Einsatz der stellungsisomeren 1-Phenylbutanone in die Willgerodt—Kindler-Reaktion

Zusammenfassung Setzt man die stellungsisomeren 1-Phenylbutanone mit Morpholin und Schwefel bei etwa 130°C um, so erhält man neben dem zu erwartenden 4-Phenylbuttersäurethionmorpholid (Willgerodt-Kindler-Produkt) in allen Fällen das 2-Morpholino-5-phenylthiophen. Die Ausb. an 4-Phenylbuttersäurethionmorpholid und 2-Morpholino-5-phenylthiophen nehmen vom 1-Phenyl-butanon-(1) zum 1-Phenylbutanon-(3) hin zu. Die Ausbeuten an beiden Produkten wurden durch Kombination klassischer Methoden und der Radiodünnschichtchromatographie ermittelt.2-Morpholino-5-phenylthiophen entsteht während der Reaktion aus dem 4-Phenylbuttersäurethionmorpholid.

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Treatment of position isomeric 1-phenylbutanones with morpholine and sulfur at 130°C gives 4-phenyl-thio-butyromorpholide (Willgerodt-Kindler product) and unexpected 2-morpholino-5-phenylthiophen. The yields of theWK-product and of the 2-morpholino-5-phenyl-thiophen increase corresponding to the position of the carbonylgroup from 1-phenylbutanone-(1) to 1-phenylbutanone-(3).The yields of both the products were determined by combination of classic methods with radio thin layer chromatography.2-Morpholino-5-phenylthiophen originates from theWK-product in course of the reaction.

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Mit 1 Abbildung.

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Herrn Univ.-Prof. Dr.F. von Wessely zum 70. Geburtstag gewidmet.

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1.–3. Mitt.:F. Asinger undK. Halcour, Mh. Chem.,94, 1030, 1047 (1963);95, 24 (1964).

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Vgl. auchF. Asinger, W. Schäfer, K. Halcour, A. Saus undH. Triem, Angew. Chem.75, 1050 (1963).

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Vgl. auchF. Asinger, H. Offermanns undH.-D. Köhler, Tetrahedron Letters7, 631 (1967).

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Teil der Dissert.A. Mayer, Techn. Hochschule Aachen, 1966.     

Comparison of microwave-assisted acid leaching techniques for the determination of heavy metals in sediments, soils, and sludges

Microwave-assisted EPA method 3051 for nitric acid leaching of environmentally key elements from sediments, soils, and sludges was tested, and the influence of leaching temperature and time on element recovery for an estuarine sediment (CRM 277) was investigated. The extraction efficiencies for four certified reference materials applying EPA method 3051, an optimized nitric acid procedure, and an aqua regia (HCl/HNO₃ 3:1) procedure were compared. Digestions were carried out in a high-pressure microwave system offering simultaneous temperature and pressure control for all digestion vessels employed. Eight elements (Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) were determined by ICP-AES and ICP-MS. Extraction efficiency strongly depended on the applied leaching parameters and varied for certain elements among different materials when a nitric acid procedure was applied. In general, element recoveries obtained from the aqua regia procedure were superior to those obtained from nitric acid procedures and showed good agreement with the 95% confidence interval of the certified value for most of the elements investigated. Received: 27 March 1998 / Revised: 29 June 1998 / Accepted: 3 July 1998     

Bimetallic complexes from amphoteric group 13/15 ligands: syntheses and X-ray crystal structures

Bimetallic, pentel-bridged complexes of the type [(dmap)Me2M-E(SiMe3)2-M'(CO)n] (M=Al, Ga; E=P, As, Sb; M'=Cr, Fe, Ni; DMAP=4-(dimethylamino)pyridine) are formed by reactions of DMAP-coordinated monomeric Group 13/15 compounds [(dmap)Me2M-E(SiMe3)2] with the transition metal complexes [(Me3N)Cr(CO)5], [Fe3(CO)12], and [Ni(CO)4]. For the first time, this reaction offers a general pathway to compounds containing a Group 13 metal and a transition metal bridged by a pentel atom. Complexes prepared in this way were characterized by IR and multinuclear NMR spectroscopy and by single-crystal X-ray structure analysis. Their electronic and structural properties are discussed in detail. The Group 13/15 ligands are very weak acceptors, which is likely to be due to the electropositive Group 13 metal, and the complexes feature comparatively long pentel-transition metal bonds. In addition, the synthesis and structural characterization of the parent DMAP-coordinated gallanes [(dmap)Me2Ga-E(SiMe3)2] (E=P, As) are reported.     

Crystal Structures of the Potassium and Silver Salts of Nitroform

The solid state structures of three nitroformate (NF) salts were determined using single crystal X‐ray crystallography. The NF anion was found to be a non‐planar moiety which adopts either the commonly observed C_2v conformation or distorted propeller conformation (D₃) in the case of the silver salts, or, a C₂ conformation in the case of the potassium salt. This latter C₂ conformation has been uniquely observed for potassium nitroformate. All structures exhibit cation‐anion interactions that influence the structure of the anion. The ¹³C and ¹⁴N NMR spectra of the NF anion show broad singlets, which indicates the equivalence of the nitro groups in solution within the NMR time‐scale. In addition, the vibrational and mass spectra of potassium nitroformate and silver nitroformate monohydrate were recorded. Furthermore, the gaseous decomposition products of potassium nitroformate at 25 °C were detected using IR spectroscopy and mass spectrometry.     

Abbau von Palustrin zu (−)-Dihydropalustraminsäure ((2R, 6S, 1′S)-[6-(1′-Hydroxypropyl)-2-piperidyl]essigsäure) und Struktur von Palustrin und Palustridin. Mitteilung über Schachtelhalmalkaloide

Degradation of palustrin to (?)-dihydropalustramic acid ((2R,6S,1′S)-[6-(1′-hydroxypropyl)-2-piperidyl]acetic acid), and the structure of palustrin and palustridin The structure of the macrocyclic alkaloid palustrin is shown to be 1a . Its piperidine unit can be obtained as (?)-dihydropalustramic acid ( 6a ) by the following sequence of degradation reactions (Scheme 1): catalytic hydrogenation of 1a followed by methylation and Hofmann degradation provides the allyl base 4 . the regioselectivity of the Hofmann elimination is explained by intramolecular proton abstraction at C(3) by C(18)-O^?. Catalytic reduction of 4 and subsequent acidic hydrolysis yielded 6a and N, N-dimethylputrescine (?N,N-dimethyl-1,4-butanediamine; 7 ). Loss of the N-alkyl group in the formation of 6a occurs during the catalytic hydrogenation step. This interpretation is supported by the results of model experiments. The position of the double bond in 1a is deduced from the IR. spectrum of the bromo-δ-lactone 19 prepared by treatment of 1a with N-bromosuccinimide at pH 4 (Scheme 3). Some of our previously published results on the degradation of dihydropalustrin ( 2a ) are obviously at variance with the newly proposed structure for palustrin ( 1a ). They can easily be explained by assuming a partial hydrogenolysis of the C(17)-N(1) bond during the preparation of dihydropalustrin from palustrin. Periodate cleavage of dihydropalustramic acid methyl ester ( 6b ) liberates propionaldehyde, which can be trapped by working at pH 7.5 (Scheme 2); at lower pH values it condenses rapidly with the simultaneously generated 3,4,5,6-tetrahydropyridine derivative 15 . The structure of the condensation product is proposed to be 16 on the basis of the isolation of its hydrogenation product, an isomeric dihydropalustramic acid ( 17 ).     

Synthese,Kristallstruktur und festkörper‐NMR‐spektroskopische Untersuchung neuer Oxonitridosilicate der Mischkristallreihe Ba4−xCaxSi6N10O

The new oxonitridosilicates Ba_4?xCa_xSi₆N₁₀O have been synthesized by means of high‐temperature synthesis in a radio‐frequency furnace, starting from calcium, barium, silicon diimide and amorphous silicon dioxide. The maximum reaction temperature was at about 1450 °C. The solid solution series Ba_4?xCa_xSi₆N₁₀O with a phase width 1.81 ≤ x ≤ 2.95 was obtained. The crystal structure of Ba_1.8Ca_2.2Si₆N₁₀O was determined by X‐ray single‐crystal structure determination (P2₁3, no. 198), a = 1040.2(1) pm, Z = 4, wR2 = 0.082). It can be described as a highly condensed network of corner‐sharing SiN₄ and SiON₃ tetrahedra, the voids of which are occupied by the alkaline earth ions. The structure is isotypic with that of BaEu(Ba_0.5Eu_0.5)YbSi₆N₁₁. In the ²⁹Si solid‐state MAS‐NMR spectrum two isotropic resonances at ?50.0 and ?53.6 ppm were observed.     

Chromatographische Trennung und Identifizierung diastereomerer Carotinoide mit grossem räumlichem Abstand der chiralen Zentren

Chroma to graphic Separation and Identification of Diastereomeric Carotinoids with Distant Chiral Centers The high-performance liquid chromatographic separation of diastereomeric C₄₀-carotinoids is described possessing chiral centers which are separated by 18 C-atoms (nonaene system). The method is applied to the separation of the two diastereomers of 6,6′-dihydrorhodoxanthin 1a and 1b (ε,ε-carotene-3,3′-dione) and the six diastereomers of tunaxanlhin (ε,ε-carotene-3,3′-diol; 2a–2f ). Conditions for the separation of lutein [(3R, 3′R, 6′R)-β,ε-carotene-3.3′-diol, 3a ], 3′-epi-lutein [(3R,3′S,6′R)-β, ε-carotene-3,3′-diol, 3b ] and its 13′-cis- ( 3c ) and 13-cis-stereo-isomers( 3d ) are also reported. Identification of the different chromatographic fractions was possible by use of authentic synthetic samples or by ¹H-NMR. spectroscopy.     

The chemical bond in polyphosphides: crystal structures, the electron localization function, and a new view of aromaticity in P4(2-) and P5(-)

The incongruent solvation of M(I)4P6 species (M(I) = K, Rb, Cs) in liquid ammonia leads to a broad variety of polyphosphides such as P7(3-), P11(3-), and the putatively aromatic P4(2-) and P5(-), which we investigated by using NMR spectroscopy and single-crystal X-ray structure analysis. The structures of Cs2P4 x 2 NH3, (K@[18]crown-6)3K3(P7)2 x 10 NH3, Rb3P7 x 7 NH3, and (Rb@[18]crown-6)3P7 x 6 NH3 are discussed and compared. The electron localization function ELF is used in a comparison of the chemical bonding of various phosphorus species. The variances of the basin populations provide a well-established measure for electron delocalization and therefore aromaticity. While comparable variance is calculated for P4(2-) and P5(-) it is observed in the lone pairs rather than in the basin populations of the bonds as in the prototypical aromatic hydrocarbons such as benzene or the cyclopentadienide anion. For this behavior, the term "lone pair aromaticity" is proposed.     

A note on the vacuum structure of an SU(2) Yang-Mills theory

We discuss different compactifications of the spacial part ³ of Minkowski space and give classifications of the vacuum structure for a Yang-Mills theory.Partially supported by DFG and by Simon Fraser UniversityPartially supported by National Research Council of Canada grant 751-010