摘要:

Chemical Synthesis of the Nonanucleosideoctaphosphate dA‐T‐G‐A‐T‐G‐A‐A‐AFor studies on the specifity of enzymes, the nonanucleoside octaphosphate dATGATGAAA was required. Its chemical synthesis is reported starting with th

ISSN:0021-8383    

DOI:10.1002/prac.19783200102

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Das polarographische Verhalten des Benzylidenbenzhydrazides in Lösung in Abhängigkeit vom pH‐Wert. Der Effekt der Hydrolyse auf den ReduktionsmechanismusDas polarographische Verhalten des Benzylidenbenzhydrazides (BBH) in Lösung wurde durch Änderung des pH‐Wertes innerhalb des Konzentrationsbereiches 1 · 10−4bis 1 · 10−3mol untersucht. Die Polarogramme bestehen im sauren Medium jeweils aus einer Welle. Die Stufenhöhe nimmt mit steigendem pH‐Wert ab. Bei pH 8.6 tritt eine zweite Welle auf. Diese nimmt in der Höhe zu, bis ein konstanter Wert im alkalischen Medium erreicht wird.Der Effekt des pH‐Wertes auf den Grenzstrom und E1/2sowie auf den Reduktionsmechanismus werden diskutiert. Die kinetischen Parame

ISSN:0021-8383    

DOI:10.1002/prac.19783200103

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractThe complexation of La3+, Ce3+, Pr3+and Sm3+ions with isopropylmercaptan has been studied by potentiometric and conductometric titration techniques in aqueous – 10% ethanolic (V/V) medium. Title metal ions form 1:1, 1:2 and 1:3 complexes in the pH range 6.0–8.0 with considerable overlapping. Their log Kstab.values are determined at 15°, 25° and 35°C at ionic strength μ = 0.1 M (NaClO4) by applying Calvin and Melchior's extension of Bjerrum method. The values of thermodynamic parameters ΔG, ΔH and ΔS have been calculated at 25°C with the help of an isobar and Gibb's Helmholtz equation. The trend in the stability constant values of the metal‐complexes has been found to be\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Sm}\left({{\rm III}} \right) > {\rm Pr}\left({{\rm III}} \right) > {\rm Ce}\left({{\rm III}} \right) > {\rm La}\left({{\rm III}} \right) $$\

ISSN:0021-8383    

DOI:10.1002/prac.19783200104

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Preparation and Reactions of α‐Halogenobenzyl‐silanesα‐Bromobenzyl‐dimethylchlorosilane3, bis‐(α‐bromobenzyl)‐dimethylsilane8and the corresponding α‐chlorobenzyl‐compounds5and13have been prepared by reaction of benzyl‐dimethylchlorosilane1resp. dibenzyl‐dimethylsilane2with N‐bromosuccinimid and sulfurylchlorid.The α‐halogenobenzyl‐dimethylchlorosilanes3and5have been treated with water, alcohols and phenol, to give the corresponding silanols15and16, siloxanes17and18, alkoxy‐ and phenoxysilanes19and20.Reactions of3with brenzcatechin, o‐aminophenol and o‐aminobenzylalcohol give 6‐

ISSN:0021-8383    

DOI:10.1002/prac.19783200105

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Abstract10,10′‐Dimethyl‐9,9′‐biacrilydene in pinacolone reacts with ozone at −45°C to give a thermally unstable product, the decomposition of which results in N‐methylacridone and emission of light with a quantum yield of over 10−2Einstein · mole−1, showing the reaction to be one of the most efficient chemiluminescent reactions known. As the chemical reaction is known to yield dioxetanes and the primary exited product is shown to be N‐methylacridone, positive evidence is provided that the Lucigenin light reaction proceeds via a d

ISSN:0021-8383    

DOI:10.1002/prac.19783200106

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

The Nature of the Transition Metal to Carbon σ‐bond. II. Mass Spectrometric Investigations of Mono‐organyl‐Transition Metall Complexes of Phthalocyanine and SalenIn the mass spectra of monomethyl and monophenyl complexes of Fe(III) and Co(III) phthalocyanines (RMPc) there are observed peaks at higher mass numbers than that of the molecular ion which are described to products containing more than one organyl group.It is concluded from the mass spectra and the ionization efficiency curves of the ions R2MPc+, RMPc+and MPc+that, due to the high temperature in the inlet system of the mass spectrometer, in the solid state a loss of the organyl residue R and an attack of the radicals at the phthalocyanine ring takes place.The mass spectra of methyl‐ and phenyl‐cobalt(III)‐salen do not contain any peaks at higher mass numbers than the molecular ion. The problems of mass spectrometric determination of the strength of the transition metal to carbon σ‐bon

ISSN:0021-8383    

DOI:10.1002/prac.19783200107

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

AbstractDurch Addition von Nitrosylhydrogensulfat an trisubstituierte Olefine in flüssigem Schwefeldioxid als Lösungsmittel sind die entsprechenden α‐Sulfatooxime zugänglich. Die Sulfatooxime sind zersetzlich. Sie reagieren mit Nucleophilen unter Austausch der Sulfatgruppe; die Reaktion verläuft wahrscheinlich nach einem Eliminierungs‐Additions‐Mechanismus über Nitrosoolefine als kurzlebige Zwischenprodukte. Setzt man Nitrosylhydrogensulfat in Gegenwart von Schwefelsäure und von niederen gesättigten Kohlenwasserstoffen mit trisubstituierten oder asymmetrisch disubstituierten Olefinen un und hydrolysiert das Gemisch dann vorsichtig mit Wasser bzw. mit wässerigen Lösungen von Ammoniak oder Natronlauge, so erhält man in guten Ausbeuten die entsprechenden α‐Hydroxyoxime. Setzt man Nitrosylhydrogensulfat mit Eisessig‐Lösungen von unsubstituierten Cycloolefinen um, so erhält man in mäßigen Ausbeuten die ents

ISSN:0021-8383    

DOI:10.1002/prac.19783200108

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Sydnone Ethylenes. II. Electronic Interactions in 4‐Styryl‐sydnonesAn estimation of intramolecular donor/acceptor interactions in 4‐styryl‐sydnones can be made by the substituent incrementsZtransderived from the corresponding vinyl compounds and by the comparison of the u.v.‐spectra of ω(E)‐substituted styrols. Because of the different anisotropic effects of sydnone and aryl groups the chemical shifts of the ethylene protons are not suitable for this purpose. The observed and calculated u.v.‐spectra show that the electronic excitation of 4‐styryl‐sydnones causes a strengthening of the sydnone donor effect and a decrease of the bond‐ord

ISSN:0021-8383    

DOI:10.1002/prac.19783200109

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Sydnone Ethylenes. III. Chemical Reactions of Excited 4‐Styryl‐sydnonesDependent on the character of the substituents in the photo reactions of 4‐styryl sydnonesZ/E‐isomerism competes with CO2‐elimination. Excited p‐nitrostyryl sydnones exhibit a relatively strong degradation of the bond order in the CC region. Their quantum yields ofZ/E‐isomerism are therefore much higher than those of compounds with p‐substituents of lower acceptor effect. In these compounds the cleavage of the sydnone ring with elimination of carbon dioxide is favoured especially if a methyl group is in 3‐posi

ISSN:0021-8383    

DOI:10.1002/prac.19783200110

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Fragmentation of Some Dibromooxabicycloalkanes on Electron ImpactThe dibromooxabicycloalkanes1ato1e,2aand2b, which are available from cycloalkadienes, undergo a characteristic fragmentation in electron impact mass spectrometry. The most important primary process is a CBr‐cleavage; in addition an important concurrent fragmentation appears in1cas a result of αCC

ISSN:0021-8383    

DOI:10.1002/prac.19783200111

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY