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1. |
From the Principle of Areno‐Analogy to Heterocyclopolyaromatic Compounds |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 1-19
Thomas Kauffmann,
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摘要:
AbstractOrganometallic linkage of heteroaromatic compounds provided a means of synthesizing complicated combinations of heteroaromatic compounds; not only nucleophilic aromatic substitution, but also “ArCu/ArHal linkage”, “organometallic oxidative linkage”, and “metal amide linkage” have been employed. The heterocyclopolyaromatic compounds are made of one, two, or three kinds of heteroaromatic species as ring members. These syntheses illustrate the construction of heterocycles from large, performed structural units. Competition experiments showed that the reactivity typical of the individual species is enhanced in open‐chain combinations (ArNu)nand (ArE)n(ArNu, ArE: nucleo‐ and electrophilic heteroaromatic systems, respectively); the opposite situation is mostly encountered in the case of ArNuAEcombinations.—Cycloocta[1,2‐b:4,3‐b′5,6‐b″:8,7‐b‴]tetrathiophene, the only heterocyclopolyaromatic system yet to have been studied in detail, proved surprisingly inclined
ISSN:0570-0833
DOI:10.1002/anie.197900013
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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2. |
The Art of Titration. From Classical End Points to Modern Differential and Dynamic Analysis |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 20-49
Ruthild Winkler‐Oswatitsch,
Manfred Eigen,
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摘要:
AbstractTitration represents the quantitative determination of a chemical change in response to the variation in concentration of a standrad. Information on reaction parameters is usually obtained from an analysis of the shape of the titration curve. In this paper the derivatives of titration functions with respect to concentration variables and with respect to equilibrium parameters are compared with one another. The latter can be determined directly from amplitudes and time constants of the dynamic responses to equilibrium perturbations, brought about by fast alterations of temperature, pressure or electirc field.Three general situations have to be distinguished: 1. If the interaction is very strong (i.e.the complex stability is high:K→ ∞), the (average) number of sample praticles can be counted directly by means of their reaction with a calibrated number of standard particles.—2. If, on the contrary, the interaction is weak (i.e.the complex stability is low), the sample will react quantitatively only in the presence of a large excess of standard; the half‐way point of which provides a direct measure of the binding constant.—3. Only for moderate interactions can individual curves characteristic of the binding strength be observed. The limiting cases 1 and 2 yield titration curves which reflect only the general class to which the system belongs.The dynamical procedures are fairly insensitive in case 1, which represents the classical end‐point situation and is most suitable for quantitative anlaysis,i.e.for a determination of sample concentrations. For case 2, the classical and dynamical techniques yield comparable information: mass‐action parameters are obtained from the extrema of the curves, which occur only in the presence of an excess of the standard. In case 3 the dynamical treatment provides a more direct access to the equilibrium constants, and also to the enthalpies or volumes of reaction as well as to the rate constants. The advantage of the dynamic method is due to the fact that in the two derivatives of the titration function dTi/d lnqand dTi/d lnp(whereqis the titration variable,i.e.the ratio of standard and sample concentration, andpthe mass‐action parameter,i.e.a reduced binding constant) the terms resulting from a differentiation with respect topare more closely related to the reaction parameters than those following from a variation ofq.The dynamic analysis is generalized for applications to multiple‐step titration processes, where it allows for the measurement fo equilibrium and rate parameters ofindividualsteps. A uniform representation utilizing trigonometric functions was chosen which expresses clearly the singualr character of the end‐point. The relations are summarized intabular form. They provide in conjunction with the illustrations the basis for a com
ISSN:0570-0833
DOI:10.1002/anie.197900201
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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3. |
Plastics as Optical Materials |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 49-59
Helmut Dislich,
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摘要:
AbstractThe Principal material used in optics is glass. Plastics can only gain acceptance in optics if they have properties not encountered with glass or if a desired article can be produced more rationally from a plastic. An example of the first case is provided by UV light guides consisting of a quartz glass core surrounded by a plastic cladding; there is no glass with a sufficiently low refractive index. Examples of the second case are viewfinder optics for camerás and lenses for sunglasses and industrial safety spectacles
ISSN:0570-0833
DOI:10.1002/anie.197900491
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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4. |
Synthesis and Structure of thenido‐Cluster (CH3)5C5Sn+ |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 59-60
Peter Jutzi,
Franz Kohl,
Carl Krüger,
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ISSN:0570-0833
DOI:10.1002/anie.197900591
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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5. |
Bis(trimethylislyl)zinc and ‐cadmium |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 60-61
Lutz Rösch,
Gerald Altnau,
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ISSN:0570-0833
DOI:10.1002/anie.197900601
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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6. |
Coordination Number 3 in CoII: Na10[Co4O9], an Oligooxocobaltate(II) |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 61-62
Wilfried Burow,
Rudolf Hoppe,
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ISSN:0570-0833
DOI:10.1002/anie.197900611
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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7. |
Extreme Liquid Chromatographic Separation Effects in the Case of Diastereomeric Amides Containing Polar Substituents |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 62-63
Günter Helmchen,
Günter Nill,
Dieter Flockerzi,
Willi Schühle,
Mohamed S. K. Youssef,
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ISSN:0570-0833
DOI:10.1002/anie.197900621
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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8. |
Preparative Scale Directed Resolution of Enantiomeric Carboxylic Acids and LactonesviaLiquid Chromatography and Neighboring‐Group Assisted Hydrolysis of Diastereomeric Amides |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 63-65
Günter Helmchen,
Günter Nill,
Dieter Flockerzi,
Mohamed S. K. Youssef,
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ISSN:0570-0833
DOI:10.1002/anie.197900631
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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9. |
Preparative Scale Directed Resolution of Enantiomeric AminesviaLiquid Chromatography of Diastereomeric 4‐Hydroxybutyramides |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 65-66
Günter Helmchen,
Günter Nill,
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ISSN:0570-0833
DOI:10.1002/anie.197900651
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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10. |
Xe(OTeF5)6, A Deep‐Colored Noble Gas Compound, and OXe(OTeF5)4—The Existence of Kr(OTeF5)2 |
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Angewandte Chemie International Edition in English,
Volume 18,
Issue 1,
1979,
Page 66-67
Dieter Lentz,
Konrad Seppelt,
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ISSN:0570-0833
DOI:10.1002/anie.197900661
出版商:Hüthig&Wepf Verlag
年代:1979
数据来源: WILEY
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