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  • 1
    Electronic Resource
    Electronic Resource
    Reaktionen an Indolderivaten, XI. Die stereoselektive Totalsynthese von DL-Ajmalicin, DL-19-epi-Ajmalicin, DL-Formosanin und Isoformosanin (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 3558-3572 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ausgehend vom ungesättigten Keton 1 gelingt die stereoselektive Totalsynthese mehrerer heterocyclischer Indol- und Oxindol-Alkaloide. Speziell der stereoselektive Aufbau der C-19-Konfiguration sowie der Einfluß dieses Zentrums auf die Folgereaktionen werden diskutiert. Die Massenspektren der verschiedenen stereoisomeren Zwischenprodukte werden gegenübergestellt.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691021034
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  • 2
    Electronic Resource
    Electronic Resource
    Auf der Suche nach Stabilen Carbenen (1998)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 32 (1998), S. 6-14 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article follows a thread through the history of the quest for stable carbenes. The story begins in 1835 with the attempts by Dumas to dehydrate methanol to produce methylene. It continues through modern times to a point where the accumulation of many false starts in stable carbene synthesis led to the conventional wisdom that carbenes are so highly reactive that they exist only as labile, short-lived molecules. The report of the isolation of the first stable crystalline carbene in 1991 began a renaissance in the chemistry of isolable carbenes. Much of the older chemistry is currently being revisited and reinterpreted with the aid of modern analytical techniques. Easily handled carbenes are opening many new opportunities in both exploratory chemistry and industrial applications.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19980320103
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  • 3
    Electronic Resource
    Electronic Resource
    Monitoring the quality of mix of polymer melts with particulate fillers using fluorescence spectroscopy (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 1759-1765 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fluorescence spectroscopy has been employed to monitor the mixing of polymer melts with filler material. The polymer melts were low molecular weight polybutadiene and PBAN, a terpolymer consisting of 85% butadiene, 11% acrylonitrile, 4% acrylic acid, and the filler material was aluminum oxide. To carry out the fluorescence observations, a dopant chromophore was mixed into the polymer melt at very low concentrations, 10-4 to 10-6 molar or 11 to 0.11 ppm by weight. The mixing experiments were carried out using a small laboratory mixer which had glass walls for viewing the fluorescence spectra from the dopant chromophore. Fluctuations in fluorescence intensity were observed to decrease as a function of mixing time indicating that the spatial distribution of the fluorescent chromophores was becoming more uniform. Concerning the mixing of polymer melt and filler, we hypothesize that uniform mixing of ingredients is achieved when fluorescence intensity as a function of time is constant. In order to obtain quantitative support for this hypothesis, we used a fluorescence microscope to measure fluorescence intensity and optical transmittance from microscopic regions of well-mixed and poorly mixed specimens.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760292405
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanism of accelerated photofading of thioether anthraquinone dyes in styrene butadiene resinsPresented, in part, at the IUPAC Photochemistry Symposium at Interlaken, Switzerland, July 1984. (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 1205-1219 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Many anthraquinone dyes fade in visible light up to 100 times faster in styrene butadiene copolymers than in polyester resins or polystyrene. A mechanistic investigation of the photofading of 1,5-dihydroxy-2,6-diisobutyl-4-thiophenylanthraquinone has established that the dye sensitizes formation of singlet oxygen, a very reactive species, which attacks the double bonds in the styrene butadiene, resulting in extensive chain cleavage and peroxide formation. The major process is the oxidation of the polymer, and the dye fading is a minor process whereby the dye is apparently attacked by polymeric peroxides. The mechanism appears to be general for anthraquinone dyes, especially those with thioether, amino, hydroxy, or double-bond functionality. Unfortunately the fading is unaffected by most anticxidant stabilizers: the best result achieved was a doubling of half-life with 1 wt% Spinuvex A-36. This is still insufficient to give colored styrene butadiene copolymer resins the intrinsic dye stability available in other polymers, rendering styrene butadiene unsuitable for applications requiring high photostability of anthraquinone dyes.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360520
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of mislabeled samples on the performance of the linear learning machine (1990)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 4 (1990), S. 47-50 
    Details
    ISSN: 0886-9383
    Keywords: Classification ; Pattern recognition ; Preprocessing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Over the past 15 years the linear learning machine has been applied to a large number of chemical problems. The learning machine approach is conceptually simple and does not require knowledge about the statistical distribution of the data. However, there are problems associated with this approach. One problem which has not been investigated is the influence of mislabeled samples on the positioning of the hyperplane in feature space. If a few samples in a data set are incorrectly tagged prior to training (i.e. the samples are labeled as members of class 2 even though they are actually members of class 1), it is still possible using the linear learning machine to achieve a classification success rate of 100% for the training set. However, unfavorable results will be obtained for the prediction set. The magnitude of this effect and its potential implications regarding the proper use of the linear learning machine are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180040106
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  • 6
    Electronic Resource
    Electronic Resource
    The controlled flocculation of submicron emulsion particles. I. A three-step synthetic route to supermicron polymer particles (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 3061-3069 
    Details
    ISSN: 0887-624X
    Keywords: aggregation ; emulusion polymerization ; flocculation ; latex ; particles ; polymer ; size distribution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The basic features of a three-step experimental process to produce supermicron polymer particles are described. First, a submicron emulsifier-free latex is prepared by a well-known technique. Second, the latex is aggregated by destabilizing with cetyl pyridinium chloride under constant stirring conditions, to yield roughly spherical clusters of 6-12 μ diameter. Third, the aggregates are stabilized with poly(vinyl alcohol) and internally coalesced by heating at or above the glass transition temperature. The final product particles have relatively smooth surfaces. Results are qualitatively interpreted in terms of a dynamic equilibrium where the aggregate size is determined by a balance between attractive interparticle potentials and stirring shear forces. Bimodal aggregate size distributions suggest the aggregate break-up mechanism may involve the erosion of individual latex particles and small fragments from the surface of aggregates. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1996.866
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  • 7
    Electronic Resource
    Electronic Resource
    Dispersion polymerization of styrene in polar solvents. IV. Solvency control of particle size from hydroxypropyl cellulose stabilized polymerizationsPresented in part at the Canadian High Polymer Forum, Ottawa, August, 1987, and the NATO ASI on Polymer Colloids, Strasbourg, July, 1988; for Paper I of this series, see Ref. 1 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2485-2500 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Changing solvent has a dramatic effect on the outcome of HPC stabilized dispersion polymerization of styrene in polar solvents. In methoxyethanol/ethanol mixtures, particle size varies from essentially infinity for unstabilized reactions (below 30% ethanol) to about 3 microns in ethanol. In a series of n-alcohols, there was a maximum in particle size at intermediate chain length: particle size increased from 2 microns in methanol to 8.3 microns in pentanol, then decreased again to 1 micron in octadecanol. These results were rationalized in terms of the three-component Hansen solubility parameters. The largest particles were obtained in solvents with Hanson polarity and hydrogen bonding terms closest to HPC. The generality of the three-component solubility parameter approach was examined by reactions performed in eight mixed solvents with the same values of all three Hansen terms. Seven of the eight solvents gave particles of similar size and molecular weight. The two critical effects of solvent on both particle size and molecular weight appear to be: (a) the solubility properties of the grafted HPC-PS formed, and (b) the partitioning of monomer and initiator between solution and particle phases subsequent to nucleation.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280921
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  • 8
    Electronic Resource
    Electronic Resource
    Control of surfactant level in starve-fed emulsion polymerization. I. Sulfate-containing oligomers: Preparation and application as surfactant in emulsion polymerization (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1597-1606 
    Details
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; surfactants ; oligomers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is well known that the amount of surfactant must be carefully controlled during starve-fed emulsion polymerization processes. Too little surfactant leads to emulsion instability and coagulation, while too much surfactant leads to secondary particle formation. Although these relationships are qualitatively understood in the art, there is little quantitative basis to guide the synthetic chemist, especially in multistep starve-fed emulsion polymerization processes to make larger supermicron particles. We have developed a method, which will be described in a companion article, to control the surfactant level by monitoring the surface tension during polymerization. In order to quantitatively predict how much surfactant to add at any given time, one needs to know in advance the adsorption characteristics of the soap. Further complicating the matter is the formation of “in situ” or oligomeric surfactant during polymerization with aqueous initiators such as ammonium persulfate.This work demonstrates how to prepare surface-active oligomers and how to make latex particles using them as surfactant. First, we established the mass balance for the initiator-derived sulfate groups in seed latexes by conductometric, potentiometric, and iodometric titrations. Based on the characterization of seed latexes, a method for determining the effective sulfate concentration has been developed. When surface-active oligomers were used as the only surfactant, we obtained a series of monodisperse, supermicron copolymer latex particles with diameters up to 3.22 μm. This is a similar result to that obtained with a commercially made anionic surfactant. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331006
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  • 9
    Electronic Resource
    Electronic Resource
    An application of arene-iron chemistry in the synthesis of a novel liquid crystalline polymer (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 447-453 
    Details
    ISSN: 0887-624X
    Keywords: polyether ; polyester ; aryl ether ; nucleophilic substitution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arene-iron chemistry was applied in the synthesis of a novel liquid crystalline polymer. The chemistry, which is based on iron cyclopentadienyl (FeCp) arene complexes, allows sequential nucleophilic substitution of the chlorides from 1,3-dichlorobenzene-FeCp complex and photolytic decomplexation of the products to afford asymmetrical aryl ethers. This methodology provides easy access to novel polyether-esters, and is potentially useful in the synthesis of various functional polyarylates. © 1997 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    A comment on the paper “uniform polymer particles by dispersion polymerization in alcohol,” by C. M. Tseng, Y. Y. Lu, M. S. El-Aasser, and J. W. Vanderhoff [J. polym. sci. polym. chem. Ed. 24, 2995 (1986)]Presented, in part, at the NATO ASI on Polymer Colloids (Strasbourg, July 1988). This is Paper 5 in a series including Refs. 5-8 (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2569-2574 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280928
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