摘要:

AbstractThin‐layer chromatography (TLC) has been in general use since 1958. The prerequisites were the use of very small particle size material in the layers and the demonstration that not only lipophilic mixtures but also mixtures of cardiac glycosides, alkaloids, sugars, and amino acids could be separated quickly and simply on silica gel layers. The impressive separations obtained using the method later encouraged attempts to use adsorbants having such, narrow‐range small particles in column chromatography. In order to achieve sufficient flow rates the use of high pressures was necessary. Thus, high pressure or high performance liquid chromatography (HPLC) was born, whose godfather, as far as instrumental development is concerned, was gas chromatography (GC). Today, chromatography is classified according to the nature of the transport phase: liquid, gas, or “electro” chromatography. Sample preparation often requires more time than the actual separation. rapid thermal separation and application techniques (TAS, TFG) have brought advantages to TLC. As before, the art of chromatography consists in choosing the appropriate mobile phase, stationary phase, and separation technique. Gradient TLC offers new possibilities; for example, gradient layers make it possible to obtain selective information on the individual components of a mixture and also allow significant focussing effects to be achieved. Sequential and centrifugal TLC have paved the way for further advances. The questions arise whether the standard conditions, formulated 25 years ago, are still applicable and how the variations which have been introduced should be judged. Group‐ and substance specific methods of detection are discussed in addition to universal methods. Quantitation is critically discussed and it is concluded that HPLC has the better chance in the furture. Combination and coupling techniques ease the positive identification of individual substances. Finally, it is discussed why TLC is the simplest, most versatile, most cost effective, and most widely used chromatographic method and reasons are proposed as to why it will remain so for the foreseeab

ISSN:0570-0833    

DOI:10.1002/anie.198305073

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractIn recent years both acyclic and cyclic sulfur ylides have proved to be interesting and versatile ligands in preparative organometallic chemistry. In addition to paralleling the coordination chemistry of their phosphorus analogues, sulfur ylide complexes show specific structural and chemical features; they are becoming more important in preparative inorganic and organic chemistry, and may also be biochemically relevant as methylene transfer agents. Recent studies of the complexes of the ylidic λ4‐thiabenzenes and λ6‐thiabenzene 1‐oxides have frequently demonstrated unexpected and novel reactions, and thereby enriched the chemistry both of ylides and of carbony

ISSN:0570-0833    

DOI:10.1002/anie.198305161

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractConsideration of chemiluminescent and bioluminescent processes invariably brings to mind the four‐membered ring peroxides, 1,2‐dioxetanes and α‐peroxylactones. Nevertheless, while chemiluminescence and bioluminescence are well established fields of scientific study, isolable and characterized “high‐energy” molecules such as the 1,2‐dioxetanes and α‐peroxylactones are of relatively recent vintage, about a decade. These intriguing compounds produce electronically excited products which manifest themselves by light emission during their thermal decay; more importantly, these transformations are involved in luminescent as well as dark enzymatic processes. It is not our intention to present a comprehensive overview in this progress report, but rather to focus on those aspects which requ

ISSN:0570-0833    

DOI:10.1002/anie.198305291

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198305421

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1983, 812. DOI:10.1002/anie.198308120

ISSN:0570-0833    

DOI:10.1002/anie.198305432

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1983, 803. DOI:10.1002/anie.198308030

ISSN:0570-0833    

DOI:10.1002/anie.198305441

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1983, 710. DOI:10.1002/anie.198307100

ISSN:0570-0833    

DOI:10.1002/anie.198305451

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198305461

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1983, 786. DOI:10.1002/anie.198307860

ISSN:0570-0833    

DOI:10.1002/anie.198305471

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198305481

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY