摘要:

AbstractStarting from 2‐methyl‐ and from 2,3‐dimethyl‐1,4‐diphenyl‐butadiene‐1, 3 respectively, the 5‐methyl‐ and the 5,6‐dimethyl‐11, 12‐dihydro‐indeno[2.1‐a]fluorene are synthesized in 4 steps. The 5, 6‐diphenyl‐11, 12‐dihydro‐indeno[2.1‐a]fluorene is obtained by reduction of the already known 11, 12‐dioxoderivative. Accesorily a new preparation of the

ISSN:0018-019X    

DOI:10.1002/hlca.19720550502

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractThe stereochemistry of the epoxycardanolides8,21,24and33, derived from digitoxigenin (1), digoxigenin (15), 3β, 14, 15β‐trihydroxy‐5β, 14β‐card‐20(22)‐enolide (23) and gitoxigenin (27) respectively, is discussed on the basis of NMR. data. In the case of1and15the absolute configuration of the chiral centres C(20) and C(21) is assigned. Treatment of the cardenolides with KOH in methanol gave on dilution with methanol and subsequent acidification a number of acetal derivatives, the properties of which

ISSN:0018-019X    

DOI:10.1002/hlca.19720550503

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractAn X‐ray crystal structure investigation of the macrotetrolide antibiotic nonactin is reported. The shape of the molecule is discussed with special reference to the conformational changes involved in passing from free nonactin to the K+‐comp

ISSN:0018-019X    

DOI:10.1002/hlca.19720550504

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

Abstract1‐cis, 2‐cis‐Dipropenylbenzene (cis,cis‐1) isomerises thermally at 215–235° with 1st order kinetics to givetrans,cis‐1andvice versa. At equilibrium 89%trans,cis‐ and 11%cis,cis‐1are present. It is shown by thermal rearrangement ofcis,cis‐2′, 2″‐d2‐1that the isomerisation is attributable to aromatic [1, 7a]‐sigmatropic H‐shifts.trans,trans‐1rearranges thermally at 225–245° to yield 2, 3‐dimethyl‐1, 2‐dihydronaphthalene (2). The formation of2can be visualized by disrotatory ring closure followed by an aromatic [1, 5s]‐sigmatropic H‐shift.2is also formed when,cis,cis‐ ortrans,cis‐1are heated for 153 h at 225°. Besides2a small amount (3%) of 1‐ethyl‐1, 2‐dihydronaphthalene (5) is formed. The rearrangement oftrans,trans‐1andtrans,tr

ISSN:0018-019X    

DOI:10.1002/hlca.19720550505

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractThe scheme 1 shows those tetrahydro‐ and dihydroderivatives of the 3,6‐dimethyl‐1,2,4,5‐tetrazine (ors‐tetrazine),8, which are theoretically possible without consideringcis‐transisomerism, together with the reaction pathways. We did not succeed in synthetizing the 3,6‐dihydroderivative,7, and could not isolate the 1,2‐dihydrocompound,4, the latter being probably easily convertible to the thermodynamically more stable 1,4‐dihydro‐s‐tetrazine,5,viatheir common conjugate base4,5B. The 1,4‐dihydro‐s‐tetrazine,5, gives with 3,6‐dimethyl‐s‐tetrazine8, a charge transfer complex,15. The same compounds form in acidic or basic aquious solution stable radicals,16Band16S. The mode of formation of these radicals and the subsequent r

ISSN:0018-019X    

DOI:10.1002/hlca.19720550506

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractThe ‘observed’ π‐orbital energies ϵv,j= −Iv,jderived from the vertical ionization potentials obtained by a photoelectron spectroscopic investigation of the acenes benzene A(1), naphthalene A(2), anthracene A(3), naphthacene A(4) and pentacene A(5) have been compared with π‐orbital energies calculated by three different approximations: (a) the standardHückelHMO model; (b) a first‐order perturbation treatment, based on (a), that takes into account bond length changes which follow the ionization process; (c) a SCF π‐electron model of the type proposed byPopleand byPariser&Parr. In agreement with previous experience it is found that model (b) yields the most satisfactory parametrization of the

ISSN:0018-019X    

DOI:10.1002/hlca.19720550507

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractThe solubility of thallium sulfide in 1MNaClO4at 25° ranges between 105Mas a function of pH and total sulfide concentration.Soluble thallium was analysed by anodic stripping using the hanging mercury drop electrode.The following complexes have been identified and their stability constants calculated: Tl2(HS)+, Tl(HS), Tl2(OH) (HS) 22−and Tl2(OH)2(HS)

ISSN:0018-019X    

DOI:10.1002/hlca.19720550508

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractThe preparation and some properties of large lead halide crystals are described. The photolysis of these crystals was followed by chemical etching (photosolubilization), showing that the rate of solubilization decreases if the crystal is exposed in the presence of oxygen.

ISSN:0018-019X    

DOI:10.1002/hlca.19720550509

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractThe enthalpies of formation of the nine cyclic ketones CnH2n−2O (n = 4–12) were determined by combustion calorimetry. The heats of vaporization were determined by measuring the vapor pressure as a function of temperature and the heats of fusion of the three compounds with n = 8, 9, 12 which are solids at room temperature, by

ISSN:0018-019X    

DOI:10.1002/hlca.19720550510

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY

摘要:

AbstractDie Darstellung von 2‐Dicyanmethylen‐indandion‐1,3‐monophenylhydrazonen wird beschrieben und die intensive, blaugrün bis violette Farbe der Verbindungen2a–ddiskutiert. Durch Vergleich mit dem gelb gefärbten 2‐Isopropyliden‐indandion‐1,3‐monophenylhydrazon (3c) wird der spezifische Einfluss der Dicyanmethylengruppe auf den Farbcharakter nachgewiesen.2 aundbsind thermisch und lösungsmittelabhängig instabil und cyclisieren zu substituierten Indenopyridazinen4a–b, deren chemische Reakt

ISSN:0018-019X    

DOI:10.1002/hlca.19720550511

出版商:WILEY‐VCH Verlag GmbH    

年代:1972

数据来源: WILEY