Search

The diethyl oxalate process features two reaction sections with two of the fresh feeds (oxygen and ethanol) and a recycle stream containing nitric oxide fed into the first reactor, which produces ethyl nitrite and water. Water is removed in a distillation column and the ethyl nitrite is fed to the second reactor along with the third fresh feed (carbon monoxide). Diethyl oxalate and nitric oxide are produced in this reactor. The product diethyl oxalate is recovered in a distillation column, and the nitric oxide is recycled back to the first reactor. The intermediate components (nitric oxide and ethyl nitrite) and inert nitrogen circulate between the two reaction sections. A recent paper proposed a plantwide control structure for this complex process that requires four on-line composition controllers to handle disturbances in throughput and the compositions of the three fresh feed streams. The purpose of this paper is to demonstrate that a less complex control structure with only one composition measurement can achieve stable regulatory control.

Diethyl oxalate (DEO) is widely used in fine chemical industry. In comparison with traditional esterification process, carbon monoxide coupling process is a novel routine for DEO production. This environmentally friendly process provides better selectivity and yield. Its unique feature is that a closed regeneration-coupling circulation is formed. Toxic byproduct-nitric oxide (NO) from coupling reaction is recycled to re-produce ethyl nitrite through regeneration reaction. This avoids significant amount of NOx emission. However, due to a few NOx emission, a contaminant handling system is applied for environmental protection. A systematical environmental analysis is also carried out to assess this process. Regeneration-coupling circulation brings interaction behaviors and some trade-offs including reactor size and recycle flowrate, regeneration and coupling reaction, loss of reactants and NO emission. Thus, a rigorous steady simulation is established to investigate these trade-offs. Then DEO process is optimized to obtain the optimal design. Finally a more economic flowsheet to produce DEO is proposed.

The method for assessing the level of nitric oxide (II) (NO) by voltammetric monitoring of nitrite ions was carried out on models M1 and M2 of polarized macrophages induced from monocytes of human peripheral blood with the addition of lipopolysaccharide (LPS) and interleukin-4 (IL-4), respectively. The model of induction of M1 and M2 macrophages was used in the work to achieve the corresponding shifts in the functional status of studied cells. Ethyl nitrite (EtONO) was used as a standard compound of nitrite ions for electrochemical measurements. Electrochemical determination of nitrite ions was performed by anodic linear sweep voltammetry in the first-order derivative mode (ALSV FOD) in Britton-Robinson (BR) buffer with pH 4.02 on carbon ink modified graphite electrode. EtONO calibrations were linear over a concentration range from 2 to 9 μmol L−1 with corresponding regression equation y = 0.768c − 0.048. Limit of detection (LOD) (S/N = 3) was 0.38 μmol L−1. The results of the study showed the fundamental possibility of using voltammetry to assess indirectly the production of nitric oxide by cells in supernatants of the monocytic macrophage lineage. The level of nitric oxide metabolites (nitrite ions) in supernatants was associated with the functional state of macrophages.

Diethyl carbonate (DEC) is a well-known linear organic carbonate that has wide applications. Besides its use as a fuel additive, DEC is an excellent electrolyte for lithium ion batteries and is used for the production of polycarbonates, which are globally used engineering plastics. The synthesis of DEC from CO2 helps in CO2 mitigation. It was earlier synthesized by phosgenation of ethanol, which is a toxic and dangerous process. Certain non-phosgene routes have been developed in recent years, which include oxidative carbonylation of ethanol, trans-esterification of carbonate, alcoholysis of urea, ethanolysis of CO2 and the ethyl nitrite route for DEC synthesis. This review underlines various non-phosgene methods for the synthesis of DEC by critically evaluating the catalysts used, operating conditions and mechanism of synthesis. The performances of various catalysts have been compared graphically along with the identification of problems and potential solutions. Certain engineering aspects, including kinetics and thermodynamics of the various routes, have also been highlighted. The shortcomings and research gaps have been explicitly mentioned and discussed along with required future developments and research work for DEC synthesis.

Disruption of microvascular blood flow is a common cause of tissue hypoxia in disease, yet no therapies are available that directly target the microvasculature to improve tissue oxygenation. Red blood cells (RBCs) autoregulate blood flow through S-nitroso-hemoglobin (SNO-Hb)-mediated export of nitric oxide (NO) bioactivity. We therefore tested the idea that pharmacological enhancement of RBCs using the S-nitrosylating agent ethyl nitrite (ENO) may provide a novel approach to improve tissue oxygenation. Serial ENO dosing was carried out in sheep (1–400 ppm) and humans (1–100 ppm) at normoxia and at reduced fraction of inspired oxygen (FiO(2)). ENO increased RBC SNO-Hb levels, corrected hypoxia-induced deficits in tissue oxygenation, and improved measures of oxygen utilization in both species. No adverse effects or safety concerns were identified. Inasmuch as impaired oxygenation is a major cause of morbidity and mortality, ENO may have widespread therapeutic utility, providing a first-in-class agent targeting the microvasculature.

This study investigates the autoignition behavior of two gasoline surrogates doped with an alkyl nitrate cetane enhancer, 2-ethyl-hexyl nitrate (2EHN) to better understand dopant interactions with the fuels, including influences of accelerating kinetic pathways and enhanced exothermicity. A primary reference fuel (PRF) blend of n-heptane/iso-octane, and a toluene reference fuel (TRF) blend of n-heptane/iso-octane/toluene are used where the aromatic fraction of the latter is set to 20% (liquid volume), while the content of n-heptane is adjusted so that the overall reactivity of the undoped fuels is similar, e.g., Anti-Knock Index (AKI) of ∼91, Cetane Number (CN) ∼25. Doping levels of 0.1, 1.0 and 3.0% (liquid volume basis) are used where tests are conducted within a rapid compression machine (RCM) at a compressed pressure of 21 bar, covering temperatures from 675 to 1025 K with stoichiometric fuel–oxygen ratios at O2 = 11.4%. At the experimental conditions, it is found that the doping effectiveness of 2EHN is fairly similar between the two fuels, though 2EHN is more effective in the aromatic blend at the lowest temperatures, while it is slightly more effective in the non-aromatic blend at intermediate temperatures. Kinetic modeling of the experiments indicates that although some of the reactivity trends can be captured using a detailed model, the extents of predicted Cetane Number enhancement by 2EHN are too large, while differences in fuel interactions for the two fuels result in excessive stimulation of the non-aromatic blend. Sensitivity analysis using the kinetic model indicates that the CH2O and CH3O2 chemistry are very sensitive to the dopant at all conditions. The rate of 2EHN decomposition is only important at low temperatures where its decomposition rate is slow due to the high activation energy of the reaction. At higher temperatures, dopant-derived 3-heptyl radicals are predicted to play an important role stimulating ignition. Finally, nitrogen chemistry is important through the ’NO – NO2 loop’ where this can generate substantial amounts of OH. However, at the highest doping levels the formation of methyl and ethyl nitrite, and nitric acid significantly competes with this so that less OH is generated and this constrains the reactivity enhancement of 2EHN.

Chirped-pulse (CP) Fourier transform rotational spectroscopy is uniquely suited for near-universal quantitative detection and structural characterization of mixtures that contain multiple molecular and radical species. In this work, we employ CP spectroscopy to measure product branching and extract information about the reaction mechanism, guided by kinetic modeling. Pyrolysis of ethyl nitrite, CH3CH2ONO, is studied in a Chen type flash pyrolysis reactor at temperatures of 1000-1800 K. The branching between HNO, CH2O, and CH3CHO products is measured and compared to the kinetic models generated by the Reaction Mechanism Generator software. We find that roaming CH3CH2ONO → CH3CHO + HNO plays an important role in the thermal decomposition of ethyl nitrite, with its rate, at 1000 K, comparable to that of the radical elimination channel CH3CH2ONO → CH3CH2O + NO. HNO is a signature of roaming in this system.

Background It is well known that ethanol can cause significant morbidity and mortality, and much of the related toxic effects can be explained by its metabolic profile. Objective This work performs a complete review of the metabolism of ethanol focusing on both major and minor metabolites. Method An exhaustive literature search was carried out using textual and structural queries for ethanol and related known metabolizing enzymes and metabolites. Results The main pathway of metabolism is catalyzed by cytosolic alcohol dehydrogenase, which exhibits multiple isoenzymes and genetic polymorphisms with clinical and forensic implications. Another two oxidative routes, the highly inducible CYP2E1 system and peroxisomal catalase may acquire relevance under specific circumstances. In addition to oxidative metabolism, ethanol also originates minor metabolites such as ethyl glucuronide, ethyl sulfate, ethyl phosphate, ethyl nitrite, phosphatidylethanol and fatty acid ethyl esters. These metabolites represent alternative biomarkers since they can be detected several hours or days after ethanol exposure. Conclusion It is expected that knowing the metabolomics of ethanol may provide additional insights to better understand the toxicological effects and the variability of dose response.

High catalytic activity of a gold N-containing ligand complex in the homogenous carbonylation of alkyl nitrite to dialkyl carbonate with KI as the promoter is reported. [AuCl 2 (phen)]Cl/KI (phen = 1,10-phenanthroline) complex has been used as a catalyst in the carbonylation of ethyl nitrite. The use of iodide as a promoter resulted in a significant increase in activity (TOF: 35.8 mol•mol Au − 1 •h − 1 ) and selectivity (91.7%) for diethyl carbonate at 3.0 MPa, 80 °C and 5 h. Based on the results of ESI-MS, UV-Vis, and cyclic voltammetry (CV) experiments, a mechanism is proposed for the carbonylation of alkyl nitrite in a homogeneous system using a gold N-containing ligand complex as a catalyst.

A novel Pd–Fe/α-Al 2 O 3 /cordierite monolithic catalyst was prepared for the synthesis of diethyl oxalate from CO and ethyl nitrite. The palladium-based monolithic catalyst with an optimal thickness (15 μm) of Al 2 O 3 washcoat showed excellent catalytic activity and selectivity in a continuous flow, fixed-bed microreactor. The physicochemical properties of catalyst were studied by a variety of characterization techniques. Catalytic performances of Pd–Fe/α-Al 2 O 3 /cordierite monolithic catalysts were dependent on particle size of alumina-sol, thickness of Al 2 O 3 washcoat, pore structure, surface acidity of carrier, and distribution of active metal component on the Al 2 O 3 washcoat. Under the mild reaction conditions, CO conversion was 32% and the space–time yield of diethyl oxalate was 429 g/(L h). Pd efficiency (DEO(g)/Pd(g)/h) of the monolithic catalyst (274 h −1 ) was much higher than that of a reference pellet catalyst (46 h −1 ), probably due to high dispersion of the Pd nanoparticles on the surface of the monolithic catalyst.

Background and Purpose— S -nitrosylated hemoglobin ( S -nitrosohemoglobin) has been implicated in the delivery of O 2 to tissues through the regulation of microvascular blood flow. This study tested the hypothesis that enhancement of S -nitrosylated hemoglobin by ethyl nitrite inhalation improves outcome after experimental subarachnoid hemorrhage (SAH). Methods— A preliminary dosing study identified 20 ppm ethyl nitrite as a concentration that produced a 4-fold increase in S -nitrosylated hemoglobin concentration with no increase in methemoglobin. Mice were subjected to endovascular perforation of the right anterior cerebral artery and were treated with 20 ppm ethyl nitrite in air, or air alone for 72 hours, after which neurologic function, cerebral vessel diameter, brain water content, cortical tissue P o 2 , and parenchymal red blood cell flow velocity were measured. Results— At 72 hours after hemorrhage, air- and ethyl nitrite–exposed mice had similarly sized blood clots. Ethyl nitrite improved neurologic score and rotarod performance; abated SAH-induced constrictions in the ipsilateral anterior, middle cerebral, and internal carotid arteries; and prevented an increase in ipsilateral brain water content. Ethyl nitrite inhalation increased red blood cell flow velocity and cortical tissue P o 2 in the ipsilateral cortex with no effect on systemic blood pressure. Conclusions— Targeted S -nitrosylation of hemoglobin improved outcome parameters, including vessel diameter, tissue blood flow, cortical tissue P o 2 , and neurologic function in a murine SAH model. Augmenting endogenous P o 2 -dependent delivery of NO bioactivity to selectively dilate the compromised cerebral vasculature has significant clinical potential in the treatment of SAH.

The synthesis of ethyl nitrite by the reaction of C 2 H 5 OH, O 2 , and NO, called the regeneration reaction in the synthesis of ethylene glycol (EG) by the coupling reaction-hydrogenation process, is carried out in a trickle bed reactor filled with θ-mesh rings at 313–343 K and atmospheric pressure. It is shown that the conversion of O 2 increases with the NO/O 2 and the EtOH/NO molar ratios, and decreases with the N 2 volume fraction and the liquid hourly space velocity (LHSV). O 2 conversion reaches a maximum (∼90.9%) at 333 K, NO/O 2 molar ratio of 6:1, EtOH/NO molar ratio of 3:1, N 2 volume fraction of 50%, and LHSV of 2.65 h −1 . The synthesis reaction is a fast one and takes place in a liquid film. A kinetics model based on the two-film model of gas–liquid reaction is proposed. The experiment data fit the kinetics model very well and statistical tests also show their reliability.

A method to maintain organ blood flow during laparoscopic surgery has not been developed. Here we determined if ethyl nitrite, an S-nitrosylating agent that would maintain nitric oxide bioactivity (the major regulator of tissue perfusion), might be an effective intervention to preserve physiologic status during prolonged pneumoperitoneum. The study was conducted on appropriately anesthetized adult swine; the period of pneumoperitoneum was 240 minutes. Cohorts consisted of an anesthesia control group and groups insufflated with CO2 alone or CO2 containing fixed amounts of ethyl nitrite (1-300 ppm). Insufflation with CO2 alone produced declines in splanchnic organ blood flows and it reduced circulating levels of S-nitrosohemoglobin (i.e., nitric oxide bioactivity); these reductions were obviated by ethyl nitrite. In a specific example, preservation of kidney blood flow with ethyl nitrite kept serum creatinine and blood urea nitrogen concentrations constant whereas in the CO2 alone group both increased as kidney blood flow declined. The data indicate ethyl nitrite can effectively attenuate insufflation-induced decreases in organ blood flow and nitric oxide bioactivity leading to reductions in markers of acute tissue injury. This simple intervention provides a method for controlling a major source of laparoscopic-related morbidity and mortality: tissue ischemia and altered postoperative organ function.

Ethyl and sodium nitrite were studied for their genetic toxicity in bacteria and barley. At physiological pH the organic nitrite had a greater mutagenic effectiveness than the inorganic nitrite. Concurrent treatments with ethyl nitrite and primary amines resulted in enhanced effects. The implication of these results in the genetic health hazards due to environmental pollution is discussed.

Rationale: Inhaled nitric oxide (NO) has been used to prevent bronchopulmonary dysplasia, but with variable results. Ethyl nitrite (ENO) forms S-nitrosothiols more readily than does NO, and resists higher-order nitrogen oxide formation. Because S-nitrosylation is a key pathway mediating many NO biological effects, treatment with inhaled ENO may better protect postnatal lung development from oxidative stress than NO.Objectives: To compare inhaled NO and ENO on hyperoxia-impaired postnatal lung development.Methods: We treated newborn rats beginning at birth to air or 95% O2 ± 0.2–20.0 ppm ENO for 8 days, or to 10 ppm NO for 8 days. Pups treated with the optimum ENO dose, 10 ppm, and pups treated with 10 ppm NO were recovered in room air for 6 more days.Measurements and Main Results: ENO and NO partly prevented 95% O2–induced airway neutrophil influx in lavage, but ENO had a greater effect than did NO in prevention of lung myeloperoxidase accumulation, and in expression of cytokine-induced neutrophil chemoat...

A multistep mechanism has been elucidated for the reduction of NOx in the presence of added ethanol over Ag/γ-Al2O3 at 320 °C. Under these conditions, ethanol principally reacts with oxygen to form acetaldehyde. Surface acetate ions, which are formed from adsorbed acetaldehyde, react with NO2 to yield nitromethane. Evidence is presented indicating that the aci-anion of nitromethane is an intermediate. In contrast, NOx reduction with ethanol over Ag/γ-Al2O3 at 200 °C is inefficient, because surface acetate ions are much less reactive at 200 °C than at 320 °C. At 200 °C, the dominant pathway for ethanol oxidation is reaction with NO2, producing ethyl nitrite, which decomposes into a number of products, including N2O, which is stable under reaction conditions. On the basis of these mechanistic data, conditions can be defined under which NOx reduction with ethanol may be viable.

The mechanism for the reaction of CO coupling to diethyl oxalate (DEO) over Pd–Fe/α-Al2O3 in gaseous phase at normal pressure was studied by X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared spectroscopy (DRIRS) techniques. The adsorption of two reactants, carbon monoxide and ethyl nitrite, on the catalyst was observed, respectively with in situ DRIRS as well as the catalysts after ethyl nitrite adsorption and after in situ reaction were also characterized by XPS measurement. These observational results show that (1) The ethyl nitrite on the catalyst surface has a dissociative chemisorption which leads to the oxidation of Pd0 to Pd2+ (active component on the catalyst). So the reaction is a redox process; (2) Two intermediates, palladium complexes, in the reaction process are involved. From this, the mechanism steps of the reaction were proposed and the two intermediates were inferred.

A vapor phase synthesis of diethyl carbonate (DEC) from carbon monoxide and ethyl nitrite (EN) was studied in a continuous flow micro fixed-bed reactor at atmospheric pressure. PdCl 2 –CuCl 2 /AC (activated carbon) catalyst exhibited better catalytic activity compared with other binary catalyst systems. The suitable Pd-loading is about 2.0 wt%, and some additives (LaCl 3 , CeCl 3 , PrCl 3 ) are benefit for the DEC yield and selectivity. Influences of various reaction parameters on the DEC yield and selectivity were tested. The optimum reaction temperature lies in 378–388 K and the suitable gas hourly space velocity (GHSV) range is 2500–3000 h −1 considering both factors of DEC production and CO conversion. An optimum CO/C 2 H 5 ONO mole ratio exists for catalytic activity, which is about 1/1. The stability of PdCl 2 –CuCl 2 /AC catalyst and PdCl 2 –CuCl 2 –CeCl 3 /AC catalyst was also investigated. The possible reason of the deactivation behavior of catalysts was discussed with the help of XRD.

The coupling reaction of carbon monoxide to diethyl oxalate in the presence of ethyl nitrite at atmospheric pressure over supported palladium catalyst was investigated in a continuous flow integral-type fixed-bed reactor with the aim of kinetic modeling and reactor performance studies. The effect of reaction conditions on the global rate and selectivity was studied. The main products formed were diethyl oxalate (DEO) and diethyl carbonate (DEC). The results at dp

The reaction kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate was studied in the presence of ethyl nitrite over supported palladium catalyst in gaseous phase at atmospheric pressure. The experiments were performed in a continuous flow fixed-bed differential type reactor. It was discovered that the rate-determining step is the surface reaction between adsorbed species and that ethyl nitrite dissociates into ethoxy radical (EtO−) and NO species and are adsorbed on two active sites. The kinetic model was proposed, with which some observations concerning with the reaction behaviors of the system can be readily accounted for. In the presence of hydrogen, the kinetics of the reaction system was also investigated. It was revealed that hydrogen, with adsorption and dissociation, reacts with adsorbed ethoxy radical to ethanol.

The mid-IR spectrum of gas-phase C2H5OO has been measured over the spectral range of 800−4000 cm-1. The employed experimental technique was long-path-length absorption in which a White cell was coupled to an FTIR spectrometer. Radicals were generated in a mixing manifold prior to the absorption cell by passing an F2/He mixture through a microwave discharge to create fluorine atoms followed by the reaction of atomic fluorine with an ethane/oxygen mixture. A number of absorption bands were observed to increase in intensity with increasing atomic fluorine concentration. Verification that the observed bands originated from the ethyl peroxy radical was done first by comparing measured band frequencies with the spectra of possible secondary reaction products and second by titrating C2H5OO• with excess nitric oxide and observing the nitrogen dioxide and ethyl nitrite products that ultimately result from the titration reaction. Bands were assigned to normal modes of C2H5OO• through comparing the observed band pos...

The synthesis of diethyl oxalate from ethyl nitrite and carbon monoxide was studied in a continuos flow micro fixed-bed reactor at atmospheric pressure. Two palladium catalysts supported on α-Al2O3 of different pore structures were studied under mild conditions. One catalyst (1 wt.% Pd/α-Al2O3-1) showed higher catalytic activity and selectivity than the other catalyst (1 wt.% Pd/α-Al2O3-2). X-ray diffraction patterns have confirmed that both supports are well-defined α-Al2O3. Palladium dispersions were greater on the 1 wt.% Pd/α-Al2O3-1 catalyst than that on the 1 wt.% Pd/α-Al2O3-2 catalyst as determined by hydrogen chemisorption. The FTIR spectroscopy study indicated that the 1 wt.% Pd/α-Al2O3-1 catalyst adsorbed CO easily in the linear form (band at 2089 cm−1) and bridge form (bands at 1950 and 1880 cm−1), and as carbonate species (at 1628 cm−1). There was little CO adsorption on 1 wt.% Pd/α-Al2O3-2. The average pore size of the support α-Al2O3-1 was 41.6 A, and 14.0 A for α-Al2O3-2. This study reveals that the pore structure of the supports remarkably affects the palladium dispersion of the catalysts and alters the CO adsorption behavior, therefore, dramatically affect the catalytic performance. In the case of CO+C2H5ONO reactions, diethyl oxalate was efficiently formed over the 1 wt.% Pd/α-Al2O3-1 catalyst.

Nitrosonium ethyl sulfate (1), which is generated in situ from ethyl nitrite and sulfur trioxide, is a convenient reagent for the one-pot transformation of olefins and dienes into substituted aldeh...

Ab initio and density functional (DFT) methods were used to investigate the rotamers of ethyl nitrite. The potential energy surface for rotations around the C-O and the N-O bonds was calculated at different levels of theory. From the four geometrically possible conformers, only three were found to be stable when correlation effects are taken into account in the calculations. This result is consistent with a microwave study of Turner (J. Chem. Soc., Faraday Trans. 2 1979, 317.) as well as with the presented IR spectrum of matrix-isolated ethyl nitrite which clearly distinguishes three different N dO stretching modes. A simulated IR spectrum generated from the results of the DFT calculations is in good agreement with this matrix spectrum and allows us to tentatively assign groups of frequencies.

The pathway by which inhaled NO gas enters pulmonary alveolar epithelial cells has not been directly tested. Although the expected mechanism is diffusion, another route is the formation of S-nitroso-L-cysteine, which then enters the cell through the L-type amino acid transporter (LAT). To determine if NO gas also enters alveolar epithelium this way, we exposed alveolar epithelial-rat type I, type II, L2, R3/1, and human A549-cells to NO gas at the air liquid interface in the presence of L- and D-cysteine+/-LAT competitors. NO gas exposure concentration dependently increased intracellular NO and S-nitrosothiol levels in the presence of L- but not D-cysteine, which was inhibited by LAT competitors, and was inversely proportional to diffusion distance. The effect of L-cysteine on NO uptake was also concentration dependent. Without preincubation with L-cysteine, NO uptake was significantly reduced. We found similar effects using ethyl nitrite gas in place of NO. Exposure to either gas induced activation of soluble guanylyl cylase in a parallel manner, consistent with LAT dependence. We conclude that NO gas uptake by alveolar epithelium achieves NO-based signaling predominantly by forming extracellular S-nitroso-L-cysteine that is taken up through LAT, rather than by diffusion. Augmenting extracellular S-nitroso-L-cysteine formation may augment pharmacological actions of inhaled NO gas.

By acting as a bioreactor, affording chemical and mechanical conditions for the reaction between dietary components, the stomach may be a source of new bioactive molecules. Using gas chromatography-mass spectrometry we here demonstrate that, under acidic gastric conditions, ethyl nitrite is formed in µM concentrations from the reaction of red wine or distilled alcoholic drinks with physiological amounts of nitrite. Rat femoral artery rings and gastric fundus strips dose-dependently relaxed upon exposure to nitrite:ethanol mixtures. In contrast, when administered separately in the same dose ranges, nitrite evoked only minor vasorelaxation while ethanol actually caused a slight vasoconstriction. Mechanistically, the relaxation effect was assigned to generation of nitric oxide (-NO) as supported by direct demonstration of -NO release from ethyl nitrite and the absence of relaxation in the presence of the soluble guanylyl cyclase inhibitor, ODQ. In conclusion, these results suggest that ethanol in alcoholic drinks interacts with salivary-derived nitrite in the acidic stomach leading to the production of the potent smooth muscle relaxant ethyl nitrite. These findings reveal an alternative chemical reaction pathway for dietary nitrate and nitrite with possible impact on gastric physiology and pathophysiology. http://www.sciencedirect.com/science/article/B6T38-4SCDB0R-4/1/5f2ae4cd1ef8af7eca3f5d4ee8f353ad

International audience; The isomerization process between ionized phenol and ionized cyclohexadienone is studied by performing ion/molecule reactions with several alkyl nitrites in a hexapole collision cell inserted in a six-sector mass spectrometer. The distinction between both isomeric species is readily achieved on the basis of the completely different reactivity patterns observed for them in subsequent reactions. When reacting with alkyl nitrite, ionized phenol undergoes two competitive reactions corresponding to the formal radical substitution of the hydroxylic hydrogen atom by respectively (i) the nitrosyl radical (m/z 123) and (ii) an alkoxyl radical (m/z 138 if alkyl=ethyl). Both reactions were theoretically demonstrated by density functional theory calculations [B3LYP/6-311++G(d,p)+ZPE] to involve hydrogen-bridged radical cations as key intermediates. The ion/molecule reaction products detected starting from ionized cyclohexadienone as the mass-selected ions arise from *OAlkyl, *OH, and NO2* radical additions. The occurrence of a spontaneous ring-opening of cyclohexadienone radical ion into a distonic species is suggested to account for the observed ion/molecule reaction products. We also demonstrated that ionized cyclohexadienone is partly isomerized during a proton-transfer catalysis process into ionized phenol inside the Hcell with ethyl nitrite as the base. The molecular ions of phenol generated in such conditions consecutively undergo reactions producing m/z 123 and 138 radical cations. The proposed mechanism is supported by results of quantum chemical calculations.

The first-order rate constants of 8 organic substances were measured using the ethyl nitrite and nitrogen dioxide photolyses and their relative rates with respect to n-hexane rate constant were calculated. These were compared with literature data. Relatively small photolysis rates of alkane and aromatics were shown for our photosystems and the alkenes were rapidly photolyzed. For mixed photooxidation reactions of various organics, it would be reasonable for organics of the group classified by their molecular structures to be discussed on their reactivities with OH radicals.

The reaction pathways for the interaction of the nitrite ion with ethyl chloride and ethyl bromide in DMSO solution were investigated at the ab initio level of theory, and the solvent effect was included through the polarizable continuum model. The performance of BLYP, GLYP, XLYP, OLYP, PBE0, B3PW91, B3LYP, and X3LYP density functionals has been tested. For the ethyl bromide case, our best ab initio calculations at the CCSD(T)/aug-cc-pVTZ level predicts product ratio of 73% and 27% for nitroethane and ethyl nitrite, respectively, which can be compared with the experimental values of 67% and 33%. This translates to an error in the relative DeltaG* of only 0.17 kcal mol(-1). No functional is accurate (deviation

We investigated the 14N quadrupole coupling of three rotational isomers of ethyl nitrite in the ground state by microwave Fourier transform spectroscopy. Centrifugal distortion analyses were necessary to assign the transitions with high J quantum numbers. We found an additional splitting of some c-type transitions of the trans-gauche rotamer presumably arising from tunneling through the barrier separating the two equivalent gauche forms. This assumption could not be confirmed yet.

While nitrosation of 6-substituted 2, 4-dimethylpyrimidines with ethyl nitrite in liquid ammonia occurred preferentially at the 4-methyl group to give the corresponding pyrimidine-4-aldoximes, the same reaction of 1, 2, 4-trimethyl-6-oxo-1, 6-dihydropyrimidine (IV) afforded 1, 4-dimethyl-6-oxo-1, 6-dihydropyrimidine-2-aldoxime. Acylation of IV with ethyl benzoate and diethyl oxalate under basic conditions also gave α-(1, 4-dimethyl-6-oxo-1, 6-dihydro-2-pyrimidinyl) acetophenone and ethyl 3-(1, 4-dimethyl-6-oxo-1, 6-dihydro-2-pyrimidinyl) pyruvate, respectively.

The reactions of human hemoglobin and sperm whale myoglobin with ethyl nitrite under aerobic conditions have been examined in kinetic detail. Ethyl nitrite converts two equivalents of oxyhemoglobin or oxymyoglobin to their oxidized counterparts with concurrent production of one equivalent each of molecular oxygen, nitrate ion, and ethyl alcohol. Inverse first order kinetic dependence on the concentration of molecular oxygen has been observed and is interpreted by a mechanism in which oxygen dissociation from the oxyhemoprotein occurs prior to rate-limiting oxidation by ethyl nitrite. The rate constant for ethyl nitrite oxidation of hemoglobin from which the fourth oxygen has dissociated is calculated to be 45 times greater than the corresponding rate constant for oxidation of deoxyhemoglobin. This rate enhancement is proposed to be a reflection of the oxidative susceptibility of the R and T conformational states of hemoglobin. Results obtained for the oxidation of myoglobin confirm this interpretation as do kinetic data for hemoglobin and myoglobin oxidations by iron(III) and copper(II) complexes. The effects of organic phosphates on rates for hemoglobin oxidations are interpreted in terms of oxidation inhibition by molecular oxygen.

Benzoylation of 2, 4-dimethyl-(Ia), 2, 4, 6-trimethyl-pyrimidine (Ib), 2, 4-dimethyl-quinazoline (Ic), 2, 4-dimethyl-(Id), 2, 4, 6-trimethyl-pyridine (Ie), and 2, 4-dimethyl-quinoline (If) with ethyl benzoate under basic conditions were performed. In analogy with the nitrosation with ethyl nitrite, methyl groups on the 4-position of IIa-f were preferentially benzoylated to give 4-phenacyl derivatives. Structures of all the products were determined by chemical derivatization.

In anaerobic phosphate buffer, pH 6.3-7.5, deoxyhemerythrin is oxidized to semi-methemerythrin (semi-met) by excess sodium nitrite. This oxidation is quantitative as judged by EPR spectroscopy. Further oxidation to methemerythrin is not detected. The absorbance changes of hemerythrin during the oxidation are biphasic. The rate of the faster first phase is linearly dependent on [H+] and [NO2-] suggesting that the oxidant is nitrous acid rather than nitrite. During the slower second phase, the characteristic EPR spectrum of semi-methemerythrin appears. The first phase can be interpreted by a scheme in which nitrous acid transforms deoxyhemerythrin (FeIIFeII) to the semi-met nitrosyl adduct (FeIIFeIIINO) and hydroxide. Independent experiments confirm that the combination of semi-met plus NO produces an EPR-silent adduct. The rates of the absorbance changes for the second phase are nearly independent of nitrite concentration and pH in the range 6.3-7.5. This slower phase involves the transformation of the EPR-silent intermediate to the semi-met nitrite adduct (FeIIFeIIINO2-) and is consistent with rate-limiting dissociation of nitric oxide followed by rapid attachment of nitrite. Nitrite appears to be a unique oxidant of deoxyhemerythrin in that when employed in excess, the final, stable product is semi-met- rather than methemerythrin. The lack of reactivity of ethyl nitrite with deoxyhemerythrin suggests that HONO oxidizes deoxyhemerythrin via an "inner-sphere" process in contrast to oxidants such as Fe(CN)6(3-). A proposed generalization is that excesses of "inner-sphere" oxidants convert deoxy to (semi-met)R, which is stabilized with respect to (semi-met)R, which is stabilized with respect to (semi-met)0 and met because the oxidant and/or a product of the oxidant can bind to the iron site.

The reactions of human hemoglobin with sodium nitrite and ethyl nitrite in deoxygenated media have been examined in kinetic detail. Nitrous acid has been identified from kinetic pH dependence studies as the principal oxidant of hemoglobin in reactions with sodium nitrite. Nitrosylhemoglobin is produced concurrently with methemoglobin as a result of reductive release of nitric oxide from nitrous acid. However, oxidation of hemoglobin by nitric oxide competes with association, and this process is proposed to arise from the action of the nitric oxide dimer on hemoglobin. Ethyl nitrite, which serves as a model for nitrous acid, reacts with hemoglobin at rates that are at least 10 times slower than those extrapolated for nitrous acid, and hydrolysis of the alkyl nitrite is not competitive with oxidation of hemoglobin. The composite experimental results are interpreted to describe alkyl nitrite, and, presumably, nitrous acid association with hemoglobin followed by rate-limiting electron transfer resulting in nitric oxide and alkoxide (or hydroxide) production. Proton transfer resulting in alcohol (or water) formation occurs subsequent to the rate-limiting step as do reactions of hemoglobin with nitric oxide.

The reactions of NO(4II) molecules, generated by Hg 6(3P1) photosensitization, with methane, ethane, propane, neopentane, and benzene have been studied at room temperature in a circulatory system. In the case of ethane the following reaction products were identified: N2, N2O, H2O, NO2, CO, CO2, C2H4, acetaldehyde, nitroethane, ethyl nitrite, ethyl nitrate, nitroethylene, nitromethane, methyl nitrite, methyl nitrate, formaldehyde. For hydrocarbon consumption, under comparable conditions, the following quantum yield values were established: [Formula: see text]. The most probable primary process may be represented by the sequence[Formula: see text] [Formula: see text]Alkyl free radicals catalyze the chain disproportionation of nitric oxide at room temperature according to the stoichiometric equation[Formula: see text]A minimal value of 12 was established for the average chain length.

A method of assay was tried for ethyl nitrite in spirits, based on IR absorbance between 5.5 and 7.0 μ in chloroform solution. Conditions, such as temperature and proportion of alcohol to chloroform in sample, standard, and blank, must be made as closely identical as possible. Experiments indicate that ethyl alcohol, when dissolved in chloroform, shows a prominent peak at 6.17 μ, in the same region as the nitrite group (6.3–6.4 μ). Since the ethyl alcohol in ethyl nitrite spirits has approximately the same infrared absorbance peak as the ethyl nitrite, this procedure does not appear practical.

Edible oil deodorizing equipment and processes have been developed as a result of advances in hot-pressing and extraction of oil-bearing materials. Early methods included masking of odors by means of aromatics, washing out of odors and neutralization or destruction of odors by means of various chemical treatments.

Methyl nitrate (CH 3 ONO 2 ) is the most explosive of the nitrate esters, and previous studies have been confined mainly to the slow thermal decomposition, and to the vapour phase explosion at low pressures in closed vessels. A stationary decomposition flame has now been maintained and studied spectrographically. A t low pressures the zones of reaction are clearly separated. From the early stages of the flame strong formaldehyde bands are emitted. This decomposition flame has been successfully simulated in artificial mixtures of methyl nitrite with oxygen. The results obtained are in accord with the preliminary fission of the nitrate molecule in the pre-heat zone of the flame: CH 3 ONO 2 →CH 3 O + NO 2 . The combustion flame of m ethyl nitrate with oxygen, nitric oxide and nitrogen dioxide has also been examined at low pressures. At atmospheric pressure, m ethyl nitrite (CH 3 ONO) has been found to support a decomposition flame of very small burning velocity. However, the combustion of m ethyl nitrite with oxygen at atmospheric pressure is an extremely fast and vigorous flame. It has been observed in both pre-mixed and diffusion systems and information about the changes occurring in it have been obtained by absorption and emission spectroscopy. All the experimental results may be interpreted in terms of two general principles: the reluctance of nitric oxide to react except at high temperatures and pressures and the frequent occurrence in flames of extensive pyrolytic reactions before the main reaction zone is reached.

The auto exhaust was irradiated with xenon light or solar light under static conditions, and the concentration changes of hydrocarbons, nitrogen oxides, formaldehyde and irradiation products were analysed. The concentrations of each component were determined by hydrogen flame ionization gas chromatography for hydrocarbons, and colormetry for nitrogen oxides and formaldehyde, and electron capture gas chromatography for irradiation products, respectively. From these experiments, it was noticed that the concentrations of hydrocarbons and nitrogen oxides decreased, whereas that of formaldehyde increased. The irradiation products were also found to be methyl nitrite, ethyl nitrite, methyl nitrate, ethyl nitrate, n-propyl nitrate, isobutyl nitrate, biacetyl and PAN. Therefore these photochemical reactions of auto exhaust were assumed to occur in the atomosphere.