摘要:

AbstractThe differences between compounds of carbon and of silicon are discussed, and the role of silicon as a fundamental structural component in inanimate nature is described. Starting with silicic acid and silicates, the structure and properties of the silicones and of compounds having SiCSi skeletons are described. The possibilities for the formation of high molecular‐weight compounds between elements of Groups 3 and 5 of the periodic system are considered, with particular reference to boron nitride and to aluminum‐phosphorus co

ISSN:0570-0833    

DOI:10.1002/anie.196800011

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractThe present article describes the discovery of a new procedure for aldol condensations for the preparation of α,β‐unsaturated carbonyl compoundsG. Wittig,H. Pommer, andW. Stilz, German Patent 1199252 (April 5, 1963), BASF; Chem. Abstr.63, P 1739c (1965).. The scope of this process is demonstrated by many examples, including some from the natural products sector; at the same time, however, these examples also mark its limitations. The metalated Schiff's bases may be classified as ambident anions; this also explains acylations on the nitrogen. A comparison of the new directed aldol condensation with the formation of unsaturated carbonyl compounds through olefination via phosphorylids shows that the latter method fails when a ketone is used as the substrate. This is where the described procedure using metalated Schiff's bases proves its va

ISSN:0570-0833    

DOI:10.1002/anie.196800071

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractThe principles of circular dichroism and of optical rotatory dispersion are described. Examples are given to illustrate the use of these methods for the determination of the configurations and conformations of natural and synthetic products. Some limitations of the octant rule are mentioned.

ISSN:0570-0833    

DOI:10.1002/anie.196800141

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

Abstractα‐Lactams have often been postulated as intermediates in numerous processes. The isolation of the first α‐lactam, N‐tert‐butyl‐3‐phenylaziridinone, was accomplished in 1962. Since then, further N‐ and C‐3‐substituted α‐lactams have been synthesized. Most of these very reactive compounds undergo easy thermal decomposition; remarkable is the relative stability of 1,3‐di‐tert‐butylaziridinone, which does not start to decompose below 140°C. The α‐lactam ring is opened by nucleophilic reagents. — The correlation of stability and substituents is discussed in the last section. An acyclic, planar or almost planar, charge‐delocalized intermediate is sugge

ISSN:0570-0833    

DOI:10.1002/anie.196800251

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractUnder appropriate conditions, the photolysis of iodoaromatic compounds yields derivatives of biphenyl and phenanthrene, as well as organometallic compounds. Ring closures of o‐terphenyls to triphenylenes and of benzanilides to phenanthridones are described. The formation of dehydrobenzene (benzyne) on photolysis of 1,2‐diiodobenzene in solution has been established. The photolysis of various substituted iodoaromatic compounds or of substances such as CH3I, ICN, ICH3, COOH, or RCCI, provides a general method for the generation of a large variety of free radicals in solution. The potential uses of photochemically initiated exchanges of iodine in ArI for131I, Li, D, Cl, or Br are

ISSN:0570-0833    

DOI:10.1002/anie.196800361

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractThis review describes the properties of the cool‐flame and two‐stage ignition processes that characterize the gaseous oxidation of hydrocarbons and discusses the chemical reactions that are responsible for these phenomena. Cool flames result from a chainthermal acceleration of reaction rate. It is probable that the free‐radical chain involved is propagated by the reaction of an alkyl radical with oxygen to give an alkyperoxy radical which isomerizes to a hydroperoxyalkyl radical. The decomposition of this radical produces a hydroxyl radical, which attacks the hydrocarbon rapidly and unselectively to regenerate an alkyl radical. Branching probably results from the pyrolysis of mono‐ and dihydroperoxides, from the oxidation of aldehydes, and from radical‐molecule reactions. This reaction scheme explains the existence of a low‐temperature ignition peninsula and the relation of the extent and shape of this peninsula to the molecular structure of the hydrocarbon. The chemical relevance of cool flames to abnormal combustion phenomena, such as knock, in gasoline engines i

ISSN:0570-0833    

DOI:10.1002/anie.196800451

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196800612

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196800621

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196800632

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196800641

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY