Reaction Of Nitrite Research Articles

Visible-Light-Induced Multi-Component Nitrooxylation Reactions of α-Diazoesters, Cyclic Ethers, and Tert-Butyl Nitrite Leading to Organic Nitrate Esters.

A simple and efficient strategy has been developed for the synthesis of organic nitrate esters via visible-light-induced multi-component nitrooxylation reactions of α-diazoesters, cyclic ethers, and tert-butyl nitrite under open air atmosphere. This transformation could be conducted under mild and metal-free conditions to provide a number of organic nitrate esters in moderate to good yields using air as the green oxidant.

Pulsed Laser‐Initiated Dual‐Catalytic Interfaces for Directed Electroreduction of Nitrite to Ammonia

Green and highly selective synthesis of ammonia (NH3) via electrochemical reduction reaction of toxic nitrite (NO2−RR) in a neutral electrolyte is a feasible solution for energy and environmental issues. Dual‐nature electrocatalysts combining metal and metal‐derived materials are crucial for enhancing the selectivity parameter and efficacy of this reaction. Here, Pd‐, Pt‐, Ru‐, and Ir‐decorated Co3(PO4)2 (CoPi) composites with a robust metal–support interaction are obtained via the one‐pot pulsed laser ablation in liquid method. Among the designed composites, Ir–CoPi affords ≈100% Faradaic efficiency, mass balance, and selectivity toward NH3 product at sufficiently low potentials. Further, it affords the highest NH3 yield rate of 19.13 mg h−1 cm−2 with 78.1% removal of toxic NO2− with a rate constant kapp = 0.31 mm min−1 under −1.6 V versus Ag/AgCl. In situ experiments and theoretical investigations reveal the underlying mechanisms responsible for this outstanding performance of Ir–CoPi, which can be accredited to the generation of specific active sites on the Ir component. Insights derived from the evolving intermediate reactive species provide new opportunities for large‐scale NH3 production through electrochemical techniques, density functional theory calculations, and the improvement of the corresponding industrial processes.

Highly sensitive two-dimensional ion chromatography mass spectrometry method for nitrite determination in hydroxypropyl methylcellulose

Due to their potential adverse health effects, some N-nitrosamines in drug products are strictly regulated with very low maximum daily intake limits. Nitrosamines can be formed from the reaction of nitrite and secondary or tertiary amines when both species co-exist in the drug synthesis or formulation process. One key strategy to mitigate nitrosamine risk in drugs is to select low-nitrite containing pharma excipients for formulation. It is necessary to develop a sensitive method for trace nitrite determination in pharma excipients as it enables drug producers to study nitrosamine formation kinetics and select excipient suppliers. This study details the development and validation of a two-dimensional ion chromatography mass spectrometry (2D-IC/MS) method for trace nitrite determination in hydroxypropyl methylcellulose (HPMC), one of the most important pharmaceutical excipients used in many drug formulations. The 2D-IC system was operated in heart-cutting mode with a concentrator column coupling the two dimensions. A standard bore anion-exchange column was used in the first dimension (1D) to enable a large volume injection for increased sensitivity and provide improved resolution between nitrite and the interfering chloride peak. A high efficiency microbore anion-exchange column with different selectivity was used in the second dimension (2D) to resolve nitrite from other interfering species. The use of 2D-IC resulted in significantly improved resolution, solving the sensitivity loss issue due to ion suppression from an otherwise 1D separation. MS detection with selective ion monitoring and isotope labeled nitrite internal standard further improve the method specificity, accuracy, and ruggedness, as compared with conductivity detection. For trace determination, it is also extremely important to have a clean blank. For this purpose, a novel cleaning procedure using a strong anion wash was developed to remove nitrite contamination from labware. The optimized method was validated with linearity of nitrite in the concentration range of 18.5–5005.8 ng/g having a regression coefficient of >0.9999, precision with RSD at 3.5–10.1 % and recovery of 90.5–102.4 %. The limit of detection and limit of quantitation were 8.9 and 29.6 ng/g relative to the HPMC sample, or equivalent to 89 and 296 pg/g in the sample solution, respectively.

Electrochemical Synthesis of Urea: Co-Reduction of Nitrite and Carbon Dioxide on Binuclear Cobalt Phthalocyanine.

Exploration of molecular catalysts with the atomic-level tunability of molecular structures offers promising avenues for developing high-performance catalysts for the electrochemical co-reduction reaction of carbon dioxide (CO2) and nitrite (NO2 -) into value-added urea. In this work, a binuclear cobalt phthalocyanine (biCoPc) catalyst is prepared through chemical synthesis and applied as a C─N coupling catalyst toward urea. Achieving a remarkable Faradaic efficiency of 47.4% for urea production at -0.5V versus reversible hydrogen electrode (RHE), this biCoPc outperforms many known molecular catalysts in this specific application. Its unique planar macromolecular structure and the increased valence state of cobalt promote the adsorption of nitrogenous and carbonaceous species, a critical factor in facilitating the multi-electron C─N coupling. Combining highly sensitive in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) with density functional theory (DFT) calculations, the linear adsorbed CO (COL) and bridge adsorbed CO (COB) is captured on biCoPc catalyst during the co-reduction reaction. COB, a pivotal intermediate in the co-reduction from CO2 and nitrite to urea, is evidenced to be labile and may be attacked by nitrite, promoting urea production. This work demonstrates the importance of designing molecular catalysts for efficient co-reduction of CO2 and nitrite to urea.

Sensitive and reliable hybrid nanosensor (Co2+-CDs@R-CDs) for ratiometric fluorescent and colorimetric detecting NO2−

A ratiometric fluorescent and colorimetric detecting assay for NO2− was realized by a hybrid nanosensor (Co2+-CDs@R-CDs) utilizing firstly through the redox reaction of nitrite (NO2−) with Co2+, of which the hybrid nanosensor Co2+-CDs@R-CDs was fabricated by Co2+-doped carbon dots (Co2+-CDs) and a reference of red-emitting carbon dots (R-CDs). The ratiometric fluorescent linear detection range of NO2− was 2.5–45 μM and the limit of detection (LOD) was 0.068 μM with the response time of 120 s. While, the colorimetric linear detection range of NO2− was 2.5–60 μM and the LOD was 0.075 μM. In addition, a portable smartphone system which could measure the R (red), G (green), and B (blue) values of the fluorescence and the visible color of the coated Co2+-CDs@R-CDs paper strip-based sensor had also been developed and successfully applied to detect NO2− in sausage, pickles and tap water samples.

Hydroxylamine supplementation accelerated the rates of cell growth, aerobic denitrification and nitrous oxide emission of Pseudomonas taiwanensis EN-F2

Hydroxylamine can disrupt the protein translation process of most reported nitrogen-converting bacteria, and thus hinder the reproduction of bacteria and nitrogen conversion capacity. However, the effect of hydroxylamine on the denitrification ability of strain EN-F2 is unclear. In this study, the cell growth, aerobic denitrification ability, and nitrous oxide (N2O) emission by Pseudomonas taiwanensis were carefully investigated by addition of hydroxylamine at different concentrations. The results demonstrated that the rates of nitrate and nitrite reduction were enhanced by 2.51 and 2.78 mg/L/h after the addition of 8.0 and 12.0 mg/L hydroxylamine, respectively. The N2O production from nitrate and nitrite reaction systems were strongly promoted by 4.39 and 8.62 mg/L, respectively, through the simultaneous acceleration of cell growth and both of nitrite and nitrate reduction. Additionally, the enzymatic activities of nitrate reductase and nitrite reductase climbed from 0.13 and 0.01 to 0.22 and 0.04 U/mg protein when hydroxylamine concentration increased from 0 to 6.0 and 12.0 mg/L. This may be the main mechanism for controlling the observed higher denitrification rate and N2O release. Overall, hydroxylamine supplementation supported the EN-F2 strain cell growth, denitrification and N2O emission rates.

Reactions of oximates, aroxides, carboxylates, carbonate, nitrite and tetraarylantimony nitrate with arenesulphone acids

Reactions of oximates, aroxides, carboxylates, carbonate, nitrite and tetraarylantimony nitrate with arenesulphone acids

Rapid colorimetric assay based on the oxidation of 2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid-diammonium salt for nitrite detection in meat products

This work developed a rapid colorimetric method for nitrite detection in meat products. The detection was based on the reaction of nitrite with 60 mM HCl to produce radicals which further oxidized ABTS (50 µM) to form a water-soluble blue-green product (ABTS•+). The absorbance was measured at a maximum absorption wavelength of 412.5 nm. Parameters such as concentration of HCl, concentration of ABTS and reaction time were evaluated. The absorbance was linearly proportional to the concentration of nitrite (0.1–20 µM) with the limit of detection of 0.34 µM. The proposed method was a time-saving assay since it required only 2 min to complete one measurement. There was no effect of the interference produced by other ions. The assay was robust with 2.5%RSD (n = 50). In meat product samples, high accuracy was observed with the recoveries between 100 ± 2.2% and 105 ± 3.7%. The amount of nitrite in meat products detected by the ABTS method was found in the range of 5.41 − 7.62 mg/kg. The conventional Griess method was applied to determine nitrite in the same meat products. There was no statistically significant difference between the two methods (P = 0.05).

Study of hydroxyl and nitrite radicals concentration in plasma-activated water by photoluminescence spectroscopy

The atmospheric pressure plasma in water has numerous applications, including utilizing reactive species in the dye degradation process for polluted water remediation. In the current study, an air plasma jet generated atmospheric pressure plasma, transporting reactive oxygen and nitrogen species (RONS) onto the solution surface, such as OH and NO2 radicals, which immediately developed in an aqueous solution. The identification and concentration of radicals are determined using photoluminescence spectroscopy (PL) and irradiation over the surface of an aqueous solution. Based on the reaction between hydroxyl ions and terephthalic acid, fluorimetric methods for hydroxyl ions determination are developed. In addition, 2,3-diamino naphthalene was selected for the nitrite reaction. The jet nozzle-to-solution-surface distance, treatment time, and carrier air flow rate substantially impacted determining the radical’s concentration in aqueous solution.

Synergistic Activation of Nitrite and Thiocarbonyl Compounds Affords NO and Sulfane Sulfur via (Per)thionitrite (SNO- /SSNO- ).

(Per)thionitrite (SNO- /SSNO- ) intermediates play vital roles in modulating nitric oxide (NO) and hydrogen sulfide (H2 S) dependent bio-signalling processes. Whilst the previous preparations of such intermediates involved reactive H2 S/HS- or sulfane sulfur (S0 ) species, the present report reveals that relatively stable thiocarbonyl compounds (such as carbon disulfide (CS2 ), thiocarbamate, thioacetic acid, and thioacetate) react with nitrite anion to yield SNO- /SSNO- . For instance, the reaction of CS2 and nitrite anion (NO2 - ) under ambient condition affords CO2 and SNO- /SSNO- . A detailed investigation involving UV/Vis, FTIR, HRMS, and multinuclear NMR studies confirm the formation of SNO- /SSNO- , which are proposed to form through an initial nucleophilic attack by nitrite anion followed by a transnitrosation step. Notably, reactions of CS2 and nitrite in the presence of thiol RSH show the formation of organic polysulfides R-Sn -R, thereby illustrating that the thiocarbonyls are capable of influencing the pool of bioavailable sulfane sulfurs. Furthermore, the availability of both NO2 - and thiocarbonyl motifs in the biological context hints at their synergistic metal-free activations leading to the generation of NO gas and various reactive sulfur species via SNO- /SSNO- .

Synergistic Activation of Nitrite and Thiocarbonyl Compounds Affords NO and Sulfane Sulfur via (Per)thionitrite (SNO−/SSNO−)

Abstract(Per)thionitrite (SNO−/SSNO−) intermediates play vital roles in modulating nitric oxide (NO) and hydrogen sulfide (H2S) dependent bio‐signalling processes. Whilst the previous preparations of such intermediates involved reactive H2S/HS− or sulfane sulfur (S0) species, the present report reveals that relatively stable thiocarbonyl compounds (such as carbon disulfide (CS2), thiocarbamate, thioacetic acid, and thioacetate) react with nitrite anion to yield SNO−/SSNO−. For instance, the reaction of CS2 and nitrite anion (NO2−) under ambient condition affords CO2 and SNO−/SSNO−. A detailed investigation involving UV/Vis, FTIR, HRMS, and multinuclear NMR studies confirm the formation of SNO−/SSNO−, which are proposed to form through an initial nucleophilic attack by nitrite anion followed by a transnitrosation step. Notably, reactions of CS2 and nitrite in the presence of thiol RSH show the formation of organic polysulfides R‐Sn‐R, thereby illustrating that the thiocarbonyls are capable of influencing the pool of bioavailable sulfane sulfurs. Furthermore, the availability of both NO2− and thiocarbonyl motifs in the biological context hints at their synergistic metal‐free activations leading to the generation of NO gas and various reactive sulfur species via SNO−/SSNO−.

Regioselective Cycloaddition of Alkenes with tert-butyl Nitrite: A Cascade Approach to the Formation of Δ2-Isoxazolines.

A route for cycloaddition reaction of alkenes and tert-butyl nitrite to synthesize Δ2-isoxazolines has been developed. The overall process involves the formation of multiple chemical bonds without the use of a catalyst. This methodology features mild reaction conditions and good functional group tolerance, providing a direct approach for the preparation of isoxazolines.

Kinetic study on the reaction of sodium nitrite with neurotransmitters secreted in the stomach

Nitroso-compounds are potentially mutagenic and carcinogenic compounds due to their ability to alkylate DNA bases. One of the most common sources of human exposure to nitroso-compounds is their formation in the acidic environment of the stomach by the reaction between electron-rich molecules present in the lumen and sodium nitrite ingested in the diet. To date, the formation of nitroso-compounds by the reaction of nitrite with food components has been investigated in depth, but little attention has been paid to substances secreted in the stomach, such as dopamine or serotonin, whose reaction products with nitrite have proven mutagenic properties. In this article, we present a kinetic study with UV–visible spectroscopy of the nitrosation reactions of both molecules, as well as of L-tyrosine, the amino-acid precursor of dopamine. We determined the kinetic parameters and reaction mechanisms for the reactions, studying the influence of the reactants concentration, pH, temperature, and ionic strength on the reaction rate. In all cases, the favoured reaction product was a stable nitroso-compound. Serotonin, the molecule whose product was the most mutagenic, underwent two consecutive nitrosation reactions. These findings suggest that additional biological research is needed to understand how this reaction alters the function of these neurotransmitters as well as the potentially toxic effects they may have once nitrosated.

Modeling the Impact of Excipients Selection on Nitrosamine Formation towards Risk Mitigation.

Risk control for nitrosamine impurities in drug products is currently a major challenge in the industry. Nitrosamines can form during drug product manufacturing and storage through the reaction of nitrites with amine-containing APIs or impurities. The level of nitrites in excipients and the rate of reaction often control the build-up of nitrosamine. Although the variability in nitrite levels across excipient types and suppliers is well recognized, the impact of excipient selection on the level of nitrosamine formed has not been systematically studied. This gap of knowledge is addressed in the current work. We present theoretical case studies of formulations where microcrystalline cellulose (MCC), or lactose supplier, or superdisintegrant type are changed in pursuit of lower levels of nitrite. The impact of the average, maximum, and minimum levels of nitrites in each excipient on nitrosamine formation in the dosage form is calculated. The input data for this calculation are the formulation composition, nitrosamine molecular weight (MW), percentage of conversion, and nitrite levels per excipient. The percentage of conversion (based on the formulation and manufacturing variables) and nitrite levels were taken from the recent literature. We show that changing the supplier of a single excipient, or of the three most critical excipients, can reduce nitrosamine formation by up to -59% and -89%, respectively. We also show that high-risk formulations, e.g., high MW nitrosamines, high dosage weights, and high percentages of conversion (e.g., wet granulation), can often be de-risked below regulatory acceptable daily intake via careful excipient selection. Finally, we provide an open-access tool that enables users to calculate the theoretical formation of nitrosamines in their specific formulations. This calculation template can be used for (i) the preliminary screening of the risk of nitrosamine formation in drug products and (ii) the preliminary assessment of the impact of excipient selection for risk mitigation.

Three-component reaction of tert-butyl nitrite with indoles and halides: A facile and efficient synthesis of oxime ether derivatives

A mild and efficient one-pot method has been developed for the synthesis of oxime ether derivatives with up to 85% yield by employing tert-butyl nitrite (TBN) as nitrogen source, which occurs under room temperature and exhibits wide substrate scope. The single electron transfer mechanism and the cascade reactions approach have been confirmed.

Simple method for visual detection of nitrite using fluorescence and colorimetry by poly (tannic acid) nanoparticles

The nitration reaction of nitrite and phenolic substances was first used to identify and detect NO2− by taking fluorescent poly (tannic acid) nanoparticles (FPTA NPs) as sensing platform. With the low cost, good biodegradable and convenient water-soluble FPTA NPs, a fluorescent and colorimetric dual modes detecting assay was realized. In fluorescent mode, the linear detection range of NO2− was 0–36 μM, the LOD was as low as 3.03 nM, and the response time was 90 s. In colorimetric mode, the linear detection range of NO2− was 0–46 μM, and the LOD was as low as 27 nM. Besides, a smartphone with FPTA NPs@ agarose hydrogel formed a portable detection platform to test the fluorescent and visible color changes of FPTA NPs for NO2− sensing as well as for accurate visualization and quantitative detection of NO2− in actual water and food samples.

Tunable Key [3 + 2] and [2 + 1] Cycloaddition of Enaminones and α-Diazo Compounds for the Synthesis of Isomeric Isoxazoles: Metal-Controlled Selectivity

The three-component reactions of enaminones, α-diazo esters/ketones, and t-butyl nitrite (TBN) for the switchable synthesis of isomeric isoxazoles have been realized. The catalysis with Cu(II) salt provides 3,4-disubsituted isoxazoles via [3 + 2] cycloaddition. On the other hand, the catalysis of Ag(I) with identical substrates leads to isomeric isoxazoles with reversed C3 and C4 substitution based on a key [2 + 1] cycloaddition.

Noninterventional target-embolization combined with NO gas therapy for solid tumors by pH-responsive poly(amino acid)s with S-nitrosothiols group

Gas therapy and embolization are important treatment methods for solid tumors. In order to improve the efficacy of NO therapy and simplify the operation of interventional embolization, we designed and prepared the microacidic-gelled poly[(L-Glutamic acid-ran-L-Tyrosine)-b-L-Threonine-b-L-S-nitrosocysteine]s (PGTTSNCs, obtained by the reaction of tert-butyl nitrite with thiol side groups of poly[(L-Glutamic acid-ran-L-Tyrosine)-b-L-Threonine-b-L-Cysteines]s, PGTTCs.) for noninterventional embolization combined with NO gas therapy for solid tumors. The results of in vivo experiments indicated that PGTTSNCs from PGTTCs-6.4 (the gelled-pH value is 6.4) has significant target-accumulation and therapy effects, and at 10 days post-injection only scars were found at the tumor site. After 20 days, the tumors of model mice were completely disappeared. The method is extremely simple and efficient for solid tumors, which is not only a great innovation of tumors theranostic, but also a qualitative development in nanomaterials.

Thermally Activated Nitrogen/Heat Generating Reaction: A Kinetic Study.

Sodium nitrite and ammonium chloride are the most widely used thermochemicals in the oil and gas industry. The kinetics of this reaction when activated with acids or acid precursors were the subject of extensive research by several researchers. The activation of such a highly spontaneous/vigorous reaction by heat is considered a promising reaction control. In this work, a kinetic study was carried out for the reaction of sodium nitrite and ammonium chloride salt activated by heat at 1-5 M and temperatures of 50-90 °C. The study was carried out in both closed and open systems, with the monitoring of gas evolution and generated pressure. The study showed a relatively higher order for ammonium chloride than sodium nitrite. The excess amount of ammonium chloride, a weak acid, enhanced the reaction as it could be catalyzed by both heat and acid. The obtained kinetics of the nitrogen generating reaction is given as dc/dt = -7.66 × 1011 C o 2.45 e (-91.44kJ/mol)/RT . The reaction kinetics in this study differs from what is reported in the literature regarding the order of NH4Cl, which was reported to be higher than that of NaNO2 under examined conditions. This study has practical significance for controlling the reactivity of the NH4Cl/NaNO2 nitrogen/heat generating system and calculating/optimizing nitrogen generation for a specific field application.

Photocatalytic Regioselective [2 + 2 + 1] Radical Annulation of Alkenes with tert-Butyl Nitrite and gem-Dihalides.

A visible-light photocatalytic regioselective [2 + 2 + 1] radical annulation reaction of alkenes, tert-butyl nitrite, and gem-dihalides has been developed. The protocol provides an efficient and practical approach to obtain isoxazolines in good yields under mild conditions. Significantly, gem-dihalides serve as C1 synthons, while cheap tert-butyl nitrite acts as an ideal "N-O" synthon.