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  • Baseline Surface Radiation Network; Brewer Ozone Spectrophotometer, Sci-Tec; BSRN; DATE/TIME; Germany; LIN; Lindenberg; Monitoring station; MONS; Ozone total  (274)
  • Chemistry  (197)
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  • 1
    Electronic Resource
    Electronic Resource
    Crystallization of potassium chloride: The additives ZnCl2, Na6 [(PO3)6] and K4 [Fe(CN)6] (1995)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 18 (1995), S. 295-301 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The batch crystallization of potassium chloride from aqueous solution is investigated without impurities, with zinc chloride I (30, 100, 1000 ppm), with sodium hexametaphosphate II (100 ppm) and potassium hexacyanoferrate (II) III (100, 500, 1000, 16 × 25 ppm). The dominant particle size of the pure system LN, D = 427 μm increases by 40% by addition of I and by 250% by addition of II. While I does not affect the habit II changes it from cubes to octahedrons. In cases of low concentration, III leads to dendrites.It is shown that addition of III decelerates growth and increases the metastable zone width. Hence a high supersaturation is formed, the solution impoverishes fast while III gets incorporated and therefore a strong nucleation starts in a relatively pure solution. By quasi-continuously adding 16 × 25 ppm of III the dominant particle size increases by 160% with little fines. In this case the content of III in the product is relatively low.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270180502
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  • 2
    Electronic Resource
    Electronic Resource
    Organometallic tin complexes derived from 2-guanidinobenzimidazole (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 9 (1998), S. 637-641 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination compounds derived from 2-guanidinobenzimidazole 1 and R2SnCl2 (2 R = Me, 3 R = Bu, 4 R = Ph), and SnCl4 7 were prepared and their structures investigated by 1H, 13C, 119Sn, 15N NMR, mass spectrometry (FAB or EI), infrared, and elemental analysis. The NMR data suggest pentacoordinated (5 and 6) or hexacoordinated tin atoms 2-4 and 7. In all cases, 2-guanidinobenzimidazole acts as a bidentate ligand. In the solid state, 2-4 and 7 are associated by bridging chlorine atoms in polymeric chains. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9: 637-641, 1998
    Additional Material: 3 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Versatile behavior of 2-guanidinobenzimidazole nitrogen atoms toward protonation, coordination and methylation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 8 (1997), S. 397-410 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure, dynamic behavior, protonation, methylation, and coordination sites of 2-guanidinobenzimidazole 1a were investigated. Structures of compounds [2-guanidinium-1,3,10-trihydrobenzimidazole]sulfate 1b, [2-guanidinium-1,3-dihydro-benzimidazole]sulfate 1c-1d, [2-guanidinium-1,3-dihydro-benzimidazole]tetrafluoroborate 1e, [2-guanidinium-1,3-dihydro-benzimidazole]chloride 1f, [2-guanidinium-1,3-dihydro-benzimidazole] perchlorate 1g, 2-guanidino-1-methyl-benzimidazole 2a, [2-guanidinium-1,3-dimethyl-benzimidazole]iodide 2b, [2-guanidinium-1-methyl-3-hydro-benzimidazole]chloride 2c, [2-guanidinium-1,10-dihydro-benzimidazole]acetate 3, 2-guanidino-1-hydro-3-borane-benzimidazole 4a, 2-guanidino-1-methyl-3-borane-benzimidazole 4b, (2-guanidino-benzimidazole)dimethyltin 5, [bis(2-guanidino-10-hydro-benzimidazole)nickel(II)] 6, and [bis(2-guanidino-1,10-dihydro-benzimidazole)zinc(II)]nitrate 7 were determined based on 1H, 13C, and 15N NMR spectroscopy. The X-ray diffraction structures of 2a, 2b, 3, 6, and 7 were obtained. The results show that 1a has an open structure without an intramolecular hydrogen bond in DMSO or DMF. The imidazolic N-3 is the preferred basic site in solution for protonation, methylation, and coordination and not N-10 as was suggested from semiempirical calculations. Under strong acidic conditions, diprotonation occurs at N-3 and N-10. In the solid state, 3 and 6 were protonated preferently at N10 rather than at N-1. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 397-410, 1997
    Additional Material: 11 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Utility of a liquid crystalline diacrylate for bistable switching cholesteric gel displays (1994)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 5 (1994), S. 433-437 
    Details
    ISSN: 1042-7147
    Keywords: Liquid crystals ; Electro-optical effects ; Anisotropic gels ; Anisotropic networks ; 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
    Notes: We investigated cholesteric liquid crystals containing an anisotropic polymer network created by in situ photo-polymerization of a mesogenic diacrylate. In contrast to previous studies, we used a liquid crystalline diacrylate to achieve bistable switching between the reflecting Grandjean texture and the diffuse scattering focal conic texture. The switching behavior depends considerably on the orientation of the liquid crystal during the polymerization. For polymerization in the Grandjean texture, the response times for switching to the reflecting state were lowered compared to the pure liquid crystal. The chromaticity coordinates indicate that this new type of display is very promising for additive color mixing.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1994.220050806
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  • 5
    Electronic Resource
    Electronic Resource
    Bimetallic Sesquifulvalene Complexes-Compounds with Unusually Large Hyperpolarizability βCooperative effect in π ligand bridged dinuclear complexes, Part 16. Part 15: U. Behrens, J. Heck, M. Maters, G. Frenzen, A. Roelofsen, H. T. Sommerdijk, J. Organomet. Chem. 1994, 475, 233.Dedicated to Prof. Dr. H. Schumann on the occasion of his 60th birthday (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 98-103 
    Details
    ISSN: 0947-6539
    Keywords: bimetallic complexes ; NLO materials ; sandwich complexes ; sesquifulvalenes ; solvatochromism ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to construct bimetallic organometallic donor-acceptor complexes with nonlinear optical (NLO) properties, the bimetallic sesquifulvalene complexes [{CpFe(η5-C5H4)}Z{η7-C7H6)Cr-(CO)3}]BF4 (2BF4) have been synthesized with different bridging functions Z (2a: Z = - 2b: Z = C2; 2c: Z = (E)-C2H2). X-ray structure determinations show that 2a BF4 and 2c BF4 crystallize in acentric space groups (P41, P212121), whereas crystalline 2b BF4 has the centric space group P21/c. The organometallic fragments in 2a adopt a transoid conformation, those in 2b and 2c are cisoid. The cyclo-C5 and cyclo-C7 rings of the sesquifulvalene ligands are almost coplanar; this allows an optimum electronic interaction between the ferrocenyl donor and the [η7-C7H6)Cr(CO)3]+ acceptor moiety in the crystalline state. Cyclovoltammetric studies show an electrochemically reversible one-electron oxidation ( 〉 0 mV vs. FeH/FcH+, FcH = ferrocene) and an irreversible one-electron reduction (≤-900 mV), which are assigned to the ferrocenyl and [(η7-C7H6)Cr(CO)3]+ units, respectively. UV/vis spectra reveal low-energy absorptions for 2a-c at about λ=600 nm, showing strong negative solvatochromism. These absorption maxima are related to a charge-transfer excitation between the ferrocenyl and the [(η7-C7H6)Cr(CO)3]+ groups, indicating considerable nonlinear optical properties. Determination of the first hyperpolarizability β by means of hyper Rayleigh scattering yields exceptionally large β values: β(2b) = 570 × 10-30 esu and β(2c) = 320 × 10-30 esu. These unexpectedly large β values are explained by resonance enhancement.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19960020117
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of the productivity of a continuous algal culture system (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 29 (1987), S. 488-492 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We describe a first-principles analysis of a system for the continuous culture of the green alga Scenedesmus obliquus under light-limiting conditions. According to this analysis, the productivity of the algal culture is given by the relation Y = EmI0AK(1 - e-αcl) - GRcV, where Y = yield (g cells/h), Em = 0.20 (the maximum attainable photosynthetic conversion on an energy basis), A = illuminated area (m2), K = 0.156[(g cells/h/W), the energy equivalent of the algae], I0 = light intensity (W/m2), α = extinction coefficient (L/cm/g),c = cell concentration (g/L), I = light path (cm), R = respiration rate (g carbon/g cells/h), V = culture volume (L), and G = ratio of g cells to g carbon (2.04). This formula is completely determined and has no free adjustable parameters. Using parameter values determined independently, the model accurately predicted the relationship of productivity to cell density in the culture system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260290413
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  • 7
    Electronic Resource
    Electronic Resource
    Transient free-surface flows: Motion of a fluid advancing in a tube (1987)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 33 (1987), S. 1178-1186 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fluid motion at a free surface advancing into a mold or duct is appreciably different from its steady state behavior in well-developed flow; this affects the residence time distribution and structure of macromolecular fluids as they are frozen in injection molding processes. In this work such motion is treated numerically and measured precisely for Newtonian fluids. While the three-phase contact line represents a special problem conceptually and analytically, a very simple algorithm is seen to represent the fluid motion in this region accurately.Good agreement is found over wide ranges of the governing dimensionless groups (the Reynolds, Jeffrey, and capillary numbers). Since viscous forces are dominant under the circumstances studied, this finding is not surprising but it confirms the applicability of the numerical methods developed herein to the modeling of these flows under conditions of actual interest. As a result, simulations may be made with confidence to predict flow patterns encountered in practice but difficult to reproduce in laboratory experiments.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690330712
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  • 8
    Electronic Resource
    Electronic Resource
    Enantioselective Lithiation and Substitution of (E)-Cinnamyl N,N-Diisopropylcarbamate through Use of (-)-Sparteine Complexes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 2397-2403 
    Details
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Chiral allylic anions ; (-)-Sparteine ; Enantioselective deprotonation ; Stereochemistry of electrophilic allylic substitution ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title reaction leads to diastereomeric lithium carbanion pairs that are configurationally unstable and equilibrate even at temperatures below -50 °C. The initially formed epimer (1S)-epi-10 is rapidly converted to the thermodynamically more stable (1R)-10 (in toluene solution). Carboxylation, acylation with acid chlorides, stannylation, and silylation take place at the α-position with stereoinversion (79-86% ee). Methylating agents attack the γ-position; here, the stereochemical course depends on the leaving group, anti-SE′ for the iodide (50% ee) and syn-SE′ (48% ee) for the tosylate.
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Isoquinolinium N-Arylimides and Some Cycloadditions to Heterocumulenes (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 379-385 
    Details
    ISSN: 1434-193X
    Keywords: Isoquinolinium N-arylimides ; Azomethine imines ; Cycloadditions ; Heterocycles ; 1,3-Dipoles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The red isoquinolinium N-arylimides 19-23 are azomethine imines of which the C=N bond is part of an aromatic ring. The N-(4-nitrophenyl)imide 22 and the N-(2-pyridyl)imide 23 were obtained crystalline; in solution the latter equilibrates with the hexahydrotetrazine 24 as its dimer. The N-phenylimide 19 is not stable; an isolated solid appears to be a tetramer. Generated by deprotonation of 11-13, the N-arylimides 19-21 undergo in situ cycloadditions to carbon disulfide, phenyl isocyanate, phenyl isothiocyanate, and diphenylketene. The storable CS2 adduct 29 offers a neutral source of theN-phenylimide 19, since a cycloreversion equilibrium is established in solution.
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  • 10
    Electronic Resource
    Electronic Resource
    Über Metallcarbonyle. XLI Die Bildung von Eisen-, Kobalt- und Nickelcarbonyl durch Hochdrucksynthese aus Halogeniden in vergleichender Darstellung (1942)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 249 (1942), S. 26-42 
    Details
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Hand umfangreichen Versuchsmataterials wird der Mechanismus der Hochdruckthesen von Carbonylen der Eisenreihe aus ihren Halogeniden untersucht. Hierbei ergaben sich auch für die Bildung von Eisenpentacarbonyl oder Nickelcarbonyl dieselben GesetzmäBigkeiten, wie sie schon früher für die Entstehung von Kobaltcarbonyl aus Kobalthalogeniden aufgedeckt wurden:1Die Carbonylbildung erweist sich zunächst abhängig von der Natur des Halogens und nimmt mit der Fähigkeit zur Halogenabspaltung, d. h. in der Reihe Chlorid → Bromid → Jodid zu. Für den besonders leichten Umsatz der Jodide spielen die primär entstehenden Carbonyljodide Fe(CO)4J2 oder CoJ2 · CO eine wesentliche Rolle. Sie disproportionieren sich alsdann je nach ihrer Beständigkeit mehr oder weniger leicht in die reinen Carbonyle. So erklärt sich auch die „katalytische Wirkung“, die bereits Spuren Jod bei der Carbonylbildung aus Metal1 und Kohlenoxyd ausüben.2Die Anwesenheit halogenbindender Metalle, wie Kupfer oder Silber, begünstigt wesentlich die Entstehung von Metallcarbonylen aus den betreffenden Halogeniden, und zwar um so mehr, je größer die Bildungswärme der Halogenverbindungen dieser Metalle ist. Kupfer erweist sich so als wirksamer als Silber, und zwar bei allen Versuchen im selben Verhältnis. Bestimmend ist somit bei diesen Reaktionen der Grad der Umsetzung zwischen den betreffenden Halogeniden der Eisenreihe und der „Begleitmetallo“ (Cu oder Ag) in festem Zustand, der der Warmetönung der Reaktion parallel geht. Das Kohlenoxyd ist diejenige Reaktionskomponente, die infolge der exothermen Carbonylbildung den Umsatz dieser Trockenreaktionen entsprechend steigert.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19422490103
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