Ultramicrodetermination of nitrogen in organic compounds : III. Rise in pressure of a gas in a nitrometer due to the capillary phenomenon

A method is described for the decimilligram determination of nitrogen in organic compounds based on measuring by interpolation the volume of nitrogen collected in a capillary tube. The blank value is determined indentically.     

Ultramicrodetermination of nitrogen in organic compounds : VII. Determination of total nitrogen in dilute aqueous solution by sealed-tube method

The capillary immutability due to corrosion of glasses exposed to various solutions was studied. The analytical error of volume change caused by glass corrosion in a micro- and ultramicronitrometer was discussed. The present work has shown that the graduated tube of a decimicronitrometer made of borosilicate glass, which is used frequently in Dumas method, should be recalibrated after 1.5–2.3 months use. We therefore recommend the sealed tube method using an improved nitrometer for ultramicrodetermination of nitrogen in organic compounds.     

Ultramicrodetermination of nitrogen in organic compounds: Centimilligram determination of nitrogen with sealed tube method

A new improved nitrometer was developed for centimilligram determination of nitrogen by the sealed-tube method. A combustion tube having an internal volume of 1 ml was used and the sample was weighted in a boat made of copper foil, which was made by a simple device. The accurate volume of a gas granule of the blank was evaluated by observation with a micrometer microscope. A standard deviation of 0.240% was rapidly and conveniently obtained with organic compounds having a range of 5.94–66.4% nitrogen.     

Ultramicrodetermination of nitrogen in organic compounds : IV. Thermal behavior of a gas in a nitrometer due to local variations of temperature

To more accurately measure nitrogen temperature for ultramicrodetermination of nitrogen, the variation of local temperature in the nitrometer was investigated. Two or three parts of the nitrometer were simultaneously measured. Based on our results, we designed a new improved nitrometer equipped with a water jacket.     

Ultramicrodetermination of nitrogen in organic compounds: I. Application of interpolation in the sealed tube method

A method is described for the decimilligram determination of nitrogen in organic compounds based on measuring by interpolation the volume of nitrogen collected in a capillary tube. The blank value is determined indentically.     

Ultramicrodetermination of nitrogen in organic compounds: X. Handling of volatile solid samples in the sealed-tube method

A method for handling volatile solid samples in the ultramicrodetermination of nitrogen by the sealed-tube method is described. It involves the use of a thin-walled capillary in which the sample is sealed after replacing an air in that with gas mixture. Satisfactory results were obtained with volatile solid samples.     

Ultramicrodetermination of nitrogen in organic compounds: XI. Removal of interference from iodine for the sealed-tube method

The interference from iodine in ultramicrodetermination of nitrogen in organic compounds with the sealed-tube method was investigated and attempts to minimize it are discussed. Use of 30 to 50 mg G.R. tungsten trioxide prepared by heating in a current of air at 800 °C for 1 hr is recommended. Errors were almost always within ±0.3%.     

Ultramicrodetermination of nitrogen in organic compounds: II. A new simple nitrometer for the sealed tube method

A new simple nitrometer has been developed for use in the ultramicrodetermination of nitrogen by the sealed-tube method. The nitrometer consists of a water-filled receiving chamber in which the capillary containing collected nitrogen is placed, and a vertical graduated measuring tube. Nitrogen in the capillary is displaced into the measuring tube by water injected through a hypodermic syringe introduced through a rubber sealing cap at the end of the receiving chamber.     

Ultramicrodetermination of nitrogen in organic compounds: 8. Weighing of hygroscopic and volatile samples for the sealed-tube method

A new method for handling hygroscopic and volatile samples for decimilligram determination of organic nitrogen by the sealed-tube method was described. It involves the use of a copper-foil capsule in which hygroscopic and volatile samples can be dried to constant weight and weighed. Satisfactory results were obtained with this method.     

Ultramicrodetermination of nitrogen in organic compounds: IX. A new method for handling volatile liquids in the sealed-tube method

A new method for handling volatile liquids in the ultramicrodetermination of nitrogen by the sealed-tube method, using a weighing tube of thin-walled capillary containing a capillary of sample, is described. Before sealing the weighing tube, the air present can be replaced with a gas mixture of CO₂ and CH₄ having approximately the density of air. The weighing tube is broken by tapping prior to combustion, and analysis is not affected by volatilization.     

Photochemical behavior of inorganic and organic selenium compounds in various aqueous solutions

Selenium possesses interesting chemical, biochemical and geochemical behaviors. However, studies of its photochemical properties in aqueous systems are scarce. A better understanding of these phenomena is of great importance for further application of such properties to selenium speciation. In this work, the photochemical behavior of selenium and some of its organic compounds have been systematically studied in various aqueous matrices under UV irradiation at 300 nm. It was observed that the photochemical oxidation rate of Se(IV) to Se(VI) was greatly enhanced in the presence of HN0₃ at ≥1 × 10⁻³ M, but not by NaNO₃. However this photo-oxidation could be inhibited by the presence of Cl⁻. Under UV irradiation, organoselenium compounds went through two successive photochemical reactions in pure water: a direct photolysis (photo-cleavage) followed by a photo-oxidation to form Se(VI). These two steps could also be greatly accelerated in presence of NO₃⁻ although the second step required an acidic condition. The photo cleavage rates varied from one organic compound to another and 10-fold differences were observed. Similarly to Se(IV), the further oxidation to Se(VI) could be prevented by Cl⁻ for all studied organoselenium compounds. Detailed reaction mechanisms involving OH radicals are proposed to explain Se photochemical behaviors in different matrices.     

Photoelectron spectra of organic compounds—VI : Exocyclic methylene compounds

The photoelectron spectra of methylene and dimethylene derivatives of bridged and unbridged cyclohexane and cyclohexene were recorded and interpreted on the basis of an LCBO model. The conjugative interaction is found to be appreciably smaller for exocyclic cis-dienes than for the corresponding endocyclic cis-dienes, whereas the homoconjugative interaction between exocyclic and endocyclic double bonds and between two endocyclic double bonds is about the same.     

Determination of nitrogen in organic compounds

Summary A simplified method is described for the electrolytic generation of oxygen for use in the micro-Dumas determination of nitrogen. A flowmeter with an adjustable range is also described.

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Zusammenfassung Eine vereinfachte Anordnung zur elektrolytischen Sauerstoffentwicklung für die Verbrennung stickstoffhältiger Substanzen nach dem MikroDumas-Verfahren in einer Kohlendioxyd-Sauerstoff-Atmosphäre wird angegeben. Außerdem wird ein justierbarer Strömungsmesser beschrieben.

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Résumé On décrit une méthode simplifiée pour la production électrolytique de l'oxygène utilisé dans le microdosage de l'azote suivantDumas. On décrit aussi un fluxmètre à échelle réglable.

     

Fragmentation of organic compounds on electron-impact—VI. Dideuteriooctanes

Eleven isomeric octenes were converted to the corresponding dideuterio derivatives and the mass spectra recorded. The cracking patterns of the various dideuterioctanes are unique and the distribution of peaks representing the higher molecular weight ions can be predicted using a simple fragmentation model. The application of this technique to the determination of the position of the double bond in olefins of known carbon skeleton is discussed.     

Inhibition of the corrosion of iron by oxygen and nitrogen containing compounds

Summary Corrosion inhibition by quinine, ephedrine, brucine, cinchonine, codeine, and harmaline with respect to the dissolution of iron in 2M sulphuric acid was measured using electrochemical methods. Polarization curves indicated that these compounds act as mixed-type inhibitors,i.e. both the cathodic and anodic curves are affected. The observed effect follows theTemkin adsorption isotherm. The effect of the different structural features of these compounds on their inhibition efficiency has been studied. Results indicate that the rate of corrosion of iron increases with increasing temperature over the range 30–50 °C both in the absence and in the presence of inhibitors. Some thermodynamic functions were also computed and are discussed.

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Korrosionshemmung bei Eisen durch Sauerstoff- und Stickstoffverbindungen

Zusammenfassung Die von Chinin, Ephedrin, Brucin, Chinchonin, Codein und Harmalin ausgeübte Korrosionshemmung bei der Auflösung von Eisen in 2M Schwefelsäure wurde mittels elektrochemischer Methoden untersucht. Polarisationskurven zeigen, daß die erwähnten Verbindungen als Inhibitoren gemischten Typs fungieren, d. h. sowohl die kathodische als auch die anodische Kurve wurde beeinflußt. Der beobachtete Effekt folgt derTemkinschen Adsorptionsisotherme. Die Auswirkung von Strukturänderungen auf die Effizienz der Hemmung und einige thermodynamische Funktionen werden diskutiert. Die Korrosionstrate von Eisen steigt sowohl in Gegenwart als auch in Abwesenheit der Inhibitoren im Bereich von 30–50°C mit steigender Temperatur.

     

Colloid and nanodimensional catalysts in organic synthesis: VI. Hydrogenation and hydrogenolysis of carbonyl compounds

Aldehydes and ketones are found to be hydrogenated to alcohols with hydrogen at atmospheric pressure under the catalysis with nickel nanoparticles. The reaction under study may be used as technologically available and cheap method for hydrogenation of carbonyl groups. It is found that in the case of aromatic ketones hydrogenolysis of C=O bond with partial hydrogenation of aromatic groups takes place.     

Radiation-induced nitration of organic compounds in aqueous solutions

Radiation-induced nitration of organic compounds in aqueous solutions was studied. It was found that γ-irradiation of solutions containing acetic and nitric acid and/or their salts gives nitromethane. Dependences of the product yield on the absorbed dose and the contents of components were established. The mechanism of radiation nitration involving radicals is discussed.