A simple laboratory generator for low concentrations of sulphur dioxide

The generator is based on permeation of sulphur dioxide through silicone rubber tubes immersed in a buffered, thermostated solution of sodium hydrogensulphite. The generator contains three (or more) permeation tubes of different lengths immersed simultaneously in the generation solution. The tubes can be connected stepwise to the carrier gas source, so that three (or more) different concentrations of SO₂ in the carrier gas can be obtained from a single solution. The tested generator produced 1.25–25.4 ng s^?1 SO₂, depending on the hydrogensulphite concentration in the solution. Long-term stability was tested for the production of 10.49 ng s^?1 over 50 h; the relative standard deviation was 1.57%. The experimental conditions affecting the production of SO₂ are discussed. An equation is derived for estimating the SO₂ production for various solution compositions and surface areas of the permeation tubes.     

Vergleich zwischen dem dielektrischen und dem mechanischen Relaxationsverhalten

Zusammenfassung Auf Grund theoretischer Überlegungen ist es bei der Bestimmung des Relaxationsverhaltens hochpolymerer Stoffe bei verschiedenen Beanspruchungsarten sinnvoll, zur Bestimmung der Relaxationszeiten die Maxima der Imaginärteile der elastischen Moduln und der reziproken Dielektrizitätskonstanten auszuwerten und die in Abhängigkeit von der Frequenz bei konstanter Temperatur gemessenen Dispersionskurven in die Anteile der Hauptund Nebendispersionsgebiete zu zerlegen. Durch Anwendung dieses Verfahrens auf die an Polyvinylchlorid gewonnenen Ergebnisse wird nachgewiesen, daß bei diesem Stoff die mechanisch und dielektrisch gemessenen Relaxationszeiten identisch sind und daß somit die vonThurn undWolf (1) vorgeschlagene Deutung der Unterschiede zwischen mechanischem und dielektrischem Relaxationsverhalten keine allgemeine Gültigkeit hat. Ein verbessertes Verfahren zur Bestimmung der Ultraschallgeschwindigkeit und der Ultraschalldämpfung in hochpolymeren Stoffen wird angegeben.     

Note on a theoretical interpretation of the isotopic ratio vOH/vOD versus vOH in isotopically diluted HDO molecules in solid hydrates

A simple intra- and inter-molecular potential for water molecules engaged in hydrogen bonding has been used in a one-dimensional approximation for a theoretical interpretation of the experimental correlation $\text{v}$_OH/$\text{v}$_OD versus $\text{v}$_OH in solid hydrates. The variation in the equilibrium OH(D) distance has also been considered.     

Highly enantioselective organocatalytic addition of unmodified aldehydes to N-Boc protected imines: one-pot asymmetric synthesis of β-amino acids

Highly enantioselective catalytic routes to Boc protected β-amino aldehydes, β-amino acids and γ-amino alcohols are presented. The organocatalytic asymmetric reactions between unmodified aldehydes and N-Boc protected aryl imines proceed with excellent chemo- and enantioselectivities to give the corresponding compounds in high yields with up to >19:1 dr and 93% to >99% ee.     

Determination of mercury in seafood by flow injection-cold vapor atomic absorption spectrometry after microwave digestion: NMKL interlaboratory study. Nordic Committee on Food Analysis

Ten laboratories participated in an interlaboratory method-performance (collaborative) study of a method for the determination of mercury in foods of marine origin by flow injection-cold vapor atomic absorption spectrometry after wet digestion using a microwave oven technique. The study was preceded by a training round of samples of known identity. The method was tested on a total of 7 seafood products: blue mussel (Mytilus edulis), cod muscle (Gadus morhua), crab (Cancer pagurus), scampi (Nephrops norwegicus), black scabbard fish (Aphnopus carbo), longnose velvet dogfish (Centroscymus crepidater), and Portuguese dogfish (Cenbroscymus coelolepis) with mercury concentrations of 0.14, 0.24, 0.35, 0.59,11.42, 4.2, and 13.2 microg/g, respectively. The materials were presented to the participants in the study as blind duplicates, and the participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) for mercury ranged from 2.4 to 14.0%. Reproducibility relative standard deviations (RSDR) ranged from 7.7 to 16.6%. HORRAT values for all samples were <1.0.     

Versatile solid-phase synthesis of secondary amines from alcohols. Development of an N-Boc-(o-nitrobenzene)sulfonamide linker

The development of a versatile amine releasing linker based on the modified o-nitrobenzene sulfonamide protective group is described. This new N-Boc-o-nitrobenzenesulfonamide (Boc-ONBS) linker enables the elaboration on resin of primary and secondary amines by sequential substitution of the sulfonamide moiety using the Mitsunobu reaction. A 16-member array of secondary and Boc protected primary amines was then prepared using this linker.     

Alkylamino- und Dialkylamino-phenoxy-methylsilane

Zusammenfassung Alkyl-und Dialkylamino-phenoxy-methylsilane ließen sich sowohl durch Umsetzung von Phenoxy-methyl-chlorsilanen mit primären und sekundären Aminen unter Cl/NRR-Austausch als auch durch Reaktion von Phenoxymethylsilanen mit substituierten Alkaliamiden unter C₆H₅O/NRR-Austausch gemäß den Gl. (1) bis (6) darstellen. Ihre Eigenschaften sind aus Tab. 1 zu ersehen.

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We succeeded in preparing alkyl- and dialkylamino-phenoxymethylsilanes by reaction of phenoxy-methyl-chlorosilanes with primary and secondary amines (Cl/NRR-exchange) as well as by reaction of phenoxymethylsilanes with substituted alkaliamides (C₆H₅O/NRR-exchange)according equations (1) to (6). Their properties are to be seen in table 1.

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53. Mitt.:U. Wannagat undG. Schreiner, Mh. Chem.96, 1902 (1965).

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Mit Auszügen aus der DissertationG. Schreiner und der DiplomarbeitJ. Pohl, Techn. Hochsch. Graz, 1964.     

Studies of the reactions between indole-2,3-diones (isatins) and 2-aminobenzylamine

Reflux of equimolecular amounts 2-aminobenzylamine and isatins in acetic acid produced indolo[3,2-c]quinolin-6-ones in good yields. A proposed mechanism involving initial formation of a spiro compound is given. This isolable intermediate subsequently rearranges via a sequential isocyanate ring opening and a cyclisation process to a urea derivative which finally cyclized to the indolo[3,2-c]quinolin-6-ones. The urea derivative could be prepared separately and cyclized selectively to indolo[3,2-c]quinolin-6-one. Reaction of N-acetylisatin with 2-aminobenzylamine at room temperature yielded the 1,4-benzodiazepinone 3-(2-acetamidophenyl)-1,5-dihydro-1,4-benzodiazepin-2-one whereas its isomer 2(2-acetamidophenyl)-4,5-dihydro-1,4-benzodiazepin-3-one was obtained from 2-(2-acetylaminophenyl)-N-(2-aminobenzyl)-2-oxoacetamide in acetic acid at room temperature.The previously unknown linear isomer of indolo[3,2-c]quinolin-6-one, i.e. indolo[2,3-b]quinolin-11-one, has been prepared by thermal (260°C) cyclization of methyl 2-phenylamino indole-3-carboxylate, which in turn was prepared in two steps from methyl indole-3-carboxylate.