Chemistry of thienopyridines. VII. Mechanistic studies on the synthesis of thieno[2,3-c] pyridine by thermolytic cyclization

A study was made of the formation of thieno[2,3-c]pyridine (1) from hydrogen sulfide and 4-vinylpyridine in a flow system at 630°. 2-(4-Pyridyl)ethanethiol and bis-2-(4-pyridyl)ethyl sulfide were found to be likely intermediates. Based on these studies, there was devised a two-step practical preparative method for I (optimum overall yield 58%) which consists of preliminary conversion of 4-vinylpyridine to benzyl 2-(4-pyridyl)ethyl sulfide and subsequent thermolysis (at 605°) of this substance.     

The composition of the evolved gases from the thermal decomposition of certain metal sulfates

By the use of TG—MS, the thermal dissociation of anhydrous CuSO₄ and Al₂(S0₄)₃ was found to proceed according to the reactions:

followed by the reactions:

No SO₃ was indicated in the dissociation of alunite. The sulfate ion appears to dissociate by at least two different mechanisms although the parameter which controls the mechanisms has not been elucidated.     

Spectrochemical determination of impurities in telluric acid

An emission spectrographic method is described for determination of 20 elements present as impurities in telluric acid. Samples are excited in a 12-A. d.c. arc with the use of NaCl-KCl as a spectrographic buffer and germanium as internal standard. The limit of determination lies between 10(-5) and 10(-2)%. The precision of the method calculated as relative standard deviation is 10-25%.     

An investigation of some experimental parameters in atomic fluorescence spectrophotometry

Atomic fluorescence in flames is measured by an adaptation of a commercially available flame spectrophotometer. A study is reported of the effect of background radiation and source scattering on 3 flames, air-propane, air-hydrogen and air-acetylene, and of the effects of variation of fuel gas pressure, zone of measurement in the flame, analysing monochromator slit-width and wavelength of measurement. The air-propane flame appears to offer several advantages. The atomic fluorescence of 10 metals is described; those of Co, Fe and Mn have not been previously reported. Excitation of spectra is achieved by means of an a.c. xenon arc lamp or individual discharge lamps.     

Die chemische Analyse als Wegbereiter der Metallkunde und der Metallurgie

Zusammenfassung Die Reaktionen zwischen Roheisenschmelzen, Hochofenschlacken und dem elementaren Kohlenstoff des Schmelztiegels werden als Beispiele dafür angeführt, wie groß doch der Anteil der analytischen Chemie zu sein hat, wenn man tieferen Einblick in technische Verfahren wie den Hochofenprozeß gewinnen will. Gute analytische Ergebnisse lassen sich auch meist in recht einfacher Weise ordnen. Erstaunlich sind die Einblicke, zu denen die dem Chemiker selbstverständlichen, aber lästigen Stoffbilanzen verhelfen.Der Chemiker verfügt über Kenntnisse und experimentelle Einrichtungen, die weit über die übliche Elementaranalyse hinaus anwendbar sind. Als Beispiel dazu wird die Bestimmung des Kohlenstoffs im Stahl betrachtet, die ohne ein zusätzliches Hilfsmittel gestattet, die Entkohlung beim Zundern von Stahl laufend zu verfolgen. Die Phänomene an der Grenzfläche Metall-Oxid und viele weitere Erscheinungen bieten sich dar.

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Summary The reactions between pig iron melts, blast furnace slags and the elementary carbon of the fusion crucible are cited as examples of the extent required of chemical analysis if a deeper insight into the technical operations is to be obtained, such as blast furnace processes. Good analytical results can usually be arranged in a rather simple manner. The troublesome material balances assist in opening truly astounding insights that are self-evident to the chemist.The chemist has available knowledge and experimental devices that are applicable far beyond the conventional elementary analyses. A pertinent instance is the determination of carbon in steel, which without an auxiliary aid permits the operator to follow the course of decarbonization continuously during the scaling of steel. The phenomena at the interface metal-oxide and numerous other occurrences present themselves.

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Résumé On donne comme exemple les réactions entre le fer brut fondu, les scories des hauts fourneaux et le carbone élémentaire du creuset dans lequel s'effectue la fusion, pour montrer combien grande doit être la contribution de la chimie analytique si l'on veut avoir une vue plus profonde du procédé technique et réactionnel dans le haut fourneau. La plupart du temps, on peut classer d'une manière très simple, les bons résultats expérimentaux. Très surprenantes sont les idées auxquelles conduisent les rendements qui vont de soi pour le chimiste mais qui sont onéreux.Le chimiste dispose de connaissances et de dispositifs expérimentaux qui sont largement applicables à l'analyse élémentaire usuelle. On prend comme exemple le dosage du carbone dans l'acier, qui permet sans moyen auxiliaire de suivre d'une façon continue la décarburation pendant l'inflammation de l'acier. Les phénomènes à l'interface métal-oxyde et de nombreux autres phénomènes se présentent.

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Auszug aus einem Vortrag anläßlich des Kolloquiums für metallkundliche Analyse mit besonderer Berücksichtigung der Elektronenstrahl-Mikroanalyse, Wien, 22. Oktober 1964.     

Analysis of anions in hydrofluoro ethers by ion chromatography

Hydrofluoro ethers (HFES) are considered to be an ideal cleaning solvent in applications like vapor degreasing and wet cleaning. It is also a good solvent replacement for CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), HFCs (hydrofluorocarbons) and chlorinated solvents because they have a short atmospheric lifetime and low global warming potential. Based upon their properties, hydrofluoro ethers are ideally suited for the demands of the electronics industry. However, the electronics industry requires these solvents to have high purity, especially in the area of residual anions. This paper will present information on an extraction methodology for the transfer of anions from the hydrofluoro ether to water. Then, an analytical method utilizing ion chromatography that is capable of detection of 10 anions (fluoride, acetate, formate, chloride, nitrite, bromide, nitrate, sulfate, oxalate, and phosphate) in the part per billion level will be demonstrated.     

A photoplate calibration technique applied to the determination of hafnium in zirconium by SSMS

A photoplate calibration procedure is suggested for spark source mass spectrometry /SSMS/ with photoplate detection. The technique uses the Churchill two-line method applied to the two stable isotopes of copper. The calibration curve thus obtained is split into fragments and each fragment is approximated by a polynomial. The method was applied for the quantitative determination of Hf as impurity in zirconium sponge obtained from a pilot plant dedicated to the depletion of the hafnium content in zirconium by fractional crystallization.     

Raman study NH4Cl near the tricritical point

The Raman spectrum of NH₄Cl has been studied as a function of temperature and pressure close to the multicritical point at which the λ-transition changes from first to second order. Variations in the intensities of appropriate bands have been used to calculate the critical exponents for the order parameter. By varying the temperature at fixed pressures of zero, 3.0 k bar and 1.5 k bar, exponent values of β = 0.154 ± 0.012, β = 0.33 ± 0.06 and β = 0.26 ± 0.06 have been obtained for the first-order, second-order and multicritical regions respectively.Our first-order exponent value is close to that observed by previous workers, our second-order value is close to that predicted by the three dimensional Ising model, and our multicritical value is close to that predicted by mean field theory.     

THE KINETICS OF REDUCTION OF CYTOCHROME c BY SEMI-REDUCED FLAVIN

Abstract— Flavin mononucleotide radicals, FMNH', generated by laser flash photolysis of FMN in the presence of the electron donors, histidine, guanosine monophosphate or EDTA, were found to reduce cytochrome c with an apparent rate constant of 6 ± 10⁷ M ⁻¹ s⁻¹. These flash photolysis results were, however, complicated by the electron donor radicals formed simultaneously which, particularly with EDTA, also lead to reduction of cytochrome c. Pulse radiolysis of a nitrous oxide saturated aqueous solution of FMN containing a high concentration of HCOONa, leads to the exclusive formation of FMNH'. By adding small concentrations of cytochrome c to this solution, a rate constant of 4.0 ± 10⁻¹ M ⁻¹ s⁻¹ was obtained for the reduction of cytochrome c by FMNH'. Replacement of the HCOONa by EDTA in such solutions leads to further routes for reduction of cytochrome c on radiolysis. as in the photolytic situation. The relevance of these results to flavin-photosensitised reduction of cytochrome c and other components of the mitochondrial electron transport chain is discussed.