摘要:

AbstractThe growth of interest in carbenes has led to a need for methods that allow their generation in unimolecular decomposition processes, possible also in the gas phase, without troublesome by‐products. Besides the decomposition of diazo compounds, thermal cycloeliminations from carbocycles and heterocycles with odd numbers of ring atoms have been found to be suitable for this purpose. The problems, structural requirements, and scope of such cycloelimination reactions are discussed in the present progress report. The advantages of carbene generation by thermal cycloelimination are demonstrated with reference to dialkoxycarbenes, which are very dfficult to obtain in any other wa

ISSN:0570-0833    

DOI:10.1002/anie.197105291

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractA wide variety of shelf stable substrates undergo photochemical cycloelimination under relatively mild conditions. Suitable substrates include cyclopropanes, oxiranes, aziridines, and diazirines, as well as 3 H‐pyrazoles and 1,3‐dioxolanes. Carbenes prepared from these substrates as well as certain cyclic carbonates, sulfites, and phosphoranes behave chemically in a manner similar to divalent carbon species produced from conventional diazo precursors, namely, they react with alkenes to give cyclopropanes and undergo insertion into CH bonds of alkanes. In many cases the carbenes formed may also be detected by EPR and optical spectroscopic me

ISSN:0570-0833    

DOI:10.1002/anie.197105371

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractBreaks or curvatures in the plot of log vbrvs. 1/T have been described in the literature for a number of reactions. If sufficiently small temperature intervals are used in the investigation of the temperature dependence (STI method) a trend line is obtained instead. It is then possible to distinguish regions of linear behavior and regions of anomalous behavior. The effects of e. g. the pH, the ionic strength, and added salts as well as of the size of the enzyme and substrate molecules on the anomalies were examined. The anomalous temperature dependence of the reaction rate was found to be a particularly sensitive indicator of the reaction event on the enzyme. The course of the reaction is evidently affected even by relatively small changes in conformation, particularly in the region of the active center.

ISSN:0570-0833    

DOI:10.1002/anie.197105481

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197105552

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197105561

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197105571

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197105581

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197105591

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197105601

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.197105621

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY