摘要:

Reaction of Hepten‐(3) and Allyl Cyanide with CoO/MoO3/Al2O3and WO3/SiO2CatalystsThe influence of the β nitrilgroup in allylcyanid was determined by comparison of the activity of hepten‐(3) and allylcyanid.Hepten‐(3) give with CoO/MoO3/Al2O3and WO3/SiO2catalysts mainly methathesis which is never observed with allylcyanid. This product gives only isomerisation in crotonitril and finally dimerisation – trimerisation of t

ISSN:0021-8383    

DOI:10.1002/prac.19783200202

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Heteroorganic Substances. IL. Reactions between N‐morpholinosulfenylchloride and Ethane‐alcoxy‐thiophosphonous Acids and Ethane‐ethyl‐dithiophosphonic AcidThe syntheses of bis‐(ethane‐alkoxy‐thiophosphonyl)‐monosulfides3a–cand bis‐ethane‐ethoxy‐thiophosphonyl)‐trisulfide5are described. It is established, that the reaction path depends on the acidity of the starting compounds. In the first case (pK ∼ 7 the reactions between ethane‐alkoxy‐thiophosphonous acids and morpholinosulfenylchloride are three‐step reactions, the intermediates being the unknown S‐morpholino‐ethane‐alkoxy‐dithiophosphonates1a–cas well as the sulfenylchlorides of ethane‐alkoxy‐thiophosphonic acid2a–c. In the second case (pK ∼ 3) a fourth reaction has to been taken into account. The intermediate sulfenamide derivatives are isolated and characterised. The sulfenylchlorides derivatives could not been isolated; their prese

ISSN:0021-8383    

DOI:10.1002/prac.19783200203

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Liquid Crystalline Phenyl‐trans‐4‐n‐alkylcyclohexanecarboxylatesThe syntheses of p‐substituted phenyl‐trans‐4‐n‐alkylcyclohexanecarboxylates1–12and cyclohexyl‐p‐n‐alkylbenzoates15–17and their mesomorphic properties are described. p‐n‐Alkoxyphenyl‐trans‐4‐n‐alkylcyclohexanecarboxylates1–8exhibit larger thermal stability of mesophases than analogous phenylbenzoates13. Trans‐4‐subst. cyclohexyl‐p‐n‐alkylbenzoates15–17and S‐phenyl‐thio

ISSN:0021-8383    

DOI:10.1002/prac.19783200204

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Synthesis and Photochemistry of Sydnonazomethines‐(4)Sydnon‐4‐aldehydes1–3react with prim. amines or N‐sulfinylanilines to sydnon‐azomethines. The i.r.‐spectra are discussed. Sydnonazomethines undergo a photoinducedE/Z‐isomerisation, at room temperature; a rapid thermic back‐reaction (Z/E‐isomerisation) takes place, however. The photostationary states at −75°C are analyzed. The rate constants of the thermic back‐reaction at 18°C are measured by means of flash‐photolysis. The quantum yields for theE/Z‐isomerisation (at −75°C) and the photolytic decomposition have the

ISSN:0021-8383    

DOI:10.1002/prac.19783200205

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Studies on the Formation of the Arg‐Arg Bond Using Different Coupling MethodsThe protected peptide Boc‐Arg(NO2)‐Arg(NO2)‐Glu(OBzl)‐Ala‐OBzl, prepared by condensation of Boc‐Arg(NO2) with Arg(NO2)‐Glu(OBzl)‐Ala‐OBzl, was synthesized by ten different coupling methods. On the basis of the yields obtained and the purity of the product the coupling methods were compared concerning their efficiency on forming the Arg‐Arg bond. The best results were obtained using the mixed anhydride method and the pentafluorophenyl ester pr

ISSN:0021-8383    

DOI:10.1002/prac.19783200206

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Analysis of Hydrocarbons by Means of Mass Spectrometry. IV. The Quantitative Determination of Paraffins by Low Voltage Electron ImpactThe exactness of the quantitative determination of paraffins by means of electron impact mass spectrometry on the basis of the molpeak methodes can be much improved by reducing the ion‐source temperature.The time for carrying out the analysis in order to determine calibrated values is reduced by using the ion‐source of the mass spectrometer as a pressure measuring‐instrument.The determination of the amount of iso‐paraffines is possible by the sum of molpeak‐intensities with a relative deviatio

ISSN:0021-8383    

DOI:10.1002/prac.19783200207

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Vibrational Spectroscopic Investigation of Some 4,4′‐Bisseleno‐Substituted Azobenzene and Biphenylene CompoundsInfrared‐spectra of 4,4′‐dibromazobenzene, 4,4′‐bis(selenenylbromido)azobenzene, 4,4′‐bis(selenenylbromido)biphenyl, some 4,4′‐bis(alkylseleno)azobenzenes (alkyl = methyl, n‐butyl, n‐octyl), 4,4′‐bis(alkylseleno)biphenyl (alkyl = methyl, ethyl), and the raman‐spectra of 4,4′‐dibromazobenzene, 4,4′‐bis(methylseleno)azobenzene, and 4,4′‐bis(methylseleno)biphenyl are given and assigned. The alkylseleno groups and the diselenoazobenzene or diselenobiphenyl groups, resp., are spectroscopically independent. The spectroscopic results suggest a planar structure of the biphenyl (and, of

ISSN:0021-8383    

DOI:10.1002/prac.19783200208

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

On the Preparation of Isocyanatoderivatives of Aliphatic DiethersA method for the preparation of some isocyanates of aliphatic diethers of the general formula: CH3(NCO)O[CH2]nOCH(NCO)CH32a–e, where n = 1–5 has been reported. The syntheses conditions, properties, as well as the conversion of the obtained diisocyanates into the new urea derivatives wer

ISSN:0021-8383    

DOI:10.1002/prac.19783200209

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Reactions of Cyclobutendiones. LII. Reaction of 4‐Hydroxy‐3‐phenyl‐3‐cyclobuten‐1‐ones with ArylhydrazinesIn the reaction of hydroxycyclobutenones of the typ1–4with arylhydrazines5an unexpected reaction behaviour is found. The major products are hydrazones of different structure, the well known hydroxy‐cyclopropane‐carboxylicacid hydrazines6[1] are byproducts. The direction of the reaction depends on the substituents X, on the different substituted arylhydrazin

ISSN:0021-8383    

DOI:10.1002/prac.19783200210

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

A Simple Calculation Method for the Estimation of the Inductive Effect of Different SubstituentsA new method without great mathematical operations for the estimation of the inductive effect of any substituents is described. The starting values are the electronegativities and the bond lengths of the atoms of the corresponding substituent.The IDvalues, received by this method show a good correlation with the known electronic parameters (

ISSN:0021-8383    

DOI:10.1002/prac.19783200211

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY