摘要:

AbstractTheoretical investigation of a chemical reaction requires detailed knowledge of the potential energy of the molecular system. As a first step in such a study, minimum‐energy reaction paths have to be mapped on a generally multidimensional molecular potential surface. Even at this stage problems are encountered that have only recently been solved satisfactorily. The difficulties involved and various ways to handle them are discussed in connection with a two‐parametric model potential. Three chemical reactions examined illustrate the usefulness of such theoretical investigations as well as their current limitati

ISSN:0570-0833    

DOI:10.1002/anie.198000013

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractA number of racemates can be resolved into optically pure enantiomers by chromatography on optically active adsorbents. Synthetic polymers with optically active amide, amino acid, and crown ether groups, natural products such as starch and cellulose, and also microcrystalline triacetylcellulose are suitable for this purpose. Racemates can also be resolved by gas chromatography on optically active stationary phases.

ISSN:0570-0833    

DOI:10.1002/anie.198000131

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractMany technically interesting porous solids,e.g.ion exchangers or adsorbents for catalysis, are swellable polymers,i.e.the pore structure depends on the solvent medium. A method based on exclusion chromatography, permits determination of the pore size and pore size distribution in the swollen state.—Size exclusion chromatography, also referred to as gel permeation, gel filtration, or molecular sieve chromatography, is a widely employed method for the separation of dissolved substances—mostly polymer mixtures—according to their molecular size. Porous solids are used as stationary phase. Conversely, pore sizes and other structural data can be determined by exclusion chromatography. This application requires a series of standards (polymer samples) of known molecular weight. As a simple and rapid method, it has already proven valuable for such determinations in the case of rigid solids; in the case of swellable solids, this constitutes the sole method by which the pore structure can be characterized: classical methods require dry sa

ISSN:0570-0833    

DOI:10.1002/anie.198000241

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

摘要:

AbstractThe orientation defect model can be used for quantitative estimates and for understanding the properties of H‐bonded liquids, such as water and alcohol. The defect concentrations can be determined by vibrational spectroscopy, and the applicability of the approximation procedure derives from considering H‐bonds as chemical equilibria. Possible extensions of the simple model are critically discus

ISSN:0570-0833    

DOI:10.1002/anie.198000281

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198000411

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198000431

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198000441

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198000451

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198000461

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198000471

出版商:Hüthig&Wepf Verlag    

年代:1980

数据来源: WILEY