Effect of Spark Discharge Plasma on Water,Physiological Saline,and Hanks’ Solution

The effect of the duration of a current pulse of spark discharge in air on the composition of products formed in liquid both by the action of plasma radiation and with the participation of species formed in the discharge itself has been studied. The products formed in water, 0.9% NaCl, and in Hanks’ solution have been determined. It has been that in all the cases, nitrous acid is one of the primary products. The yield of nitrous acid is the same in all the three solutions. With a decrease in the current pulse duration, the influence of the species formed in the discharge itself on the yield of nitrous acid increases. The products formed in water decompose within up to 13 days. Peroxynitrite and N₂O₃ were identified as degradation products.     

The behavior of the cyclopropyl phenyl sulfide and phenoxycyclopropane in the reaction with nitrous acid

The behavior of cyclopropyl phenyl sulfide and phenoxycyclopropane in the nitrosation reaction was studied. Cyclopropyl phenyl sulfide was found to convert quantitatively to cyclopropyl phenyl sulfoxide under the action of nitrous acid formed in situ. Under the same conditions, phenoxycyclopropane undergoes transformation to 5-phenoxyisoxasoIine (nitrophenols are formed as byproducts in this reaction).     

Determination of the purity of methyl nitrite

The purity of methyl nitrite prepared by the esterification of methanol with aqueous nitrous acid was determined by absorbing gaseous samples in solutions of acidic potassium permanganate and hydriodic acid. Nitrate formed in the oxidation reaction was determined by steam distillation, and iodomethane formed in hydriodic acid was determined by gas-liquid chromatography. The method was used to evaluate purification procedures.     

Nitration of Durene and Pentamethylbenzene with Nitronium Salts in Nitromethane and Acetonitrile

Nature and proportions of the products formed in the nitrations mentioned in the title are affected by the process of mixing. Pentamethylnitrobenzene, formed initially in the nitration of pentamethylbenzene, is attacked by a nitronium ion at a position meta to the nitro-group. In the σ-complex formed, loss of a proton from a methyl group leads to production of by-products and release of nitrite ions. The nitrous acid formed is protonated, and water is displaced from the nitrous acidium ion by the anion, PF₆^?, giving the nitrosonium ion which forms a 1:1 symmetric molecular complex with pentamethylbenzene. A similar complex is formed in the reaction between durene and nitronium salts. The results are consistent with the view that no σ-bond is formed between the aromatic compound and the nitrosonium ion.     

乙醇胺类原料形成亚硝胺的比较

为了探究目前表面活性剂生产和应用中用脂肪酸甲基单乙醇酰胺或脂肪酸单乙醇酰胺替代脂肪酸二乙醇酰胺的趋势的可行性,本文首先采用亚硝酸叔丁酯法合成3种乙醇胺的亚硝胺化合物作为基准物,通过鉴定产物结构研究亚硝胺的形成历程,然后以亚硝酸法合成亚硝胺化合物,通过生成率比较3种乙醇胺形成亚硝胺化合物的难易程度。 亚硝化历程分析结果表明,二乙醇胺或甲基单乙醇胺均直接形成相应的亚硝胺,而单乙醇胺通过歧化反应生成二乙醇胺继而形成少量N-亚硝基二乙醇胺。 与二乙醇胺相比,甲基单乙醇胺或单乙醇胺更不易生成亚硝胺,因此用脂肪酸甲基单乙醇酰胺或脂肪酸单乙醇酰胺替代脂肪酸二乙醇酰胺是合理可行的。 本研究结果对保障人类生命健康安全具有理论和实践意义。     

Influence of urea on initiation and termination of reaction between nitric acid and formic acid

The influence of urea on initiation and termination of the reaction between nitric and formic acids was experimentally examined. The urea injection can terminate the denitration reaction in 2 to 10M salt-free nitric acid solutions and the simulated high level liquid wastes (HLLWs) with a nitric acid concentration of 2 to 6M. An excess of urea can interrupt the initiation of denitration in both simulated HLLW and salt-free nitric acid solutions. The initiation and termination of denitration are in relation with nitrous acid formation and decomposition. Urea reacts with nitrous acid easily in the denitrating solution and decomposes nitrous acid. As the urea concentration increases in the solution, the continuance of denitration become impossible because the decomposition rate of nitrous acid exceeds the generation rate. In addition, the nitrous acid concentration can not be high enough to initiate the denitration in the solution with an excess of urea because nitrous acid is decomposed by urea.     

Spectrophotometric determination of azathioprine in pharmaceutical formulations

Four simple and sensitive visible spectrophotometric methods (A–D) have been described for the assay of azathioprine (ATP) either in pure form or in pharmaceutical formulations. Methods A and B are based on the oxidation of ATP with excess N-bromosuccinimide (NBS) or chloramine-T (CAT) and determining the consumed NBS or CAT with a decrease in colour intensity of celestine blue (CB) (method A) or gallocyanine (GC) (method B), respectively. Methods C and D are based on the diazotisation of reduced azathioprine (RATP) with excess nitrous acid and estimating either the consumed nitrous acid (HNO₂) with cresyl fast violet acetate (CFVA) (method C) or by coupling reaction of the diazonium salt formed with N-1-naphthyl ethylene diamine dihydrochloride (NED) (method D). All of the variables have been optimized and the reactions presented. The concentration measurements are reproducible within a relative standard deviation of 1.0%. Recoveries are 99.2–100.3%.     

Kinetic studies on the oxidation of uranium(IV) in nitric acid solution

The kinetics of oxidation of U(IV) in nitric acid solution by nitrous acid and air oxygen have been studied. The effects of concentrations of U(IV), nitric acid, hydrogen ion and nitrous acid in aqueous solution or oxygen in gas on the oxidation rate have been examined. The oxidation rate increases with increasing temperature and the activation energies are 47 kJ mol^–1 for nitrous acid and 91 kJ mol^–1 for oxygen. The mechanisms for both oxidation reactions are discussed.     

Electrolysis of Nitric Acid by Using a Glassy Carbon Fiber Column Electrode System

The electrochemical redox behavior of nitric acid was studied using a glassy carbon fiber column electrode system, and its reaction mechanism was suggested and confirmed in several ways. Electrochemical reactions in less than 2.0M nitric acid was not observed. However, in more than 2.0M nitric acid, the reduction of nitric acid to nitrous acid occurred and the reduction rate was slow so that the nitric acid solution had to be in contact with an electrode for a period of time long enough for an apparent reduction current of nitric acid to nitrous acid to be observed. The nitrous acid generated in more than 2.0M nitric acid was rapidly and easily reduced to nitric oxide by an autocatalytic reaction. Sulfamic acid was confirmed to be effective to destroy the nitrous acid. At least 0.05M sulfamic acid was necessary to scavenge the nitrous acid generated in 3.5M nitric acid.     

Synthesis of analogs of 5(4)-aminoimidazole-4(5)-carboxamide and purines. 9. peculiarities of the reaction of 5(4)-aminoimidazole-4(5)-carboxhydrazide with nitrous acid and of 5-diazoimidazole-4-carboxazide with amines

The reaction of 5(4)-aminoimidazole-4(5)-carboxhydrazide with nitrous acid was investigated. A mixture of four compounds, viz., 5-diazoimidazole-4-carboxazide, 5-diazoimidazole-4-carboxylic acid, 5(4)-aminoimidazole-4(5)-carboxazide, and 2-azahypoxanthine, is formed under all of the investigated conditions, 5(4)-Azidoimidazole-4(5)-carboxamide derivatives were obtained in the reaction of diazoimidazole-carboxazide with various amines in protic and aprotic solvents. 5-N-(Piperidyl)-azoimidazole-4-carboxazide was isolated only in the reaction with piperidine in an aqueous medium.See [1] for Communication 8.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1536–1540, November, 1980.     

Molten sodium nitrite—potassium nitrite eutectic: the reaction of some compounds of molybdenum

Molybdenum(VI) oxide, ammonium molybdate and molybdic acid reacted in molten sodium nitrite—potassium nitrite eutectic to form orthomolybdate, nitrogen dioxide and nitric oxide (with nitrate as a secondary product), a more polymerised polymolybdate being formed as an intermediate product. Tungsten(VI) oxide reacted similarly but less rapidly. Molybdenum and tungsten metals reacted to form the orthoxyanion and nitrogen, the latter metal reacting considerably faster and forming smaller amounts of nitric oxide and nitrous oxide. Reaction temperatures and stoichiometries are given and reaction pathways suggested.     

Manual and flow-injection spectrophotometric assay of thiols, based on their S-nitrosation

A general assay procedure for a wide variety of thiols is described. The technique has three steps: (1) formation of S-nitrosothiols with nitrous acid, (2) destruction of the excess of nitrous acid, (3) hydrolysis of the S-nitrosothiols with mercuric ions and subsequent formation of an azo-dye by means of the nitrous acid liberated. Both manual and flow-injection analysis (FIA) versions of the assay are described. Since the final step of the assay does not depend on the thiol assayed but only on the reaction of nitrous acid to form azo-dyes, the calibration graphs should be identical for all thiols. The manual system is about four times as sensitive as the FIA system, but the latter permits a high sample throughput and shows significantly lower sensitivity to interference by tryptophan. Though this general technique cannot be used for the assay of many sterically hindered thiols, it can be used for the assay of some protein thiol groups.     

Oxidations and reductions of iron-cyanogen compounds of cobalt,nickel, cadmium and zinc

I. Cobalt ferrocyanide is oxidized by bromine water, by nitrous acid or by hydrogen peroxide in presence of acids to cobalt ferroferricyanide (cobalt Prussian blue), while cobalt ferricyanide is reduced by sulfurous acid to cobalt Prussian blue.II. Nickel ferrocyanide is oxidized by nitrous acid or by hydrogen peroxide in presence of acids to nickel ferricyanide.III. Nickel ferrocyanide and cadmium ferrocyanide are oxidized by bromine water to the ferricyanides.IV. The ferricyanides of nickel, cadmium and zinc are reduced by sulfurous acid to the ferrocyanides.     

Alkyl 2-amino-5,6-dialkyl-3-cyanopyridine-4-carboxylates in reactions with electrophilic reagents

In reaction of alkyl 2-amino-5,6-dialkyl-3-cyanopyridine-4-carboxylates with isocyanates formed unstable ureas, and with nitrous acid at 60–70°C alkyl 5,6-dialkyl-2-oxo-1,2-dihydro-4-pyidinecarboxylates were obtained. It was shown for the latter that their reactions with organic acids and amides occurred at the cyano group, and the alkaline hydrolysis involved the ester group.     

γ-Nitro-γ-butyrolacton

γ-Nitro-γ-butyrolactone By oxidation of 3-(1-nitro-2-oxocyclohexyl)propanal ( 1 ) with KMnO₄, besides 3-(1′-nitro-2′-oxocyclohexyl)pripionic acid ( 2 ), the complete hydrolysis product 4-oxononanedioic acid ( 4 ) and the oxidized semi-hydrolysis product 5-(2-nitro-5-oxotetrahydro-2-furyl)pentanoic acid ( 3 ) were formed. The crystalline 3 decomposes at r.t. forming 4 and nitrous gases; its structure was established by X-ray determination.     

Peroxynitrite: A Re-examination of the Chemical Properties of Non-thermal Discharges Burning in Air Over Aqueous Solutions

The main compounds of non-thermal plasmas generated by a discharge in humid air at atmospheric pressure are re-examined to explain the twin chemical properties of discharges over aqueous waste solutions, i.e. the acid and oxidizing effects. The acid effects are attributed to transient nitrous and peroxynitrous acids and to stable nitric acid. The matching oxidizing power of the discharge species onto solutes is due to water soluble H₂O₂ provided by the dimer formation of °OH and also to peroxynitrous acid ONOOH and its salt which are involved in the oxidation process of nitrous to nitric acid.     

Oxidation of benzyl alcohols by nitrous and nitric acids in strong sulfuric acid media

We have studied the oxidation of benzyl alcohols by nitrous and nitric acid in sulfuric acid media. The oxidation by nitrous acid is rapid and has an activation energy of 10.6 ± 0.8 kcal mol^?1. A Hammett plot of logk₂ vs. σ⁺ is linear with a ρ value of ?1.4. The oxidation by nitric acid in sulfuric acid media is autocatalytic. From the kinetic and product analyses, it is concluded that a common oxidant, the nitrosonium ion is involved when either nitrous or nitric acid is used. A mechanism is proposed which involves the abstraction of hydride from the alcohols as the rate determining step. It is demonstrated that the autoxidation of the alcohols is catalyzed by nitrous acid or nitric oxide.     

Simultaneous spectrophotometric determination of uranium, nitric acid and nitrous acid by least-squares method in PUREX process

Multi-wavelength linear regression spectrophotometry combined with method of least squares for simultaneous determination of uranium, nitric acid and nitrous acid in PUREX (Plutonium/URanium EXtraction) process was developed. The molar absorbance matrix was calibrated with absorbance data measured in the wavelength range of 350–500 nm for a series of standard solutions by linear least-squares regression. This method used information from the absorption spectra of U(VI)–nitrous acid–nitric acid solutions to determine U(VI), nitrous acid and nitric acid. In the range of 0.95–74.1 g/L U(VI), 5 × 10^?4–2 × 10^?3 mol/L nitrous acid and 3–5 mol/L aqueous nitric acid solution, the measuring precision for determination of U(VI), nitrous acid and nitric acid was 0.46, 4.09, and 0.68 % respectively. In the solution of 30 % TBP–kerosene, the measuring precision for determination of U(VI) and nitrous acid was 0.42 and 4.2 % respectively in the range of 0.95–74.1 g/L U(VI) and 5 × 10^?4–2×10^?3 mol/L nitrous acid. The spectrophotometric method can be valuable for monitoring and controlling of both species in PUREX process operation, thanks to its simplicity, efficiency and accuracy.     

The reactions of perfluoroalkanesulfinates: II. A new method for the synthesis of N,N-bisperfluoroalkylhydroxylamine1

The reaction of sodium or silver perfluoroalkanesulfinate with nitric acid, nitrous acid or nitrogen dioxide in aqueuos solution gave a moderate yield of N, N-bisperfluoroalkylhydroxylamine accompanied by perfluorocarboxylic acid, amide and nitrosoperfluoroalkane.     

Diels-alder reactions of 3-(2-nitrovinyl)indoles: Formation of carbazoles and bridged carbazoles

The Diels-Alder reactions of 1-substituted-3-(2-nitrovinyl)indoles 3 with quinones and acetylenes give aromatized 1:1 adducts (- nitrous acid) ( 1 ) or (- nitrous acid, -2 hydrogens) 2,5 . Likewise, dimerization (-2 nitrous acids) of 3 gives aromatized 2-(3-indolyl)carbazoles 4 . In contrast, 3 reacts with maleimides 6 to give 1:2 adducts (- nitrous acid or -2 hydrogens) 10 and 11 , respectively, along with smaller amounts of 1:1 adducts (- nitrous acid, -2 hydrogens; or -4 hydrogens) 12 and 13 , respectively. A mechanism for formation of the nitro products 11 and 13 is discussed. A 1:2 adduct (-2 hydrogens) 19 was also obtained from a Diels-Alder reaction between maleimide and the vinylindole produced in situ by condensing 1-methylindole with acetone. The stereochemisty of this 1:2 adduct has been determined by X-ray crystallography.