bluuebunny/crossref_metadata_2025_split huggingface dataset:
MO‐LCAO‐calculations on polymethines. XIV. Alternative Fragmentation Modes in Describing Benzenoid Chromophores
Authors: Fabian J. 
Published: December 2004

MO‐LCAO‐Berechnungen an Polymethinen. XIV. Alternative Fragmentierung bei der Beschreibung benzoider ChromophoreDie Lichtabsorption donator‐acceptor‐substituierter Benzene wird allgemein an Hand des Benzenchromophors interpretiert. Ein alternatives Konzept, welches zumindest einen Teil der Verbindungen in die Betrachtung einbezieht, nimmt auf ein Polymethin‐Teilchromophor Bezug. Wie durch PPP‐Berechnungen (einschließlich Konfigurationsanalyse) an ortho‐Aminobenzonitrilen gezeigt wird, führen Donator‐ wie auch Acceptorsubstituenten in jenen Ringstellungen des ortho‐Aminobenzonitrils zu einer bathochromen Verschiebung, die im Heptamethin‐Teilchromophor ein gleichartiges Verhalten zeigen. Dieser Befund stützt die Ansicht von DÄHNE, daß sowohl die KAUFFMANNsche wie auch die CALIEZYsche Farbregel durch das Polymethinkonzept verständlich werden.Vorhersagen werden jedoch dann schwierig, wenn Polymethinketten sehr stark in cyclische Strukturen eingeschlossen sind, wie beispielsweise im para‐Aminobenzonitril. Dann führen Donator‐ und Acceptorsubstituenten in beiden freien Ringstellungen zu einer bathochromen Verschiebung. Wie kürzlich für ähnliche Fälle in der Literatur gezeigt wurde, widerspricht dieser Befund auch den DEWAR‐KNOTTschen Farbregeln.
Reaktionen von Malonsäureethylesteraniliden mit Heterokumulenen
Authors: Rudorf W.‐D. , Koch K. , Augustin M. 
Published: December 2004

Reactions of Malonanilic Acid Ethyl Esters with HeterocumulenesMalonanilic acid ethyl esters 1 react with carbon disulfide in the presence of sodium hydride to give disodium salts 2. Treatment of 2 with an alkylation reagent yields the openchain or cyclic ketene S,S‐acetals 3 and 4, respectively. Adding only one equivalent of methyl iodide to 2 and acidifying the reaction mixture lead to the dithioesters 5. Reaction of 3 with amines or o‐amino‐thiophenol yields S,N‐ and N,N‐acetals only in some cases. S,N‐acetals 6 are further available by addition of phenyl isothiocyanate to 1 whereas N,N‐acetals are synthesized, too, by chlorination of 3 and reaction with amines. Acidifying of 11 gives the thioacetoanilides 12. Some more reactions (oxidation of 3a, d and saponification/decarboxylation of 4a) are discussed.
Steroide. LXX [1]. Stereoselektive Epoxidation von 14,15‐ungesättigten Östratrien‐3‐methylethern. Zum syn‐dirigierenden Effekt von Urethanen
Authors: Ponsold Kurt , Schubert Gerd , Wunderwald Manfred , Tresselt Dieter 
Published: December 2004

Steroides. LXX. Stereoselective Epoxidation of 14,15‐Unsaturated Estratriene‐3‐methyl Ethers. On the syn‐Directive Effect of UrethanesThe stereochemistry of the epoxidation of 14,15‐unsaturated estratriene‐3‐methyl ethers with peroxyacids is examined. The influence of different 17‐substituents and of the solvent on the stereoselectivity is discussed. Whereas on epoxidation of 17β‐esters and 17β‐ethers mainly 14α, 15α‐epoxides are formed (up to 89%), the 17β‐urethane derivatives yield the 14β, 15β‐epoxides up to 87% by a syn‐directive effect.
Cobaltchelate als Hydrierkatalysatoren. Zur Reduktion von Nitro‐ zu Aminoverbindungen mit Kohlenmonoxid und Wasser als Hydriermittel
Authors: Bremer J. , Dexheimer V. , Madeja K. 
Published: December 2004

Cobalt Chelate Complexes as Hydrogenation Catalysts. The Reduction of Nitro Compounds to Amines with Carbon Monoxid and Water as Hydrogenation AgentCobalt complexes of tetradentate chelating agents have been found to catalyse the selective homogeneous reduction of nitroaryls to amines with carbon monoxide and water at room temperature and atmospheric pressure. The cobalt complexes are highly specific. Dinitroaromatics can be reduced to the intermediate nitro amines in good yields; mixtures of nitroaryls can be reduced likewise sequentially. The reaction rate depends on the pH of the reaction solutions.
Tetrathiafulvalene. XV. Mößbauer‐spektroskopische Untersuchung von monomeren und polymeren Eisendithiolenkomplexen
Authors: Poleschner H. , Fanghänel E. , Mehner H. 
Published: December 2004

Tetrathiafulvalenes. XV. Mössbauer Spectroscopic Investigation of Monomeric and Polymeric Iron Dithiolene ComplexesThe Mössbauer spectra of iron bis dithiolene chelates with 1,2‐dithiole‐2‐one‐4,5‐dithiolate and 1,2‐dithiole‐2‐thione‐4,5‐dithiolate ligands are compared with those of the polymeric iron complexes with ethene tetrathiolate and tetrathiafulvalene tetrathiolate ligands. The spectroscopic results are discussed in relation to the structure of these compounds. In all investigated complexes the isomer shift shows trivalent iron ions as the main component in the samples. Whereas the monomeric complexes show a double doublet spectrum, which is unusual for iron bis dithiolene chelates, the polymeric compounds produce spectra, whose quadrupole splitting is typical for distorted octahedral coordination geometry.
Stabilität von Ionenaustauschern gegen Salpetersäure und Bestrahlung. I. Nitrosierender Abbau der Iminodiessigsäuregruppen in Chelonaustauschern
Authors: Pfrepper Gerd 
Published: December 2004

The Stability of Ion Exchangers towards Nitric Acid and Radiation. I. Nitrosative Cleavage of the Iminodiacetic Acid Groups in Chelating Ion ExchangersThe behaviour of the chelating ion exchangers Wofatit MC 50, Dowex A 1 and Chelex 100 with aminoacetic acid – and iminodiacetic acid‐groups towards nitric acid in the range of the concentration 1…︁10,5 mol/l and at temperatures ⩽68°C was determined. It is found that the COOH capacity and the N content are rapidly reduced leading to the formation of CO2 and N2. If the exposure to HNO3 continues there is again a rise in the COOH capacity.The i.r.‐ and mass spectra show that the iminodiacetic acid‐groups are destroyed by nitrosative cleavage and CHO groups result, which are then oxidized to COOH groups. The mass spectrum shows that the aminoacetic acid‐groups of the resin are nitrosated, which has also been confirmed by the use of nitric acid labelled with 15N.
Folgeprodukte halogenierter Aldehyde. XVII. Reaktionen des N‐(1,2,2,2‐Tetrachlorethyl)‐trichloracetaldimins mit Alkoholen und Mercaptanen
Authors: Zinner H. , Boede W. , Künzel H. , Leske H. , Schnell M. 
Published: December 2004

Derivatives of Halogenated Aldehydes. XVII. Reactions of N‐(1,2,2,2‐Tetrachloroethyl)trichloroacetaldimine with Alcohols and ThioalcoholsReactions of N‐(1,2,2,2‐tetrachloroethyl)trichloroacetaldimine 1 with methanol lead to 1,2,2,2‐tetrachloroethyl‐(2,2,2‐trichloro‐1‐methoxyethyl)amine 2a, N‐(2,2,2‐trichloro‐1‐methoxyethyl)trichloroacetaldimine 3a and bis‐(2,2,2‐trichloro‐1‐methoxyethyl)amine 5. After the reaction of the aldimine 1 with ethanol or propanol only the N‐(1‐alkoxy‐2,2,2,‐trichloroethyl)trichloroacetaldimines 3b, c are isolated; with thioalcohols only the N‐(1‐alkylthio‐2,2,2‐trichloroethyl)‐trichloroacetaldimines 4a–c are obtained. The aldimines 3a–c and 4b, c are decomposed on treatment with hydrochloric acid and an excess of an alcohol or thioalcohol to yield the amine hydrochlorides 6a–c, 7b, c, which are transformed into the amines 8a–c and 9b, c. From these amines the derivatives 10–15 are prepared.
Metallporphyrinkomplexe. VI, Synthese von Polymethacrylsäureestern mit kovalent gebundenem Eisen(III)‐protoporphyrin IX
Authors: Kühn M. , Wesuls E. , Mohr P. , Ristau O. , Benes M. 
Published: December 2004

Metalloporphyrin Complexes. VI. Synthesis of Polymethacrylates with Covalently Bound Iron (III)‐protoporphyrin IXConvenient synthesis of polymeric iron (III)‐protoporphyrin IX (hemin) compounds is described. The covalent linkage via the carboxylic groups of hemin is possible by the reaction of the activated ester of hemin with polymethacrylates containing aliphatic amino groups. Polymethacrylates with aromatic amino groups are suitable to immobilize the hemin via its methine bridges. The hemin‐containing polymers are characterized by visible spectra and e.p.r.‐spectroscopy.
Untersuchungen zum Mechanismus der Chlorhydrinierung von Olefinen
Authors: Buss E. , Rockstuhl A. , Schnurpfeil F. R. D. 
Published: December 2004

Studies on the Mechanism of the Chlorohydrination of OlefinsWe studied the rate‐determining and the product‐determining steps of the chlorohydrination of olefins with Cl2/H2O and HOCl. In competitive kinetic experiments with 3‐ethylpent‐2‐ene and cyclohexene we determined the relative rate constants krel = 1,5 (with Cl2/H2O) and krel = ∞ (with HOCl). This shows that the rate‐determining steps of the chlorohydrination with Cl2/H2O and with HOCl are different. In order to investigate the product‐determining steps we determined the proportion of alkyl‐(2‐chloroethyl)‐ethers 3 and ethylene chlorohydrine 2 in the reaction of ethylene with Cl2 and with HOCl in alcohol/water‐mixtures. The proportion of both the reaction products 3/2 was independent of the chlorinating agent used. Also the proportion of MARKOVNIKOV and anti‐MARKOVNIKOV products in the chlorohydrination of propylene with Cl2/H2O or HOCl was independent of the type of chlorinating agent. In the chlorohydrination of cyclohexene both agents (Cl2/H2O and HOCl) yielded only the trans‐chlorohydrine. From the results obtained it may be concluded that the product‐determining step of chlorohydrination is the same for both the chlorinating agents studied.
Photochemie adsorbierter Moleküle. V. ESR‐Untersuchungen von Phenylkationen bei der Photolyse von Arendiazoniumsalzen im Festkörper und im adsorbierten Zustand
Authors: Bäzold D. , Fassler D. , Kunert R. 
Published: December 2004

Photochemistry of Adsorbed Molecules. V. E.S.R.‐Investigations of Phenyl Cations during Photolysis of Arendiazonium Salts in the Polycrystalline and the Adsorbed StateDuring photolysis of 4‐NR2‐substituted arene diazonium salts ground state triplets occur at low temperatures in the e.s.r.‐spectra with (π)5(sp2)1 configuration in the polycrystalline as well as in the adsorbed state on SiO2. The influence of anions and the reaction order of decay processes are discussed. The decay of the aryl cations were also investigated in the presence of pyrene as π‐electron donor. Reaction takes place with coadsorbed molecules and the decay mechanism changes from ionic character to radical character.
Benzalanilines and 2‐Phenyl‐indolenines ‐ characterization of their excited electronic states and interpretation of their U.V. spectra
Authors: Mehlhorn Achim , Fabian Jürgen , Perez Carlos 
Published: December 2004

Benzalaniline und 2‐Phenyl‐indolenine — Charakterisierung ihrer elektronischen Anregungszustände und Interpretation ihrer UV‐SpektrenDie UV‐Spektren einiger substituierter Benzalanilin‐ und 2‐Phenylindolenin‐derivate werden unter Verwendung des PPP‐ und des CNDO/S‐Verfahrens berechnet. Die Übereinstimmung zwischen theoretischen Übergangsenergien und experimentellen Spektren ist gut, wenn man die PPP‐Methode benutzt, aber weniger befriedigend für das CNDO/S‐Verfahren. Eine Mischung zwischen nπ*‐ und ππ*‐Übergang führt zu einer Bandenaufspaltung im langwelligen Spektralbereich, wenn der Chromophor des Benzalanilins nicht‐planar wird. Die elektronischen Übergänge werden interpretiert durch PPP‐Konfigurationsanalyse der angeregten Zustände, wobei auf unterschiedliche Teilchromophore abgebildet wird. Frühere Zuordnungen werden kritisch überprüft.
Photokatalytische Systeme. XLVIII. Ungewöhnliche lichtinduzierte Redoxreaktionen von Cobalt(III)‐, Eisen(III)‐ und Kupfer(II)‐Komplexverbindungen in Gegenwart von Chromsäureestern
Authors: Hennig H. , Scheibler P. , Wagener R. , Thomas P. , Rehorek D. 
Published: December 2004

Photocatalytic Systems. XLVIII. Unusual Light‐Induced Redox Reactions of Cobalt(III), Iron(III) and Copper(II) Complexes in Presence of Chromic Acid EstersThe coordination compounds[Co(NH3)5H2O]3+,[Co(NH3)4(H2O)2]3+,[Co(en)2(H2O)Cl]2+ (en = ethylendiamine), [L2(H2O)Fe‐O‐Fe(H2O)L2]4+ (L = 1,10‐phenanthroline; 2,2′‐bipyridine) and [CuL2]2+ (L = 2,9‐dimethyl‐1,10‐phenanthroline) show no or neglegible photo redox reactions upon irradiation wave‐length above 350 nm. However, in the presence of chromate(VI), water, and different alcohols like methanol, ethanol, i‐propanol and n‐propanol a very efficient light‐induced formation of cobalt(II), iron(II) and copper(I) (ϕ = 0,7; Λirr = 375 nm) can be observed together with reduced generation of chromium(III). The participation of chromium(V) in the primary step of the photolysis of chromic acid esters was shown to be the reason for these unusual light‐induced redox reactions. The coordination compounds under discussion behave as very efficient scavengers for chromium(V) connected with simultaneous reoxidation to chromate(VI) and reduction to the appropriate cobalt(II), iron(II) and copper(I) compounds. The general importance of the participation of chromium(V) in the primary step of the photolysis of chromate(VI) in non‐aqueous solvents is also shown by investigations of the photochemical behaviour of the system metal complex/CrO4—, Cr2O7—/dimethylsulfoxide. Possible mechanisms of the light‐induced reductions of the metal complexes are discussed.
Synthesen und Eigenschaften Mono‐ und diphenylsubstituierter Monothio‐β‐dicarbonylverbindungen und ihrer Nickel(II)chelate
Authors: Pulst M. , Beyer L. , Weissenfels M. 
Published: December 2004

Syntheses and Properties of Mono‐ and Disubstituted Monothio‐β‐dicarbonyl Compounds and their Nickel(II) chelatesReaction of phenylacetaldehyde with phosphorous oxichloride and dimethylformamide yielded 3‐chloro‐2‐phenyl‐propenal, which was converted into 2‐phenyl‐monothiomalonic dialdehyde 2 by treating with sodium sulfide nonahydrate. Furthermore the reactions of other mono‐ and diphenylsubstituted monothio‐β‐dicarbonyl compounds with aniline on the one side and nickel(II)acetate on the other side have been studied. It was shown, that compounds 1–6 react in different way with aniline yielding either sulfur free products or in case of 1 and 4 enaminothioketones, which are of interest as building blocks for syntheses.In contrast to this the nickel complexes of 1–6 indicates an one another similar, typical chelate structure, which have been elucidated by u.v.‐vis‐, i.r.‐ and x‐ray photoelectron spectroscopy.
Löschung der Fluoreszenz aromatischer Urethane durch Ketone
Authors: Stumpe J. , Schwetlick K. , Kuzmin M. G. 
Published: December 2004

Fluorescence Quenching of N‐Arylurethanes by KetonesFluorescence and photo‐Fries reaction of N‐aryl‐urethanes can be quenched by diffusion‐controlled energy transfer to biacetyl, acetone and other aliphatic ketones. Quenching of the photo reaction and fluorescence obeys the Stern‐ Volmer Equation.The efficiency of quenching may by influenced by solvents and substituents changing the S1 energies of donors and acceptors. The identical rate constants determined by independent methods demonstrate that quenching of urethane fluorescence and photoreaction by aliphatic ketones occurs completely by singlet energy transfer.
Zur Gültigkeit des Prinzips des quasistationären Zustandes
Authors: Just G. , Bittrich H.‐J. 
Published: December 2004

On the Validity of Steady State PrincipleConsidering the simple case

reduced concentrations were calculated by solving the exact differential rate equation by assuming a steady state and by assuming an „equilibrium”︁ between A1 and A2. In a broad field of reduced rate constants Ki/k1 the range in which these assumptions are valid within ±5% was determined for different values of time.
Chinon‐sensibilisierte photochemische Dediazonierung von Arendiazoniumsalzen
Authors: Becker H. G. O. , Jirkovsky J. , Fojtik A. , Kleinschmidt J. 
Published: December 2004

Photochemical Dediazoniation of Arene Diazonium Salts Catalyzed by QuinonesThe rate constants of the hydrogen abstraction of triplet‐excited p‐benzoquinone (BQ), duroquinone (DQ), p‐chlorophenyl‐p‐benzoquinone (PQ) and 2, 5‐di(p‐chlorophenyl)‐p‐benzoquinone (P2Q) from n‐heptane and acetonitrile are determined by laser flash photolysis as well as the rate constants for the reactions with oxygen.The semiquinones formed are in equilibrium with their respective semiquinone anions; at pH 3 and pH 7, respectively, it was possible in acetonitrile/water solution to determine separately the rate constants for their disproportionation affording quinones and hydroquinones and the rate constants for electron transfer to p‐chlorbenzene diazonium tetrafluoroborate. It comes out that the electron transfer to the diazonium compound only competes favorably with the disproportionation in the case of the semiquinone anions.
Eindeutige Synthese des 4,7‐Dihydro‐4‐oxo‐1 H‐pyrazolo[3,4‐b]pyridins – Bemerkungen zur „(NC)‐Umlagerung”︁ von (2‐Alkoxycarbonyl‐vinyl‐amino)pyrazolen
Authors: Dorn Helmut , Ozegowski Rüdiger 
Published: December 2004

Unambiguous Synthesis of 4,7‐Dihydro‐4‐oxo‐1H‐pyrazolo[3,4‐b]pyridine — Further Comments on the “(NC)‐Rearrangement” of (2‐Alkoxycarbonyl‐vinyl‐amino)pyrazols4,7‐Dihydro‐4‐oxo‐1H‐pyrazolo[3,4‐b]pyridine1ais synthesized by decarboxylation of 1‐benzyl‐5‐carboxy‐4‐hydroxy‐pyrazolo[3,4‐b]pyridine4band debenzylation of 1‐benzyl‐4,7‐dihydro‐4‐oxo‐pyrazolo[3,4‐b]pyridine1bwith sodium in liquid ammonia. The product from 3‐amino‐pyrazol and methyl propiolate, formerly described as1a, obviously is the 6‐oxo isomer2a.Use of the parameter δ13(CO) for the structural assignment of pyrazolo[3,4‐b]pyridones is only permitted, if in the corresponding media mainly the oxo‐tautomer is existing. It is again demonstrated that DMSO is often an insufficient medium.Debenzylation of1band similar compounds with SeO2is only possible, if the α‐position of CO is blocked by a substituent. Otherwise diselenids of type6are formed. This obviously is a general reaction of cyclic lactames.The cyclisation of (2‐alkoxycarbonyl‐vinyl‐amino)pyrazols7in acidic media, and with catalytical amounts of the corresponding amino‐pyrazols gives 6,7‐dihydro‐6‐oxo‐pyrazolo[3,4‐b]pyridines2via amino 4‐(2‐alkoxycarbonyl‐vinyl)pyrazols8, i.e. via products of an “(NC)‐rearrangement”, while by thermal cyclisation of74,7‐dihydro‐4‐oxo‐pyrazolo[3,4‐b]pyridines1are formed.
Synthesen mit 1,3‐Dithietanen. XIV. Ringumwandlungen von substituierten Dihydropyrazolo[5, 1‐b]thiazolcarbonsäureestern
Authors: Peseke K. , Vogel C. 
Published: December 2004

Syntheses with 1,3‐Dithietanes. XIV. Ring Transformations of Substituted Dihydropyrazolo [5,1‐b]thiazolecarboxylatesDihydropyrazolo[5,1‐b]thiazolecarboxylates 2 react with aliphatic amines to give dihydrothiazolo[2,3‐g][1,2,4]triazepinecarboxylates 4. Compounds 2c, d and o‐phenylenediamine, o‐amino‐phenols or o‐amino‐thiophenol afford substituted ethyl benzimidazol‐, benzoxazol‐ or benzothiazol‐2‐yl‐acetates 6. Hydrazine hydrate and compounds 2 yield derivatives of ethyl pyrazolidin‐4‐yliden‐4‐thiazoline‐5‐carboxylates 8.
Free radicals of phenothiazine and related compounds. IV. Phenothiazinyl‐ and Diphenothiazine‐ Copper Complexes as intermediates and products in the interaction of phenothiazines with copper(II) halides
Authors: Diudea Mircea V. , Silberg Ioan A. 
Published: December 2004

Freie Radikale des Phenothiazins und ähnliche Verbindungen. IV. Phenothiazinyl‐ und Diphenothiazin‐Kupferkomplexe als Zwischen‐ und Endprodukte in der Reaktion von Phenothiazin mit Kupfer (II)‐halogenidenDarstellung und Eigenschaften einiger Komplexverbindungen des 10‐Phenothiazinylradikals und deren Dimerisierungsprodukte mit Cu(I)‐ und Cu(II)‐ionen werden beschrieben.Ein Mechanismus für die selektive Chlorierung von Phenothiazinen in Position 1 mittels CuCl2 wird diskutiert. Die Möglichkeit ähnlicher Bromierungen mittels CuBr2 wird demonstriert.
Azomethinimine. V. 1H‐NMR‐Spektren und sterischer Bau von arylsubstituierten Pyrazolidon‐Azomethiniminen
Authors: Geissler G. , Hippius M. , Tomaschewski G. 
Published: December 2004

Azomethineimines. V. 1H‐N.M.R. Spectra and Steric Properties of Arylsubstituted Pyrazolidone‐AzomethineiminesFrom the results of 1H‐n.m.r.‐spectroscopic investigations we tried to draw conclusions regarding the steric properties of pyrazolidone‐azomethineimines 1a–k. The influence of aromatic systems on chemical shift of the methineproton of the 1,3‐dipolar centre was calculated using the ring current model. Without the twisted 9‐anthryl‐substituted compound 1f experimental results show a good correspondence to the values of chemical shift calculated for two of four possible isomeric structures.
Zur Synthese und zum Reaktionsverhalten von 2,6‐disubst.‐5‐Acyl‐4H‐1,3‐oxazin‐4‐thionen
Authors: Dehne H. , Krey P. 
Published: December 2004

Synthesis and Chemical Behaviour of 2,6‐Disubst.‐5‐acyl‐4H‐1,3‐oxazine‐4‐thionesNew 2,6‐disubst.‐5‐acyl‐4H‐1,3‐oxazine‐4‐thiones 4 are synthesized by addition‐cyclocondensation reaction between 1,3‐diketones and acylisothiocyanates.With perchloric acid ring opening of 4 takes place and N‐acyl‐acylthioacetamides 5 are obtained. The compounds 5 can be S‐alkylated by alkyl halides to form 6. 2‐Aroyl‐1‐aroylamino‐1‐arylaminoethenes 7 are prepared from 5 or 6 with primary amines. Spectroscopic measurements of 4–7 are discussed.
Reaktion von methylenaktiven Nitrilen und Cyanamid mit acylierten Enaminen
Authors: Gewald K. , Schäfer H. , Bellmann P. 
Published: December 2004

Reaction of Methylene Active Nitriles and Cyanamide with Acylated EnaminesThe addition products from enamines onto isocyanates and isothiocyanates, i.e. substituted β‐aminoacrylo amides 1 and thioamides 2, react with malononitrile to yield the 6‐amino‐1‐aryl‐5‐cyano‐pyridin‐2‐ones 3 and ‐thiones 4 among them 5,6,7,8‐tetrahydroisoquinolin‐1‐ones and ‐thiones. From ethyl cyanoacetate the 5‐cyano‐6‐hydroxy‐pyridin‐2‐ones 7 and from benzoyl acetonitrile the 6‐phenyl‐pyridin‐2‐ones 8 are formed. The replacement of malononitrile by cyanamide yields the 2‐amino‐3‐aryl‐pyrimidin‐4‐ones 5 and ‐thiones 6 among them 5,6,7,8‐tetrahydroquinazolin‐4‐ones and ‐thiones. The not isolated β‐acyl enamines derived from enamines and acid chlorides react with malononitrile or cyanamide to form the pyridin‐2‐ones 14 or pyrimidin‐2‐ones 15 caused by Dimroth‐rearrangement.
Untersuchungen über den Thermischen Zerfall von n‐Dodecylcyclopentan in der Gasphase
Authors: Zychlinski W. , Anders G. , Zimmermann G. 
Published: December 2004

Investigations on the Thermal Decomposition of n‐Dodecylcyclopentane in the Gas PhaseIn the thermal decomposition of n‐dodecylcyclopentane at 670 and 750°C in a laboratory tubular reactor mixtures of hydrogen and 57 and 113 hydrocarbons respectively are formed. The mixtures have been analyzed and identified by capillary gas chromatography and by mass spectrometry. The distribution of the reaction products is used for mechanistic discussions.
Desaktivierungsverhalten von Arenen und Heteroarenen. XXXIII. Zur statischen Löschung der Fluoreszenz von Azinium‐Anthracenen in Lösungsmitteln mit n‐Donatoreigenschaften
Authors: Bendig Jürgen , Helm Siegrun , Kreysig Dieter , Wilda Jürgen 
Published: December 2004

Deactivation Behaviour of Arenes and Heteroarenes. XXXIII. Static Fluorescence Quenching of Azinium‐Anthracenes by Solvents of n‐Donor PropertiesThe fluorescence of azinium‐anthracenes is quenched by solvents of n‐donor properties. A model of static quenching by electron transfer is developed analogous to the dynamic process. The rates of quenching correlate with the donor properties of the solvent (ionization potential) and the acceptor properties of the fluorophor (reduction potential). In the same way as in the case of dynamic quenching this static process is characterized by a high free enthalpy of activation. The existence of a thermally induced step in the process of the electron transfer affects the temperature dependence of the fluorescence quantum yields. The analysis of this temperature dependence on the basis of an Arrhenius equation shows a linear relationship.