摘要:

Structure Elucidation of Bromination Products of N‐Aryl‐2, 4‐dimethyl‐buta‐1,3‐diene‐sultames‐1, 4The structure of bromination products of N‐aryl‐2, 4‐dimethyl‐buta‐1, 3‐diene‐sultames‐1, 41a–d,fis determined by 13‐C‐n.m.r. spectroscopy. As mono bromination product of N‐phenylsultam1athe 4‐bromomethyl derivative2awas isolated. Dibromination of sultames1yields 1‐brom‐4‐brommethyl‐sultames3and by tribrominat

ISSN:0021-8383    

DOI:10.1002/prac.19823240302

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. V. Reactions of β,γ‐Unsaturated Carbamic Acid Esters with Sulfenyl Chlorides — Synthesis of 3,5,5‐Trisubstituted Oxazolidine‐2‐onesN,N‐Disubstituted β,γ‐Unsaturated urethanes1have been cyclized to 3,5,5‐trisubstituted oxazolidine‐2‐ones3by aromatic sulfenyl chlorides in methylene chloride. The same oxazolidine‐2‐ones3were obtained by reaction of 5‐bromomethylox

ISSN:0021-8383    

DOI:10.1002/prac.19823240303

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Theoretische Beschreibung von Lösungsmitteleffekten. V. Der Mediumeinfluß auf die Lactim‐Lactam‐Tautomerie von HydroxyazinenDer Lösungsmitteleffekt auf die Tautomeriegleichgewichte der Titelverbindungen wird mit Hilfe klassischer und quantenchemischer Versionen der Solvatonen‐ und der Reaktionsfeldtheorie berechnet. In Übereinstimmung mit dem Experiment ergeben alle getesteten Verfahren eine Gleichgewichtsverschiebung zugunsten der Lactamform. Zur quantitativen Beschreibung dieses Effektes ist jedoch das Reaktionsfeldmodell besser

ISSN:0021-8383    

DOI:10.1002/prac.19823240304

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Eine neue Esterkomponente in der Stobbe‐Kondensation. I. Kondensation einiger aromatischer Aldehyde mit Diethyl‐β,β‐dimethylglutaratKondensation von Benzaldehyd und p‐Anisaldehyd mit Diethyl‐β,β‐dimethylglutarat in Gegenwart von Natriumhydrid ergibt die kristallinen (Z)‐Halbester (1aundb) und ölige Halbesterfraktionen, die die E‐Isomeren2aundbenthalten.Im Falle von p‐Chlorbenzaldehyd werden die (Z)‐ und (E)‐Halbester (1cund2c) in reiner kristalliner Form erhalten. Die Konfiguration wurde durch Cyclisierung der entsprechenden Anhydride3zu den Oxoin

ISSN:0021-8383    

DOI:10.1002/prac.19823240305

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Electosynthesis of N‐Substituted DL‐Arylglycineesters and 1,2‐Diarylamino‐1,2‐diarylethanes by Cathodic Reduction of Azomethines in the Presence of Carbon DioxideThe electroreduction of the N‐arylidene‐arylamines1–12in CO2‐saturated solvents of low proton availability as DMF at markedly more positive potentials than carbon dioxide end up in carboxylating the C‐atom and hydrogenating the nitrogen of the double bond. The resulting N‐arylsubstituted DL‐arylglycines and traces of carbamates may be isolated as esters, adding ethylchloride during the electrolysis. A competing pathway of the electrocarboxylation is the CC‐hydrodimerisation and the hydrogenation of the double bond, whose importance increases with the water content of the solvent. Based on cyclic‐voltametric evidence and product analysis the mechanism of the reductive electrocarboxylation reaction is discussed in terms of nucleophilic attack of the azomethine ani

ISSN:0021-8383    

DOI:10.1002/prac.19823240306

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Fluorescence Quenching of N‐Arylurethanes by KetonesFluorescence and photo‐Fries reaction of N‐aryl‐urethanes can be quenched by diffusion‐controlled energy transfer to biacetyl, acetone and other aliphatic ketones. Quenching of the photo reaction and fluorescence obeys the Stern‐ Volmer Equation.The efficiency of quenching may by influenced by solvents and substituents changing the S1energies of donors and acceptors. The identical rate constants determined by independent methods demonstrate that quenching of urethane fluorescence and photoreaction by aliphatic ketones occurs completely by singlet ener

ISSN:0021-8383    

DOI:10.1002/prac.19823240307

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Quenching of Excited Singlet States of N‐Arylurethanes by Intra‐ and Intermolecular Resonance Energy Transfer to Salicylic Acid Esters and AmidesFluorescence and photo‐Fries reactions of N‐arylurethanes are quenched by energy transfer to salicylic acid esters and amides. Quenching of photo reaction and fluorescence obeys the Stern‐Volmer equation and is accompanied by sensitization of salicylic acid ester fluorescence.The rate constants of energy transfer are greater than the diffusion rate constants and show that resonance energy transfer occurs.The influence of solvent viscosity, donor lifetime, and spectral overlap is discussed. The rate constants of energy transfer are slightly decreased by increasing the solvent viscosity.The results are in good agreement with the treatment of

ISSN:0021-8383    

DOI:10.1002/prac.19823240308

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Tetrathiafulvalenes. XVI. Spectroscopic and Electrical Properties of TTF and TTF‐TCNQ‐ComplexesUV‐vis‐spectra of mono‐ and dications of the TTF2show in comparison to those of TTF1and3that the aryl substituent in the TTF2is more twisted from the TTF‐plane than in1and3. Absorption maxima of mono‐ and dications from TTF1and3lie at a significantly greater wavelength than absorption maxima of mono‐ and dications from TTF2, because a better electronic interaction between substituents in the aryl‐group and the positively charged dithiolium‐ring is possible. TCNQ‐complexes of smoother TTF3also have a higher electrical conductivity th

ISSN:0021-8383    

DOI:10.1002/prac.19823240309

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Epoxide Reactions. V. Chromatographic Studies of Some Reactions Involving Epoxide FormationsA reverse phase liquid chromatographic method has been applied for the quantitative determination of some products in epoxide forming reactions. The reaction of chlorohydrinethers of bisphenol A with aqueous sodium hydroxide has been studied quantitatively under different conditions.The influence of side products originating from epichlorohydrin on the course of the main reaction is discussed.In addition preparative liquid chromatographic methods have been developed to separate epoxide oligomers and some chlorohydrinethers of bisphenol A.

ISSN:0021-8383    

DOI:10.1002/prac.19823240310

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

On the Validity of Steady State PrincipleConsidering the simple case\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm A}_1\mathop{\rightleftharpoons}^{\rm k_{1}}_{\rm k_{-1}}{\rm A}_2 \mathop{\longrightarrow}^{\rm k_2}{\rm A_3} $$\end{document}reduced concentrations were calculated by solving the exact differential rate equation by assuming a steady state and by assuming an „equilibrium”︁ between A1and A2. In a broad field of reduced rate constants Ki/k1the range in which these assumptions are valid within ±5% was determined for different values o

ISSN:0021-8383    

DOI:10.1002/prac.19823240311

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY