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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1937-1938 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photoreduction of CH3Cl was used to detect the transmission of electrons through layers of H2O and Xe on Ni(111) under ultrahigh vacuum (UHV) conditions. At a laser wavelength of 248 nm with H2O spacers, the electron intensity exhibited a nearly exponential decay to zero signal with the 1/e point at about 2 monolayers. At 193 nm with H2O spacers, the signal decayed with the 1/e point at about 4 monolayers to a constant value due to the direct photofragmentation of the CH3 Cl possible at this wavelength. At 248 nm with Xe spacers, the signal decayed by a factor of 4 in the first 2 monolayers, after which the signal was nearly constant and nonzero for at least 64 monolayers, indicating a long electron mean free path. CH3Br is shown to behave similarly with H2 O spacers at 248 nm.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 18 (1998), S. 183-187 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Laser triangulation is a very efficient non-contact point-measurement procedure, very similar to a mechanical gauge, but much faster. However, the special characteristics of the laser triangulation sensor (LTS) must be taken into account for its use. The correct selection of sensor and test-equipment verification, complying with norm ISO 9001, can be facilitated or implemented with the test-bench for LTS, developed in the quality and production measurement technology laboratory of the Neu-Technikum Buchs, Switzerland. A wide range of LTSs has been collated in a market analysis; differences of performance have been determined in a widespread comparison.
    Type of Medium: Electronic Resource
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  • 4
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    Unknown
    Köln : Periodicals Archive Online (PAO)
    Zeitschrift für Religions- und Geistesgeschichte. 30 (1978) 229 
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  • 5
    ISSN: 0022-328X
    Keywords: Catalysis ; Heterometallics ; Hydrogenation ; Phosphorus ; Rhodium ; Titanium
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Topics in catalysis 13 (2000), S. 249-252 
    ISSN: 1572-9028
    Keywords: high throughput screening ; combinatorial chemistry ; heterogeneous catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We are presenting an effective method to prepare and test heterogeneous catalysts much faster than by the conventional way. A catalyst array was prepared via an incipient wetness method by combination of different amounts of Pt, Zr, and V on Al2O3 by means of an automatic liquid handler. For catalytic testing for methane oxidation a ceramic monolith reactor module, the channels of which contain the different catalyst compositions, was developed in which up to 250 catalyst compositions can be prepared and tested in parallel. Gas samples from each channel of the monolith were analysed sequentially by a mass spectrometer by moving the QMS inlet capillary into the channels using a three-dimensional positioning system which works at high temperatures. By comparison of the testing results with experiments carried out in flow reactors it is shown that the monolithic reactor is an efficient tool for fast screening of heterogeneous catalysts.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 103 (1972), S. 1163-1177 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung N-Aryl-S,S-dimethylsulfimide können entweder in aprotischen Lösungsmitteln in Gegenwart von Basen (Triäthylamin) oder in protischen Lösungsmitteln (Alkohole, Wasser) ohne Zusatz von Basen in o-Methylthiomethylaniline umgelagert werden. Die Geschwindigkeit der Umlagerung wird bestimmt von der Abspaltung eines Protons aus einer S-Methylgruppe und von der Lage des Gleichgewichts für die Protonierung am Stickstoffatom, was aus einem kinetischen Isotopeneffekt und aus der Richtung des Einflusses von p-Substituenten geschlossen wurde. Die eigentliche Umlagerung des intermediären S-Ylids ist rascher als seine Reprotonierung durch protische Lösungsmittel und entspricht einer sigmatropen [2,3]-Verschiebung.
    Notes: Abstract N-Aryl-S,S-dimethyl sulfimides may be rearranged to yield o-methylthiomethyl anilines either in aprotic solvents in presence of bases (triethyl amine) or in protic solvents (alcohols, water) without addition of base. The rate of the rearrangement is determined by the rate of proton abstraction from one of the S-methyl groups as well as by the position of the equilibrium for protomation of the nitrogen atom, as indicated by kinetic isotope effects and the influence of p-substituents, respectively. The rearrangement of the intermediate S-ylide is faster than its reprotonation by protic solvents and represents a sigmatropic [2.3]-migration.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 103 (1972), S. 1178-1193 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine Reihe von Hydroxybenzylalkoholen wurde durch Reaktion von Phenolen mit Formaldehyd bzw. durch NaBH4-Reduktion der entsprechenden Hydroxybenzaldehyde dargestellt. Die Oxydation mit K3Fe(CN)6 führte in den meisten Fällen unter Abspaltung von Hydroxymethylgruppen als Formaldehyd zu polymeren Kupplungsprodukten, im Falle von 2,6-disubstituierten p-Hydroxybenzylalkoholen zu linearen Polyphenylenäthern. p-Hydroxybenzylalkohole mit elektronenanziehenden Substituenten ergaben die entsprechenden p-Hydroxybenzaldehyde. Die Oxydation mit O2 inDMSO in Gegenwart von Cu(I)Cl führte im Falle der o-Derivate meist zu oligomeren Produkten, die p-Derivate hingegen ergaben neben Oligomeren und p-Chinonen zumeist die entsprechenden Benzaldehyde als Hauptprodukte.
    Notes: Abstract Several hydroxy benzyl alcohols were prepared by reaction of phenols with formaldehyde, or by reduction of the corresponding hydroxy benzaldehydes with NaBH4. Oxidation with K3Fe(CN)6 yielded mainly polymeric products by radicalic coupling and loss of hydroxymethyl groups as formaldehyde (in case of 2,6-disubstituted p-hydroxy benzyl alcohols linear poly-phenyleneoxides were obtained). p-Hydroxybenzyl alcohols with electran withdrawing substituents gave the corresponding benzaldehydes. Oxidation with O2 inDMSO in the presence of Cu(I)Cl afforded in the case of o-hydroxy derivatives mainly oligomeric products, whilst in the case of p-derivatives the corresponding benzaldehydes were obtained as main products besides some oligomeres and p-quinones.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 102 (1971), S. 913-923 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine Reihe von Phenolen wurde durch Umsetzung mit Dimethylsulfoxid-Pyridin-SO3-Triäthylamin in o-Methylthiomethylphenole übergeführt. Diese Methode zur Methylthiomethylierung von Phenolen bringt bei Umsetzungen von reaktiven Phenolen gegenüber bisher bekannten Methoden präparative Vorteile, da kaum Nebenprodukte und praktisch nur o-methylthiomethylsubstituierte Produkte gebildet werden. 6-Alkylguajacole ergeben Gemische von jeweils zwei isomeren Cyclohexadienonen. Die Resultate stützen den angenommenen Bildungsmechanismus einer cyclischen Synchronumlagerung eines intermediären Phenoxysulfoniumylids, welche zum Teil den Charakter einer intramolekularen SN2′-Reaktion trägt.
    Notes: Abstract The reaction of various phenols withDMSO and the complex formed from pyridine and SO3 yielded in the presence of triethylamine o-methylthiomethyl phenols. Compared with known methods for methylthiomethylation of phenols, this method is of preparative value in case of reaction with reactive phenols, since only o-methylthiomethylated products and nearly no by-products are formed. 6-Alkyl guaiacols yielded mixtures of two isomeric cyclohexadienones, respectively. The results support the proposed mechanism of a concerted cyclic rearrangement of intermediate phenoxy sulfonium ylide, which has many of the characteristics of an intramolecular SN2′ reaction.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 102 (1971), S. 1571-1582 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Umlagerung von N-Aryl-S,S-dimethylsulfimiden in Toluol/Triäthylamin liefert in hohen Ausbeuten o-Methylthiomethylaniline. In Alkohol verläuft die Umlagerung ohne Zusatz von Basen rascher, als Nebenreaktion läuft aber die Spaltung zu dem zugrunde liegenden aromatischen Amin ab. 2,6-Di-substituierte N-Arylsulfimide ergeben durch analoge Umlagerung Cyclohexadienimine. Die Umlagerung von N-Aryl-S,S-dialkylsulfimiden erfolgt langsamer als die der S-Methylderivate; sie führte in einem Fall in hohen Ausbeuten zu einem durch 1,2-Wanderung entstandenen N-Alkylthioalkylprodukt. Die Ergebnisse liefern Aufschlüsse über den Mechanismus von Methylthiomethylierungen von anilinen und Phenolen.
    Notes: Abstract Rearrangement of N-aryl-S.S-dimethyl sulfimides in toluene/triethyl amine yields high amounts of o-methylthiomethylated anilines. Rearrangement in ethanol without addition of base proceeds faster, but yields also the original aniline as by-product. 2.6-Di-substituted N-aryl sulfimides yielded on analogous rearrangement cyclohexadiene imines. The rearrangement of N-aryl-S.S-dialkyl sulfimides is slower than that of the S-methyl derivatives, and yielded in one case high amounts of N-alkylthioalkyl product formed via 1.2-migration. The results offer some informations on the mechanism of methylthiomethylations of anilines and phenols.
    Type of Medium: Electronic Resource
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