Addition Of NaNO2 Research Articles

Sodium nitrite (NaNO2) regulating myoglobin-mediated lipid oxidation in washed bovine mince

ABSTRACT This study investigated the effect of NaNO2 on inhibiting myoglobin-mediated lipid oxidation in muscle using a washed bovine mince model. We measured various parameters, including TBARS and PV to determine lipid oxidation, non-heme iron release, protoporphyrin destruction, and nitrosylmyoglobin production. The results of the study showed that the addition of NaNO2 during myoglobin-mediated lipid oxidation significantly reduced the fading and lipid oxidation of washed muscle (p < 0.05). Additionally, the addition of NaNO2 reduced the release of non-heme iron and the degradation of protoporphyrin in myoglobin. Nitrosylmyoglobin was formed in the washed mince supplemented with NaNO2 and myoglobin. These findings suggest that NaNO2 can effectively inhibit the lipid oxidation process induced by myoglobin, which could be a crucial aspect of nitrite inhibition of lipid oxidation in cured meat products. Overall, the study provides evidence for the potential use of NaNO2 as a food preservative to prevent lipid oxidation in meat products.

Titania spheres with nanochannel-restricted NaNO2/MgO for improving cyclic CO2 adsorption stability

ABSTRACT NaNO2/MgO/titania spheres prepared via aerosol-assisted self-assembly (AASA) were used as sorbents for CO2 adsorption at moderate temperature. The titania framework as support would allow MgO to disperse well, thereby increasing the contact between MgO and NaNO2 to enhance carbonation. In this study, the effect of Mg/Ti molar ratio and NaNO2 addition amount on CO2 adsorption was investigated. Results showed that the sorbent prepared by AASA with Mg/Ti molar ratio of 2 following the introduction of 30 wt% NaNO2 presented ∼1 μm particle size with rough sphere surface morphology and mesoporous properties, where the surface area and pore volume were 72 m2/g and 0.18 cm3/g, respectively. With NaNO2 addition, the kinetics and capacity of CO2 adsorption significant increased. In the cyclic adsorption/desorption experiment, the superior stability over the NaNO2/MgO/titania spheres was mainly ascribed to the confined space suppressed the degree of the sintering effect. These results indicated the potential application of the nanochannel-restricted sorbent for rapid, high-capacity, and stable CO2 capture at moderate temperatures.

Nitrogen salt fertilization vs. substrate availability: Two strategies to improve nitrification during the production of the white shrimp Litopenaeus vannamei.

This study aimed to evaluate the use of inorganic salts of ammonia (NH4Cl) and/or nitrite (NaNO2) and substrate availability (biofilm and biofloc) on the nitrification process before and during shrimp production. Three experiments were carried out individually in systems with clear water, biofilm and bioflocs in two phases: without (phase 1) and with (phase 2) shrimp in 200 L tanks and salinity 25. Each experiment had the following treatments: 1) addition of NH4Cl – final concentration of 1.75 mg TAN L−1; 2) addition of NaNO2 – final concentration of 7.6 mg N-NO2− L−1; and 3) addition of NH4Cl + NaNO2 – final concentrations of 1.75 mg TAN L−1 and 7.6 mg N-NO2‐− L‐−1. Inorganic fertilization was carried out in the first phase. In the second phase, the shrimp were stocked in the previously fertilized experimental units, and a control treatment was added in this phase. In the clear water experiment, the control was water without the addition of nitrogen salt. In the biofilm experiment, the control received a clean artificial substrate, and no salt was added. The control in the biofloc experiment started with the addition of organic carbon in clear water, but no nitrogen salts were added. The biofilm and biofloc experiments resulted in an increase in nitrate at the end of inorganic fertilization (phase 1); this result was in contrast to the clear water experiment, where there was no decrease in nitrite, with concentrations ≥ 6 mg N-NO2− L−1 at the end of the experimental treatments with NaNO2. After the addition of the shrimp L. vannamei in the second experimental phase, the biofilm experiment showed greater nitrification efficiency, with lower concentrations of nitrite. The nitrite peaks in the biofilm experiment were approximately 3 mg N-NO2− L−1, whereas in the biofloc experiment, they were approximately 10 mg N-NO2− L−1. The biofilm experiment showed higher final shrimp biomass in comparison to the biofloc experiment. Thus, this study demonstrated the importance of stimulating nitrifying bacteria with nitrogen salt addition prior to shrimp production. However, experiments with the use of substrates, especially biofilm, were able to maintain ammonia and nitrite concentrations at safe levels during L. vannamei production, probably due to better conditions found by nitrifying bacteria growing on the biofilm.

Effect of low-dose sodium nitrite treatment on the endogenous antioxidant capacity of yak meat during wet curing: Pros and cons

This study aimed to investigate the effects of sodium nitrite treatment on antioxidant enzyme activity and free radical changes in yak meat during wet curing. The effect on superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and nitric oxide synthase (iNOS, TNOS) activity; superoxide anion (O2−) content and production rate; hydrogen peroxide (H2O2) content; nitric oxide (NO) content; and meat hydroxyl radical (OH) inhibition ability were determined. The results showed that NaNO2 treatment effectively increased the activity of CAT, GSH-Px, and NOS (TNOS, iNOS) over the first 3, 5, and 7 days (P < 0.01) following application, respectively, while simultaneously inhibiting the activity of SOD (P < 0.01). In addition, NaNO2 treatment resulted in an increase in O2− content and rate of O2− production in meat, as well as a decrease (P < 0.01) in H2O2 content on the third day of curing. With the addition of NaNO2, the inhibition ability of OH first increased and then decreased, and the NO content in meat increased (P < 0.01). The preliminary study showed that low-dose sodium nitrite could improve the endogenous antioxidant capacity of yak meat during the wet curing process, although it also had negative effects.

Control of Clostridium perfringens spore germination and outgrowth by potassium lactate and sodium diacetate in ham containing reduced sodium chloride

The effect of potassium lactate and sodium diacetate mixture (Opti.Form PD4®) on Clostridium perfringens spore germination and outgrowth during abusive cooling of reduced sodium ham was evaluated. A ham formulation containing NaNO2 (0 or 100 ppm), NaCl (1 or 2%) and Opti.Form PD4® (0, 1.5 or 2.5%) was prepared. Meat (10 g) was vacuum-packaged, stored under refrigeration (5 °C) for 3 or 24 h and inoculated with a three-strain C. perfringens spore cocktail. Samples were vacuum-packaged, heat treated (75 °C, 20 min) and cooled from 54.4 °C to 7.2 °C within 9, 15 or 21 h. C. perfringens population increases of 5.18 and 4.26 log CFU/g were observed in non-cured ham (control; stored for 3 h) formulated with 1 or 2% of NaCl, respectively and cooled exponentially within 21 h. Incorporation of Opti.Form PD4® (1.5%) inhibited C. perfringens spore germination and outgrowth regardless of the cooling rate (9, 15 or 21 h). Addition of NaNO2 (100 ppm) enhanced antimicrobial activity of Opti.Form PD4®. In general, abusive cooling (≥15 h) of ham after 24 h of storage resulted in greater populations of C. perfringens. Addition of NaNO2, Opti.Form PD4® and processing immediately resulted in greater inhibition of C. perfringens spore germination and outgrowth.

The electrochemical behavior of corrosion and passivation for Q235 carbon steel in acidic phosphate buffer solutions without and with NO2−

PurposeThe purpose of this paper is to reveal the mechanism of nitrite (NO2−) for the surface passivation of carbon steels in acidic environments through investigating the influences of 0.01 mol/L NaNO2addition on the corrosion and passivation behaviors of Q235 carbon steel in acidic phosphate buffer (APB) solutions (pH 2 to 6).Design/methodology/approachThe electrochemical techniques including open circle potential evolution, potentiodynamic polarization, electrochemical impedance spectroscopy and cyclic voltammetry were applied.FindingsIn APB solutions without NO2−, the Q235 steel presented the electrochemical behaviors of activation (A), activation-passivation-transpassivation and self-passivation-transpassivation at pH 2 to 4, pH 5 and pH 6, respectively; the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6.Originality/valueIn APB solutions without NO2−, the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6. With the addition of 0.01 mol/L NaNO2, into APB solutions, the variation of corrosion rate showed the same rule, but the surface passivation occurred over the whole acidic pH range, including the anodic passivation at pH 2 to 4 and the spontaneous passivation at pH 5 to 6.

Modelling the Mineralization of Formaldehyde by Treatment with Nitric Acid

Formaldehyde is a recalcitrant pollutant, which is difficult to remove from wastewater using conventional and advanced treatments. The objective of this research was to remove the organic matter from formaldehyde from an industrial wastewater, achieving its total mineralization and allowing the reuse of the water. The treatment was based on the reaction of formaldehyde with nitric acid, which was first studied and modelled with synthetic waters. Results show that it was possible to almost completely mineralize the formaldehyde (&gt;95% TOC removal) at the best conditions studied (1.72 M of nitric acid and 85 °C of temperature). The addition of NaNO2 accelerated this reaction; however, after 2 h of reaction time, its effect was negligible at the maximum concentration of HNO3 studied. The results obtained with industrial wastewater fit well with the model. It is concluded that formaldehyde in actual wastewaters can be successfully removed through direct mineralization with nitric acid, under selected conditions.

Ion-ion interactions enhance aluminum solubility in alkaline suspensions of nano-gibbsite (α-Al(OH)3) with sodium nitrite/nitrate.

Despite widespread industrial importance, predicting metal solubilities in highly concentrated, multicomponent aqueous solutions is difficult due to poorly understood ion-ion and ion-solvent interactions. Aluminum hydroxide solid phase solubility in concentrated sodium hydroxide (NaOH) solutions is one such case, with major implications for ore refining, as well as processing of radioactive waste stored at U.S. Department of Energy legacy sites, such as the Hanford Site, Washington State. The solubility of gibbsite (α-Al(OH)3) is often not well predicted because other ions affect the activity of hydroxide (OH-) and aluminate (Al(OH)4-) anions. In the present study, we systematically examined the influence of key anions, nitrite (NO2-) and nitrate (NO3-), as sodium salts on the solubility of α-Al(OH)3 in NaOH solutions taking care to establish equilibrium from both under- and oversaturation. Rapid equilibration was enabled by use of a highly pure and crystalline synthetic nano-gibbsite of well-defined particle size and shape. Measured dissolved aluminum concentrations were compared with those predicted by an α-Al(OH)3 solubility model derived for simple Al(OH)4-/OH- systems. Specific anion effects were expressed as an enhancement factor (Alenhc) conveying the excess of dissolved aluminum. At 45 °C, NaNO2 and NaNO3-containing systems exhibited Alenhc values of 2.70 and 1.88, respectively, indicating significant enhancement. The solutions were examined by Raman and high-field 27Al NMR spectroscopy, indicating specific interactions including Al(OH)4--Na+ contact ion pairing and Al(OH)4--NO2-/NO3- ion-ion interactions. Dynamic evolution of the α-Al(OH)3 particles including growth and agglomeration was observed revealing the importance of dissolution/reprecipitation in establishing equilibrium. These studies indicate that incomplete ion hydration, as a result of the low water activity in these concentrated electrolytes, results in: (i) enhanced reactivity of the hydroxide ion with respect to α-Al(OH)3; (ii) increased concentrations of Al(OH)4- in solution; and (iii) stronger ion-ion interactions that act to stabilize the supersaturated solutions. This information on the mechanisms by which α-Al(OH)3 becomes supersaturated is essential for more energy-efficient aluminum processing technologies, including the treatment of millions of gallons of Al(OH)4--rich high-level radioactive waste.

Long term effect of corrosion inhibitor and associated cation type of chloride ions on chloride profile of concrete exposed to composite chloride-sulfate environment

This paper experimentally investigated the effect of nitrite-based corrosion inhibitor and cation type namely Na+, Mg2+ and Ca2+ associated with chloride ions on free chloride (CF) and total chloride (CT) ion concentrations of concrete exposed to composite chloride-sulfate (Cl-+SO42-) environment. Concrete cubes were prepared using Portland pozzolana cement and w/c ratio of 0.55. Sodium nitrite (NaNO2) was used as a corrosion inhibitor at an admixed dosage of 3% by weight of cement. After curing, the cubes were subjected to composite Cl-+SO42- solutions such as NaCl + MgSO4, MgCl2 + MgSO4, and CaCl2 + MgSO4. Powder samples were collected at different depth intervals from the cubes to determine the CF and CT concentrations. Fourier transform infrared (FTIR) spectroscopy and Field emission scanning electron microscope (FESEM) analyses were carried to examine the microstructure of concrete. The experimental results indicated that addition of NaNO2 in concrete reduced the penetration of chloride ions. Concrete exposed to CaCl2 + MgSO4 solution mostly showed higher CF and CT concentrations than NaCl + MgSO4 solution followed by MgCl2 + MgSO4 solution. Results of microstructure study indicated the formation of different compounds in concrete exposed to composite Cl-+SO42- solutions.

The Comparative Investigation of Corrosion and Passivation for X65 Carbon Steel in pH 1 to 5 HNO3 Solutions without and with 0.01 mol L–1 NaNO2

The influence of 0.01 mol L-1 NaNO2 addition on the corrosion and passivation of X65 carbon steel in pH 1 to 5 HNO3 solutions was investigated and compared by electrochemical methods and microstructural techniques. In the pH 1 to 5 solutions without NaNO2, the X65 steel presented the electrochemical characteristic of active dissolution, and the corrosion rate of X65 carbon steel decreased gradually with the raise of pH value. By contrast, with the addition of 0.01 mol L-1 NaNO2 in pH 1 to 5 HNO3 solutions, the electrochemical characteristic of X65 carbon steel transferred from the active dissolution in the pH 1 to 5 solutions without NaNO2 to the anodic passivation in the corresponding pH solutions with NaNO2. For the X65 steel in the pH 1 to 5 solutions with NaNO2, with the raise of pH value, the corrosion rate also decreased gradually but the passivation capability strengthened obviously. The corrosion and passivation of X65 carbon steel in pH 1 to 5 HNO3 solutions without and with 0.01 mol L-1 NaNO2 were related to the cathodic reactions of H+ reduction, O2 reduction and NO2-/HNO2 reduction.

Protective characterization of low dose sodium nitrite on yak meat myoglobin in a hydroxy radical oxidation environment: Fourier Transform Infrared spectroscopy and laser Micro-Raman spectroscopy

The effect of NaNO2 in hydroxyl radical-mediated oxidative damage of yak meat myoglobin was investigated. Laser micro-Raman spectroscopy and Fourier Transform Infrared spectroscopy were used to assess protein (carbonyls, total sulfhydryl and Disulfide bonds) oxidation, atomic (or molecular) interactions and secondary structural changes. The addition of NaNO2 during the oxidation of myoglobin significantly reduced the content of carbonyl and disulfide bonds and protected the sulfhydryl groups from hydroxyl radical oxidation (P < 0.05). There was no significant difference in the secondary structure of myoglobin between the control group and the SN treatment group(P > 0.05). At the same time, NaNO2 had an inhibitory effect on the expansion of the hemoglobin center size and the transition of Fe from a low spin state to a high spin state caused by radical-oxidized. These findings suggest that NaNO2 has potential for treatment effects in a hydroxyl radical-oxidized myoglobin.

Nitrite scavenging impact of fermented soy sauce in vitro and in a pork sausage model

The objective of this study was to determine nitrite scavenging activity of fermented soy sauce in vitro and in a pork sausage model. In vitro nitrite scavenging activity (pH 6.0) of fermented soy sauce (10 mg/mL) was 13.2%. Within selected concentrations (10–100 mg/mL), in vitro nitrite scavenging activity and total phenol content of fermented soy sauce were highly dose-dependent (P < 0.001). In pork sausage model containing 120 mg/kg of NaNO2, fermented soy sauce resulted in significantly lower residual nitrite content (35.28 mg/kg) compared to only NaNO2 addition (40.12 mg/kg) at initial storage. During 4 weeks of cold storage, however, fermented soy sauce showed little effect on the residual nitrite content. This study indicates that fermented soy sauce could initially contribute to reduce residual nitrite content, and the nitrite scavenging impact of fermented soy sauce was less effective in the pork sausage model than in vitro evaluation.

Corrosion inhibition of 3003 aluminum alloy by cerium chloride-sodium nitrite blend in flue gas condensate

The inhibition behavior of cerium chloride (CeCl3)–sodium nitrite (NaNO2) blend in acidic flue gas condensate was studied using electrochemical approaches, full immersion tests, and surface analysis. The electrochemical results revealed that the inhibition efficiency of CeCl3 reached to about 64.1% at 750 mg/L. In contrast, the inhibition efficiency of CeCl3–NaNO2 blend reached to around 91.0%, which is increased by 42.0%. It was considered that Ce3+ was oxidized to Ce4+ by NaNO2. CeO2 which is more stable than Ce2O3 formed during corrosion. Besides, NaNO2 addition promoted the generation of much finer passive film. Therefore, CeCl3–NaNO2 blend improved the corrosion protection performance.

Comparative study on the effect of NaNO2 in corrosion inhibition of micro-alloyed and API-5L X65 steels in E20 simulated FGE

The effect of sodium nitrite (NaNO2) in the corrosion inhibition of micro-alloyed and API-5L X65 steels in E20 simulated fuel grade ethanol (SFGE) have been investigated via gravimetric method and morphological examination. While NaNO2 addition may positively slow down corrosion rate, its concentration within the tested range of 0.2 – 1.0 g/L plays an insignificant role in improving the corrosion resistance of API-5L X65 and micro-alloyed steels. Morphological examination of both steels after immersion tests in the presence and absence of the inhibitor showed pitting corrosion mechanism. Furthermore, statistical analysis confirms with 90 % confidence, that there is no significant difference between the corrosion behaviour of the two steels in E20 SFGE with and without NaNO2 inhibitor. Highest protection of the metal surface was achieved at 62.63 % with 0.2 g/L NaNO2 for API-5L X65 in E20.

Characteristics of Denitrification Inhibiting Sulfate Reducing Process

In this study, a set of two-stage UASB reactor was used to study the characteristics of denitrification inhibiting sulfate reduction in oil field gathering and transportation system and some high salt wastewater, and the characteristics of granular sludge and microbial characteristics were studied after the stable operation of the process. The results showed that the addition of NaNO2 increased the number of denitrifying bacteria (DNB) from 7.0×103 CFU·(100 mL)-1 to 7.3×105 CFU·(100 mL)-1 and remained stable in the process from start to mature. The competitive inhibition caused by DNB decreased the number of SRB from 8.0×105 CFU·(100 mL)-1 to 7.6×104 CFU·(100 mL)-1. Meanwhile, the sulfate reduction was inhibited, and the inhibition rate increased and finally stabilized to 82%. The study on mass ratio of microbial mass to nitrite effecting on denitrification efficiency showed that the inhibition rate of S2- was the highest, reaching 92%, when the mass ratio was 1200. The inhibition rate of the process could remain at about 92%, with good stability. The particle size and sedimentation rate of granular sludge were measured to determine whether the process conditions were favorable for the formation of granular sludge. The study showed that the denitrifying granular sludge formed was brown, basically ellipsoidal and spherical, with smooth surface and high density. Before the denitrification inhibition, the particle size of granular sludge was 1.0-1.4 mm and the average diameter was 1.17 mm, and after denitrification inhibition, the particle size distribution was 1.2-1.6 mm, the average particle size was 1.21 mm, which indicated that the denitrification inhibition increased the size of granular sludge. The average sedimentation velocity of denitrifying granular sludge was 47.6 m·h-1, which revealed the good settling performance of the granular sludge. The results of PCR-DGGE analysis showed that the denitrification inhibition reduced the number of microbial species from 18 to 14 and the number of dominant species decreased from 4 to 3, indicating the decreasing microbial diversity. The similarity of microbial population before and after nitrification was 62.6% and the population structure changed greatly from SRB to DNB. The number of dominant SRB species decreased from 4 to 2 after denitrification inhibition and the abundance of every species decreased obviously. The main functional bacterial species of the inhibition process was uncultured Sulfurimonas sp., which is a kind of autotrophic denitrifying bacteria. It dominated and competed with SRB for electrons, inhibiting the sulfate reduction and the production of sulfide.

Addition of sodium nitrite and biofilm in a Litopenaeus vannamei biofloc culture system

This study evaluates the effects of the previous addition of sodium nitrite (NaNO 2 ) and biofilm in a Litopenaeus vannamei biofloc culture. Five treatments were tested in 180 L - tanks: NaNO 2 (-20) addition of NaNO 2 for 20 days before stocking and without artificial substrates; NaNO 2 +B (-20) addition of NaNO 2 for 20 days before stocking, with 150% additional artificial substrates; NaNO 2 (Stocking) addition of NaNO 2 at stocking and no artificial substrates; NaNO 2 +B (Stocking) addition of NaNO 2 at stocking, with 150% additional artificial substrates and; Control, without NaNO2 addition and without artificial substrates. The study was carried out in two phases: shrimps (0.21 ± 0.08 g) were stocked at a density of 400 ind m -2 /1,100 ind m -3 , for 30 days (nursery). After this period, the animals were restocked at a lower density (120 ind m -2 /400 ind m -3 ) for 18 more days (grow-out). The turbidity and seattleable solids were higher in treatments without artificial substrates, independently of the addition of NaNO 2 . The ammonia and nitrite were lower in control, and the nitrate concentrations were higher in treatments with addition of NaNO 2 without biofilm. At the end of the nursery, the survival was lower in treatment NaNO 2 (-20), and at the end of grow-out the final biomasses were higher in treatments with addition of NaNO 2 at the stocking day. In conclusion, the use of a dose of NaNO2 at the stocking day could increase the nitrite-oxidizing bacteria, and the biofilm may contribute to the reduction in suspended particles in water, enhancing shrimp production in biofloc technology system.

In vitro modelling of simultaneous interactions of Listeria monocytogenes, Lactobacillus sakei, and Staphylococcus carnosus.

The Jameson effect model describes suppression of microorganism growth as being dependent on non-specific competition. This model was developed for simultaneous growth in a liquid medium and microbial interactions between Listeria monocytogenes, Lactobacillus sakei, and Staphylococcus carnosus with addition of NaNO2 to mimic the manufacturing process of salami for 48 h at 21°C and then for 14 days at 17°C. L. monocytogenes in the presence of L. sakei was inhibited by 2.120 log CFU/mL in the presence of NaNO2, and 1.146 log CFU/mL without NaNO2. Inhibition of L. monocytogenes cocultured with S. carnosus was 2.248 log CFU/mL at 48 h, but after 336 h was not significantly (p>0.05) different from L. monocytogenes in mono-culture. The interspecific competition parameter (β) <1 indicated that the prevailing competition in co-cultures was intraspecific. Differentiation between 2 bacterial species interactions can be applied for use in starter cultures with pathogenic flora.

Influences of urea and sodium nitrite on surface coating of plasma electrolytic oxidation

Urea and sodium nitrite are generally viewed as nitridation additives in the electrolyte for plasma electrolytic oxidation (PEO) of aluminum alloys. We study the influences of these two convenient chemicals in presence of sodium aluminate and find very different effects on film growth. Urea addition enhances the nitrogen content of PEO layer, diminishes the layer thickness, increases the porosity, interferes with the α-alumina formation, and promotes precipitation in the electrolyte. Hence, the electrolytic urea content ought to be maintained less than 45gdm−3. On the other hand, sodium nitrite behaves like an oxidation additive, more than a nitridation additive. NaNO2 addition effectively introduces nitrogen in the PEO layer at low concentration, yet the nitrogen content of oxide layer decreases with increasing NaNO2 concentration. The effects of NaNO2, such as increasing layer thickness, reducing porosity, promoting α-alumina formation are attributed to oxidation enhancement, not because of nitridation.

Synthesis of 3,4,5-Trisubstituted Isoxazoles from Morita-Baylis-Hillman Acetates by an NaNO2 /I2 -Mediated Domino Reaction.

An efficient NaNO2 /I2 -mediated one-pot transformation of Morita-Baylis-Hillman (MBH) acetates into alkyl 3-nitro-5-(aryl/alkyl)isoxazole-4-carboxylates is described. In a cascade event, initial Michael addition of NaNO2 to the MBH acetate furnishes the allylnitro intermediate which undergoes I2 -catalyzed oxidative α-CH nitration of the nitromethyl subunit followed by [3+2] cycloaddition to afford the title compounds. Structural elaborations of these highly substituted isoxazoles by SN Ar reactions and hydrogenolysis allows access to useful products.

Synthesis of 3,4,5‐Trisubstituted Isoxazoles from Morita–Baylis–Hillman Acetates by an NaNO2/I2‐Mediated Domino Reaction

AbstractAn efficient NaNO2/I2‐mediated one‐pot transformation of Morita–Baylis–Hillman (MBH) acetates into alkyl 3‐nitro‐5‐(aryl/alkyl)isoxazole‐4‐carboxylates is described. In a cascade event, initial Michael addition of NaNO2 to the MBH acetate furnishes the allylnitro intermediate which undergoes I2‐catalyzed oxidative α‐CH nitration of the nitromethyl subunit followed by [3+2] cycloaddition to afford the title compounds. Structural elaborations of these highly substituted isoxazoles by SNAr reactions and hydrogenolysis allows access to useful products.