摘要:

AbstractHeterolytic fragmentation is a widespread but neglected class of organic reactions. It involves the regulated cleavage of molecules containing certain combinations of atoms such as carbon, oxygen, nitrogen, sulfur, phosphorus, silicon, boron and halogens. Fragmentation reactions are useful in degradation and structure elucidation, some are also of preparative value. A knowledge of the structural and electronic requirements makes it possible to predict and influence the course of reactions. From a theoretical viewpoint the recognition of heterolytic fragmentation has lead to the classification and correlation of a large number of apparently diverse reactions. Selected cases are reviewed in this article.

ISSN:0570-0833    

DOI:10.1002/anie.196700011

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

摘要:

AbstractThe possible mechanisms of the preparatively so productive Diels‐Alder reactions are discussed critically on the basis of experimental data. Although most of the facts can be explained readily by a synchronous mechanism, a number of problems remain

ISSN:0570-0833    

DOI:10.1002/anie.196700161

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

摘要:

AbstractThe distribution of the unpaired electron over the oxygen and the 24 carbon atoms in the free 2,4,6‐triphenylphenoxy radical was determined by electron spin resonance spectroscopy and quantum‐mechanical approximation methods. The hyperfine splitting was evaluated with the aid of the spectra of triphenylphenoxyls deuterated in some or all of the substituent phenyl groups. The results of the quantum‐mechanical approximations were checked by recording the ESR spectra of triphenylphenoxyls labeled with13C in positions 1,2,3, or 4 of the central ring. The spin density distribution permits a first discussion of the17O‐coupling constants of correspondingly labeled triphenylphenoxyl and other organic free r

ISSN:0570-0833    

DOI:10.1002/anie.196700341

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

摘要:

AbstractSome years ago we found that α‐halogenoorganolithium compounds (carbenoids) previously postulated as transient intermediates in organolithium‐initiated α‐eliminations can be obtained in a stable form. The present paper is a review of the methods for their preparation and of their reactivity. They possess both nucleophilic and electrophilic properties, which can be utilized singly or combained for the synthesis of substances of very different types. Their thermolability, which is considerably reduced (with only one known exception) by the solvent tetrahydrofuran, is due to electrophilic secondary reactions, in which carbenes evidently do not occur as intermediates. A mechanism is proposed which fits the experimental data for various carbenoid re

ISSN:0570-0833    

DOI:10.1002/anie.196700411

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

摘要:

AbstractThe present paper deals with a new class of inorganic coordination compounds, the first member of which, tetrakis(trifluorophosphine)nickel(0), was discovered in 1951. Not only have the neutral metal(0) trifluorophosphines been prepared, but also a number of their derivatives (trifluorophosphinemetal hydrides and trifluorophosphinemetallates, as well as nitrosyl, carbonyl, halogeno, and aromatic trifluorophosphine complexes). These compounds have been characterized by their chemical behavior and by spectroscopic and magnetochemical studies. Trifluorophosphine has the strongest π‐acceptor properties of all neutral ligands, and is therefore particularly suitable for the stabilization of unusually low oxidation states (zero and negative) of transition meta

ISSN:0570-0833    

DOI:10.1002/anie.196700531

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

摘要:

AbstractHalogen lamps have been on the market for some time; they are replacing the conventional lamp in many fields except general service (domestic) applications. Their relatively small bulbs contain small amounts of halogen is addition to an inert gas. The mode of action of the iodine lamp, which depends on the presence of traces of oxypgen, has been elucidated. Tungsten evaporating from the filament is returned to it by a cyclic process involving a tungsten oxide and WO2I2. No tungsten is ever deposited on the bulb wall of such a lamp. A regenerative cycle in which the vaporized tungsten is deposited on the hottest (and hence most vulnerable) parts of the filament can, in principle, be realized by the use of fluorine compounds.

ISSN:0570-0833    

DOI:10.1002/anie.196700681

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196700742

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196700752

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196700762

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196700771

出版商:Hüthig&Wepf Verlag    

年代:1967

数据来源: WILEY