摘要:

Synthesis of 2‐[Benzazolyl‐(2)]‐3,3‐bis‐(alkylthio)‐acrylnitriles and Their Reactions with N‐NucleophilesThe reactions of benzazolyl‐(2)‐acetonitriles1(1H‐benzimidazolyl‐, 1‐methylbenzimidazolyl‐, benzoxazolyl‐ and benzothiazolyl‐) with carbon disulfide in the presence of sodium hydride in dimethylsulfoxide and methylation yield the 2‐[benzazolyl‐(2)]‐3,3‐bis‐(alkylthio)‐acrylonitriles3–5reacting with amines to the keten‐S,N‐acetals6–9.If dinucleophilic reag

ISSN:0021-8383    

DOI:10.1002/prac.19823240102

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

The Autoxidation of Some Asymmetric p‐DialkylbenzenesThe autoxidation mixtures of p‐ethyltoluene, p‐isopropyltoluene, and p‐ethylcumene were reduced with lithium alanate and the alcohols formed analyzed gaschromatographically. From the results obtained the relative reaction rates of primary, secondary, and tertiary CH‐bonds with the chain‐propagating peroxy radicals were estimated

ISSN:0021-8383    

DOI:10.1002/prac.19823240103

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Wittig Synthesis and13C‐N.M.R. Investigation of Pyridineanalogous ChalconesWittig type reaction of the three isomeric pyridinealdehydes with benzoylmethyl‐enetriphenylphosphorane yields azachalcones1a–cwhich have the E‐configuration. The complete13C‐n.m.r. analysis of these compounds is reported. From the chemical shifts of the Cα‐signals and on the basis of a Hammett relationship σ‐values of the three isomeric pyridine groups are calculated and compared

ISSN:0021-8383    

DOI:10.1002/prac.19823240104

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

A Simple Route to N(2′‐Hydroxy)‐arylidene‐nitroanilienes‐Versatile Synthones for CoumarinesIn a three‐component reaction with ortho formic esters and nitroaniline activated phenols are easily transferred to N(2′‐hydroxy)‐arylidene‐nitroanilines. The reaction is commonly applicable and gives the N(2′‐hydroxy‐4′‐N,N‐dialkylamino)‐benzylidene‐nitroanilines10in good yields also with the air‐unstable m‐N,N‐dialkylaminophenols8. The prepared 2‐hydroxy‐azomethines are convertable into boroncomplex

ISSN:0021-8383    

DOI:10.1002/prac.19823240105

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

d‐N.M.R. Investigations of the Restricted Rotation at the NC(X)‐Bonding Fragment. XV. Influence of the Rotational Barrier in the NR2C(X)–R1‐Bonding Fragment by Electronic and Steric Substituent Effects.The rotational barriers ΔG≠of the restricted rotation about partial C,N‐double bonds are determined for 4 series of urea‐derivatives, and analogous compounds by complete lineshape analysis and approximation equations. Some general conclusions are drawn about the validity range of the approximations independence on the low temperature splitting Δν, the possible corrections within the margin of error and the internal temperature measurement. The dependence of the determined free enthalpies of activation about the effect of heteroatoms X, the NR2‐substituents and the electronic and steric influence of the substi

ISSN:0021-8383    

DOI:10.1002/prac.19823240106

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Photooxidation of Leuco Dyes. III. Sensitized Photooxidation of Leuco FluoresceinQuantum yields of the sensitized photooxidation of leuco fluorescein are reported. Fluorescein and benzophenone were found to be efficient sensitizers of photooxidation of leuco fluorescein. There is a characteristic dependence of quantum yields on concentration of leuco fluorescein and oxygen in the solution. The results are discussed on the basis of reaction scheme proposed for the sensitized formation of fluorescein.

ISSN:0021-8383    

DOI:10.1002/prac.19823240107

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Efficiency of the Photochemical Co‐C‐Bond Cleavage in σ‐Alkyl‐Co(III)(salen)‐and‐Co(III)(salphen)‐Complexes.The photodealkylation rate of RCoIII(chel) X complexes (R = methyl, ethyl; chel = salen, salphen; X = H2O, py, PPh3) depends on the nature of ligands and solvents as well as on the concentration of oxygen and scavengers for alkyl radicals. The rapid recombination of the fragments R. and Co(chel)X is responsible for the low quantum yields of the anaerobic dealkylation. The quantum yields may reflect the H‐donating ability of the solvents used. Lewis bases X in the trans position generally cause a decrease of quantum yields relative to the pentacoordinated species RCo (chel). The anaerobic photolysis can be accelerated by the addition of scavengers for alkyl radicals (e. g. Koelsch radical, nitrosodurene, styrene). The quantum yield also increases in the presence of oxygen, preventing the recombination of the fragments of the cobalt‐carbon bond scission by forming alkyl‐peroxocomplexes ROOCo(chel)X.α‐Hydroxyalkylradicals arising from the decomposition of the ROOCo(chel)X complexes via secondary reactions probably react with the starting σ‐alkyl complexes and cause the dependence of quantum yie

ISSN:0021-8383    

DOI:10.1002/prac.19823240108

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

On the Initiation of the Polymerization of Vinylchloride with Manganese(III) ‐acetyl‐acetonateThe initation reaction of the polymerization of vinyl chloride in dimethylformamide with manganese acetylacetonate is investigated. The reduction of the transition metal, the splitting of a ligand of the metal chelat and its incorporation into the polymer molecule is proved and the structure of the initiating radical is determined. The rate and efficiency of initiation is measured by the inhibition met

ISSN:0021-8383    

DOI:10.1002/prac.19823240109

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Protonentransferreaktionen in angeregten Elektronenzuständen — Freie‐Enthalpie‐Beziehungen und kinetische Deuterium‐IsotopieeffekteFür Protonentransferreaktionen in angeregten Elektronenzuständen werden Freie‐Enthalpie‐Beziehungen und kinetische Deuterium‐Isotopieeffekte mit Hilfe der Multiphononentheorie der chemischen Reaktivität untersucht. Es wird ein Vergleich der theoretischen Freie‐Enthalpie‐Beziehungen mit allen gegenwärtigen verfügbaren experimentellen Daten entsprechender Reaktionsreihen durchgeführt. Modellrechnungen zeigen, daß unter bestimmten Voraussetzungen eine oszillierende Temperaturabhängigkeit des Isotopieeffektes zu erwarten ist. Damit kann die unterschiedliche Temperaturabhängigkeit des kinetischen Deuterium‐Isotopieeffektes für die Deprotonierung von 2‐Naphthol und C

ISSN:0021-8383    

DOI:10.1002/prac.19823240110

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY

摘要:

Synthesis of Heterocyclic Compounds by CC‐bond Closure. V. A Novel Pyridone SynthesisUnder the action of alkali two moles of N‐primary alkyl cyanoacetamides5condense to form 1‐alkyl‐5‐alkylaminocarbonyl‐4,6‐diamin

ISSN:0021-8383    

DOI:10.1002/prac.19823240111

出版商:WILEY‐VCH Verlag GmbH    

年代:1982

数据来源: WILEY