Thio-claisen rearrangements of some ketene derivatives

A number of 1-allylthio and 1-crotylthio 1-aminoalkenes derived from ketones and active methylene compounds has been prepared and rearranged to the corresponding thioamides (thio-Claisen rearrangement). Besides rearrangement products, small amounts of 1-alkyl-thio-N-alkyl-N-phenyl-1-aminoalkenes have also been isolated. When the ketene derivatives did possess a H-atom on nitrogen, cleavage of the formed thioamide produced phenyl isothiocyanate and substituted active methylene compounds.     

Automated determination of traces of mercury in biological materials by substoichiometric radioisotope dilution

Solid samples (1-2 g) are burned in oxygen in a flask containing radiomercury in dilute hydrochloric acid, in which the non-active mercury to be determined is immediately absorbed. All mercury is subsequently extracted by dithizone in carbon tetrachloride and then re-extracted into dilute hydrochloric acid. This aqueous phase is further analysed automatically (AutoAnalyzer, 20 samples hr ) as previously described. Liquids (up to 100 ml) are analysed in the same way but instead of being burned in oxygen are first oxidized with potassium permanganate in acid medium. Quantities between 2 and 0.00004 ppm Hg were determined in various materials. Results for international biological standards agreed well with values obtained by activation analysis: kale 0.159 ppm Hg (relative standard deviation 2%) and IAEA cereals 0.0435 ppm Hg (+/- 5%). The new method is far more simple and rapid than activation analysis and just as sensitive; it is therefore more suitable for routine work. About 100 samples can be analysed per day.     

Polarographische Untersuchung der Nickel- und der Zinkkomplexe der Adipinsäure

Zusammenfassung Die Nickel- und Zinkkomplexe der Adipinsäure werden polarographisch untersucht. Es zeigt sich, daß Zink reversibel reduziert wird, wogegen Nickel eine irreversible Stufe ergibt. Die Stabilitätskonstanten des Zink—Adipinsäurekomplexes werden nachDeFord undHume berechnet. Der Einfluß des pH-Wertes auf die Zink- und die Nickelstufe wird untersucht. Zink und Nickel werden in Gegenwart vieler störender Kationen halbquantitativ bestimmt.

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The said complexes have been studied by polarography. Zn is found to be reversibly reduced while Ni gives an irreversible wave. Stability constants of the Zn complex are calculated byDeFord andHume method. Effect of pH on Zn and Ni wave are reported. Estimations of Zn or Ni are carried out separately or in presence of interfering cations.

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Mit 7 Abbildungen     

1,3,5-Trisubstituted hexahy drotriazines as mannich reagents. I. Preparation of secondary aminomethyl sulfide hydrochlorides

1,3,5-Trisubstituted hexahy drotriazines react with hydrogen chloride in the presence of anhydrous solvents to form useful intermediates for the introduction of the RNHCH₂- group into compounds which undergo the Mannich reaction. The effectiveness of the new aminomethyl-ating agent has been demonstrated by the preparation of secondary aminomethyl sulfide hydro-chlorides.     

Automated multiresidue analysis of pesticides in olive oil by on-line reversed-phase liquid chromatography-gas chromatography using the through oven transfer adsorption-desorption interface

A multiresidue, automated and rapid method for the determination of pesticide residues in olive oil is presented. The method employs the through oven transfer adsorption-desorption interface for the on-line coupling of reversed-phase liquid chromatography and gas chromatography. In this fully automated system, olive oil is directly injected with no sample pre-treatment step other than filtration. Methanol-water is used as eluent in the liquid chromatography pre-separation step. The selected liquid chromatography fraction containing the pesticides is automatically transferred to the gas chromatography. The liquid chromatography column flow during elution is different from the flow during the transfer. Using a flame ionisation detector, pesticide detection limits varied from 0.1 to 0.3 mg/l.     

Skin-photosensitizing properties of Zn(II)-2(3), 9(10), 16(17), 23(24)-tetrakis-(4-oxy-N-methylpiperidinyl) phthalocyanine topically administered to mice

A Zn-phthalocyanine derivative bearing four 4-oxy-N-methyl-piperidinyl peripheral substituents has been formulated in an azone-containing gel for topical administration and its potential as a photodynamic therapy agent has been investigated. The phthalocyanine displays an intense absorbance in the 680 nm range and shows a high photosensitizing activity toward a model biological substrate (N-acetyl-L-tryptophanamide). Upon administration of 20 microg cm(-2) onto the dorsal skin of Balb/c mice, maximal phthalocyanine concentrations (ca. 64.2 ng mg(-1) of skin) are reached at 1 h after the deposition. The photosensitizer appears to be localized in the epidermal layers, since (a) no detectable amounts of phthalocyanine are recovered from the mouse blood and liver; and (b) upon photoactivation with a diode laser at 675 nm, only the epidermis is heavily damaged, as shown by histological and ultrastructural analysis. The photodamage is largely of inflammatory nature and an essentially complete healing of the damaged skin is observed at 72 h after the end of the phototreatment. The minimal phototoxic dose for 20 microg cm(-2) photosensitizer and 675 nm irradiation is found to be (150 mW cm(-2)-120 J cm(-2)) or (180 mW cm(-2)-100 J cm(-2)).     

Laser desorption of DNA oligomers larger than one kilobase from cooled 4-nitrophenol

A unique matrix system consisting mostly of 4-nitrophenol has shown to be very effective for matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of large DNA oligomers when a cooled sample stage was used to prevent the sublimation of this matrix under vacuum. Using this 4-nitrophenol matrix with UV laser desorption, detection of picomole quantities of DNA oligomers containing up to approximately 800 nucleotides was routinely achieved. The effectiveness of this matrix was further demonstrated by the observation of a double-stranded DNA oligomer larger than 1000 base pairs, seen as a denatured single-stranded species, with a molecular ion mass exceeding 300 000 Da. The potential applications of 4-nitrophenol as a matrix for DNA sizing are discussed.     

First observation of the A 2Π—X 2Σ+ “red system” of 14C14N

The “red” A ²Π → X²Σ⁺ system of ¹⁴C¹⁴N was first observed in the laboratory. The wavenumbers of the two bands (0—0) and (0—1) were reduced simultaneously to give molecular parameters for the A ²Π(υ = 0) and X ²Σ⁺(υ = 0, 1) vibrational levels. Comparisons with parameters deduced from those of ¹²C¹⁴N are presented.     

The incorporation of heavy metals into diazo-type electron beam resists

Metals may be chemically incorporated into organic lithographic resists that contain or can be functionalized with ? OH groups. A wide range of metal incorporation (0.04–12% of total solids by weight) has been demonstrated for AZ-1370 (Shipley), a diazo-type photo- and electron resist. The novolac component of the resist is reacted with an organometallic halide, R_yMX (R = alkyl, aryl; M = transition or main group metal; X = CI, Br; 1 ≤ y ≤ 4, depending on M) to introduce the corresponding organometallic function into the resist.     

Electron-impact fragmentation of penta-fluorophenyldimethylsilyl ethers of some sterols of biological importance

The mass spectral properties under medium and high resolution of a new protecting group for sterols is described and its ability to direct fragmentation is compared with established derivatives. The mass spectra obtained are characterised by strong molecular ions which fragment to produce a more even ion distribution than the familiar TMS ethers. This results in enhanced abundance of hydrocarbon fragments, with molecular structural details given greater prominence than is found with other derivatives.