Effect of H2S-uptake on the conversion of cyclohexene on Ru- and Pd-promoted molybdena-alumina catalysts

The effect of H₂S on the activity and selectivity of catalysts (Ru/Al₂O₃, Pd/Al₂O₃ and Ru and Pd promoted molydena-alumina) was different (on differnt catalysts and different conversions of cyclohexene). Ru-containing catalysts showed higher sulfur sensitivities than the Pd-containing ones. The sequence of catalysts by their H₂S uptake related to mass of catalyst was PdMo/Al₂O₃RuMo/Al₂O₃Mo/Al₂O₃>Pd/Al₂O₃Ru/Al₂O₃.     

Darstellung und spektroskopische Charakterisierung von Di(halogeno)phthalocyaninato(1–)rhodium(III), [RhX2Pc1−] (X = Cl,Br, I)

Synthesis and Spectroscopical Characterization of Di(halo)phthalocyaninato(1–)rhodium(III), [RhX₂Pc^1?] (X = Cl, Br, I) Bronze-coloured di(halo)phthalocyaninato(1–)-rhodium(III), [RhX₂Pc^1?] (X = Cl, Br) and [RhI₂Pc^1?] · I₂ is prepared by oxidation of (ⁿBu₄N)[RhX₂Pc^2?] with the corresponding halogene. Irrespective of the halo ligands, two irreversible electrode reactions due to the first ringreduction (E_R = ?0,90 V) and ringoxidation (E_O = 0,82 V) are present in the cyclovoltammogram of (ⁿBu₄N)[RhX₂Pc^2?]. The optical spectra show typical absorptions of the Pc^1?-ligand at 14.0 kK and 19.1 kK. Characteristic vibrational bands are at 1 366/1 449 cm^?1 (i. r.) and 569/1 132/1 180/1 600 cm^?1 (resonance Raman (r. r.)). The antisym. (Rh? X)-stretching vibration is observed at 294 cm^?1 (X = Cl), 240 cm^?4 (Br) and 200 cm^?1 (I). Only the sym. (Rh? I)-stretching vibration at 133 cm^?1 is r. r. enhanced together with a strong line at 170 cm^?1, which is assigned to the (I? I)-stretching vibration of the incorporated iodine molecule. Both modes show overtones and combinationbands.     

Evidence of steric factors in the fungitoxic mechanisms of 8-quinolinol and its 2-, 3-, 4-, 5-, 6-and 7-chloro and bromo analogues

Summary A study was made of the fungitoxicity of 2-, 3-, 4-, 5-, 6- and 7-chloro and bromo-8-quinolinols againstAspergillus niger,A. oryzae,Myrothecium verrucaria,Trichoderma viride andTrichophyton mentagrophytes in Sabouraud dextrose broth and in Yeast Nitrogen Base supplemented with 1%D-glucose and 0.088%L-asparagine. Based on the presence or absence of synergism between pairs of substituted 8-quinolinols and reversal or nonreversal of toxicity byL-cysteine or N-acetyl-L-cysteine, the following conclusions were reached: (1) substituents on the quinoline ring change the site(s) of action of the toxicant; (2) the sites of action of the 5-, 6-, and 7-chloro-8-quinolinols are different from each other and from 8-quinolinol and its 2-, 3-, and 4-chloro analogues, and the same is true for the corresponding bromo compounds; (3) 8-quinolinol and its 3- and 4-chloro and bromo analogues appear to share common sites of action; (4) for good antifungal activity the 2 position of the ring must not be substituted by sterically bulky groups; (5) the geometry of the binding sites of action are not so constrained that they cannot accommodate the analogously substituted chloro- and bromo-8-quinolinols.

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Nachweis sterischer Faktoren bei der Fungitoxizität von 8-Chinolinol und seinen 2-, 3-, 4-, 5-, 6- und 7-Chlor- und -Brom-Analogen

Zusammenfassung Es wurde eine Studie der Fungitoxizität von 2-, 3-, 4-, 5-, 6- und 7-Chlor- und-Brom-8-chinolinol gegenüberAspergillus niger,A. oryzae,Myrothecium verrucaria,Trichoderma viride undTrichphyton mentagrophytes in Sabouraud Dextrose Nährmedium und in Hefe-N-Base mit 1%D-Glucose und 0.088%L-Asparagin unternommen. Auf der Basis des Zutreffens oder der Abwesenheit eines Synergismus zwischen Paaren von substituierten 8-Chinolinolen und der Umkehrung oder Nichtumkehrung der Toxizität durchL-Cystein oder N-Acetyl-L-cystein wurden folgende Schlußfolgerungen abgeleitet: (1) Substituenten am Chinolin-Ring ändern die Aktionsstelle(n) des Toxikans; (2) Die Angriffsstellen der 5-, 6- und 7-Chlor-8-chinolinole sind untereinander und von 8-Chinolinol und seinen 2-, 3- und 4-Chlor-Analogen verschieden, wobei das auch für die entsprechenden Brom-Verbindungen gilt; (3) 8-Chinolinol und seine 3- und 4-Chlor- und -Brom-Analogen scheinen gemeinsame Aktionsstellen zu teilen; (4) für eine gute antifungale Aktivität darf die 2-Position des Rings nicht mit sterisch anspruchsvollen Gruppen besetzt sein; (5) Die Geometrie des Bindungsstellen der Wirkung ist nicht so gespannt, daß nicht sowohl analoge Chlor- oder Brom-8-chinolinole Platz finden.

     

Synthesis of bis(cyclopentadienyl)diazadiene complexes of ytterbium. An X-ray structural study of the Cp2Yb(μ-η2:Ti2-But-N=CH-CH=N-But)Li(DME) complex

Ytterbium complexes, Cp₂Yb(-₂:²-DAB)Li(DME) (1) and CpYb(DAB)K(THF)₂ (2), containing a bridging diazadiene ligand were prepared by the reaction of CpYbCl₂(THF)₃ with (DAB)Li₂ (11) and (DAB)^–K⁺ (12) (DAB = Bu^t-N=CH-CH=N-Bu^t). The structure of complex1 was established by X-ray diffraction analysis. The complex is binuclear: the Yb atom of the Cp₂Yb fragment and the Li atom, which is bonded as well with the chelating DME molecule, are linked by the DAB ligand.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 148–151, January, 1994.     

Spektroskopische Eigenschaften von Di(phthalocyaninato)metallaten(III) der Seltenen Erden. Teil 2: Die Multikern(1H-, 13C-, 15N-, 17O- und 31P)-NMR-Spektren und Nachweis komplexgebundenen Wassers

Spectroscopical Properties of Di(phthalocyaninato)metalates(III) of the Rare Earth Elements. Part 2: The Multinuclear (¹H, ¹³C, ¹⁵N, ¹⁷O, and ³¹P) NMR Spectra and Determination of Complex Bound Water The ¹H, ¹³C, ¹⁵N, ¹⁷O and ³¹P NMR spectra of (PNP)[Ln(Pc^2?)₂] and (TDOA)[Ln(Pc^2?)₂] (Ln = La …? (—Pm) …? Lu); PNP: di(triphenylphosphine)-iminium; TDOA: Tri(n-dodecyl)n-octylammonium dissolved in CD₂Cl₂ are reported. With the exception of the nitrogen atoms of the cations all light atoms of both homologues complex salt rows have been detected and assigned. Proof of the presence of additional water contained in the (solid) complex salts has been given unambigously. The otherwise strong Fermi contact interactions diminuish rapidly with growing distance from the paramagnetic centre favouring dipolar (pseudo-contact) interactions. As a consequence the mostly element independent paramagnetic shifts of the atoms situated on the periphery of the anion as well as those of the cations and water are determined by the distance factor. Therefore a first glance of the structure of the ion-pair present in solution emerges, in which the water molecule seems to play an important role.     

Glykosylazide als Ausgangsbasis zur Gewinnung von Nucleosidanalogen, 3. Mitt. Synthese von Alkylaminotetrazol- und Uretidinonnucleosiden

The -ribofuranosylazide1 is transformed after usual derivatization by suitable protecting groups into the P–N-ylid2, which gives the corresponding N-Glykosyl-N-alkylcarbodiimides4 and a small amount of the glykosylisocyanatde-rivative3 by reaction with alkylisocyanates. The carbodiimides4 were reacted with hydrazoic acid to give the alkylaminotetrazolnucleosides5 and finally the free nucleosidanalogs6. In the case of5 c the 5-aziridinyltetrazolnucleosid5 h was formed by an usual neighbouring group reaction. In addition the compound1 is transformed into the 3,5-diprotected anchor derivative7 by reaction withTIPSCl₂. The latter could be transformed by usual steps into the alkylaminotetra-zolnucleosides8 with a free 2-OH group. In the next step the 2-p-tolylthiocarbo-nates9 were prepared followed by transformation to the 2-desoxynucleosides10 by means of tributyltinhydride. Finally the free 2-desoxynucleosides11 were prepared. By reacting the carbodiimides4 with phenylisocyanate a mixture of the two possible regiouretidinonnucleosidderivatives12 and13 are formed. In the case of the N-glykosyl-N-allylcarbodiimide4 d only the one isomer13 d arises.

Herrn Prof. Dr.A. Neckel mit den besten Wünschen zum 60. Geburtstag gewidmet.     

Characteristics of immunosorbents used as a new approach to selective solid-phase extraction in environmental analysis

Summary The trace-level determination of organic pollutants in complex matrices is difficult and often not reliable because theccurrent extraction procedures are non-selective. New extraction sorbents involving antigen-antibody interactions, called immunosorbents (ISs), have been synthesised in order to trap a group of structurally related pollutants. The IS capacity is always high for the analyte-antigen used to make the antibodies, but can be low for some related compounds. In this work, we show the relationship that exists between capacity, break-through volume and recovery of analytes because of the competition between the structurally related compounds for antibody sites. Breakthrough due to the overloading of the column should be avoided because calibration curves are no longer linear. The capacity of two ISs, one made for trapping the triazine pesticide group and the second for the phenylurea, group, have been optimised by selecting silica with 50 nm pore size. Calibration curves are linear for all the compounds in a mixture of ten phenylureas up to a concentration of 5 to 10 μg L⁻¹ for each compound when handling 50 mL water samples through a precolumn packed with 0.22 g of IS. Under these conditions, reliable quantitative results are obtained because calibration curves are similar when compounds are alone or in a mixture. Application to the clean-up of soil extracts illustrates the high selectivity and the high potential of these new sorbents in environmental analysis. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

The use of silicon in the preparation of apolar glass capillary columns

As an extention of previous reports, variables affecting the performance of columns modified by silicon deposition have been optimized. The aim of this work was to produce thermostable apolar glass capillary columns regardless of the glass type used and to maintain column performance under stressful conditions. The main parameters studied were the influence of glass type, leaching effects, and silicon layer thickness on column activity. Deactivation and stationary phase conditions were held constant. Both coated and uncoated columns were tested. The thickness of the silicon layer was found to be relatively unimportant. There was no difference whether soft glass or borosiiicate glass was used and leaching before silicon deposition did not influence column activity. Bare silicon surfaces showed considerable activity especially in respect to interactions with free acids and bases. There are indications that the surface consists of silicon oxide and other oxygenated forms of silicon rather than of the element. Treatment of the silicon layers with dilute hydrofluoric acid and the strict exclusion of traces of oxygen and water did not improve the situation. In spite of such specific interactions, silicon surfaces were easily deactivated by heat treatment with polysiloxanes. Silicon surfaces deactivated by baking with octamethyltetrasiloxane at 400°C are inert and temperature stable and show characteristics similar to persilylated surfaces.     

Synthese,Struktur und Reaktivität von Bis(dialkylamino)diphosphanen

Synthesis, Structure, and Reactivity of Bis(dialkylamino)diphosphines Starting with the aminochlorophosphines ⁱPr₂N? PCl₂ 1 and (ⁱPr₂N)₂P? Cl 2 , the synthesis of some new functionalized aminophosphines (ⁱPr₂N)₂P? SiMe₃ 3a , (ⁱPr₂N)₂P? SnMe₃ 3b , (ⁱPr₂N)(DMP)P? Cl 4 , ⁱPr₂N? P(SiMe₃)₂ 5 and ⁱPr₂N? P(SiMe₃)Cl 6 is reported. Reactions of 2 with different phosphides yield the aminodiphosphines (ⁱPr₂N)₂P? P(SiMe₃)₂ 7a , (ⁱPr₂N)₂P? P(SiMe₂^tBu)₂ 7b , (ⁱPr₂N)₂P? PPh₂ 8 and (ⁱPr₂N)₂P? PH₂ 9 . The phosphines 3a/b react with halogenophosphines to the aminohalogenodiphosphines (ⁱPr₂N)₂P? PCl₂ 10 , (ⁱPr₂N)₂P? P^tBuCl 11 and (ⁱPr₂N)₂P? P(NⁱPr₂)Cl 12 . The ambivalente aminophosphine 6 gives the aminotrichlorodiphosphine Cl(ⁱPr₂N)P? PCl₂ 13 after condensation with PCl₃, while the reactions with the corresponding lithiumphosphides yield the aminosilyldiphosphines (ⁱPr₂N)(SiMe₃)P? P(SiMe₃)₂ 14a and (ⁱPr₂N)(SiMe₃)P? P(SiMe₂^tBu)₂ 14b . The aminochlorophosphines 2/4 are reductively coupled with magnesium leading to the symmetrically substituted tetraaminodiphosphines (ⁱPr₂N)₂P? P(ⁱPr₂N)₂ 15a and DMP(ⁱPr₂N)P? P(ⁱPr₂N)DMP 15b . The functionalized aminosilyldiphosphine 7a is treated with methanol to yield the diphosphine (ⁱPr₂N)₂P? PH(SiMe₃) 16 and gives the lithium phosphinophosphide (ⁱPr₂N)₂P? PLi(SiMe₃) 17 after metallation with n-BuLi. The compounds are characterized by their NMR and mass spectra and the ³¹P-NMR values of the diphosphines are discussed according to their substituents. The crystal structures of 7b, 8 and 15b showing significantly differing conformations are presented.     

Magnetic microcapsules for targeted delivery of anticancer drugs

To achieve targeted distribution of anticancer drugs with sustained activity, ferromagnetic ethylcellulose microcapsules containing an anticancer drug, mitomycin C (FM-MMC-mc), were prepared by a method based on phase separation principles. Two prototypes of FM-MMC-mc were made: one with the drug as the core and zinc ferrite on its capsular surface (outer type); the other with both the drug and zinc ferrite as the core (inner type). Both preparations provided a sustained-release property and a sensitive response to conventional magnetic force, although certain differences in the release rate of drug, magnetic responsiveness, and particle size were found between the two dosage forms. Animal studies showed that the magnetic microcapsules could be magnetically controlled in the artery and urinary bladder. VX2 tumors in the rabbit hind limb and urinary bladder were successfully treated with magnetic control of FM-MMC-mc. Pharmacokinetic study revealed that the targeting of the microcapsules markedly enhanced the drug absorption into the surrounding tissues for a prolonged period of time. The results indicate the feasibility and effectiveness of the magnetic microcapsules as a targeted drug delivery system.