bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Self‐Organization and the Origin of Life
Authors: Kuhn Hans , Waser Jürg 
Published: December 2003

AbstractThe sequence of many small physically and chemically plausible steps that lead to self‐organization of matter are considered. These are governed by periodic temperature changes and a multi‐faceted spatial environment, both of which occurred in suitable locations on the primordial planet. The specific model described reveals the logical framework of this process, the nature and locations of fundamental difficulties as well as the means by which they might be overcome. The barriers that must be surmounted are mostly related to an accumulation of copying errors. An early stagnation barrier was hurdled by aggregate formation, by means of which erroneous copies are rejected; a further barrier was overcome by the evolution of machinery capable of synthesizing “cellular” envelopes which confine the building components. A system evolved which produced a primitive “replicase” that stabilized a rudimentary genetic code. A later stagnation phase ended when the functional system was reorganized by the evolution of separate machinery for replication and for translation of genetic information. — The purpose of this account is to stimulate experiments and theoretical efforts towards the improvement, refinement, and expansion of the model described. It also demonstrates the fruitfulness of the present style of approach that leads to assertions about the prerequisites, logical framework, and organizational structure of evolutionary processes.
Intermolecular Forces—An Example of Fruitful Cooperation of Theory and Experiment
Authors: Schuster Peter 
Published: December 2003

AbstractNew experimental techniques and extensive ab initio calculations have rendered it possible to gain a detailed knowledge of aggregates of atoms, small ions and/or small molecules in the vapor phase which are held together by intermolecular forces. Theory and experiment are often complementary regarding reliable predictions. The results obtained for complexes of three or more constituents are still fragmentary; nevertheless, they can be used to explain some properties of the condensed phase.
The Philosophy of Science: Its Possibilities and Limits
Authors: Wieland Wolfgang 
Published: December 2003

AbstractScience in the modern world has long since become a factor in the production and reproduction of goods and a condition of life in this world. At the same time, however, it is more than this. Science has therefore become caught‐up in an orientation crisis ever since scientists became aware that science can no longer be pursued merely for the sake of pure knowledge, the ideal from ancient times which had been held to be the proper guide for science in its quest for self‐understanding. Is the philosopher of science capable of providing the researcher with an answer to the questions what it is he does, and whether or not he is deceiving himself in regard to science and his relationship to it? The philosophy of science has revealed areas which demonstrate that our science is never the smooth and elegant construction composed of observation, experiments, and mathematical and formal techniques which it has often been held to be. It is not the least of the modern philosophy of science's achievements to have demonstrated that science cannot teach man what he should do with it and its results.
Syntheses of Pyrethroid Acids
Authors: Arlt Dieter , Jautelat Manfred , Lantzsch Reinhard 
Published: December 2003

AbstractIn the course of the last decade the chemistry of insecticides was expanded with the discovery of new cyclopropanecarboxylic acid esters of specific structure, far superior in action to the hitherto known insecticides of other substance classes or the natural prototypes from the group of pyrethrum constituents. The discovery quickly precipitated a host of wide‐ranging studies on the synthesis of these compounds. The development of selective methods of synthesizing complicated small rings called for a comprehensive repertoire: thus, synthesis of the compounds on an industrial scale makes use of sigmatropic rearrangement, radical addition, and nucleophilic ring closure with carbanions. These new industrial syntheses have acquired particular topicality because of their use of stereospecific and enantioselective methods.
Inorganic Pigments: Bases for Colored, Uncolored, and Transparent Products
Authors: Hund Franz 
Published: December 2003

AbstractColored and uncolored inorganic pigments have been obtained since prehistoric times from natural minerals, at first empirically, then by specially developed methods. Since the beginning of the 18th century they have also gradually come to be studied scientifically, and today such research makes use of the latest techniques of solid‐state physics and chemistry. On the basis of our knowledge of technically and aesthetically important properties, it has been possible in the last seventy years to make synthetic pigments superior to the natural ones, to increase production drastically while maintaining the pigment properties unchanged or improving them, and to broaden the range by the addition of new synthetic pigments. Nowadays it is in principle possible to write down a specification for many fields of application, taking into account aesthetic, technical, economic, and ecological aspects, and to make the corresponding inorganic pigment in adequate amounts. In what follows I shall discuss the dependence of the scattering and absorption constants of pigments on the refractive index, the wavelength of the light and the particle size, the properties of pigmented systems that depend on the particle geometry, and also some of the optical characteristics determined by the arrangement of the atoms in the crystal lattice.
ETC: A Mechanistic Concept for Inorganic and Organic Chemistry
Authors: Chanon Michel , Tobe Martin L. 
Published: December 2003

AbstractThe concept of electron transfer catalysis (ETC), or more specifically “Double Activation Induced by Single Electron Transfer” (DAISET) gives an opportunity to connect experimental facts never previously correlated. The first activation results from the transfer of an electron to (or from) a molecular species; the second activation results from the build‐up of a reaction chain able to reproduce the species formed in the first step. The starting point of this review is the SRN1 mechanism where principle and experimental diagnostic criteria are critically discussed. The thermal and photochemical exchange and substitution reactions of PtIVcomplexes are then reviewed together with the exchange reaction [AuCl4]−/Cl−, reactions with Grignard reagents and other organometallic reagents, as well as the redox behavior of electronically excited organic compounds. Photochemical applications, including solar energy conversion are discussed. New aspects are also presented for the mechanistic problem “SN2 reaction or SET process?” Moreover, the concept has significance for SH2 reactions at metal centers, molecule‐induced homolyses, reactions of complexes, as well as electrochemical processes.–Unless otherwise specified, only double activation (DAISET) processes will be discussed in this article.
The Chemistry of Acyl Cyanides
Authors: Hünig Siegfried , Schaller Rainer 
Published: December 2003

AbstractThrough improved and novel syntheses, acyl cyanides—especially aliphatic acyl cyanides—have become so readily accessible that numerous synthetic applications present themselves. The present review surveys the development of the chemistry of the acyl cyanides during the last 25 years. The syntheses and most important reaction possibilities of RCOCN are outlined in four large schemes: reactions of the CO‐ and CN‐groups—in each case with preservation of the carbon skeletal framework—as well as acylations with cleavage of cyanide ions.
2,4,6‐Cycloheptatrienylidenemalondialdehyde(8,8‐Diformylheptafulvene)
Authors: Reichardt Christian , Yun Kyeong‐Yeol 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 113. DOI:10.1002/anie.198201130
Lewis Acid Induced α‐Alkylation of Carbonyl Compounds
Authors: Reetz Manfred T. 
Published: December 2003

AbstractCarbonyl compounds undergo α‐alkylation via the corresponding silyl enol ethers using SN1 active alkyl halides or acetates in the presence of Lewis acids. This methodology extends the scope of carbonyl chemistry considerably, since SN1 active alkylating agents are generally base sensitive and therefore unsuitable for reactions with enolate anions or nitrogen analogs. A prime example is the α‐tert‐alkylation of aldehydes, ketones and esters.
Bridged C5Me5CoII Complexes— Reactive Intermediates in the Cyclopentadienylation of Cobalt(II) Halides
Authors: Kölle Ulrich , Khouzami Fouad , Fuss Bernhard 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 230. DOI:10.1002/anie.198202300
The Dianion 1,2‐Diphenylbenzocyclobutadienediide
Authors: Boche Gernot , Etzrodt Heinz , Marsch Michael , Thiel Walter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 345. DOI:10.1002/anie.198203450
Efficient Synthesis of 8‐Oxabicyclo[3.2.1]oct‐6‐en‐3‐ones, Preparatively Useful [4 + 3]‐Cycloadducts
Authors: Föhlisch Baldur , Gehrlach Eberhard , Herter Rolf 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 241. DOI:10.1002/anie.198202410
Synthesis of a Dicyanocobalt(III) D‐Didehydrocorrinate and Its Reduction to the Dicyanocobalt (III) Corrinate
Authors: Kräutler Bernhard , Hilpert Kurt 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 305. DOI:10.1002/anie.198203050
Synthesis and Structure of Triply Coordinated Sulfur Anions
Authors: Roesky Herbert W. , Schmieder Wilfried , Isenberg Wilhelm , Böhler Dieter , Sheldrick George M. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 269. DOI:10.1002/anie.198202690
Single‐Phase Polymer Alloys of Polyvinyl Chloride and New Polymers
Authors: Hardt Dietrich , Süling Carlhans , Lindner Christian , Morbitzer Leo 
Published: December 2003

AbstractPolymer alloying is acquiring ever increasing significance for the modification of polymeric materials. Polymer alloys are defined by their phase character, which in turn is determined by the mutual compatibility or incompatibility of the components. Suitable techniques for the analysis of the phase character include,inter alia, dynamic‐mechanical methods, according to which a polymer alloy may be considered in a simplified manner as single‐phase when onlyoneglass transition is observed, even if it extends over a broader temperature range than in the case of the pure components. Aliphatic (polyester)‐polycarbonates and tetramethylbisphenol‐A polycarbonate are new, PVC‐compatible, polymer modifiers. The (polyester)‐polycarbonates (from adipic acid, hexane‐1,6‐diol, neopentanediol, and diphenyl carbonate) yield with PVC single‐phase alloys that at temperatures above the glass transitions of the mixture display the characteristics of soft PVC and that are tough far below this temperature. The special high‐temperature properties of the resin‐like tetramethylbisphenol‐A polycarbonate permits the preparation of alloys with increased dimensional stability under heat (higher deflection temperatures under load).
[2 + 2]‐Cycloreversions
Authors: Schaumann Ernst , Ketcham Roger 
Published: December 2003

AbstractFour‐membered rings can be cleaved thermally, Photochemically, or catalytically into two π bonded fragments. Theoretical calculations, kinetic studies, and investigations of stereo‐ and regioselectivity have been undertaken to clarify the question of whether the reaction involves one or two steps and to permit predictions on its course. [2 + 2]‐Cycloreversions have been used to clarify the structure of four‐membered rings, to prepare highly reactive π electron‐systems and–in combination with a [2 + 2]‐cycloaddition–to protect double bonds. The combination of a cycloaddition and‐reversion can be used to convert a carbonyl group into an olefin. Starting with compounds containing annelated four‐membered rings, compounds with two functional groups or large ring systems can be prepared. [2 + 2]‐Cycloreversions have also been discussed in connection with storage of solar energy.
Synthesis and Reactions of 4‐Chromanones
Authors: Kabbe Hans‐Joachim , Widdig Arno 
Published: December 2003

AbstractMany natural products, such as the plant insecticides rotenone and ageratochromene (precocene), some fungitoxic phytoalexins, hashish constituents, vitamin E, and plant pigments, contain the chroman ring system as common structural unit. Some years ago we discovered a particularly simple entry to this class of heterocyclic compounds: The condensation of o‐hydroxyacetophenones with aliphatic aldehydes and ketones in the presence of pyrrolidine leads to 4‐chromanones in good yields. The scope of application and limitations as well as modification of this versatile synthesis are outlined; the accompanying tables give a good indication of the wealth and variety of possible substituents. The reaction of o‐hydroxyacetophenone, e. g. with glyoxylic acid or with α,β‐unsaturated ketones, proceeds atypically. The majority of the new chromanones can be used, inter alia, for the preparation of chromones, chromones and chromons, and for the synthesis of tricyclic and larger ring systems.
λ3‐Phosphazenes as Bridging η1‐Ligands
Authors: Scherer Otto J. , Konrad Rainer , Guggolz Ernst , Ziegler Manfred L. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 730. DOI:10.1002/anie.198207300
Transition Metal Complexes with cyclo‐Triphosphorus (η3‐P3) and tetrahedro‐Tetraphosphorus (η1‐P4) Ligands
Authors: Vaira Massimo Di , Sacconi Luigi 
Published: December 2003

AbstractSalts of 3d, 4d, and 5d metals in the presence of the ligands 1,1,1,‐tris(diphenylphosphinomethyl)ethane (triphos) or tris (2‐diphenylphosphinoethyl) amine (np3) react with white phosphorus P4 (or yellow As4) to produce several mononuclear sandwich and dinuclear triple‐decker sandwich complexes, which contain the unprecedented cyclo‐triphosphorus (or cyclo‐triarsenic) unit acting as a trihapto‐ligand. In these complexes the metal atoms are bonded to the there phosphorus atoms of the phosphane ligand and to the three atoms of the cyclo‐P3 or cyclo‐As3 unit. The complexes are diamagnetic or have μeff‐values corresponding to one or two unpaired electrons. The cyclo‐P3 ligand is coordinatively unsaturated as proved by the fact that the mononuclear sandwich compounds may form Lewis‐base adducts with electron‐acceptor fragments. Reaction of the complexes (np)3M (M = Ni, Pd) with white P4 leads to formation of diamagnetic compounds [(np3)M(η1‐P4)], in which the metal atom is bonded to the three phosphorus atoms of the np3‐ligand and in addition to one P atom of the intact P4 molecule, which behaves as a monohapto‐ligand. This article contains a review of the syntheses and structures of these complexes as well as a unified, albeit qualitative, approach to their bonding and properties.
Oxidation with Palladium Salts: Stereo‐ and Regiospecific Acetoxylation of 4‐Vinylcyclohexene Derivatives
Authors: Heumann Andreas , Reglier Marius , Waegell Bernard 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 922. DOI:10.1002/anie.198209220
λ3‐Phosphorins by [4 + 2]‐Cycloaddition of α‐Pyrones and Cyclopentadienones with H5C6—CP
Authors: Märkl Gottfried , Jin Gui Yu , Silbereisen Ernst 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 881. DOI:10.1002/anie.198208810
β,ε‐Dioxophosphonates by Reductive Nucleophilic Acylation of 1,3‐Dioxo Compounds: Facile Synthesis of Jasmones
Authors: Altenbach Hans‐Josef , Korff Rainer 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 777. DOI:10.1002/anie.198207770
Synthesis and Structure of the First Transition Metal Complex of a Phosphorus Compound with a Direct λ3P—λ5P Bond
Authors: Gilje John W. , Sheldrick William S. , Weferling Norbert , Schmutzler Reinhard 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 907. DOI:10.1002/anie.198209070
A Novel Bischelating Ligand with Two Tetradentate N,N,O,S Subunits–Synthesis and Properties of a Dinuclear CuII Complex
Authors: Girerd Jean Jacques , Kahn Olivier 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 953. DOI:10.1002/anie.198209530
Which Factors Determine the Reactivity and Regioselectivity of Free Radical Substitution and Addition Reactions?
Authors: Tedder John M. 
Published: December 2003

AbstractThe relative importance of bond strength, steric effects, and polarity in determining the rate and orientation of free radical subsitution and free radical addition reaction is considered. The factors which control substitution reaction (radical transfer reaction) are gathered together as five “rules”, and a similar five “rules” are proposed for addition rections. These “rules” are shown to be special cases of two “laws” which govern all free radical reactions.
Dependence of the Enantioselectivity on the Relative Concentration of Substrate in an NADH Model Reaction
Authors: Baba Naomichi , Oda Jun'ichi , Inouye Yuzo 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1021. DOI:10.1002/anie.198210210
Photochemical Evolution of H2 in the System Methyl Viologen/MnII‐meso‐Tetraphenylporphyrintrisulfonic Acid/Mercaptoethanol/Hydrogenase
Authors: Okura Ichiro , Kim‐Thuan Nguyen , Takeuchi Makoto 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1004. DOI:10.1002/anie.198210040
Cyclopentadienone Complexes as Synthons: Ring‐ and Regiospecific Nucleophilic Additions to Cobaltocenium Salts—Synthesis of Substituted Cyclopentadienes and Cyclopentenones
Authors: Tane Jeffrey P. , Vollhardt K. Peter C. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1360. DOI:10.1002/anie.198213600
Functionalization at Proanomeric Centres by Photobromination: A Novel Access to Oxo‐ and Acyloxyimino‐glycosyl Bromides
Authors: Lichtenthaler Frieder W. , Jarglis Pan 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1449. DOI:10.1002/anie.198214490
The Unambiguous Specification of the Steric Course of Asymmetric Syntheses
Authors: Seebach Dieter , Prelog Vladimir 
Published: December 2003

AbstractThe nomenclature of organic chemistry has not kept pace with the staggering advances made in asymmetric syntheses over the last 15 years. Efforts to specify the steric course of stereoselective reactions by use of the terms erythro and threo, and by other descriptors have led to ambiguous notation and consequently to an almost Babylonic confusion. We propose here a method, based on the CIP‐(Cahn‐Ingold‐Prelog) system, for the unambiguous specification of the steric course and the product configuration of diastereoselective reactions. The reflection‐invariant relative topicity of approach of reactants is defined as like (lk) and unlike (ul) if the corresponding descriptor pairs are Re*, Re*. or R*, Re*, and Re*, Si*, or R*, Si*, respectively. The descriptor pair notations (lk and ul) of reactants disclose related steric courses of reactions more often than do the relative configurations of their products, for which the configurational notation l=R*, R* and u=R*, S* is proposed. The advantage of specifying the relative topicity is demonstrated by means of a series of recent examples of importance to the synthetic organic chemist taken from the literature and from our own work.
The Thermal Conversion of 1, 5, 9‐Triynes into Arenes: [2 + 2 + 2]‐Cycloadditions or Sigmatropic Rearrangements?
Authors: Dower William V. , Vollhardt K. Peter C. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1545. DOI:10.1002/anie.198215450
From cis,trans,cis‐1,2,3,4‐Tetravinylcyclobutane to Cyclododecatetraene—Two Consecutive Cope Rearrangements
Authors: Gubernator Klaus , Gleiter Rolf 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1491. DOI:10.1002/anie.198214910
Easy Rotation about the Carbon‐Carbon Bond in Lithium Cyclopentadienyl (Ester‐)Enolates
Authors: Boche Gernot , Eiben Robert , Thiel Walter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1535. DOI:10.1002/anie.198215350
Alkyl‐Substituted 3,4‐Dihydro‐2H‐pyrans: Mass Spectroscopy, Synthesis, and Identification as Insect Constituents
Authors: Francke Wittko , Mackenroth Wolfgang 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1556. DOI:10.1002/anie.198215560
Polarity of Binary Liquid Mixtures
Authors: Langhals Heinz 
Published: December 2003

AbstractIn contrast to the thoroughly studied plarity properties of pure liquids, only little is known about the polarity of mixtures of liquids, although the majority of machanistic and preparative work is not carried out in pure phases. Using a widely applicable two‐parameter equation, polar behavior of binary liquid mixtues can be described quantitatively as a function of their composition. Based on this equation, satisfactory explanations are found for deviations observed for binary solvent mixtures from the linear correaltion of polarity scales, as well as for the unusual activation parameters estimated byWinsteinfor solvolysis oftert‐butyl chloride. Applications of the equation range from a rapid test for determining water contents of solvents, the study of reaction mechanisms, to polymer chemistry.
Synthesis and Structure of [Zn(S2N2CO)6][AsF6]2—Sulfur‐Nitrogen Rings as Ligands in Coordination Compounds
Authors: Roesky Herbert W. , Thomas Manfred , Noltemeyer Mathias , Sheldrick George M. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1813. DOI:10.1002/anie.198218130
1,2‐Dihydropentalene from 1,6‐Cyclooctadien‐3‐yne
Authors: Hanold Nobert , Molz Thomas , Meier Herbert 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 2050. DOI:10.1002/anie.198220500
Tetra‐tert‐butylallene and Its Radical Cation
Authors: Bolze Rudolf , Eierdanz Horst , Schlüter Kaspar , Massa Werner , Grahn Walter , Berndt Armin 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 2039. DOI:10.1002/anie.198220390
Novel Facile Synthesis of Multiplyortho‐Bridged Phane‐Hydrocarbons and of Dihydrocyclobutabenzenes
Authors: Klieser Brigitte , Vögtle Fritz 
Published: December 2003

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1982, 1956. DOI:10.1002/anie.198219560
“μ‐C3” Trisphosphanes by Direct Phosphane/Allylphosphane Coupling
Authors: Arpac Ertugrul , Dahlenburg Lutz 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1950. DOI:10.1002/anie.198219500