摘要:

Preparation, Configurations and N.M.R. Dates of the Acids CH3(SR)CHCOOH (R  C6H5, CH2C6H5, CH2COOH)The cis and trans isomers of the acids CH3(SR)CHCOOH (R  C6H5, CH2C6H5, CH2COOH) were prepared by addition of HSR to CH3CCCOOH in alkaline water solution and by alkaline hydrolysis of CH3C(SR)2CH2COOC2H5(R  C6H5, CH2C6H5, CH2COOC2H5). The oxidation products CH3C(SO2R)  CHCOOH (R  C6H5, CH2COOH) were also prepared. The n.m.r. dates of the acids were obtained and some relations between them

ISSN:0021-8383    

DOI:10.1002/prac.19783200302

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

MO‐LCAO Calculations on Polymethines. IX. On the Chromaticity of Coupled Oxonol and Cyanine DyesStreptopolymethines display low‐energy electronic transitions with a high transition probability and possess, moreover, a high capability to accept or to release electrons. These properties account for the absorption colour of polymethine dyes consisting of two molecular fragments. Scope and limitations of a composite‐molecule approach can be recognized by subjecting the electronic wavefunctions to the so‐called configuration analysis. Colour‐structure relationships are derived from inspection of key orbital interactions between the molecular

ISSN:0021-8383    

DOI:10.1002/prac.19783200303

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

13C‐N.M.R‐Investigations of Steroids. III. Steric Effects of 2,3 Substituted Cholestane Derivatives and their Application for the Configurational AnalysisThe steric effects on13C chemical shifts and their use for the determination of the substituent configuration of 5α and 5β‐cholestane (cholestane and coprostane), their 3‐OH derivatives and some 2‐mono‐ and 2,3‐disubstituted cholestanes are investigated. Because the substituent effect of the C8H17group at C‐17 of cholestane and coprostane is very small for the carbon atoms of the rings A and B of the steroid skeleton, the discussed results are useful also for androstane derivatives with and without substituti

ISSN:0021-8383    

DOI:10.1002/prac.19783200304

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

α‐Substituted Phosphonates. XXXI. The Reaction of N,N,N′,N′‐Tetramethyl Chloroformamidinium Chloride with P(III) CompoundsN,N,N′,N′‐Tetramethyl chloroformamidiniumchloride (4) does not react with triethyl phosphite (TEP) or isopropyl diphenylphosphinate to give the expected bisphosphoryl derivatives7and11, respectively, but primarily the monophosphorylated amidinium salts6and10respectively. The phosphine oxide10is stable, while6undergoes an elimination of ethyl chloride to the betain8. Even under more drastic conditions the reaction of4or8with TEP does not lead to the expected bis(dimethylamino)bisphosphonate7, but to the monoaminated bisphosphonate1, involving a reduction step. Similar reduction has been observed under mild conditions in Michaelis‐Arbusov reaction of dichloromethylenimonium chloride, yielding the expected trisphosphonate2and the bisphosphonate

ISSN:0021-8383    

DOI:10.1002/prac.19783200305

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Alternant and Nonalternant Polymethines – a Generalisation of the Hitherto Existing Colour RulesIn alternant polymethines the characteristic π‐electron density alternation is maintained on branching or other modification of the structure. Alternant polymethines commonly absorb at shorter wavelengths than the parent non‐branched polymethine units.Nonalternant polymethines are characterised by a perturbation of the uniform π‐electron density alternation. They absorb at considerably longer wavelengths than the constituent non‐branched polymethine units.If the polymethine structure of alternant and nonalternant polymethines is changed in favour of aromatic or polyenic systems the light absorption is shifted generally to shorter

ISSN:0021-8383    

DOI:10.1002/prac.19783200306

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Conductive Polymers with Tetrathiafulvalene StructureSynthesis and properties of phenylene‐ and biphenyl‐bridged polymer tetrathiafulvalenes are described. These polymers react with bromine or iodine and provide the radical‐cationhalides, whose electrical conductivity as powder compactions are estimated. The conductivity depends on stoichiometric composition of the radicale‐salts. The phenylene‐bridged polymer‐salts show a much higher conductivity than the biphenyl‐bridged ones and reach values of 10−3ω−1cm−1. The monomer salts have a higher conductivity than the polymer salt

ISSN:0021-8383    

DOI:10.1002/prac.19783200307

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Epaminations. II. Synthesis of Aziridines from Olefins and N‐HaloaminesChloramine, dichloramine as well as the N‐chloro‐ and N‐bromo‐derivatives of primary aliphatic amines react with olefins to give aziridines. Yields up to 75% are obtained by the reaction of N.N‐dibromamines with styrene‐type olefins. The reaction is shown to proceed stereo‐unspecifically by a chain‐mechanism with the radical RN·B

ISSN:0021-8383    

DOI:10.1002/prac.19783200308

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

1,2,3‐Triazabutadienes. VII. Investigation of the Mechanism of the Photochemical cis‐trans‐Isomerization of 1‐Aryl‐3‐[3‐methyl‐benzthiazolinyliden‐(2)]‐triazenesThe direct photoisomerizations of substituted triazabutadienes are investigated. The quantum yields do not considerably depend on substituents in the phenyl‐group of triazabutadienes, on the wavelength of irradiation light and on the solvent. The quantum yields of the cis→trans‐transformation are always higher than the quantum yields of the back reaction. The sums of quantum yields approximate 1. At low temperatures the quantum yields of photoisomerization become smaller in a significant way. With flash photolysis it is not possible to prove triplet state of triazabutadienes. Triplet quenchers have no influence on photoisomerization. The mechanism of the photochemical cis‐trans‐isomerization of

ISSN:0021-8383    

DOI:10.1002/prac.19783200309

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

Polyfunctionalized N‐Tensides. I. Nucleophilic Substitutions with Bischloronitrosocompounds. 1. Reactions with Amines, Mercaptans and Sodium AzideChloronitrosation of alkenes gives bischloronitrosocompounds1, which react with amines to α‐aminooximes (2and4), with mercaptans to α‐alkylthiooximes11, and with sodium azide to α‐azidooximes8. Reduction with LiAlH4gives vicinal substituted diamines (6,7,10) from α‐amino‐or α‐azidooximes (2,4,8) and β‐alkylthioamines13from α‐alkylthiooximes11.The determination ofE‐ orZ‐configuration in the α‐

ISSN:0021-8383    

DOI:10.1002/prac.19783200310

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY

摘要:

6‐Substituted 2,4‐diphenyl‐1,3,4‐oxadiazin‐5‐onesBy reaction of dichloro acetylchloride and β‐N‐phenyl benzhydrazide 6‐chloro‐1,3,4‐oxadiazin‐5‐one2is accessible which reacts with potassium phthalimide and potassium succinimide, respectively, to from 6‐phthalimido‐ and 6‐succinimido 2,4‐diphenyl‐1,3,4‐oxidiazinon (3and4), respectively. The phthalimido substituent can be s

ISSN:0021-8383    

DOI:10.1002/prac.19783200311

出版商:WILEY‐VCH Verlag GmbH    

年代:1978

数据来源: WILEY