ZIB

1

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Expertensysteme zur Unterstützung der analytischen Chemie: Intelligente Anwenderberatung für die ICP-Massenspektrometrie (1996)

Klages, F. ; Wünsch, G.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 16-22

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Expert Systems to Assist Analytical Chemistry: Intelligent User Counseling in ICP-Mass SpectrometryBecause ICP-mass spectrometry is a sensitive and rather new technique, some operators may lack the required thorough expertise. An intelligent system is presented which at first helps to identify any problems originating from the components of the actual sample. By demand of the user an experimental strategy to acquire any lacking information is provided. Based on this knowledge possible interferences are prognosticated. An appropriate operating procedure is then proposed, including suitable details of sample preparation. After the analytical measurement a scanned mass spectrum may be automatically checked for plausibility and for evidence of unexpected sources of error. The system is strictly organized in separated modules. It is open for easy introduction of additional knowledge and for the cooperation with the software of the spectrometer. The expert system shell Nexpert has been used as a building tool.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380103

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Synthese von spirocyclischen Isothiazoliumsalzen und deren basenkatalysierte Umsetzung zu ThianthrenenTeil des Vortrages von B. Schulze, “1,2-Thiazoliumsalze als Synthesebausteine zu neuen 6aλ4-Thia-1,6-diheteropentalenen”, 2. Fachtagung über Iminiumsalze, Stimpfach/Rechenberg, 20.-22.09. 1995Herrn Professor Dr. Rudolf Gompper zum 70. Geburtstag gewidmet (1996)

Schulze, B. ; Friedrich, Barbara ; Wagner, Sven ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 424-429

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of Spirocyclic Isothiazolium Salts and their Base Catalysed Reaction to ThianthrenesN-Phenyl-substituted isothiazolium salts 1 with active 7-methylene group react under the influence of bases to the spirocyclic isothiazolium salts rac-cis- and rac-trans-4; the salts trans-4 are not stable and react to the thianthrene derivatives rac-trans-6. Thus, a very simple separation of diastereoisomeric salts rac-cis- and rac-trans-4 is possible. The influence of donor and acceptor substituents in the phenyl group of 1 on the diastereoselective synthesis of 4 and 6 was studied. The structure of rac-cis-4 and rac-trans-6 was confirmed by X-ray analysis.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380183

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3

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Tangentially Coupled π Systems and their Through-Space Interaction - trichromophoric perylene dyes (1996)

Langhals, Heinz ; Gold, Josef

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 654-659

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Three perylene tetracarboxylic bisimide chromophores have been attached to a benzene ring in m-position (3). In this way steric and through-bond interactions of the chromophores are minimized and their through-space-interactions can be studied for which an unusually high bathochromic shift has been found. This indicates a destabilization. No exciton coupling has been observed in the trichromophoric dyes.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801124

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4

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Masthead (1996)

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996)

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380101

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5

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Effect of pressure on the reaction between 3-methyl-1-p-tolyl-triazene and benzoic acid; A kinetic study (1996)

Laila, Abdulhameed ; Isaacs, Neil S.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 691-694

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Rates of reaction between 3-methyl-1p-tolytriazene and benzoic acid were measured with variation of pressure in chloroform and acetonitrile. Activation volumes were found to be-15 and-4 cm3 mol-1, respectively. The reaction mechanism is discussed in the context of these values.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801136

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6

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cis/trans-Isomerisierung von 2,2′-Diethyl-5,5′-dimethoxy-4,4′-binaphthyliden-1,1′-dion über eine radikalische Zwischenstufe (1996)

Laatsch, Hartmut ; Kral, Andreas ; Friedrich, Manfred

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 69-73

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: cis/trans-Isomerization of 2,2′-Diethyl-5,5′-dimethoxy-4,4′-binaphthylidene-1,1′-dione from a Radical IntermediateThe 1H-NMR spectrum of 2,2′-diethyl-5,5′-dimethoxy-4,4′-binaphthylidene-1,1′-dione (1) shows flat-topped peaks at room temperature. At higher temperatures sharp peaks are observed while at deep temperatures the spectrum consists of two separated sets of lines. We propose a cis/trans-isomerization with coalescence at room temperature. The rate constants of this isomerization were obtained by dynamic line shape analysis, and an energy barrier of about 74 kJ mol-1 was calculated. The intermediate biradical was proved by ESR spectroscopy.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380112

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7

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Methoxyallene: A Reagent of Versatile Applications in organic synthesis (1996)

Zimmer, Reinhold ; Khan, Faiz A.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 92-94

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380116

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8

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Thermochromic Furofurans. IV. Approach to the synthesis of bridgehead substituted furo[3,2-b]furans and side products of McMurry reactions (1996)

Laatsch, Hartmut ; Talvitie, Antti ; Kral, Andreas ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 140-145

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Substituted dihydroxystilbenes 2 are suitable starting materials for the synthesis of photochromic systems derived from 3/4. Attempts to couple the naphthones 8a-8e by the McMurry reaction with TiCl3/LiAlH4 yielded mainly reduction products such as 8f, g or 9. However, the furofuran 3b was isolated when using the zinc-copper couple for reduction. The helicene 11 was formed as an unexpected by-product in the McMurry reaction of the pivaloylnaphthalene 8d.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380127

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9

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Selectride - effektive Reagenzien zur diastereoselektiven Synthese (1996)

Wittmann, S. ; Schönecker, B.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 759-762

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Selectrides - Highly Efficient Reagents for Diastereoselective Synthesis

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801149

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10

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P. G. Garratt, Strahlenhärtung, 1. Aufl., 184 S., 24. Abb., 2 Tab., Format 15 × 23 cm, Vincentz-Verlag, Hannover, 1996, DM 98,00, ISBN 3-87870-431-3 (1996)

Timpe, H.-J.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 766-766

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801151

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11

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Pyridine-4-selenenyl Bromides as new reagents for selenenylation of olefins (1996)

Boduszek, Bogdan ; Gancarz, Roman

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 186-189

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380137

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12

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P. Collins, R. Ferrier, Monosaccharides-their chemistry and their roles in natural products, 574 S., ca. 625 Schemata und Abb., 15 Tab., Format 23 × 15 cm, J. Wiley & Sons, Inc. Chichester, New York, 1995, Paperback, £ 22,50, ISBN 0471953423 (1996)

Miethchen, R.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 193-193

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380139

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13

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Umwandlung von (20S)-20-(Hydroxymethyl)pregna-1,4-dien-3-on in (20S)-20-(p-Toluolsulfonyloxymethyl)pregna-1,5-dien-3β-ol und -3α-ol: Zwischenprodukte für Vitamin D-Derivate (1996)

Wittmann, S. ; Krieg, R. ; Prousa, R. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 214-219

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Transformation of (20S)-20-(Hydroxymethyl)pregna-1,4-dien-3-one into (20S)-20-(p-Toluene-sulfonyloxymethyl)pregna-1,5-dien-3β-ol and -3α-ol: Intermediates of Vitamin D DerivativesEfficient three-step approaches to the two 3-epimeric 22-tosylated 1,5-diene-3,22-diols 6 and 7 starting with (20S)-20-(hydroxymethyl)pregna-1,4-dien-3-one (1) were developed and optimized. Isomerization of 1 to the 1,5-dien-3-one 3 and subsequent tosylation furnished the deconjugated 3-ketone 4. The 3β-alcohol 6 was available from 4 by means of in situ generated calcium borohydride. Treatment of 4 with lithium trisiamylborohydride (LS-Selectride) afforded the highest yield of the hitherto unknown 3α-epimer 7. Following the optimized synthesis, 6 and 7 were obtained from 1 in 60 % and 50 % overall yield, respectively.

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380145

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14

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On the Reaction of Nitrilium Salts with Heterocyclic Nitrones (1996)

Hitzler, M. G. ; Freyhardt, C. C. ; Jochims, J. C.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 243-250

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Nitrilium hexachloroantimonates 1a-c react with pyridine N-oxides 2a, d, f, j, m, o to afford bicyclic 2,3-dihydropyridinium salts 5a-p. The constitution of 5f was secured by an X-ray crystallographic analysis. Compounds 5 proved to be thermally labile (23-82°C) rearranging to 2-acylamino- pyridinium salts 6a, f-i or decomposing to tars. The benzimidazole-3-oxide 7 reacts with nitrilium salts 1a, b to 2-acylaminobenzimidazoles 9a, b. The experimental results as well as AM1 calculations support a mechanism for the reaction of nitrilium cations with heterocyclic nitrones, which has originally been suggested by Abramovitch [25, 26].

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380149

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15

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Synthesis and electrochemical investigation of azobenzene-substituted porphyrins (1996)

Hombrecher, Hermann K. ; Lüdtke, Kerstin ; Koll, Daniela

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 257-263

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The synthesis of azobenzene-substituted porphyrins (3a-g) is described. With respect to possible applications as model systems for photochemical reaction centers the spectroscopic and electrochemical properties of the synthesized compounds were investigated. For compound 3e the obtained spectroscopic and electrochemical data confirm that a light driven electron transfer from a porphyrin to the azobenzene moiety is possible.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380151

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16

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Azo bridges from azines. XV. Oxygenation of Unsaturated Cyclic Azo Compounds with peracids (1996)

Hünig, Siegfried ; Schmitt, Michael

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 74-82

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Azo bridges in compounds 3, 6, 11, 16, 20 and 22 are chemospecifically oxidized with MCPBA to the corresponding azoxy derivatives 4, 7, 12, 17, 21, and 23 in the presence of one or two (20, 22) double bonds even if these are located in a close parallel position to the azo bridge (6, 11, 20, 22). The order of reactivity of different olefinic moieties towards MCPBA was found to be bicycloheptene 〉 bicyclooctene, cyclopentene. Thus, epoxy/azoxides 5, 8, 13, 14, and 19 as well as bisepoxy/azoxides 10 and 15 were obtained. If both the azo and the olefinic bridge are part of a bicycloheptane system (24) the azo group can be no longer oxidized chemospecifically (25 + 26).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380113

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C. Arnaud, Chimie Organique, Collection des Mémo-Guides, 3ème edition revue et corrigée. Broche, 144 pages, 135 × 210. Nombreux schemas et tableaux, Masson, Paris, 1995, 96 F prix T. T. C. au 1.02.1995. ISBN 2-225-84686-3 (1996)

Viehe, H. G.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 95-95

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380117

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18

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Zweiphasen-Hydroformylierung höhermolekularer Olefine mit ethoxyliertem Tris-(p-hydroxyphenyl)phosphan als Komplexligand für den Rhodiumcarbonyl-Katalysator (1996)

Jin, Zilin ; Yan, Yuanyoung ; Zuo, Huanpei ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 124-128

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Two-phase Hydroformylation of Higher Molecular Olefins by Ethoxylated Tris(p-hydroxyphenyl)-phosphine as Complex Ligand for the Rhodiumcarbonyl CatalystWater-soluble rhodiumcarbonyl complexes with new nonionic complex ligands prepared by ethoxylation of tris(p-hydroxyphenyl)phosphine were successfully used in the two-phase hydroformylation of higher-molecular olefins. Their efficiency depends likely on a temperature controlled circulation of the catalyst complex between the organic and the water phase: At the temperature of the hydroformylation (100-130 °C) the ethoxylated tri-(p-hydroxyphenyl)phosphine becomes water-insoluble (appearance of a miscibility gap) and is now available for the catalysis in the organic phase. After cooling to room temperature the catalyst system is dissolved again in the water phase and can be recovered by a simple phase separation.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380125

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19

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Ring closure reaction of 5-hydroxy-pyrido[2,3-d]pyrimidine-2,4,7-triones to benzo[b]pyrimido[4,5-h]1,6-naphthyridine-1,3,6-triones (1996)

Khattab, Ahmed F. A. ; Van Tinh, Dang ; Stadlbauer, Wolfgang

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 151-156

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: N-Substituted aminouracils (1) react with malonates by cyclocondensation to 5-hydroxy-pyrido[2,3-d]pyrimidine-2,4,7-triones (2), which give with triethylorthoformate and aniline 6-(phenylaminomethylene)-pyrido[2,3-d]pyrimidine-tetraone (3). Halogenation of 2a-d (with R2 = Me) with phosphorylchloride leads to 5,7-dichloro-pyrido[2,3-d]pyrimidine-2,4-diones (4) by cleavage of the methyl group at N-8, whereas Vilsmeier reaction of 2 affords 5-chloro-6-formyl derivatives (6), which cyclize with arylamines to give benzo[b]pyrimido[4,5-h] 1,6-naphthyridines (9). Compounds 9 were obtained independently by amination of the tosylates 5 to the 5-arylamino compounds 8, and Vilsmeier formylation to yield 9.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380129

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An Effecient and Safe Method for the Preparation of Alkyl Vinyl Sulfides (1996)

Rosenstock, Thomas ; Herzog, Renate ; Steinborn, Dirk

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 172-174

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380133

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21

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Ozonide von isomeren Octalinen durch trockene Ozonolyse auf Polyethylen (1996)

Griesbaum, Karl ; Krieger-Beck, Petra

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 179-181

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Ozonides of Isomeric Octalins by Dry Ozonolysis on Polyethylene

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380135

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J. D. Woollins (ed.), Inorganic experiments, 286 pages with 86 figures and 8 tables, VCH Verlagsgesellschaft mbH, 1995, Weinheim, New York, Basel, Cambridge, Tokyo, Softcover, DM 58,00/ÖS 452.00/SFr 58.00, ISBN 3-527-29253-5 Hardcover DM 148.00/ÖS 1.154.00/SFr 140,00, ISBN 3-527-29235-7 (1996)

Sartori, P.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 193-194

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380140

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23

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Direktsynthesen, Modifizierungen und Anwendungsmöglichkeiten von Poly(carbosilanen) (1996)

Sartori, Peter ; Habel, Wolfgang

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 197-205

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: „One-Pot“ Syntheses, Modifications and Applicabilities of Poly(carbosilanes)The modification of poly(carbosilanes) and the investigation of their application as binding agents and sintering additives in the production of pressurelessly sintered SiC-bulks as well as their effectiveness as precursors for SiC-fibers is of considerable interest. The synthesis of suitable compounds considers the variation of the carbosilane bridge, the following reactions of functional groups, the backbone branching at silicon and carbon atoms, and the insertion of heteroelements, especially boron and titanium. Different synthetic routes were used for the preparation of modified phenyl-containing poly(carbosilanes). The pyrolytic method, developed by YAJIMA and coworkers, transformed the methyl-containing poly(silanes) into poly(carbosilanes). The addition of polyborodiphenylsiloxane gave products with boron in the molecular sceleton. The development of a one step synthesis in analogy to the Wurtz-polycondensation leads to a series of methylene- and phenylethylene-bridged oligomeric compounds. Furthermore, branched and the heteroelements boron- and titanium-containing poly(carbosilanes) were obtained. The substitution of the functional phenyl groups leads to halogenated and alkyl-, alkenyl-, as well as alkynyl-substituted oligomers. Modified poly(carbosilanes) with unsaturated functional groups or SiH were prepared via Grignard-coupling. Beside benzylidene the units diphenylmethylene, p-xylylene and p-phenylene were used as carbosilane bridges. Directly synthesized copolymers were applicable as binding agents and sintering additives for the production of pressurelessly sintered SiC-bulks. Ethynyl-substituted poly(carbosilanes) were used as precursors for the production of oxygen-free SiC-fibers.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380143

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24

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Expertensysteme zur Unterstützung der Analytischen Chemie: Realisierung von Lernfähigkeit und Plausibilitätsprüfung am Beispiel der ICP-Massenspektrometrie (1996)

Wünsch, G. ; Klages, F.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 593-597

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Expert Systems to Assist Analytical Chemistry: Realization of Learning Ability and Plausibility Checking Demonstrated for ICP Mass SpectrometryCertain, uncertain and lacking knowledge has to be considered for intelligent counseling. In the ICP mass spectrometry the composition of the actual sample and the ionization rates are the most important parameters to be prognosticated. The way of storage and retrieval of data and of decision making should be automatically checked and improved with respect to the success of previous guesses. The Dempster-Shafer theory is used for the combination and propagation of uncertainties.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801115

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Chiral 2-(ω-Aminoalkyl)-oxazolines by ring transformation of lactam derivativesPresented in part at the 2nd Iminiumsalz-Tagung in Stimpfach-Rechenberg, Germany (September 20-22, 1995)Dedicated to Professor Dr. Rudolf Gompper on the Occasion of his 70th Birthday (1996)

Rottmann, Antje ; Liebscher, J.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 397-402

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 2-(ω-Aminoalkyl)-oxazolines 7 as starting materials for further asymmetric synthesis can be prepared in enantiomerically pure form by ring transformation of lactim ethers 1 or lactam acetals 2 with chiral 2-aminoalcohols 3. Hydroxyethyllactam imines 5, lactamimino-alkyloxazolines 8, or ω-aminoalkaneamides 9 can be formed as by-products by condensation without ring transformation, by further reaction with lactim ether 1, or by hydrolysis, respectively.

Additional Material: 5 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380179

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K. Cammann, H. Galster: Das Arbeiten mit ionenselekti ven Elektroden. Eine Einführung für den Praktiker, 3. Aufl., 296 S., 104 Abb., 52 Tab., 607 Literaturzitate, Springer-Verlag, Berlin, Heidelberg, New York, Barcelona, Budapest, Hongkong, London, Mailand, Paris, Santa Clara, Singapur, Tokio, DM 128,00, ISBN 3-540-59153-2 (1996)

Schindler, J. G.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 688-689

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801134

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27

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Kohlenstoff-verzweigte Poly(phenylcarbosilane) und Derivate (1996)

Habel, Wolfgang ; Sartori, Peter ; Windmann, Thomas

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 702-705

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Carbon-branched Poly(phenylcarbosilanes) and DerivativesA series of carbon cross-linked poly(phenylcarbosilanes) was synthesized through the reaction of dichlorodiphenylsilane, α,α,α-trichlorotoluene and dibromomethane with sodium as the reducing agent. The oligomeric and solid products of the general composition [(Ph2Si)n+1,5(PhC) (CH2)n]x (with n = 2, 3, 5 or 10) were analysed and investigated by IR, 1H, 13C, 29Si NMR spectroscopy, and gel permeation chromatography. The ceramic yields were determined via pyrolysis at 1000 °C. The branched poly(carbosilane) [(Ph2Si)4,5(PhC)(CH2)3]x was chlorinated with HCl and the product obtained was transformed by the Grignard reaction with ethynylmagnesiumbromid into the unsaturated poly(carbosilane) [((HC≡C)2Si)4,5(PhC)(CH2)3]x.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801138

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Alkaliinduzierte Bildung von ortho-Semidinen aus 3-Nitro- und 3-Azo-carbazolen - Synthese von 8,16-Dialkyldiindolo[3,2-a,d]phenazinenHerrn Prof. Dr. Dr. h.c. mult. Karl-Heinz Büchel zum 65. Geburtstag gewidmet (1996)

Fanghänel, E. ; Chtcheglov, D.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 731-737

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Alkali-induced Formation of ortho-Semidines from 3-Nitro- and 3-Azocarbazoles - Synthesis of 8,16-Dialkyldiindolo[3,2-a,d]phenazinesThe ortho-semidines 9-alkyl-4-(9-alkylcarbazol-3-ylamino)-3-aminocarbazoles (2a-d) are formed either by reduction of 9-alkyl-3-nitro-carbazoles (1a-d) or of the azo-(6) or the azoxycarbazoles (7) with zinc in alkaline alcoholic solution. It could be shown by cross experiments that the semidines 2 result from an intramolecular rearrangement. The compounds 2a-d are oxidized by air or H2O2 to the 8,16-dialkyldiindolo[3,2-a,d]phenazines (3a-d). Reduction of 1a-c with Raney-alloy affords the 9-alkyl-3-azoxycarbazoles 7a-c in good yields.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801143

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Titanhaltige Molekularsiebe als Katalysatoren für selektive Oxidationsreaktionen mit Wasserstoffperoxid (1996)

Höft, E. ; Kosslick, H. ; Fricke, R. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 1-15

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Titanium Containing Molecular Sieves as Catalysts for Selective Oxidation Reactions with Hydrogen PeroxideTitanium silicalite (TS-1) is known to be a highly-efficient and selective redox molecular sieve that has been found to catalyze a range of synthetically useful oxidation reactions with hydrogen peroxide under mild conditions. Among these reactions which are often influenced also by the shape-selective properties of the Ti-containing molecular sieve are olefin epoxidation, the oxidation of alcohols to carbonyl compounds, aromatic hydroxylations and ammoximation of cyclohexanone to cyclohexanone oxime. A critical review on the present literature on TS-1 catalysts and further Ti-containing molecular sieves is given mainly focused on the questions connected with the identification of the catalytic active titanium species and the mechanism of some of the reactions. Therefore, the procedure of the synthesis of TS-1 as well as the results obtained from the most of the physico-chemical investigations are analyzed.There are no final correlations to realize between the parameters of the synthesis, the results of characterization and the catalytic properties of TS-1.

Additional Material: 9 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380102

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Hexaazapolycyclen durch selektive Multimethylenierungen mit Dichlormethan und Base oder mit Urotropin (1996)

Kaupp, Gerd ; Sailer, Klaus

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 47-50

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Hexaazapolycycles by Selective Multimethylenations with Dichloromethane and Base or with HexamethylenetetramineMultiple methylenations of 2-aminomethylbenzimidazole with dichloromethane and methylamine or ammonia or with hexamethylenetetramine lead to highly selective formations of 6 new single bonds to give only a polycyclic bis-spiro-1,5-diazocine 2 or only a polycyclic spiro-1,3,6-triazonine 4 or only a polycyclic 1,3,6,8-tetrazecine derivative 6. 4 and 6 may be equally well obtained starting with 2-chloromethyl-benzimidazole. All of these selectively formed products are concave cryptands with 6 amino nitrogen atoms. No template metals are used in their syntheses. The reasons for the unusual changes in selectivity are investigated using semi-empirical PM3 calculations and mechanistic considerations. Experimental and spectroscopic details are given.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380107

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NMR-spektroskopische Untersuchungen zum Komplexbildungsverhalten von Hydrazonen des Thiocarbazinsäure-O-methylesters mit Zink(II)-Ionen (1996)

Knoll, S. ; Tschwatschal, F. ; Himmelreich, U. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 60-64

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Complexes of Zn(II) with Schiff Bases of Hydrazine-O-methylcarbothionates - NMR-Spectroscopic InvestigationsSchiff bases of hydrazine-O-methylcarbothionates react as bi- or tridentate ligands with Zn(II) ions forming neutral metal complexes (1a-1g). 1H-, 13C- and 15N-NMR-spectra of these complexes show the existence of configurational isomers of the C=N-double bond. Furthermore, depending on the ligands 4 different coordination patterns with the donor atoms N2S2, N4, N2O2 and NOS are demonstrated.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380110

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Facile enantioselective synthesis of (S)-5-(2-methyl-1,2-dicarba-closo-dodecaborane(12)-1-yl)-2-aminopentanoic acid (L-MeCBA) using the bislactim ether method (1996)

Kessels, M. M. ; Qualmann, B.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 89-91

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380115

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Ch. Arnaud, Exercises de synthèses organiques (Collection Enseignement de la Chimie), 2. Aufl, 321 S., Format 16 × 24 cm, Masson, Paris, Mailand, Barcelona, 1995, Paper-back, ISNB 2-225-84709-6 (1996)

Deloisy, Sandrine

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 95-95

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380118

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Triethylamine Trishydrofluoride in Synthesis (1996)

Haufe, Günter

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 99-113

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Triethylamine trishydrofluoride is a highly versatile fluorinating agent without the disadvantages of liquid hydrogen fluoride or other mixtures of HF with bases. The main types of fluorination using this reagent are reviewed: Nucleophilic substitutions, reactions using this reagent as nucleophilic partner in electrophilic additions, electrofluorinations and deprotection of silylethers.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380122

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Synthesis of Vinylallenes by Conjugate 1,6-, 1,8-, 1,10- and 1,12-Addition Reactions of Organocuprates with Acetylenic Michael Acceptors and Their Use as Dienes in Intermolecular Diels-Alder Reactions (1996)

Koop, Ulrich ; Handke, Gabriele ; Krause, Norbert

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1487-1499

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ISSN: 0947-3440

Keywords: Vinylallenes ; Organocuprates ; Conjugate addition ; Diels-Alder reactions ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Various vinylallenes were synthesized by conjugate cuprate additions to acetylenic Michael acceptors. Thus, 1,6-addition reactions with 2-en-4-ynoates 1, 3, and 5a, respectively, furnished vinylallenes 2, 4, and 7 after regioselective electrophilic capture of the allenyl enolates formed. Likewise, 1,8-addition to 2,4-dien-6-ynoates 8a and 10 gave the vinylallenes 9 and 11, whereas the 1,10-addition of Me2CuLi to 2,4,6-trien-8-ynoate 12 provided allene 13, and the analogous 1,12-addition to 2,4,6,8-tetraen-10-ynoate 14 furnished the polyene 15. These vinylallenes are valuable dienophiles in regio- and stereoselective Diels-Alder reactions, as evidenced by the formation of the cycloaddition products 16-24. In the presence of Lewis acids, vinylallene 4a presumably rearranges to a cyclopentadiene derivative which then forms the cycloadducts 25 and 26.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961002

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Bifunctional Catalysis of Ester Aminolysis - A Computational and Experimental Study (1996)

Wang, Li-Hsing ; Zipse, Hendrik

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1501-1509

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ISSN: 0947-3440

Keywords: Aminolysis ; Esters ; Pyridones ; Catalysis ; Calculations, ab initio ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Various pathways for the reaction of methylamine with methyl acetate catalyzed by 2(1H)-pyridone have been investigated at the Becke3LYP/6-31G**/HF/6-31G** level of theory. The most favorable pathway consists of a one-step reaction, in which all bond-forming and -breaking processes occur in concert. These modeling studies also show the pyridone to function as an acid, which led to the investigation of several substituted pyridones. 4-Cyano-, 3-cyano-6-methyl-, and 3-cyano-2(1H)-pyridone have indeed been shown to provide better catalysis in the ester aminolysis reaction by ab initio modeling at the Becke3LYP/6-31G**/HF/3-21G level. In order to verify the theoretical results, the catalytic activities of various substituted 2-pyridones in the reaction of n-butylamine with p-nitrophenyl acetate in chlorobenzene solution have been determined. The observed catalytic rate constants are indeed in agreement with the theoretical predictions. Other catalyst characteristics such as solubility and state of aggregation are, however, also of paramount importance in this reaction.

Additional Material: 8 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961003

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Synthesis of (1S,2R,5R)-2-Ethyl-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane, the Aggregation Pheromone of Male Beech Bark Beetles, Taphrorychus bicolor (Col., Scol.) (1996)

Francke, Wittko ; Schröder, Frank ; Kohnle, Ulrich ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1523-1527

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ISSN: 0947-3440

Keywords: Bicyclic acetals ; Bark beetle ; Pheromones ; Taphrorychus bicolor ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The absolute configuration of the new bicyclic acetal 2-ethyl-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (1), identified as an aggregation pheromone of males of the beech bark beetle, Taphrorychus bicolor, was determined by unambiguous synthesis and NMR experiments. The syntheses of the racemates of both diastereomers and of optically pure samples are described. The natural product proved to show (1S,2R,5R) configuration.

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961005

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Concave Macrobicycles: Absorption Spectra, Luminescence Properties, and Endocavital Complexation of Neutral Organic Guests (1996)

Vögtle, Fritz ; Michel, Ingo ; Berscheid, Ralf ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1697-1704

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ISSN: 0947-3440

Keywords: Alkyne bridges ; Charge transfer ; Host compounds ; Molecular cavities ; Toposelectivity ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: By a mild modified Eglinton coupling a series of diynebridged macrobicyclic hosts capable of endocavital complexation were synthesized and their structures and complexation properties investigated by X-ray analysis. The inclusion of DMSO in 7 suggests a direct correlation between steric fit and orientation of the guest. On the basis of this hypothesis, the orientation of acetone in an endocavital inclusion of 2 was predicted and verified by X-ray analysis. Comparison of the single-crystal X-ray structures of the vacant macrobicycle 3 and of a family of macrobicycles showing endocavital or “pocket” complexation of neutral organic guests suggests that torsion of the cavities upon complexation results from induced fit. Hydrogenation of the triple bonds leads to the more flexible macrobicycles 10-12 with collapsable cavities. The absorption and emission spectra of the diynebridged macrobicyclic hosts 1 and 3, of their hydrogenated analogues 11 and 12, and of a hemicage parent compound of 2 (14) were investigated. The macrobicyclic compounds 3, 11, 12 and 14 exhibit a strong fluorescence in CH2Cl2 solution at room temperature. The lack of fluorescence of 2 under such conditions is attributed to the presence of low-energy charge-transfer excited states, as indicated by the charge-transfer bands in the absorption spectrum. In a rigid CH2Cl2 matrix at 77 K all the examined compounds are fluorescent.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961102

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Synthesis and Properties of 2-Carboxyalkyl-1,2-benzisoselenazol-3(2H)-ones and Related Organoselenium Compounds as Nitric Oxide Synthase Inhibitors and Cytokine Inducers (1996)

Mlochowski, Jacek ; Juchniewicz, Leszek ; Kloc, Krystian ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1751-1755

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ISSN: 0947-3440

Keywords: Amino acids ; 1,2-Benzisoselenazol-3(2H)-ones ; Cytokine inducers ; Ebselen ; Nitric oxide synthase inhibitors ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A convenient synthesis of the 2-carboxyalkyl-1,2-benzisoselenazol-3(2H)-ones 4a-k and their esters 41-p from 2-(chloroseleno)benzoyl chloride (2) and amino acids or their carboxy esters is reported. In similar way other 2-substituted 1,2-benzisoselenazol-3(2H)-ones 4q-u were synthesized. The related bis[2-(carbamoyl)phenyl] diselenides 5 were obtained by reductive conversion of 1,2-benzisoselenazol-3(2H)-ones 4 or directly by the reaction of bis[2-(chlorocarbonyl)phenyl] diselenide (3) with compounds having a primary amino group. It was found that some of compounds 4 and 5 are modest cytokine (TNF, IFN) inducers in human peripheral blood leucocyte cultures and block the constitutive endothelial nitric oxide synthase (ce NOS).

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961108

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A New Assay For Sialyltransferases Using Fluorescein-Labelled Acceptors (1996)

Limberg, Gerrit ; Slim, George C. ; Furneaux, Richard H. ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1773-1784

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ISSN: 0947-3440

Keywords: Sialyltransferase ; Acceptor-specific assay ; LacNAc ; Fluorescein labelling ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A novel HPLC assay system for sialyltransferase activity based on the use of fluorescein-labelled acceptor oligosaccharides is described. The fluorescein-labelled disaccharides βGal-(1→4)-βGlc-OR (4), βGal-(1→4)-βGlcNAc-OR (17), and βGal-(1→3)-βGlcNAc-OR (22) where OR consists of a six carbon spacer with fluorescein attached, were synthesised. Synthetic standard products were produced chemo-enzymatically on a preparative scale to yield fluorescein-labelled trisaccharides. The use of reverse phase HPLC with an ionpairing agent allowed the separation of starting materials from products and separation of the two isomeric trisaccharides αNeu5Ac-(2→3/6)-βGal-(1→4)-βGlcNAc-OR (24 and 25), so that the assay could be used to measure the different silalyltransferase activities in a mixture. The assay was successfully applied to the detection of sialyltransferase activity of commercially available enzymes and a crude preparation of bovine colostrum. The predominant sialyltransferase activity in bovine colostrum adds sialic acid α(2-6) to 17.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961111

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Synthesis of Protected Enantiopure Erythrulose Derivatives (1996)

Alberto Marco, J. ; Carda, Miguel ; González, Florenci ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1801-1810

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ISSN: 0947-3440

Keywords: Monosaccharides ; Ascorbic acid as chiron ; Isoascorbic acid as chiron ; Erythrulose, protected derivatives of ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: D- and l-Erythrulose derivatives 2-6 bearing protective O-silyl and O-benzyl groups in various positions were synthesized in enantiopure form from l-ascorbic acid, D-isoascorbic acid, and D-glucose.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961114

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Photochemical Behavior of Doubly Bridged Dewar Benzenes - Synthesis of PrismanesDedicated to Professor Horst Prinzbach on the occasion of his 65th birthday. (1996)

Gleiter, Rolf ; Ohlbach, Frank ; Haberhauer, Gebhard ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1627-1634

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ISSN: 0947-3440

Keywords: Photochemistry ; Cage compounds ; Dewar benzenes ; Prismanes ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: In this paper we report on the photochemistry of Dewar benzenes bridged at the 1,4- and 5,6-positions and substituted at the 2,3-positions. It was found that simple alkyl substitution leads to prismanes only to a minor extent. Introduction of phenyl groups into the 2- or 2,3-positions gives the corresponding doubly bridged prismanes in yields up to 80% Pentamethylene-bridged bis-Dewar benzenes 19 rearrange upon irradiation to 22. Irradiation of the doubly bridged Dewar benzene derivatives with one ester group at the 5-position does not yield isolable products. However, introduction of one tert-butylsulfonyl group such as 30-33 gives almost quantitative yields of isolable prismanes if pentamethylene or hexamethylene bridges are used. The nonbridged species, 2-tert-butylsulfonyl-1,4,5,6-tetramethylbicyclo[2.2.0]hexa-2,5-diene (44), aromatizes upon irradiation into 1-(tert-butylsulfonyl)-2,3,4,5-tetramethylbenzene (45). In contrast to the pentamethylene-bridged monosulfone 47, the corresponding disulfone 38 undergoes no photochemical reaction. This could be explained by the X-ray structure, which reveals a strong interaction between one of the tert-butyl groups and the pentamethylene chain bridging the double bond in 38.

Additional Material: 8 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961020

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Secondary Mould Metabolites, LIIFor part LI see: A. Arnone, U. Brambilla, G. Nasini, O. Vajna de Pava, Tetrahedron 1995, 51, 13357-13364.. Structure Elucidation of Diatretol - A New Diketopiperazine Metabolite from the Fungus Clitocybe diatreta (1996)

Arnone, Alberto ; Nasini, Gianluca ; Pava, Orso Vajna De ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1875-1877

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ISSN: 0947-3440

Keywords: Diatretol ; Diketopiperazine ; Metabolites, secondary ; Basidiomycetae ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: In the culture broth of the fungus Clitocybe diatreta a novel diketopiperazine metabolite, diatretol (1), was detected by chemical screening. The structure was established on the basis of 1H- and 13C-NMR data and single-crystal X-ray analysis. Diatretol exhibits a low antibacterial activity and inhibits the growth germination of Lepidium sativum.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961123

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Synthesis of 4′,7-Dihydroxy-6-methoxyisoflavone 7-O-β-d-Glucopyranoside (Glycitin) (1996)

Nógŕdi, Mihály ; Szöllosy, Áron

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1651-1652

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ISSN: 0947-3440

Keywords: Isoflavones ; Glucoside synthesis ; Glycitein ; Glycitin ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The aglycone glycitein (1) of the title glucoside glycitin (2) was prepared by oxidative rearrangement of the fully protected chalcone 4 by Tl(NO3)3 in MeOH into 5 followed by deprotection and ring closure. Its glucosylation with α-acetobromoglucose and subsequent saponification gave 2 as the main product.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961024

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Antibiotics from Gliding Bacteria, LXXVIIIPart LXXVII: Ref.. Ripostatin A, B, and C: Isolation and Structure and Structure Elucidation of Novel Metabolites from Sorangium cellulosum (1996)

Augustiniak, Hermann ; Höfle, Gerhard ; Irschik, Herbert ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1657-1663

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ISSN: 0947-3440

Keywords: Antibiotics ; Polyketides ; Sorangium cellulosum ; RNA polymerase inhibitors ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Three closely related new metabolites named ripostatins were isolated from the myxobacterium Sorangium cellulosum and their structures elucidated by spectroscopic methods. Two of them, ripostatin A (1a, b) and B (2a), are 14-membered macrolides with an acetic acid and a phenylalkyl side chain, whereas the third metabolite ripostatin C (3a) is an acyclic derivative of ripostatin A. By application of the method of Helmchen the absolute stereochemistry could be determined as (11R,13R) for ripostatin A, 11R,13S,15R for ripostatin B and 11S for ripostatin C. The polyketide origin of A was revealed by feeding experiments with 13C-labeled precursors demonstrating the incorporation of one molecule of phenylacetic acid derived from phenylalanine, one propionate unit, and ten acetate units.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961026

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Asymmetric Strecker Synthesis of the Four α-Quaternary 1-Amino-2-methylcyclohexanecarboxylic AcidsDedicated to Professor J. Knabe, Saarbrücken, on the occasion of his 75th birthday. (1996)

Volk, Franz-Josef ; Frahm, August Wilhelm

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1893-1903

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ISSN: 0947-3440

Keywords: Asymmetric Strecker synthesis ; α-Amino nitriles ; Homochiral cyclic α-amino acids ; Kinetic or thermodynamic control ; Solvent effects ; Optical rotation increments ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The synthesis of the four 1-amino-2-methylcyclohexanecarboxylic acids 13, 14, 15, and 16 from diastereomeric mixtures of the α-amino nitriles 1-4 by successive application of conc. H2SO4, Pd/C H2, and conc. HCl is described. The amino nitriles 1-4 were prepared by asymmetric Strecker synthesis under various reactions, The formation of 1-4 is thermodynamically controlled in protic solvents (e.g. MeOH), whereas the reaction is under kinetic control in non-protic solvents (e.g. hexane), The separation of the α-amino amides 5-8, which were obtained by partial hydrolysis of 1-4, was achieved by CC, LPLC, and HPLC. The absolute configuration of all synthesized compounds was determined by means of only two X-ray analyses with consecutive correlations. The steric control of the asymmetric Strecker synthesis is discussed.

Additional Material: 8 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961126

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van-der-Waals-Komplexe, Intermediate monomolekularer Reaktionen (1996)

Roth, Wolfgang R. ; Hunold, Frank

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1917-1928

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ISSN: 0947-3440

Keywords: Diradicals ; Supercritical fluid reactions ; O2 trapping ; Reaction force field ; Cage effect ; Cope reaction ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: van der Waals Complexes, Intermediates in Unimolecular ReactionsThermolysis of rac- and meso-1,1′,2,2′,3,3′ -hexamethyl-1,1′-biindenyl and (1E, 5E)-1,3,4,6-tetraphenyl-1,5-hexadiene in supercritical CO2 in the presence of oxygen allows to identify three types of intermediates, the free radicals (2 and 5) and the equilibrating complexes I and II consisting of radical pairs. From the oxygen dependence of the trapping and rearrangement rates it is shown, that the complex I is the primary thermolysis product, which in contrast to the complex II does not react with oxygen. The temperature dependance of these rates allows to calculate the enthalpy well of the complex II, which agrees well with predictions of our reaction force field.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961128

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Synthesis of Medium and Large Ring Compounds, XLIIIPart XLII: B. Bollbuck, P. Kraft, W. Tochtermann, Tetrahedron 1996, 52, 4581-4592.. Synthesis and Isomerization of 8,9-Dimethyl[6]paracyclophane and Its Bridged Dewar Isomer (1996)

Tochtermann, Werner ; Rodefeld, Lars ; Dreeskamp, Herbert ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1959-1961

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ISSN: 0947-3440

Keywords: [6]Paracyclophane ; Dewar isomer ; Reaction enthalpy ; Activation energy ; Calorimetry ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: An improved sonochemical procedure for the synthesis of dimethyl [6]paracyclophane-8,9-dicarboxylate (2a) on a 10-g scale is described. The title compound 2d was synthesized from 2a in three steps. Irradiation of 2d yielded the Dewar isomer 3. In solution, the reaction enthalpy for the thermal isomerization of 3 to 2d was determined to be -162 ± 16 kJ · mol-1, while the activation energy for this reaction was found to be 123 ± 12 kJ · mol-1.

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961203

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Photochemistry of Phenyl Azides Bearing 2-Hydroxy and 2-Amino Groups Studied by Matrix-Isolation Spectroscopy: Generation and Characterization of Reactive o-Quinoid Compounds (1996)

Tomioka, Hideo ; Matsushita, Takeshi ; Murata, Shigeru ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1971-1980

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ISSN: 0947-3440

Keywords: 1,4-H Migration ; Calculations, ab initio ; Photochemical interconversion ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Broad-band irradiation (λ 〉 370 nm) of 2-hydroxyphenyl azide (1) in Ar at 10K monitored by IR resulted in the formation of at least three major products, all of which were shown to be photointerconvertible under these conditions. The two products showing carbonyl stretching absorption bands were assigned to an E/Z mixture of 6-imino-2,4-cyclohexadien-1-one (3), while the product showing sharp absorption bands in the cumulenic double bond region was assigned to 6-imino-1,3,5-hexatrien-1-one (4). These assignments were fully supported by comparison of the experimental IR spectra with the theoretical data calculated at the HF/6-31G** level of theory. Similar irradiation (λ 〉 350 nm) of 2-aminophenyl azide (6) in Ar at 10 K also afforded three photointerconvertible products, which were assigned to a mixture of (E,E)-(E,Z)- and (Z,Z)-1,2-diimino-3,5-cyclohexadiene (8). The assignments were again supported by ab initio calculations. The reactions are discussed in terms of a 1,4 H shift in the photolytically generated phenylnitrenes (2 and 8) from the azides (1 and 7).

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961206

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Matrix Isolation of o-Quinoid Compounds - 6-Imino-2,4-cyclohexadien-1-one and 1,2-Diimino-3,5-cyclohexadiene (1996)

Morawietz, Jens ; Sander, Wolfram

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2029-2037

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ISSN: 0947-3440

Keywords: Matrix isolation ; Rearrangements ; o-Quinoid compounds ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 6-Imino-2,4-cyclohexadien-1-one (1b) and 1,2-diimino-3,5-cyclohexadiene (1c) were generated in high yields from o-azidophenol (5b) and o-azidoaniline (5c), respectively, by irradiation in argon matrices at 10 K or by flash vacuum pyrolysis (FVP) with subsequent trapping of the products in solid argon. The hydrogen shift in the phenylnitrenes 6 formed as primary intermediates is very rapid, and thus the nitrenes are short-lived transients even under the conditions of matrix isolation. Ring expansion to azacycloheptatetraenes was not observed. FVP produces the thermodynamically most stable E/Z isomers of the quinones as the main products. Photolysis of the matrix-isolated quinones results in photostationary equilibria of the E/Z isomers. The stereoisomers were identified by comparison of the matrix IR spectra with ab initio calculations at the RMP2-FC-6/31G(d) level of theory.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961213

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Acetogenic Isoquinoline Alkaloids, LXXXIIPart LXXXI: G. François, G. Timperman, J. Holenz, L. Aké Assi, T. Steenackers, G. Bringmann, Intern. J. Parasitol., in press.. Biomimetic Total Synthesis of Michellamines A-C (1996)

Bringmann, Gerhard ; Götz, Roland ; Harmsen, Sven ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2045-2058

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ISSN: 0947-3440

Keywords: Michellamines ; Korupensamines ; Alkaloids, naphthylisoquinoline ; Biaryls ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The biomimetic first total synthesis of michellamines A, B, and C (1a-c), naturally occurring quateraryl alkaloids with high anti-HIV activity, is described. Key precursors are the molecular “halves” of michellamines, the antimalarial naphthylisoquinoline alkaloids korupensamine A (2a) and B (2b), which are likewise natural products. These “monomeric” naphthylisoquinoline alkaloids were prepared by Stille-type intermolecular aryl coupling of the O-isopropyl-protected and trialkylstannyl-activated naphthalene building block 4b with the threefold benzyl-protected and brominated, enantiomerically pure tetrahydroisoquinoline building block 3a. Ultimate “dimerization” of the protected korupensamines was achieved by biomimetic oxidative phenolic coupling using silver(I) oxide, followed by deprotection to give authentic michellamines. This synthetic route should allow us to easily prepare a broad series of modified analogs of michellamines for extensive structure-activity investigations.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961215

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Electron-Transfer Chemistry and Redox-Switching of Stilbene-Like Heteroaromatic Compounds - Syntheses, Optoelectrochemical and ESR/ENDOR StudiesDedicated to Prof. M. Hanack on the occasion of his 65th birthday. (1996)

Spreitzer, Hubert ; Scholz, Markus ; Gescheidt, Georg ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2069-2077

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ISSN: 0947-3440

Keywords: Stilbenes ; Push-pull substitution ; Electron transfer ; (Z)/(E) Isomerisation ; Radical ions ; Cyclic voltammetry ; Spectroelectrochemistry ; ESR / ENDOR ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Redox-active compounds, in which the electron donor and the acceptor subunits are covalently linked by a vinylene spacer group were synthesised and their properties were investigated by cyclovoltammetry, spectroelectrochemistry, and ESR/ENDOR spectroscopy. - 10-Methylphenothiazinyl, 10-methylphenoxazinyl, and phenoxathiinyl were used as electron-donating groups whereas 9,10-anthraquinon-2-yl and phenyl groups were employed as acceptors. The synthesis of the push-pull-substituted stilbenes 1a, 1b, 1c, 2a, 2b and 2c was achieved by Wittig coupling of the heterocyclic aldehydes with the anthraquinoyl or phenyl phosphonium salts. The diastereoisomers were separated either by chromatography or by crystallization. - The redox potentials of the (Z) and (E) isomers differ only slightly. Spectroelectrochemical measurements indicate that the radical cations of the phenothiazine and phenoxazine derivatives undergo rearrangement from the (Z) to the (E) isomers. On the other hand, electron attachment leads to configurationally stable radical anions. This behaviour is rationalised in terms of the electron distribution reflected by the hyperfine data established by ESR/ENDOR spectroscopy.

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961218

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Concave Reagents, 21Part 20: Ref.[1].. Selective Acylations of Primary and Secondary Alcohols by Ketenes (1996)

Schyja, Wolfgang ; Petersen, Sönke ; Lüning, Ulrich

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2099-2105

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ISSN: 0947-3440

Keywords: Bimacrocycle ; Base catalysis ; Hydrogen bond ; Molecular recognition ; Pyridine ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Concave pyridines 1 were used to catalyze the addition of primary and secondary alcohols to ketenes 4, and the kinetic data of these catalyses were determined. In inter- and intramolecular competitions the use of 1e-g led to improved selectivities for the acylation of primary alcohols in comparison with secondary alcohols. All primary alcohols react at comparable rates. Observed rate constants were correlated with Taft's Es values. The starting materials and products were fully characterized.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961223

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Pheromone Synthesis, CLXXVIPart CLXXV: H. Takikawa, M. Takenaka, K. Mori, Liebigs Ann., in press.. Synthesis of the Four Stereoisomers of 3,13-Dimethylheptadecane, the Major Sex Pheromone Component of the Western False Hemlock Looper (1996)

Takikawa, Hirosato ; Shirai, Yasuo ; Kobayashi, Makoto ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1965-1970

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ISSN: 0947-3440

Keywords: Grignard coupling ; Heptadecane, 3,13-dimethyl- ; Nepytia freemani ; Phenylsulfone, alkylation of ; Pheromone, optically active ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: All of the four stereoisomers of 3,13-dimethylheptadecane (1), the female-produced sex pheromone of the western false hemlock looper (Nepytia freemani), were synthesized by starting from the enatiomers of citronellol (2a) and 2-methyl-1-butanol (4a).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961205

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First Synthesis of Enantiomerically Pure Primary Helical Spirocycles Based on the Repetitive Addition of Lithiated Methoxyallene to Chiral 3(2H)-Dihydrofuranone Derivatives (1996)

Hormuth, Stephan ; Schade, Wolfgang ; Reißig, Hans-Ulrich

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2001-2006

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ISSN: 0947-3440

Keywords: Methoxyallene, lithiated ; Dihydrofuranone ; Spirocycles ; Primary helical molecules ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Repetitive additions to chiral 3(2H)-Dihydrofuranones opened a route to the first enantiomerically pure primary helical spirocyclic compounds. Thus, addition of lithiated methoxyallene 2 to furanone 9 provided adduct 10 with excellent diastereoselectivity. Cyclization with potassium tert-butoxide in DMSO followed by acid hydrolysis of the resulting enol ether moiety gave spirocyclic furanone 12 in very good overall yield. Repetition of this three-step sequence converted 12 into 15. For the next series of reactions cerium compound 16 instead of 2 was employed as nucleophile which resulted in reasonable conversion of 15 into adduct 17. By application of the usual methods this compound was transformed into the enantiomerically pure tetracyclic spiro compound 19 in moderate overall yield. Functionalized spiro compounds as described in this paper may serve as enantiomerically pure building blocks in supramolecular chemistry.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961209

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Ethynylation of Aryl Halides by a Modified Suzuki Reaction: Application to the Syntheses of Combretastatin A-4, A-5 and Lunularic Acid (1996)

Fürstner, Alois ; Nikolakis, Katharina

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2107-2113

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ISSN: 0947-3440

Keywords: Suzuki reaction ; Organoboron compounds ; Palladium catalysis ; Chemo-therapeutic agents ; Alkynes ; Lunularic acid ; Combretastatin ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: On treatment with trimethyl borate sodium acetylide undergoes a palladium-catalyzed cross coupling with functionalized aryl halides or triflates in reasonable to good yields. The ethynylarenes thus obtained serve as building blocks for the formation of the highly effective tubulin polymerization inhibitors combretastatin A-4 (1) and A-5 (2) as well as for the synthesis of the plant-growth regulator lunularic acid (36).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961224

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Synthesis of (-)-Streptenol A, (±)-Streptenol B, C and D (1996)

Blechert, Siegfried ; Dollt, Heribert

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2135-2140

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ISSN: 0947-3440

Keywords: Streptenols ; Chiral building block ; Polyketides ; Dienones ; Secondary metabolites ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 2-(2,2-Dimethyl-1,3-dioxan-4-yl)acetaldehyde (3) was used for the preparation of streptenol A and B (Scheme 1) via a Grignard reaction with 1-bromopent-3-ene. Hereby optically pure (4′R)-3 gave the antipode of Streptenol A. Reaction with lithiated 1-pentyne opened access to streptenol C and D. To obtain the dienone structure of streptenol C and D, a palladium-catalyzed alkynone isomerization was induced. Kinetic differences in the acid-mediated cleavage of the 1,3-acetonide protected 1,3,5-triol system caused the stereoselectivity in the natural products. So only the (3S*,5R*) acetonide of streptenol B reacted under mild hydrolytic conditions and gave after transacetalization first a 3,5-protected streptenol B with pure relative stereochemistry and finally (3S*,5R*)-streptenol B.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961228

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Resonanzenergie von Diradikalen - 1,8-Naphthoquinodimethan (1996)

Roth, Wolfgang R. ; Unger, Christian ; Wasser, Thorsten

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 2155-2169

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ISSN: 0947-3440

Keywords: Diradicals ; NO Trapping ; O2 Trapping ; Trapping, NO and O2 ; Energy well ; Singlet-triplet splitting ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Resonance Energy of Diradicals. - 1,8-NaphthoquinodimethaneFrom the racemization of 19c and the temperature and NO dependence of the trapping rate of 20b between 218 and 288°C the energy profile for the equilibrium 19b ⇄ 20b is derived. The singlet-triplet splitting of the diradical is 2.5 kcal · mol-1 with the triplet being the ground state. By comparison of the experimental reaction enthalpy with the analogous value for 25, 26 or a hypothetical model reaction with non-interacting radicals it is shown that the stabilizing interaction of the radicals in the singlet state of 20b is negligible making the stabilization of the triplet equivalent to the singlet-triplet splitting. By using literature data it is shown by an analogous analysis that the interaction of the radicals in the bisallyl diradical 28 and in the triplet state of the trimethylenmethane derivative 29 is also negligible whereas in the singlet state of 29 the interaction is strongly destabilizing.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961230

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Einfluß von Schwermetallionen in Trinkwasser auf die Aktivität des AChE-Biosensors (1996)

Stein, Kathrin ; Schmechel, Stefan

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 114-120

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Influence of Heavy Metal Ions in Drinking Water on the Activity of the AChE-BiosensorBecause of the specific inhibition of the enzyme acetylcholinesterase (AChE) by organophosphoric ester, -thioester and N-methylcarbamates an acetylcholinesterase biosensor can be used to screen drinking water for the presence of compounds used as insecticides. The presence of heavy metal ions may also lead to a decrease in catalytic activity of the enzyme, and in this way a misinterpretation of the results of the screening is possible. In this paper the effect of lead, iron, copper and zinc ions on the activity was examined, with the view to the concentration limit given by the decree for drinking water in the Federal Republic of Germany. Zinc and copper ions in drinking water produce a detectable inhibition (3 mg/L copper produced an inhibition of 10 to 20%, 5 mg/L zinc an inhibition of 10%), therefore the presence of copper, lead and other heavy metal ions not tested in drinking water may produce wrong results in pesticide screening. The coimmobilization of albumin and enzyme was successfull in eliminating the inhibition caused by heavy metal ions. Using this membrane for a 3 mg/L copper solution an inhibition of only 0.3% higher was measured and for a 5 mg/L zinc solution an inhibition of 2.3% lower than the inhibition of TRIS-buffer itself. This results were in the range of the standard deviation, which means that no inhibition could be measured with this metal ion solution using albumin containing AChE-membranes. The use of this modified membrane in real drinking water samples shows clearly lower inhibition values than that of membranes without albumin.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380123

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Functional Derivatives of Sterically Hindered Amines: Piperazine diesters (1996)

Vašš, František ; Lustoň, Jozef

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 165-168

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Several diesters of dicarboxylic acids with pendant sterically hindered amines of the piperazine type were prepared from α-bromo- and α,α′-dibromosubstituted dicarboxylic acid esters by reactions with 14,16-dioxo-7,15-diaza-dispiro[5,1,5,3]hexadecane and 7,15-diazadispiro [5,1,5,3] hexadecane.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380131

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13C-NMR-spektroskopische Untersuchungen einfacher Oxime in CDCl3 und D2SO4 (1996)

Kaiser, Monika ; Freiberg, Walter ; Michalik, Manfred

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 182-185

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 13C NMR Spectroscopic Investigations of Simple Oximes in CDCl3 and D2SO4

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380136

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V. Best, Ökologikum, PC-Umweltlexikon auf CD-ROM, Vieweg Verlag, Wiesbaden 1994, DM 498,00, ISBN 3528 066121 (1996)

Hulpke, H.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 195-195

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380141

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63

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Neue Synthese von substituierten 4-Amino-chinazolinen und deren Heteroanalogen (1996)

Gewald, K. ; Schäfer, H. ; Eckert, K. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 206-213

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Notes: New Synthesis of Substituted 4-Amino-quinazolines and Their HeteroanalogaN-Chloracetyl-anthranilonitriles react with potassium thiocyanate in the presence of alcohol to the (4-aminoquinazolin-2-yl-thio)-acetic acid ester (5). In the presence of water or primary amine the acetic acid derivative (6) or the acetic acid amide derivatives (7) are obtained. 2,4-Diaminoquinazolines (8) arise if vigorous reaction conditions are employed. With 2-chloracetylamino-cyclopent-1-en-carbonitrile as starting material the pyrimidines (11) are formed from the reaction with potassium thiocyanate. Analogously, (4-pyrimidyl-2-yl-seleno)-acetic acid ester (12) and (thiazolo[4,5-d]pyrimid-2-yl-seleno)-acetic acid derivatives (16) can be prepared with potassium selenocyanate. N-Chloracetyl derivatives of 5-membered heterocycles with enamino-nitrile structure (13, 15, 18, 20) react with potassium thiocyanate to yield thieno[2,3-d]-, thiazolo[4,5-d]-, pyrrolo[2,3-d]-, furo[2,3-d]- and pyrazolo[4,3-d]pyrimidines (14, 16, 19a, 19b, 21).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380144

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G. A. Olah, A. Molnar, Hydrocarbon Chemistry, 1. Aufl., 632 S. mit zahlreichen Formelschemata, 16 × 24 cm, John Wiley & Sons, Inc., New York, Chichester, Brisbane, Toronto, Singapore, 1995, Karton (hardcover), $ 55,00, ISBN 0-471-11359X (1996)

Fell, B.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 290-291

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380157

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65

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Bis-(1-chlor-3-phenoxy-prop-2-yl)-sulfane - Nucleophile Substitution und Regiochemie, Diastereomerentrennung und -zuordnung. Synthese diastereomerenreiner Trithiacyclen (1996)

Heinicke, J. ; Ristau, Th. ; Jelonek, S. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 327-336

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Keywords: Chemistry ; Organic Chemistry

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Notes: Bis-(1-chloro-3-phenoxy-prop-2-yl)-sulfanes - Nucleophilic Displacement and Regiochemistry. Separation and Assignment of Diastereomers. Synthesis of Diastereomerically Pure TrithiacyclesThe title compounds 1 were substituted by a series of O-, N- and S-nucleophiles (H2O solvolysis, AgOAc, NaN3, KSCN, NaSPh, thiourea). A strong tendency to β-elimination of HCl depending on the kind of the attacking nucleophile was found. In most cases no regioisomerization could be detected in the isolated products of the nucleophilic displacement. Best results were obtained with sulfur nucleophiles. The separation of the diastereomeric mixture of the p-kresyl derivative 1b into the individual diastereomers 1bA and 1bB in a preparative scale was achieved. These 3-thia-1,5-dichlorides and several products of substitution could be assigned to the meso- or (±)-form by examination of the stereochemistry and symmetry of the corresponding sulfoxides.The 1,5-dimercapto derivatives 8 are convenient as structural units for the synthesis of diastereomerically pure cis- or trans-disubstituted trithiacycles e.g. 15bA, 15bB. The (±)-form of the 4,6-disubstituted 2,5,8-trithia[9]-(2,6)-pyridinophane 16bA was characterized by X-ray crystal structure determination.

Additional Material: 1 Ill.

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URL: http://dx.doi.org/10.1002/prac.19963380165

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NMR Investigation of a rearrangement mechanism at branched-chain uloses using 13C-labelingPresented in part at the 2. Iminiumsalz-Tagung in Stimpfach-Rechenberg, Germany (September 20-22th, 1995)Dedicated to Prof. Dr. H. Dehne on the Occasion of his 60th Birthday (1996)

Aldinger, S. ; Feist, H. ; Peseke, K. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 485-487

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380191

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67

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Chromium(II) chloride: A reagent for chemo-, regio- and diastereoselective C—C-bond formation (1996)

Hashmi, A. S. K.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 491-495

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380193

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Kuppelproduktion und Umweltpolitik: Eine Fallstudie zur Chlorchemie und zur Schwefelsäureindustrie (1996)

Faber, M. ; Jöst, Frank ; Manstetten, Reiner ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 497-505

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Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: Joint Production and Environmental Policy: A Case Study for the Chlorine and Sulphuric Acid IndustryThe chemical industry is a key sector of industrialised economy. Thus, environmental policy with a focus on the chemical industry is likely to affect the economy as a whole. In this article we show, that environmental regulation of the chemical industry has major consequences for other production sectors. Two major problem areas of the chemical industry are considered: the chlorine industry and the sulphur industry. While the chlorine industry can cope with environmental legislation by process and product innovation without a substantial impact on other sectors, this is not the case with the sulphur industry. The production of its key product, sulphuric acid, utilises joint products of other sectors as inputs. The chemical industry offers these sectors the possibility to dispose of their unwanted by-products. Environmental policy, directed towards a reduction of sulphuric acid is likely to cause a waste disposal problem in sectors which manufacture sulphur or sulphur dioxide as by-products. Solving environmental problems within the chemical industry therefore creates new problems in other sectors.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380196

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Tetrathiafulvalene. XXVIII. Diastereoselektive Bildung unsymmetrisch substituierter TetrathiafulvaleneHerrn Prof. Dr. Rudolf Taube zum 65. Geburtstag gewidmet (1996)

Fanghänel, E. ; Van Hinh, L. ; Schukat, G. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 523-531

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Tetrathiafulvalenes. XXVIII. Diastereoselective Formation of Unsymmetrically Substituted TetrathiafulvalenesAs a part of our work on chemistry of tetrathiafulvalenes, we make a contribution to elucidate the mechanism of forming tetrathiafulvalenes starting from 1,3-dithiole derivatives. We describe the synthesis of unsymmetrically substituted tetrathiafulvalenes (8a-i) starting with the 2H-1,3-dithiolium salt (7a-i)/tert. amine, 2-ethylthio-1,3-dithiolium salt (5a-i)/triphenylphosphine or 1,3-dithiole-2-thione (4a-i)/triethyl phosphite. If the 1,3-dithiole derivatives are substituted by bulky groups the isolation of the cis- and trans-isomers was possible due to differences in the solubility. In these cases (8c-i) the predominant formation of the cis-isomer is observed in the reaction of 2-ethylthio-1,3-dithiolium salts (5c-i) with triphenylphosphine or 1,3-dithiole-2-thiones (4c-i) with triethyl phosphite. This result is in agreement with the formation of an intermediate, analogously to the Wittig reaction. In the reaction of 2H-1,3-dithiolium salts (7a-i) with tertiary amines the relation of isolated cis- and trans-isomers is not 1:1 and depends on the bulkiness of the tertiary amine. These observations exclude in these three reactions a carbene mechanism for the dimerization of the 1,3-dithiole units to tetrathiafulvalenes.

Additional Material: 5 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380199

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Darstellung und Charakterisierung N-Disubstituierter 2-Amino-4-chlor-thiazol-5-aldehyde und ihrer Dicyanmethylen-Derivate (1996)

Israel, Jens Erhard ; Flaig, Ronald ; Hartmann, Horst

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 51-54

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Preparation and Characterisation of N-Disubstituted 2-Amino-4-chloro-5-formyl-thiazoles and Their Dicyanmethylene DerivativesIn contrast to N-disubstituted 3-hydroxy-anilines 5 which react with the Vilsmeier reagent to N-substituted 4-amino-salicylaldehydes 7 their heteroanalogous N-disubstituted 2-amino-4-hydroxy-thiazoles 6 react with the same reagent to N-substituted 2-amino-4-chloro-thiazole-5-aldehydes 12 via their corresponding iminium salts precursors 11. Both types of compounds can be transformed, in analogy to other 2-amino-thiazole-5-aldehydes, by reaction with malodinitrile 13 into stable N-substituted 2-amino-4-chloro-5-(2,2-dicyano-ethenyl)-thiazoles 14.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380108

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Oligomers from the reaction of 1,2-diaminoethane and malonic acid derivatives - no formation of 1,4-diaza-5,7-cycloheptanedioneDedicated to Prof. Dr. G. Seitz, Marburg, on the occasion of his 60th birthday (1996)

Imming, Peter ; Resch, Martin

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 121-123

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The reaction of 1,2-diaminoethane (5) with malonic acid derivatives (6, 7, 8, 10) gives oligo- and polymers that were characterized by MALDI-ToF mass spectrometry. Literature reports that claimed the formation of the title compound in these reactions were critically evaluated and could not be confirmed.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380124

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72

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Molmassebestimmung an Polyamiden und Reaktionsprodukten aus ε-Caprolactam und Phenylglycidether (1996)

Tänzer, W. ; Schmidt, Sibylle ; Ludwig, Ina

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 311-319

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Molar Mass Determination on Polyamides and on Reaction Products from ε-Caprolactam and Phenyl Glycidyl EtherTerminal groups (-NH2, -COOH, -OH (-OH from termination reaction with epoxides)) of aliphatic oligo- and polyamides were titrated to determine the corresponding molar masses. ε-Caprolactam terminal groups were hydrolyzed to form -COOH permitting subsequent titration. The same samples were measured by using capillary viscometry, vapour pressure osmometry and size exclusion chromatography. It was shown that the molar masses obtained depend on the reaction process of the polyamide formation (anionic process with Na-caprolactam as initiator and activated anionic process with Na-caprolactam/N-acetylcaprolactam as initiator) and on the analytical method used. Molar masses from titration of terminal groups correspond to molar masses from capillary viscometry in sulfuric acid as solvent.

Additional Material: 14 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380163

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73

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Highly Substituted Anthraquinones by Anionic Cyclization Reactions (1996)

Krohn, K. ; Böker, N. ; Gauhier, A. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 349-354

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Highly substituted anthraquinone esters (3a/b, 6, 20) and acids (12, 21) are synthesized by base induced anionic cyclizations starting from bisalkylated naphthalenes (e.g. 10) or monoalkylated naphthoquinones (e.g. 19).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380168

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74

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NMR-spektroskopische Bestimmung der Enantiomeren chiraler Carbonsäuren anhand ihrer Tri-butylzinnderivate (1996)

Knoll, Susanne ; Klein, Jens ; Ristau, Thomas ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 374-375

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: NMR-Spectroscopic Investigations of Chiral Carboxylic Acids via Their Tributyltin Derivatives

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380171

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Wechselwirkungen in Kristallen. 76. Einkristallstrukturen von 2,5-Bis(trimethylsilyl)hydrochinon ohne Lösungsmittel sowie mit Dimethoxyethan oder Dioxan: Ein Einblick in die Vielfalt von Wasserstoffbrücken-Bindungen desselben Moleküls (1996)

Bock, H. ; Nick, Sabine ; Näther, Christian ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 363-373

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Topics: Chemistry and Pharmacology

Notes: Interactions in Crystals. 76. Single Crystal Structures of 2,5-Bis(trimethylsilyl)-hydroquinone without Solvent and with either Dimethoxyethane or Dioxane: Some Insight into the Manifold of Hydrogen Bridge Bonding of the same Molecule2,5-Bis(trimethylsilyl)hydroquinone (monoclinic, C2/c, Z=12) forms infinite strings in x-direction, in which alternatingly on both sides each three molecules are bound together by three phenolic H bridges in a triangular arrangement. In the dimethoxyethane solvate (triclinic, P1, Z=1) with a 3:2 ratio of phenol to ether, the infinite strings are interlinked by twice —OH…O bonded H3COCH2CH2OCH3 chelate molecules. The smallest subunit with only two Hydrogen bonds —OHO…(CH2CH2)2O is formed in the monomeric 2:1 dioxane solvate (triclinic, P1, Z=1). The structural details of the different H bridge bonds are discussed based both on a statistical analysis from the Cambridge Structural Database as well as on PM3-calculated enthalpies of formation starting from the crystal structures determined.

Additional Material: 13 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380170

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76

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Benzothiete, a Versatile Reagent in Heterocyclic Syntheses (1996)

Meier, H.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 383-385

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380174

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77

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Zur Analytik von Oxothioarsen-Species in Schlacken und Grubenwässern (1996)

Schwedt, Georg ; Rieckhoff, Melanie

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 55-59

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Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Analysis of Oxothio Arsenic Species in Soil and WaterArsenic species in alkaline extracts of sulfidic and arsenic slags as well as in water in mines were analyzed by ion chromatography and capillary zone electrophoresis. The total arsenic was determined in both kinds of samples by FIA-hydride AAS, in the slags after microwave induced pressure digestion, and in the untreated solid samples also by RFA. Arsenate, arsenite and monothioarsenate ions could be identified and quantified as stable arsenic species.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380109

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Helmut Moritz, Science, mind and the universe. An introduction to natural philosophy, 1. Aufl., 298 S., 71 Abb., Hüthig-Fachverlage Herbert Wichmann Heidelberg, 1995, DM 98,00, ÖS 765,00, SFr 98,00, ISBN 3-87907-274-4 (1996)

Bittrich, H.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 97-97

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380121

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Synthesis of Fluoromonoterpenoids as potential suicide substrates for plant cells (1996)

Banthorpe, D. V. ; Ireland, M. J.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 279-282

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380154

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80

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Tris(4-bromophenyl)aminium and tris(2,4-dibromophenyl)aminium cation radicals - Synthetically Useful One Electron Oxidants (1996)

Kluge, Ralph

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 287-289

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380156

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81

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Biosensoren auf der Basis von Katalasemembranen unter Nutzung der enzymatischen Doppelfunktion zur molekularselektiven Carrier-Analyse von Ethanol (1996)

Schindler, J. G. ; Herna, K. ; Schindler, M. M.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 532-537

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Notes: Biosensors Based on Catalase Membranes with Utilization of Enzymatic Bifunctionality for Molecular-selective Carrier-Analysis of EthanolA robust bioelectrochemical measuring system for amperometric electroanalysis of ethanol is presented, which allows measurements between 0.01 and 99.8 vol.% of ethanol without preceeding dilution. It is distinguished by long-lived biosensors based on bifunctional catalase membranes. Besides the O2-sensitive enzymatic biosensor the design includes components for intermediate carrier analysis such as a microdialysator for analyte uptake into buffered, H2O2 containing carrier solution out of the sample solution both with tangential countercurrent fluxes, an oxigenating pump for constant pO2 in the carrier stream, a pressure adjusting chamber as protection from variing pressure on the enzyme membrane resulting from the roller pump's pulsations. Utilization of the membrane's catalatic and peroxidatic bifunctionality is the basis of ethanol analysis: peroxidatically acting catalase molecules cannot release oxygen by catalatic reaction of H2O2 at the same time.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801100

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Ein effektives Verfahren zur Herstellung von 1α,25-Dihydroxy-cholecalciferol (Calcitriol) aus 1α3β,25-Trihydroxy-cholesta-5,7-dien (Procalcitriol) (1996)

Reichenbächer, M. ; Gliesing, S. ; Lange, C. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 634-641

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

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Notes: An Effective Procedure for the Synthesis of 1α,25-Dihydroxy-cholecalciferol (Calcitriol) Starting with 1α,3β, 25-Trihydroxy-cholesta-5,7-diene (Pro-Calcitriol)In order to develop an effective synthesis of the important vitamin D metabolite 1α,25-(OH)2-cholecalciferol (calcitriol) 5a starting with pro-calcitriol 1a the influence of reaction temperature and degree of turnover of 1a to the compositions of the photoproducts at irradiation in a 500 ml photoreactor were investigated. The combination of the highly photostable filter solution consisting of 2,7-dimethyl-3,6-diaza-cyclohepta-1,6-diene-tetrafluoroborate and biphenyl in ethanol realizes the double wavelength irradiation in the range of 290 to 300 nm and 〉 330 nm resulting in a highly amount of the desired pre-calcitriol 2a. The reversible photoisomers of pre-calcitriol 2a 1α,25-(OH)2-lumisterol3 4a and 1α,25-(OH)2-tachysterol3 3a were isolated from an irradiation mixture in pure form by means of an appropriate combination of flash-chromatography, MPLC and preparative HPLC, respectively. The isomers 2a, 3a and 4a were characterized chromatographically and spectroscopically. Photoisomerization of 1a at -45 °C using the filter solution mentioned above and recycling all reversible photoisomers resulted in highly pure 5a after thermally induced isomerization of 2a isolated from the irradiation mixture by means of flash-chromatography on Ag+- impregnated silica with a yield of 68%.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801121

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Synthesis and characterization of Schiff Base Chelates of Tetramic Acids as NMR Contrast Agents for micro imaging (1996)

Tietze, O. ; Reck, G. ; Schulz, B. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 642-646

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Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Novel Cu(II) complexes derived from N,N′ P-ethylene-bis-(1′,5′,5′-trimethyltetramic acid-3′-acetiminato)copper(II) aCu [1] were evaluated as contrast agents for NMR microscopy and therefore tested for penetration into living cells (Xenopus laevis oocytes). By in vitro 1H NMR relaxation (T1) and atomic absorption spectroscopy measurements (AAS) we confirmed, that independent of the complex isomers (Z/Z, Z/E, E/E, E/Z) compounds with alkyl substituents in R1 - R5 exclusively were able to penetrate the plasma membranes. It is noteworthy that compounds containing the tetramic acid moieties from both a penetrating and a non-penetrating complex most likely were accumulated in the plasma membrane and/or plasma membrane-associated vesicles, which was concluded from in vitro NMR measurements combined with AAS trace analyses. In this context the crystal and molecular structure of the ‘chimerical’ C17H22N4O4Cu · 3H2O kCu · 3H2O were determined by x-ray analysis. The x-ray structural parameters are discussed in detail.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801122

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84

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Improved Preparation of 3,4-Dimethoxythiophene (1996)

Merz, Andreas ; Rehm, Christina

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 672-674

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801128

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85

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A Simple Synthesis of 2,3-Dichloro-6-nitrobenzonitrile (1996)

Trinka, P. ; Berecz, G. ; Reiter, J.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 679-680

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801130

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Modern colorants - synthesis and structure (3. band der serie advances in color chemistry), A.T. Peters, H. S. Freeman (eds.), 1. Aufl., 245 S., London, Blackie Academic 1995, 79,00, ISBN 0-7514-0209-5 (1996)

Hartmann, H.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 687-688

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801133

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87

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Spiroannelation reactions of 3-trifluoroacetyl- and other 3-acyl-1-methyl-lactamsDedicated to Prof. K. Kieslich on the occasion of his 65th birthday. (1996)

Bouillon, Jean-Philippe ; Wynants, Chantal ; Janousek, Zdenek ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 538-543

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 3-Trifluoroacetyl- and other 3-acyl-1-methyllactams (1-5) undergo the Robinson annelation with α,β-unsaturated ketones to produce spirocyclic cyclohexenones (6), their precursors hydroxycyclohexanones (7) or 3-acyl-3-oxobutyl-lactams (8) depending on the substitution.

Additional Material: 2 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801101

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88

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Copper(I) complexes of mono- and bis-ferrocenyl-vinyl 2,2′-bipyridine-ligands: Synthesis and electrochemical properties (1996)

König, Burkhard ; Möller, Oliver ; Zieg, Harald

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 549-552

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: New 2,2′-bipyridine ligands with one or two vinyl-ferrocenyl moieties (2, 3) have been synthezised. The coordination of the bipyridine by copper(I) ions allows the assembly of up to four ferrocenes in a defined arrangement. Although the ferrocene moieties are in close proximity, they are electronically independent, as is shown by UV-spectroscopy and cyclic voltammetry.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801103

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Kronenether mit 1,3,5-Triazinen als Ringbaustein - Synthese und Untersuchung der Alkaliselektivität durch Elektrospray-Ionisations-Massenspektrometrie (1996)

Lutze, G. ; Graubaum, H. ; Bartoszek, M. ; [et al.]

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 564-568

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Crown Ethers with 1,3,5-Triazines as Ring Building Block - Synthesis and Investigation of the Alkali Selectivity by Electrospray Ionization Mass SpectrometryThe synthesis and characterization of 5 new crown compounds 3 and some derivatives 4, containing a 1,3,5-triazine ring as subunit, based on the aminolysis of cyanuric chloride with diamines, is described. The alkali selectivity of some crown ligands were investigated by the ESI mass spectrometry.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801106

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90

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Ruppert's Reagent: Trifluoromethyltrimethylsilane (1996)

Lamberth, C.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 586-587

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801111

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G. Schwedt, Toxikologisches Lexikon zum Umweltchemikalienrecht (Schriftenreihe Umweltschutz - Entsorgungstechnik), 1. Aufl., 132 S., 60 Abb., Vogel Buchverlag 1996, Würzburg, 39,- DM, 289,- ÖS, 39,- SFr, ISBN 3-8023-1569-3 (1996)

Timpe, H.-J.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 591-592

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801114

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92

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Photokatalytische Bildung von Wasserstoff aus Thiolen in Gegenwart von Vitamin B12-Modellverbindungen mit Azid als photochemischem OpferligandenHerrn Professor Eberhard Hoyer zum 65. Geburtstag gewidmet (1996)

Hennig, Horst ; Ritter, Klaus ; Billing, Roland

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 604-613

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Photocatalytic Hydrogen Formation from Thioles in the Presence of Vitamin-B12 Model Complexes with Azide as Photochemical Sacrificial LigandThe photolysis of [N3Co(chelat)B] complexes (1-3) (chelat = dimethylglyoxime, dmg; N,N′-o-phynylenebis(salicylidenimine), salphen; N,N′-ethylene-bis(salicylidenimine), salen; B = pyridine) leads by homolytic cleavage of the Co-N3 bond to both coordinatively unsaturated cobalt(II) chelates [Co(chelat)B] and N3 ligand radicals that undergo fast decay to dinitrogen. The photolysis of the cobalt (III) complexes 1-3 in the presence of thiophenole and other thioles proceeds catalytically and yields the corresponding disulphides and dihydrogen. The mechanism of this photocatalytic generation of dihydrogen is due to the catalytic activity of the coordinatively unsaturated cobalt(II) species formed photochemically. A photocatalytic cycle is proposed describing the generation of hydrogen. Possible photochemical and thermal steps of that cycle are discussed.

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801117

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Über Oberflächenverbindungen von Übergangsmetallen. XL. Rasterelektronenmikroskopische und röntgen-mikroanalytische Untersuchungen an reduzierten Phillipskatalysatoren (1996)

Schmidt, H. ; Riederer, W. ; Krauss, H. L.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 627-633

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: On Surface Compounds of Transition Metals. XL. Characterization of Chromium Doped Silica Catalyst Systems of the Phillips Type by Scanning Electron Microscopy with Energy Dispersive Analysing System (SEM/EDS)The surface of typical supports for the Phillips catalyst was studied by SEM. The seemingly smooth surfaces are composed by closely packed, ball-shaped substructures; macro- and micro-pores can be seen. Adherent particles on the surface (φ ≪ 1 μm) show the same substructures as the usual surface. After impregnation and activation/reduction of the catalysts crystallites are seen at the surface, which are characterized as Cr2O3 by their crystal shape and EDS analysis.Polymerization of ethylene occurs at the usually doped surface, while the Cr2O3 particles do not exhibit a special activity. Mechanically inforced breaks of the catalyst grains show the formation of threadlike polyethylene with diameters of 200 to 300 nm.

Additional Material: 10 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801120

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94

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Novel tocopherol compounds. III. Reaction of 5a-Bromo-α-tocopherol with Nucleophiles (1996)

Rosenau, T. ; Habicher, W. D.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 647-653

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The synthesis of different classes of 5a-substituted tocopherols is described. These compounds are potent antioxidants and highly interesting as vitamin E carriers. The reaction of the readily available 5a-bromo-α-tocopherol with alcohols and phenols is shown to produce 5a-alkoxy-α-tocopherols (3-5, 8, 9) and 5a-aryloxy-α-tocopherols (6, 7), respectively, with high yields. 5a-α-Tocopheryl esters (10, 11) are prepared by reaction with metal carboxylates. 5a-Bromo-α-tocopherol is used as well to introduce tocopheryl groups into tertiary amines by quaternization, that renders these compounds (13, 14) soluble in water and in common organic solvents. 5a-Bromo-α-tocopherol also reacts as an alkylating agent with sterically hindered phenols in a Friedel-Crafts reaction. Phenols not highly substituted are exclusively alkylated in the para position at room temperature or below, whereas at higher temperature the para-as well as the ortho-alkylated product is observed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801123

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95

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The reaction of some brominated aminopicolines with acetic anhydride and with copper(I) cyanide (1996)

Dunn, A. D. ; Norrie, R.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 663-666

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801126

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96

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A convenient synthesis of ethyl (2-amino-5,6-dichlorobenzyl)glycinate (1996)

Trinka, P. ; Slégel, P. ; Reiter, J.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 675-678

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801129

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97

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Betmip (1-(triphenylphosphorylideneaminomethyl)benzotriazole), A unique CH2=N-PPh3+X- equivalent for organic synthesis (1996)

Katritzky, Alan R. ; Jiang, Jinlong

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 684-686

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.199633801132

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98

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Electroreduction of organic compounds. 28. Partial Hydrogenation of Polycyclic Aromatic Hydrocarbons by electroreduction in protic solvents (1996)

Anowski, S. ; Voss, J.

New York, NY : Wiley-Blackwell

Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 337-344

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ISSN: 0941-1216

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Polycyclic aromatic hydrocarbons (PAH) such as anthracene (1), phenanthrene (5), acenaphthylene (15), pyrene (17), chrysene (22), and fluoranthene (28) are selectively hydrogenated upon electroreduction at a lead cathode in ethanolic solution. The degree of hydrogenation and the structure of the products depend on the reaction conditions, in particular on the applied reduction potential.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/prac.19963380166

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99

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On Some Italicene Derivatives (1996)

Weyerstahl, Peter ; Marschall, Helga ; Christiansen, Christian ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1641-1644

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ISSN: 0947-3440

Keywords: Tricyclic sesquiterpenes ; Italicene derivatives ; α-Copaene derivatives ; Essential oils ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Oxidation of the tricyclic sesquiterpene hydrocarbon italicene (1a) or its 10-epimer 1b (isolated previously from Helichrysum oil) with SeO2 yielded mixtures of italicene-5-one (3a), italicen-15-al (4a), italicen-5-ol (9a) and italicen-15-ol (10a) or their 10-epimers 3b, 4b, 9b, 10b, whereas commercial α-copaene (6) reacted only to give a mixture of α-copaen-15-al (7) and α-copaen-15-ol (8). Jones oxidation of the allyl alcohols 9a or 9b afforded the pure ketones 3a or 3b MnO2 oxidation of the alcohols 10a or 10b furnished the aldehydes 4a or 4b. - Surprisingly, the italicene epoxides 2a or 2b rearranged with diluted HCl to the italicene ethers (epoxyacorenes) 5a or 5b, which previously were isolated from Lantana and Helichrysum oil. - The odor of 3a, 3b, 4a, 4b and 5a was evaluated.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961022

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100

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Enantioselective Total Synthesis and Absolute Configuration of the Natural Norsesquiterpene 7-Demethyl-2-methoxycalamenene by a Silane-Terminated Intramolecular Heck Reaction (1996)

Tietze, Lutz F. ; Raschke, Thomas

Weinheim : Wiley-Blackwell

Liebigs Annalen 1996 (1996), S. 1981-1987

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ISSN: 0947-3440

Keywords: Heck reaction, enantioselective ; Allylsilanes ; Norsesquiterpenes ; 7-Demethyl-2-methoxycalamenene, total synthesis, absolute configuration, and cytotoxicity of ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The total synthesis of the norsesquiterpene 7-demethyl-2-methoxycalamenene (1) by a newly developed enantioselective silane-terminated Heck reaction is described. The Pd0-catalyzed transformation of the allylsilane 7, obtained from 3-(3-methoxyphenyl)propanol (2) in 7 steps, provides the tetralin 8 in 91% yield and with 92% ee in the presence of (R)-BINAP. Transformation of 8 via 14 and 15 gives 1. The absolute configuration of 1 which has previously not been known was deduced from a single-crystal X-ray analysis of 10, obtained from the cyclization product 8 by hydroboration and acylation with camphanic acid chloride.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.199619961207

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