摘要:

AbstractElectrically conducting polymers can be prepared by various routes which will be decisive for the specific properties, e.g. conductivity, solubility, and crystallinity. This article covers the major routes for the preparation of important electrically conducting isopolymers with respect to their properties. Preparation and modification procedures of conjugated polymers are discussed in view of the enhancement of their conductivity, oxidation potential, and stability. It presents also typical examples of recent applications of electrically conducting isopolymers.

ISSN:0941-1216    

DOI:10.1002/prac.19953370102

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo new synthons, Fmoc‐L‐Arg(biphenyl‐4‐sulphonyl)‐OH (8) and Fmoc‐Arg(4‐methoxy‐3‐t‐butylbenzenesulphonyl)‐OH (14), are prepared for the synthesis of arginine‐containing peptides. These groups are cleaved by commonly employed trifluoroacetic acid and methanesulphonic acid. Kinetic studies reveal that extended bicyclic aromatic conjugation, as in biphenyl, slightly improves the acid lability compared to the electron

ISSN:0941-1216    

DOI:10.1002/prac.19953370103

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

The Liquid Junction Potential on the Diaphragm of Reference ElectrodesThe electrolyte solution flow through porous ceramic diaphragms is used for evaluating measurements of streaming potentials. With porous magnesia silicate diaphragms, by salt concentrations from 1 × 10−5to 1 M KCl, the values of zeta potentials are negative. Increases in salt concentrations lower the zeta potentials through a decrease in double layer thickness. In presence of concentrated salt solutions the streaming potential has a very small effect on liquid junction potential of reference electrod

ISSN:0941-1216    

DOI:10.1002/prac.19953370104

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe Michael addition of 2‐substituted cyclopentanones1to β‐nitrostyrene2proceeds at room temperature in the presence of catalysts such as NEt3, DMAP, KOAc, or Ni(acac)2leading to 2‐substituted 2‐(2‐nitro‐1‐phenylethyl)cyclopentanones3/4. Depending on substituents R in1compoundsrac‐3/4may be obtained with high diastereoselectivity. The influences of reaction conditions were studied and the diastereomeric ratio was determined by means of1H‐NMR spectroscopy. In the cases ofrac‐3/4a‐c,rac‐3g–i,rac‐3k, the diastereomers could be isolated in pure form. The configuration of compoundsrac‐3a,rac‐4awas establ

ISSN:0941-1216    

DOI:10.1002/prac.19953370105

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

Thiocarbamoylation of CH‐Acidic Arylsulfinyl and Arylthio CompoundsReaction of arylsulfinyl and arylthio acetonitriles (1) with phenyl isothiocyanate in the presence of sodium hydride and subsequent alkylation lead to the ketene S,N‐acetals (3a–h). Using methyl bromoacetate as alkylating agent thiazolidones (4a–c) are formed whereas phenacylbromide gives the 4‐hydroxythiazolidines (5a‐f). In an analogous way arylthio and arylsulfinyl acetophenones (6) react with phenyl isothiocyanate yielding S,N‐a

ISSN:0941-1216    

DOI:10.1002/prac.19953370106

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

Synthesis of CF3‐Substituted Quinolines from β‐Chloro‐β‐trifluoromethyl‐vinylaldehydes. I3‐(Trifluoromethyl)‐acroleines2have been synthesized through VILSMEIER's reaction from α‐Trifluoro‐methylketones1. The reaction of2with anilines and naphthylamines gives in good yields 2‐trifluoromethylquinoline

ISSN:0941-1216    

DOI:10.1002/prac.19953370107

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

Aryl‐(4‐arylimino‐4H‐pyrido[1,2‐a]pyrazine‐3‐yl)amines‐Synthesis, Complex Formation with Molybdenum(0) and OxygenationThe synthesis of p‐tolyl(4‐p‐tolylimino‐4H‐pyrido [1,2‐a]pyrazine‐3‐yl)amine8(TTPPA) is achieved by the reaction of 2‐pyridylmethylamine with oxalic acid bis(p‐tolylimidoyl)chloride. The ion‐pair [Na(THF)3][(TTPPAH)Mo(CO)4]4is obtained by the reaction of the NH‐acidic compound8with sodium bis(trimethylsilyl)amide and (nor)Mo(CO)4(nor = norbornadiene) dissolved in THF. The bidentate ligand anion TTPPA‐H is related to the 1,4‐diazadienes, but its n‐donor effect is dominating. Its trans‐influence results in different Mo‐CO‐bond lengths of4: 1.901 and 1.951 Å (trans‐positions); 2.003 and 2.031 Å (cis‐positions). In the cationic part of4the sodium is five‐coordinate (distorted tetragonal pyramidal structure). Donor atoms are the three THF, N3 of TTPPA‐H, and the oxygen atom of one CO of the moiety Mo(CO)4.8is oxygenated by hydrogen peroxide or by dioxygen on heating. In the course of a ring transformation of the 6‐membered pyrazine to the 5‐membered imidazole cycle 3‐p‐tolyl‐5‐p‐tolylimino‐2‐pyridine‐2‐yl‐2,3‐dihydro‐imidazol‐4‐one9is formed. In THF two isomers9and9aare observed i

ISSN:0941-1216    

DOI:10.1002/prac.19953370108

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractFive flavonoids were isolated from stems ofJatropha variegata(Forsk.) Vahl, the structures of which were identified as kaempferol 3‐O‐α‐rhamnopyranoside, 3‐O‐α‐L‐arabinopyranoside, 3‐O‐β‐D‐glucopyranoside, 3‐O‐β‐D

ISSN:0941-1216    

DOI:10.1002/prac.19953370109

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe hitherto unknown stereochemistry of N,N,N′,N′‐tetrasubstituted 2‐arylthioacrylamides1has been determined by X‐ray crystal analysis and systematic NMR‐investigations. Provided that the 2‐aryl group lacks ortho substituents, compounds1exist predominantly as Z‐isomers. In contrast, the major isomer has an E‐s‐trans configuration if the 2‐aryl group is ortho‐substituted. Substitution of the 3‐amino group of1by glycinates, giving 3‐aminothioacrylamides2, generally preserves t

ISSN:0941-1216    

DOI:10.1002/prac.19953370110

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

Carbon Analogues of Brasilin and HematoxylinStarting from tetrahydronaphthalin‐1‐one derivatives3aand3b, the carbon analogues10aand10bof Hematoxylin and Brasilin are synthesized. The1H‐NMR‐ and13C‐NMR‐spectra of the compounds are given. The stereo‐chemistry of the tetracycles10aand10bis studied by NO

ISSN:0941-1216    

DOI:10.1002/prac.19953370111

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY