摘要:

AbstractChromium(II) salts can be used for a variety of reductions in organic chemistry; for example, alkyl halides and suitably substituted olefins may both be reduced to alkanes, and alkynes may be converted into trans‐olefins. Several epoxyketones are reduced to α,β‐unsaturated ketones or β‐hydroxyketones, and a nitro steroid was found to give a hydroxy(hydroxyimino) compound. The reduction of alkyl halides is reported to proceed by a free‐radical mechanism; the halogen atom that is set free forms a bridge between two chro

ISSN:0570-0833    

DOI:10.1002/anie.196802471

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractAs a result of the development of measuring techniques, analytical chemists can now determine very small quantities as well as trace concentrations of the order of 10−8% with good accuracy. In exceptional cases it is even possible to detect 105atoms of an element. In this review, definitions of important analytical terms are outlined and a critical appraisal of the principal methods of trace analysis is give

ISSN:0570-0833    

DOI:10.1002/anie.196802521

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractThe present article deals with methods and results of conductance studies with special reference to nonaqueous solvents, e.g. ethanol, dioxane, dimethylformamide, acetonitrile, nitromethane, and acetone, in some cases mixed with water, as well as NH3, SO2, I2, etc. On the basis of a model in which the ions are represented as charged spheres and the solvent as a homogeneous isotropic medium, the conductance theory can (at least for low electrolyte concentrations) give a more or less complete representation of the problem. A new statistical treatment of the transport problem confirms important results of this representation. The present state of the investigation is finally outlined in a review of recent publications.

ISSN:0570-0833    

DOI:10.1002/anie.196802601

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractHigh molecular weight poly‐β‐amides with fiber‐forming properties (repeating unitNHCR2CR2CO) differ from the polyamides of the nylon series in that the amide groups are much more closely spaced. These polymers are thus the nearest of the synthetic polyamides to natural silk. The production of poly‐β‐amides was made possible by a recent synthesis of β‐lactams from olefins and chlorosulfonyl isocyanate. The anionic polymerization of the β‐lactams gives poly‐β‐amides containing up to 10 000 monomer units in the chain. The molecular weight can be controlled as desired by means of initiators and chain terminators, and the properties can be varied within wide limits by the choice of the β‐lactam or by copolymerization of several β‐lactams. Remarkable differences are observed between polymers containing structural units in the threo form and those containing erythro structural units. The poly‐β‐amides can be spun int

ISSN:0570-0833    

DOI:10.1002/anie.196802781

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196802862

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196802881

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196802891

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196802901

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196802912

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196802921

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY