摘要:

Investigation of Reactions of Pyrazolin‐Azomethin Dyes with 2‐Pyrazolin‐5‐oneThe pyrazolin‐azomethin dyes (3a–d) from 1‐phenyl‐3‐methyl‐2‐pyrazolin‐5‐one and various photographic developers have been obtained. The reactions of decolourization of dyes during the 3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one action was investigated. We ascertained that the substituent changes in the developer had not only the influence on decolourization rate but they also had influence on the order change of the reaction. The various solvents had the same influence

ISSN:0021-8383    

DOI:10.1002/prac.19863280202

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

On the Interpretation of Relative Binding Constants of Complexes with Lanthanide N.M.R. Shift ReagentsThe determination of relative complex binding constants of lanthanide n.m.r. shift reagents (LSR) with organic molecules are based on the assumption that in all cases 1:1 complexes exist. A new interpretation of relative binding constants is given which is applicable also to 1:2 complexes. The new defined constant K* describes the relative tendency of the substrate under consideration to form LSR complexes.Using this method it is shown that Eu(fod)3and Pr(fod)3form other complexes than that of the 1 : 1 type.The K* of benzaldehyde‐LSR complexes correlate linearly with the Hammett substituent parameters.The occurrence of other than 1:1 associates in the complex formation of para‐substituted benzaldehydes with Eu(fod)3and Pr(fod)3, respectively, could be shown; so we used the new model for these systems. The lg K* of the benzaldehydes in its reaction with the mentioned LSR, as well as with Eu(dpm)3, correlate linearly to the Hammett parameter of the para‐substit

ISSN:0021-8383    

DOI:10.1002/prac.19863280203

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. IX. Regiochemistry of Electrophilic Cyclofunctionalization of β,γ‐Unsaturated Carbamic Acid Esters with Bromine – Synthesis of Oxazolidine‐2‐ones and Tetrahydro‐2H‐1,3‐oxazine‐2‐onesN,N‐Disubstituted β,γ‐unsaturated urethanes (1) and bromine react in methylene chloride at room temperature. The crotyl urethanes (1a–1cand1e) and bromine give mixtures of corresponding saturated urethanes (dibromine adducts) (2a–2cand2e), the oxazolidine‐2‐ones (3a–3cand3e), and the tetrahydro‐2H‐1,3‐oxazine‐2‐ones (4a–4cand4e). The reaction of γ,γ‐dimethylallyl urethanes (1f–1h) with bromine gives similar results. A useful synthetic route to N‐substituted tetrahydro‐2H‐1,3‐oxazine‐2‐ones (4l–4q) is

ISSN:0021-8383    

DOI:10.1002/prac.19863280204

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. X. Reaction of N‐Cinnamyl Carbamic Acid Esters with Sulfenyl Chlorides—Synthesis of 3,5‐Disubstituted Oxazolidine‐2‐onesN‐Cinnamyl urethanes1have been cyclized to 3,5‐disubstituted oxazolidine‐2‐ones3by aromatic sulfenyl chlorides in methylene chloride. The tetrahydro‐2H‐1,3‐oxazine‐2‐ones6were obtained by reaction of 5‐bromotetrahydro‐2H

ISSN:0021-8383    

DOI:10.1002/prac.19863280205

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Configuration and Thermochromic Properties of Benzoine Hydrazone DerivativesZ‐Benzoine aroylhydrazones (2a–d), E‐benzoinephenylether phenylhydrazone (4) and E‐benzoinephenylether p‐chlorobenzoylhydrazone (5), respectively, are produced by acid‐catalyzed reaction of benzoine and corresponding hydrazone derivatives. The configuration of these new compounds are proved by their u.v.‐spectra and n.m.r.‐spectra data. In comparison to the Z‐isomers, the E‐isomers possess a hypsochromically shifted electron transition. In the n.m.r.‐spectra the Z‐isomers can be detected by a downfield N–H‐signal. Only the aroylhydrazones2have thermochromic properties in methanolic solutions, based on a geometrical E/Z‐isomerization. The kinetic and thermodynamic data of this reaction agre

ISSN:0021-8383    

DOI:10.1002/prac.19863280206

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Investigations Concerning Sensitization of Silver Free Information Recording Materials with Azo Dyes and Polyhalogen CompoundsRecording materials mentioned in the title are sensitive to the visible region of light. The reason therefore is an energy transfer from the azo dye to the polyhalogen compounds, preferentially CBr4. It's possible to separate the absorption spectra of azo compounds used in this work into two gaussian functions, which relates to n,π*‐ and π,π*‐transitions. Only the excitation of the n,π*‐transition causes sensitization. A mechanisms of sensitization is

ISSN:0021-8383    

DOI:10.1002/prac.19863280207

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Structure of New Systems of ThiatriazinesDepending on the nucleophilicity of exocyclic nitrogen in 2‐guanidino‐benzimidazole‐1‐carbimidic esters and 1‐carbamides cyclization with N‐sulfinyl amines leads to new 3‐amino‐1λ4, 2,4,6‐thiatriazino[2,3‐a]benzimidazole‐1‐oxide‐5‐carbimidic esters (3), 1‐oxide‐5‐carbamides (5) and 3‐(4‐chlorphenylamino)‐1‐toluene‐sulfonylimino‐1λ4,2,4,6‐thiatr

ISSN:0021-8383    

DOI:10.1002/prac.19863280208

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

4‐Acyl‐2‐acylamino‐4,5‐dihydro‐1,3,4‐thiadiazoles by Acylation of ThiosemicarbazonesThiosemicarbazones and acid anhydrides or halides react to 4‐acyl‐2‐acylamino‐4,5‐dihydro‐1,3,4‐thiadiazoles (2a–2v) in high yields. 3‐Acyl‐2‐amino‐4,5‐dihydro‐1,3,4‐thiadiazoles5are proved as intermediates in this conversion. In special cases they can be isolated or submitted to further acylation with an other acylating agent.1H‐n.m.r.,13C‐n.m.r. and mass spectroscopic data of compounds2a–2vand5a–5eare given. The preparation of the compounds2can also be carried out starting with a carbonyl compound and thiosemic

ISSN:0021-8383    

DOI:10.1002/prac.19863280209

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Reactions of Geminal Dithiolates with (Z)‐1,4‐Dichloro‐but‐2‐eneGeminal dithiolates2and7react with (Z)‐1,4‐dichloro‐but‐2‐ene either to give 4‐vinyl‐1,3‐dithiolanes3or 4, 7‐dihydro‐1,3‐dithiepines4and8, respectively. Another method for the synthesis of4and8is the reaction of ketene dichlorides5or isocyanide dichloride9with the disodium salt of (Z)‐but‐2‐ene‐1,4‐dithiol. The formation of the corresponding 1,3‐dithiolanes can be excluded in these cases.1H‐ and13C‐n.m.r. spectra are in a

ISSN:0021-8383    

DOI:10.1002/prac.19863280210

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Radical Reactions of N‐Heterocyclic Compounds. V. ESR‐Investigation of Nitroxide Radicals of Substituted 3‐Anilino‐1,5‐diphenyl‐pyrazolesThe correlation of the e.s.r. splitting constants with the Hammett values for nitroxides from substituted 3‐anilino‐1,5‐diphenylpyrazoles1a–eand substituted 1,5‐diphenyl‐3‐p‐toluidino‐pyrazoles1f–iprovides evidence for extensive interannular conjugation between the N1‐benzene ring and the pyrazole ring of these nitroxides. The conjugation between the arylamino group and the pyrazole ring is extensive only in the nitroxides derived from1f–i. The captodative substituted p‐toluidino‐nitroxides2g, hhave a better spin distribution than the nitroxide2i

ISSN:0021-8383    

DOI:10.1002/prac.19863280211

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY