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  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Methoxycarbonyl-Substituted 2,3-Dihydropyridin-4(1H)-one(= Methyl 1,2,3,4-Tetrahydro-4-oxopyridine-1-carboxylate) as Chromophore for Photochemical [2 + 2]-CycloadditionsWith olefins having an electron-acceptor as well as with olefins having an electron-donor substituent, 1-methoxycarbonyl-substituted dihydropyridinone 12 undergoes [2 + 2] cycloaddition in good preparative yields. The photochemical cycloaddition is highly regioselective. For preparative purposes, the ring junction can be equilibrated to the thermodynamically more stable cis-junction. Only the ‘endo’/‘exo’ selectivity at the C-atom bearing the olefin substituent cannot be controlled. The photodimerization of 12 is the only side reaction. Using a slight excess of the olefin, the photodimerization can be suppressed. The protecting group at the N-atom of the dihydropyridinone can be varied in order to introduce an internal sensitizer, as shown with 1-acyl-substituted compound 29, which underwent the cycloaddition process even with sunlight.
    Additional Material: 3 Ill.
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  • 2
    ISSN: 0044-2313
    Keywords: Pentagold molybdenum cluster ; trigold cobalt cluster ; [(Ph3PAu)5Mo(CO)4]PF6 ; (Ph3PAu)3Co(CO)3 ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cluster Synthesis by Photolysis of R3PAuN3. VIII. Synthesis and Crystal Structure of [(Ph3PAu)5Mo(CO)4]PF6 · CH2Cl2 and (Ph3PAu)3Co(CO)3Photolysis of a mixture of Ph2PAuN3 and Mo(CO)6 in THF yields [(Ph3PAu)5Mo(CO)4]+ (1), which can be crystallized from CH2Cl2/diisopropylether as orange 1 · PF6 · CH2Cl2 with the space group P21/c and a = 1681.4(5), b = 2215.6(12), c = 2761.5(9) pm, β = 91.54(3)°, Z = 4. The Au5Mo center of cluster 1 forms a capped trigonal bipyramid with the Mo atom in equatorial position and almost equal Mo—Au distances between 279.9(5) and 284.6(7) pm to all five Au atoms. The Au—Au distances range from 272.2(4) to 301.3(4) pm. The Mo(CO)4 group causes three v(C0) at 1975, 1915 and 1890cm-1. Reaction of Ph3PAuCo(CO)4 with Ph3PAuPF6 affords the known cluster cation [(Ph3PAu)4Co(CO)3]+ in high yield. It can be degraded with C1- to the neutral cluster (Ph3PAu)3Co(CO)3 (2). 2 forms air stable, yellow crystals with the space group P21/n and a = 1359.4(4), b = 2041.0(5), c = 1853.2(6)pm, β = 91.47(1)°, Z = 4. The Au3Co core of 2 has a tetrahedral structure with distances Co—Au between 250.4(1) and 254.0(2) pm and Au—Au between 279.5(1) and 285.1(1) pm. v(C0) are observed at 1963, 1905 and 1891 cm-1. Reaction of 2 with [(Ph3PAu)4Co(CO)3]+ yields the condensed cluster [(Ph3PAu)6AuCo2(CO)6]+.
    Notes: Die Photolyse einer Mischung von Ph3PAuN3 und Mo(CO)6 in THF ergibt den Cluster [(Ph3PAu)5Mo(CO)4]+ (l), der nach Zugabe von PF6- aus CH2Cl2/Diisopropylether als oranges 1 · PF6 · CH2Cl2 mit der Raumgruppe P21/c und a = 1681,4(5), b = 2215,6(12), c = 2761,5(9) pm, β = 91,54(3)°, Z = 4 kristallisiert. Das Au5Mo - Gerüst von 1 bildet eine einfach überkappte trigonale Bipyramide mit dem Mo - Atom in äquatorialer Position und nahezu gleich langen Mo—Au-Abständen von 279,9(5) bis 284,6(7) pm zu allen fünf Au-Atomen. Die Au—Au-Abstände liegen zwischen 272,2(4) und 301,3(4) pm. Die Valenzschwingungen v(Co) der Mo(CO)4-Gruppe werden bei 1975, 1915 und 1890cm-1 beobachtet. Reaktion von Ph3PAuCo(CO)4 mit Ph3PAuPF6 liefert das bereits bekannte Clusterkation [(Ph3PAu)4C(CO)3]+ in hoher Ausbeute. Es kann durch Umsetzung mit Cl- zum Neutralcluster (Ph3PAu)3Co(CO)3 (2) abgebaut werden. 2 bildet luftstabile, gelbe Kristalle rnit der Raumgruppe P21/n und a = 1359,4(4), b = 2041,0(5), c = 1853,2(6)pm, β = 91,47(1)°, Z = 4. Das Au3Co-Gerüst weist eine tetraedrische Struktur mit Abständen Co—Au zwischen 250,4(1) und 254,0(2) pm und Au—Au zwischen 279,5(1) pm und 285,1(1) pm auf. v(CO) treten bei 1963, 1905 und 1891 cm-1 auf. Reaktion von 2 mit [(Ph3PAu)4Co(CO)3]+ führt unter Clusterkondensation zu [(Ph3PAu)6AuCo2(CO)6]+.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 3 (1965), S. 1911-1939 
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By use of a modified, small-bore, capillary extrusion rheometer (MCER) with an Instron tensile testing machine, the flow and set-up properties of thermosetting plastics and rubbers were characterized. The majority of the experiments were performed with diallyl phthalate, where the rate of curing was also followed by infrared determination of the reduction in unsaturation as the polymerization-curing proceeded. Phenol-formaldehyde was also characterized. Finally, the curing of ethylene-propylene and ethylene-vinyl acetate copolymer rubbers with peroxide was studied and correlated with the type of peroxide used. The MCER data are shown to be of practical use for predicting the time-temperature-pressure relationships for processing thermosetting plastics and rubbers. Moreover, the history of the curing, as obtained by analysis of the continuously extruded strand, is also of theoretical interest for studying reaction kinetics and for evaluating the effectiveness of various curing systems. It is predicted the MCER will be widely used for studying the curing of thermosetting plastics and rubbers.
    Additional Material: 30 Ill.
    Type of Medium: Electronic Resource
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