80–150 Hz, 15 min per unit, 6–8 procedures per course; the patients in the control group (n = 35) were prescribed antibacterial and anti-inflammatory drug therapy, which served as a background in the main and the comparison groups. Research results. When studying the indicators of nitrogen metabolism in the blood in the initial state, an increase in the content of uric acid and creatinine was noted against the background of a decrease in the content of potassium. After the course of treatment, the most pronounced dynamics was revealed in the patients of the main group, which manifested in a significant decrease of creatinine by 15.2 % (p ˂ 0.05) and uric acid by 13.6 % (p ˂ 0.05) against the background of an 8 % increase in the content of potassium (р ˂ 0.05) in blood. Although the indicators of nitrogen metabolism improved under the influence of interferential therapy in the patients of the comparison group, the differences were not significant and were regarded only as a positive trend. Prior to the start of treatment, a decrease in pH, daily diuresis, glomerular filtration, and tubular reabsorption against the background of an increase in oxalate salts was found in daily urine. After the course of treatment, the patients in the comparison group received significant positive dynamics in all studied parameters, which manifested in an increase in pH, daily diuresis, glomerular filtration, and tubular reabsorption against the background of a decrease in the level of oxalate salts. In the control group, there was only a slight positive trend. Conclusion. Vacuum interferential therapy has an anti-inflammatory and diuretic effect to a greater extent than interferential therapy, contributing to the normalization of the excretory function of the kidneys and nitrogen metabolism in patients with urolithiasis with ureteral stones after ESWL, and can be recommended for use in wide clinical practice.

Post-collection acidification of spot urine sample is not needed before measurement of electrolytes

IntroductionKidney stone formers can have higher oxalate and phosphate salt amounts in their urine than healthy people and we hypothesized that its acidification may be useful. The study aims to compare results of urine concentrations of calcium, magnesium, and inorganic phosphorus in the midstream portion of first voided morning urine samples without (FMU) and with post-collection acidification (FMUa) in kidney stone patients.Materials and methodsThis is a prospective single center study. A total of 138 kidney stone patients with spot urine samples were included in the study. Urine concentrations of calcium, magnesium and inorganic phosphorus were measured with and without post-collection acidification. Acidification was performed by adding 5 µL of 6 mol/L HCl to 1 mL of urine.ResultsThe median age (range) of all participants was 56 (18-87) years. The median paired differences between FMU and FMUa concentrations of calcium, magnesium, and inorganic phosphorus were: - 0.040 mmol/L, 0.035 mmol/L, and 0.060 mmol/L, respectively. They were statistically different: P < 0.001, P < 0.001, P = 0.004, respectively. These differences are not clinically significant because biological variations of these markers are much higher.ConclusionsNo clinically significant differences in urinary calcium, magnesium, and inorganic phosphorus concentrations between FMU and FMUa in patients with kidney stones were found.

Photo‐Catalyzed Redox‐Neutral 1,2‐Dialkylation of Alkenes

AbstractDifunctionalization of alkenes enables construction of complex compounds in one pot. In this report, we presented an intermolecular, redox‐neutral three‐component dicarbofunctionalization of activated alkenes under mild reaction conditions. The mechanistic studies indicated tertiary alkyl radicals from oxalate salts were first added to alkenes in Giese‐type fashion, followed by nucleophilic addition with aldehydes to produce the desired 1,2‐dialkylation products. The catalyst system does not require any additives, with good functional group compatibility, regioselectivity, and constructs two tertiary carbon centers simultaneously.magnified image