摘要:

Organophosphorus Antioxidants. I. Kinetics and Mechanism of the Decomposition of Alkylhydroperoxides by o‐Phenylene Phosphites and PhosphatesThe reaction mechanism of 2‐(2, 6‐di‐tert‐butyl‐4‐methyl‐phenoxyl)‐1,3,2‐benzodioxaphosphole (1) with cumyl and t‐butyl hydroperoxide has been studied kinetically by means of31P‐n.m.r. spectroscopy and high pressure liquid chromatography.1reacts with cumyl hydroperoxide to give the corresponding 2‐oxide (2) which with more hydroperoxide and/or water forms the open chained phosphate ester5. This acidic phosphate decomposes hydroperoxide catalytically. The kinetic parameters of the separate reaction steps are given. The ionic mechanism of hydroperoxide decomposition is accompanied by a homolytic

ISSN:0021-8383    

DOI:10.1002/prac.19823240502

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Organophosphorus Antioxidants. II. Kinetics and Mechanism of the Decomposition of Alkylhydroperoxides by Esteramides of Phosphorous and Phosphoric AcidThe reaction mechanism of 2‐amido‐1,3,2‐benzodioxaphospholes (1) with cumyl and t‐butylhydroperoxide has been studied kinetically by means of31P‐n.m.r. and e.p.r. spectroscopy and high pressure liquid chromatography.1reacts with cumyl hydroperoxide to give the corresponding 2‐oxides (2) which with more hydroperoxide and/or water form the phosphate esters7and8. These acidic phosphates decompose cumyl hydroperoxide catalytically giving phenol and acetone.All amides (1) react with t‐butyl hydroperoxide stoichiometrically to give t‐butanol.The ionic mechanism of hydroperoxide decomposition is accompanied in a minor proportion by a

ISSN:0021-8383    

DOI:10.1002/prac.19823240503

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Nucleophilic Substitution to Carbonic Acid Derivatives. XVI. Kinetics and Mechanism of N,N,N′‐Triphenylchloroformamidin HydrolysisFirst order rate constants of N,N,N′‐triphenylchloroformic amidine hydrolysis in dioxane‐water have been determined by u.v.‐spectroscopy. The effects of water concentration, addition of KClO4, LiCl, HgCl2, and AgNO3or nucleophilic agents (piperidine) as well as isotopic effects have been investigated. Activation entropy and enthalpy have been determined. According to the data obtained the reaction takes place in two steps – chlorionization and reaction of the formed cation with the nucleophilic agent. Both steps have rates of the same order of magnitude, but can become slow steps in specif

ISSN:0021-8383    

DOI:10.1002/prac.19823240504

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Solvolyse von cis‐ und trans‐2‐Phenylcyclohexyl‐p‐brombenzen‐sulfonatenDie Solvolyse von cis‐ and trans‐2‐Phenyl‐cyclohexyl‐p‐brombenzensulfonaten wurde in Essigsäure, wäßrigem Dioxan und wäßrigem Ethanol untersucht und mit der des Cyclohexylsulfonatesters verglichen. In Essigsäure liegt die Geschwindigkeit des cis‐Isomeren gegenüber dem trans‐Isomeren um den Faktor 5 höher, in wäßrigem Dioxan und wäßrigem Alkohol dagegen um den Faktor 10 bzw. 12.Produkte der Acetolyse sind hauptsächlich Eliminierungsprodukte (1‐ und 3‐Phenylcyclohexen 75%) und cis‐ und trans‐Acetate (25%). In wäßrigen Lösungsmitteln entstehen vorwiegend Eliminierungsprodukte (98%).Die Erhöhung der Geschwindigkeit des cis‐Isomeren gegenüber der trans‐Verbindung ist auf eine sterische Beschleunigung zurückzuführen.Ein solvatisiertes Ionenpaar wurde als Zwischenprodukt postuliert; f

ISSN:0021-8383    

DOI:10.1002/prac.19823240505

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Komplexe der Dipicolinsäure und verwandter Verbindungen zur Oxidation organischer SubstrateDie Oxidation von methylierten Hydrochinonen zu Chinonen und von α,β‐ungesättigten Alkoholen zu Aldehyden in Gegenwart verschiedener Oxidationsmittel wurde untersucht.Günstige Ergebnisse wurden bei der Anwendung des MnO2‐Dipikolinsäure‐Systems für d'e Oxidation von Allyl‐ und Benzylalkoholen und des AgO‐Dipikolinsäure‐Systems für die oxidative Demethylierung von methylierten Hydrochinonen erreicht.Der Einfluß der Struktur von 4‐substituierten Dipicolinsäuren auf die katalytischen Eigens

ISSN:0021-8383    

DOI:10.1002/prac.19823240506

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Studies on UV/Vis Absorption Spectra of Azo Dyes. VI. The Effect of Substituents on the Color of Derivatives of 1‐Phenylazo‐2‐naphtholsThe absorption spectrum of 1‐(4′‐diethylaminophenylazo)‐2‐naphthol has been examined, and it has been found that the absorption band at 510 nm corresponds to the azo form and the shoulder at 610 nm corresponds to the hydrazone tautomeric form. Substituents in 3‐position of 2‐naphthol which have a free proton (e.g. OH, COOH, CONHR) stabilize the hydrazone tautomeric form by an intramolecular hydrogen bonding between substituent and hydrazone oxygen. Substituents which have not a free proton (e.g. OCH3, COOCH3, CONR1R2) have little influence on the absorption spectrum.The relative intensities of the two bands of the tautomeric forms are dependent on:— the electron attracting or electron releasing effect of the substituent R in CONHR— the hydrogen bonding acidity of the substituents in 2′‐position if R in CONHR is a phenylring— the hydrogen bonding acidity of the solvent.The effect of substituents in the phenylaz

ISSN:0021-8383    

DOI:10.1002/prac.19823240507

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Photochemistry of Substituted Cycloheptatrienes. XV. About the Characterization of the Electronic Transitions in 1‐Aryl‐4‐(p‐dimethylaminophenyl)‐cycloheptatrienesThe absorption spectra of the title compounds are discussed in dependence on polarity of the solvent and its ability to form hydrogen bonds. The results suggest a hybridization of the N‐atom of the dimethylamino group between sp3and sp2in the ground state. Contrary to this, the nitrogen has sp2‐hybridization in the short wavelength (SE) fluorescing state. In a second fluorescence state the geometry of the seven‐membered ring should change. Therefore the viscosity of the solvents influences both the position and the quantum yield of this long wavelength emission (LE). The influence of polarity and viscosity of the solvents is described by multiple regression. The temperature dependence of fluorescence quantum yields is dis

ISSN:0021-8383    

DOI:10.1002/prac.19823240508

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Determination of the Zero Field Parameters Optically Excited3(π,π*)‐States in Selected Aromatic SystemsExperimental zero field parameters of optically excited naphthalene and quinoxaline derivatives are presented. The (D*), (D) and (E) parameters are determined by the position of the transitions by means of simple approximation formula, magnetophotoselection and simulation of spectra. Possibilities of comparison of the zero field parameters of optically excited3(π,π*)‐states with parameters of ground state for simple aromatic hydrocarbones are pr

ISSN:0021-8383    

DOI:10.1002/prac.19823240509

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Freie Radikale des Phenothiazins und ähnliche Verbindungen. IV. Phenothiazinyl‐ und Diphenothiazin‐Kupferkomplexe als Zwischen‐ und Endprodukte in der Reaktion von Phenothiazin mit Kupfer (II)‐halogenidenDarstellung und Eigenschaften einiger Komplexverbindungen des 10‐Phenothiazinylradikals und deren Dimerisierungsprodukte mit Cu(I)‐ und Cu(II)‐ionen werden beschrieben.Ein Mechanismus für die selektive Chlorierung von Phenothiazinen in Position 1 mittels CuCl2wird diskutiert. Die Möglichkeit ähnlicher Bromierungen mittels CuBr2

ISSN:0021-8383    

DOI:10.1002/prac.19823240510

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

1,2,3‐Triazabutadienes. XV. Substituent Effects on the Nitrogen‐15 and the Carbon‐13 Chemical Shifts of Triazabutadienes and AzobenzenesNitrogen‐15 and carbon‐13 chemical shifts are reported for15N‐enriched p‐substituted triazenes1, triazenium salts2and azobenzenes3. Linear correlations between substituent induced shifts for various15N‐ and13C‐atoms and σ‐Hammett constants was found and discussed. The sensitivity of the chemical shifts of both nuclei to substituent effects in analogously constituted co

ISSN:0021-8383    

DOI:10.1002/prac.19823240511

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY