1H- und 13C-NMR-Spektren von N-Methyl-chinoliniumchalkonen: Bestimmung von σ-Konstanten für die 2-, 3- und 4-Position des N-Methyl-chinoliniumrings

¹H- and ¹³C-N.M.R. Spectra of N-Methyl-quinolinium Chalcones: Determination of σ-Constants for the 2-, 3- and 4-Position of the N-Methyl-quinolinium Ring For the N-methyl-quinolinium chalcones 1a – c the ¹H- and ¹³C-n.m.r. data are reported. The unambiguous assignment of signals is based upon the ¹H/¹H homoshift and the ¹³C/¹H heteroshift correlated 2D-n.m.r. spectra. Using a Hammett relationship we have determined σ-constants for the 2-, 3- and 4-position of the N-methyl-quinolinium ring from the ¹³C-α chemical shifts of 1a – c . Their comparison with the σ-values for the equivalent positions in the pyridine, N-methyl-pyridinium and quinoline ring indicates the additivity of anellation and quaternization effect.     

Chinolinanaloge Chalkone: Wittig-Synthese, 13C-NMR-Spektren und Bestimmung von σ-Konstanten für die 2-, 3 und 4-Position des Chinolins

Quinolineanalogous Chalcones: Wittig Synthesis, ¹³C-N.M.R. Spectra and Estimation of σ-Constants for the 2-, 3- and 4-Position of Quinoline The Wittig type reaction of the quinolinealdehydes 2a—c with benzoylmethylentriphenylphosphorane ( 1 ) gives stereoselectively the E-configurated quinolineanalogous chalcones 3a—c . These compounds react with methyl iodide to the N-methyl-quinolinium salts 4a—c . The complete ¹³C-n.m.r. analysis of 3a—c is reported. From the chemical shift of the C_α-signals and on the basis of a Hammett relationship σ-constants were calculated for the 2-, 3- and 4-position of quinoline. These values are compared with those from kinetic measurements; the observed deviations are chiefly attributed to the extent of the resonance interaction in 3a—c .     

Simultaneous removal of SO2, SO3 and H2SO4 mist from the gas after TiO2 calcining

Absorption of SO₂ and SO₃ in the solutions of waste ferrous sulfate (so-called ‘green salt’) and in the spent acid after TiO₂ hydrolysis, at H₂SO₄ concentrations ranging from 0–5 to 15 g/m³ (STP), was studied. The rate of SO₃ absorption has been found to rise linearly with increasing SO₃ concentration in the gas and to be independent on H₂SO₄ concentration in solution. The SO₂ absorption also rises linearly with increasing SO₂ content in the gas, but diminishes as H₂SO₄ concentration increases—an upper limit of 100 g H₂SO₄/kg H₂O is indicated. The initial concentration of the solution must not be higher than 40 g H₂SO₄/kg H₂O.     

Ionenchromatographische und kapillarelektrophoretische Analytik zur Bestimmung von Chromat in Lederabfällen und -schlämmen

Determination of Chromate in Leatherwaste and -sludge by Ion Chromatography and Capillary Electrophoresis The Quantitative determination of chromate in Leatherwaste and -sludge by ion pair chromatography (MPIC), ion exchange chromatography (HPIC) and capillary electrophoresis (CE) is described. 0.02 mol/l dipotassium hydrogen phosphate (pH=7) was the buffer for CE. 2 mol/l 1,2-diaminocyclohexane tetraacetic acid (DCTA), water/acetonitrile (90/10 v/v) with 1 mmol/l tetrabutylammonium hydroxide (TBAH) were used as eluents for HPIC and MPIC, respectively. The pH of eluents and samples were 7. The analytical results indicated that there is no evident differences between the three methods.     

Experimentelle Bestimmung von Wärmeübergang und Druckverlust in Multiportflachrohren

Heat transfer and pressure drop data of three smooth multiport minichannels featuring hydraulic diameters > 1 mm are presented. Experiments were conducted under single phase convection of heptane and under convection of condensing R134a. Two specifically designed testing facilities feature a novel measurement setup to register the amount of condensate generated and to measure the temperatures of the refrigerant and minichannel wall. The results for the smallest minichannel geometrie show that the assumption of an increasing heat transfer rate with decrasing hydraulic diameter is not generally valid.