bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photooxidation von Leukofarbstoffen. III. Sensibilisierte Photooxidation von Leukofluoreszein
Authors: Langbein H. , Paetzold R. 
Published: December 2004

Photooxidation of Leuco Dyes. III. Sensitized Photooxidation of Leuco FluoresceinQuantum yields of the sensitized photooxidation of leuco fluorescein are reported. Fluorescein and benzophenone were found to be efficient sensitizers of photooxidation of leuco fluorescein. There is a characteristic dependence of quantum yields on concentration of leuco fluorescein and oxygen in the solution. The results are discussed on the basis of reaction scheme proposed for the sensitized formation of fluorescein.
1H‐NMR‐Spektroskopische Isomerenzuordnung bei Cyclisierungs‐Reaktionen an Benzo‐kondensierten N‐Heterocyclen
Authors: Graubaum H. , Martin D. 
Published: December 2004

1H‐NMR Spectroscopic Assignments of Isomeres to Cyclization Reactions of Benzo‐condensed N‐HeterocyclesCyclic N‐acyl benzazoles show downfield shifts of the aromatic Ha proton at the 1H‐n.m.r. spectrum from 0.5 to 1.95 ppm which allows an assignment of possible isomeres and in some cases statements about the tautomerism. The ΔδHa values of 40 different azolo‐, azino‐, and azepino condensed benzimidazoles are given.
Phosphororganische Antioxidantien. I. Kinetik und Mechanismus der Zersetzung von Alkyl‐hydroperoxiden durch o‐Phenylen‐phosphite und ‐phosphate
Authors: Schwetlick K. , Rüger C. , Noack R. 
Published: December 2004

Organophosphorus Antioxidants. I. Kinetics and Mechanism of the Decomposition of Alkylhydroperoxides by o‐Phenylene Phosphites and PhosphatesThe reaction mechanism of 2‐(2, 6‐di‐tert‐butyl‐4‐methyl‐phenoxyl)‐1,3,2‐benzodioxaphosphole (1) with cumyl and t‐butyl hydroperoxide has been studied kinetically by means of 31P‐n.m.r. spectroscopy and high pressure liquid chromatography. 1 reacts with cumyl hydroperoxide to give the corresponding 2‐oxide (2) which with more hydroperoxide and/or water forms the open chained phosphate ester 5. This acidic phosphate decomposes hydroperoxide catalytically. The kinetic parameters of the separate reaction steps are given. The ionic mechanism of hydroperoxide decomposition is accompanied by a homolytic one in a minor proportion.
Zur Synthese und Abwandlung N‐substituierter 2(1 H)‐Pyrimidin‐thione ‐ Ein einfacher Zugang zu Pyrimidino[2,3‐b]1,3,4‐thiadiazoliumsalzen
Authors: Liebscher Jürgen , Hartmann Horst 
Published: December 2004

Synthesis and Transformation of N‐substituted 2(1 H)‐Pyrimidine‐thiones – A Simple Route to Pyrimidino [2,3‐b]1,3,4‐thiadiazolium SaltsN‐substituted 2(1 H)‐pyrimidine‐thiones 4–6 can be prepared by reaction of primary amines or unsubstituted or substituted hydrazines with 3‐isothiocyanato‐propene‐(2)‐iminium salts 2, which are easily aviable from 3‐chloro‐propene‐(2)‐iminium salts 1. The 2(1 H)‐pyrimidine‐thiones are transformed into 2‐alkylmercapto‐pyrimidinium salts 7 and pyrimidino[2,3‐b]1,3,4‐thiadiazolium salts 9, respectively.
Photoinduzierte Zersetzung von Arendiazoniumsalzen durch Pyrazolon‐ und Naphtholfarbstoffe
Authors: Timpe H.‐J. , Schubert E. , Worschech S. 
Published: December 2004

Photoinduced Decomposition of Arene Diazonium Salts by Pyrazolone and Naphthole DyesThe pyrazolone dyes 1–4 in their photoexcited singlet states bleached out by arene diazonium salts which dediazoniate during the reaction. Both compounds react in equal proportion. The quantum yields increase with the increasing of the concentration and electron acceptor properties of the diazonium salts and increasing of the electron donor properties of the dyes.The quantum yields of dye bleaching decrease on addition of DABCO or allylic thiourea, whereas the dediazoniation is not influenced. A kinetic model based on a primary electron transfer from the excited dye to arene diazonium salt is presented and used to determine rate constants for individual partial reactions.
Ionenpaargleichgewichte komplexer Carbeniumionensalze als Modelle für die aktive Spezies bei der kationischen Polymerisation
Authors: Heublein Günther , Grimmer Cornelia 
Published: December 2004

Ion‐pair Equilibria of Complex Carbenium Ion Salts as Models of the Active Species in Cationic PolymerizationThe dissociation equilibria of complex carbenium ion salts [(C6H5)3C⊕, C7H7⊕MtX⊖n+1] have been determined in chloroform, dichloroethane and nitromethane from conductance measurements. The dissociation constants remain almost unchanged for different anions, are however influenced markedly by the polarity of the solvent.The fractions of free and paired ions in these solvents have been calculated.Furthermore the enthalpies and entropies of dissociation have been evaluated.
Photochemische Primärprozesse von Xanthenfarbstoffen. I. Blitzlichtspektroskopische Untersuchung der Primärprozesse von Selenopyronin
Authors: Ortmann W. , Kassem A. , Hinzmann S. , Fanghänel E. 
Published: December 2004

Photochemical Primary Processes of Xanthene Dyes. I. Investigations of the Primary Processes of Selenopyronine by Flash ExcitationThe triplet‐state of selenopyronine absorbs light in the whole investigated spectral range (λmax = 400 nm, 480 nm, 690 nm). As results of the bimolecular triplet decay a half‐reduced (λmax = 430 nm) and a half‐oxidized (λmax = 475 nm) form of the dye are observed. p‐Benzoquinone quenches the triplet‐state (k7 = 1,5 · 109 l/mol s) and the results are the half‐oxidized form and the p‐benzosemiquinone ion. For these two products different decay processes exist. The reducing agents DABCO, EDTA and Hydroquinone also quench the triplet state (k10 = 1,2 · 106 l/mol s, k11 = 1,0 · 106 l/mol s, k12 = 1,0 · 109 l/mol s) and as result the half‐reduced form is observed. Measurements with thiopyronine give analogous results, which are in good agreement with investigations published in the literature.
Thermal decomposition of quinone: Synthesis of Anthrimidazodiones
Authors: Jain M. L. , Soni R. P. 
Published: December 2004

Thermischer Zerfall von Chinonen Synthese von AnthrimidazodionenDer thermische Zerfall von Endo‐9,10‐o‐phenylen‐2‐chlor‐3‐azido‐9,10‐dihydro‐1,4‐anthrachinon (2) in einem Überschuß einer heterocyclischen tertiären Base, z. B. Pyridin, Chinolin, Isochinolin, α‐, β‐, γ‐Picolin, Lutidin und Collidin ergibt die Anthrimidazodione (5, 6, 7). Diese werden ebenfalls durch einen Alternativweg synthetisiert: die Kondensation von Endo‐9,10‐o‐phenylen‐2,3‐dichlor‐9,10‐dihydro‐1,4‐anthrachinonen (1) mit 2‐Aminopyridin. Chinolin bzw. Isochinolin in Ethanol ergibt die Verbindungen 9a–c. Diese werden anschließend in Eisessig zu den Verbindungen 5, 6, 7 cyclisiert, deren Struktur durch Elementaranalyse und spektroskopische Daten gesichert wird.
Studies on the Synthesis of 8,15‐Dimethyl Prostanoids. A Facile Allylic Rearrangement of the 15‐Alkoxy‐15‐Methyl Prosta‐11,13‐Diene System
Authors: Schwarz S. , Weber G. , Schick H. 
Published: December 2004

Untersuchungen zur Synthese von 8,15‐Dimethylprostanoiden. Allylumlagerung des 15‐Alkoxy‐15‐methyl‐prosta‐11,13‐diensAusgehend von durch mikrobielle Transformation zugänglichem (2S, 3S)‐3‐Hydroxy‐2‐methyl‐2‐(prop‐2‐inyl)‐cyclopentanon (2) wurde der 1,9,15‐Tris‐(α‐ethoxy)ethylether des (15RS)‐1,9α,15‐Trihydroxy‐8,15‐dimethyl‐prosta‐11,13(E)‐dien‐5‐ins (22) in 9 Stufen dargestellt. Hydrolyse dieses Ethers führte zur Allylumlagerung unter Beteiligung des jeweiligen Lösungsmittels: in Ethanol entstand 11‐Ethoxy‐1,9α‐dihydroxy‐8,15‐dimethylprosta‐12,14(E)‐dien‐5‐in (23), während sich in Gegenwart von Essigsäure die entsprechende 11‐Acetoxyverbindung (24) bildete.
1H‐NMR‐spektroskopische Untersuchungen zur Stereochemie von Butadienderivaten
Authors: Castanedo N. , Peseke K. , Kelling H. , Michalik M. 
Published: December 2004

1H‐N.M.R. Spectroscopic Investigations on Stereochemistry of Substituted ButadienesThe butadienes 1–6, obtained by Knoevenagel condensation of furfuryliden, 5‐bromofurfuryliden, and benzylidenaceton with malononitril and ethyl cyanoacetat respectively, have been investigated 1H‐n.m.r. spectroscopically. Structure and configuration of the isomers could be determined with the help of deuteration experiments, anisotropy effects, and Eu(fod)3 shift reagents measurements.
NMR‐spektroskopische Untersuchungen zum Konformations‐verhalten von 2′‐ und 3′‐halogensubstituierten Pyrimidinnucleosiden
Authors: Joecks A. , Köppel H. , Schleinitz K. D. , Cech D. 
Published: December 2004

N.M.R. Spectroscopical Investigations on the Conformational Behaviour of Some 2′ ‐ and 3′‐Halogen‐substituted Pyrimidine NucleosidesA series of 2′‐ and 3′‐halogenated pyrimidine nucleosides has been synthesized and investigated by 1H, 13C and 19F n.m.r. spectroscopy. The 1H and 13C chemical shifts for the positions 2′ and 3′ depend linearly but oppositely on the substituent electronegativities XR.The conformational equilibrium N ⇌ S of the nucleosides in solution is determined. An approximately linear correlation between the prefered gauche‐gauche interaction of the exocyclic CH2OH groups and the ribose N conformation has been found.
Tetrathiafulvalene. XX. Charge‐Transfer, Radikalkonzentration und elektrische Eigenschaften von TTF und TSF‐TCNQ‐Komplexen
Authors: Fanghänel E. , Schukat G. , Schützendübel J. , Humsch W. 
Published: December 2004

Tetrathiafulvalenes XX. Charge‐Transfer, Radical Concentration and Electrical Properties of TTF‐ and TSF‐TCNQ‐ComplexesFor TTF‐TCNQ‐complexes the spin density increases with a higher degree of CT, estimated from the value of C‐N‐vibration in TNCQ. The dihydronaphthocondensed cis‐ and trans‐TSF‐TCNQ‐complexes (11, 12) show the same high conductivity, whether the complex composition is 2:1 or 1:1.
Thermitase – eine thermostabile Serinprotease. III. Synthese von N‐Acyl‐peptidmethylketonen als reversible Enzyminhibitoren
Authors: Fittkau Siegfried , Jahreis Günther 
Published: December 2004

Thermitase – A Thermostable Serine Protease. III. Synthesis of N‐Acylated Peptide Methyl Ketones as Inhibitors Reversibly Bound to the EnzymeMethyl ketone derivatives of dipeptides to pentapeptides are used as suitable tools in the investigation of the non‐covalent binding for subsite mapping of the active site of the enzyme. The synthesis is mainly performed by fragment condensation of N‐acylated peptides or amino acids with methyl ketone derivatives of amino acids. These are prepared from the Z‐protectedAbkürzungen: Ac = Acetyl, Z = Benzyloxycarbonyl, Boc = t‐Butyloxycarbonyl, Suc = Succinyl, Glp = Pyroglutamyl, OBz = Benzylester, pNA = p‐Nitranilid, CH3 = Methylketon, CH2Cl = Chlormethylketon, MA = Mischanhydridmethode, TEA = Triethylamin, NEM = N‐Ethylmorpholin, CKEE = Chlorkohlensäureethylester, CKBE = Chlorkohlensäurebutylester, MeOH = Methanol, EtOH = Ethanol, AcOH = Essigsäure, Ac2O = Acetanhydrid, Etac = Ethylacetat, THF = Tetrahydrofuran, E = Ether, PE = Petrolether, DMF = Dimethylformamid, DMSO = Dimethylsulfoxid, DMAP = 4‐(Dimethylamino)‐pyridin

cloromethyl ketones by catalytic hydrogenation. For the coupling steps the Z‐protection is preferred. The peptide methyl ketones used in kinetic studies were N‐protected by the Z, acetyl, Boc or pyroglutamyl residue.
Protonierung und Solvatation schwacher organischer Basen. I. Zur Basizität von ω‐Chloracetophenonen
Authors: Freiberg W. , Scheer J. , Streich U. , Starick E. , Kröger C.‐F. 
Published: December 2004

Protonation and Solvation of Weak Organic Bases. I. Basicity of ω‐ChloroacetophenonesThe protonation equilibria of ω‐chloroacetophenone and some p‐substituted derivates have been studied in the acid system H2O/H2SO4/SO3 by u.v. and 1H‐n.m.r. spectroscopy. From the determined H0 values for half‐protonation pKBH+ values were calculated by means of the solvation parameters m of YATES and McCLELLAND. The (H0)1/2 and the pKBH+ values were successfully correlated with σp and σp+ substituent constants.
2, 2‐Disubstituierte Cyclopentan‐1, 3‐dione. IV. Synthese prochiraler Zwischenprodukte für 8‐Methyl‐prostaglandin C2 durch C‐Alkylierung von 2‐Methylcyclopentan‐1,3‐dion mit 1‐Brom‐alk‐2‐inen
Authors: Schick H. , Schwarz H. , Theil F. , Schwarz S. 
Published: December 2004

2, 2‐Disubstituted Cyclopentane‐1, 3‐diones. IV. Synthesis of Prochiral Intermediates for the Synthesis of 8‐Methyl‐prostaglandin C2 by Alkylation of 2‐Methyl‐cyclopentane‐1, 3‐dione with 1‐Bromo‐alk‐2‐ynes.2‐Methyl‐cyclopentane‐1, 3‐dione (1) is preferentially C‐alkylated by 1‐bromo‐alk‐2‐ynes in aqueous sodium hydroxide solution. By this method it is possible to prepare 2,2‐disubstituted‐1, 3‐diones (3–8), which can be converted into prochiral intermediates for 8‐methyl‐PGC2, containing the complete carboxylic side chain.
The Reaction of Malononitrile with Enamines of some cyclic β‐Keto acid anilides and amidines
Authors: Bogdanowicz‐Szwed Krystyna , Policht Andrzej 
Published: December 2004

AbstractThe reaction of enamines 1 derivatives of cyclohexanon‐ or cycloheptanon‐2‐carboxylic acid anilides with malononitrile gave in the first step 2‐phenylcarbamoyl‐cycloalkylideno‐malononitriles 3, which in turn were converted into 1‐oxo‐2‐phenyl‐3‐amino‐4‐cyano‐cycloalkenoisoquinolines 4. Enamines containing an adjacent diphenylamidino group 6 reacted with malononitrile giving 1‐phenylimino‐2‐phenyl‐3‐amino‐4‐cyano‐cycloalkenoisoquinolines 7. The alkaline hydrolysis of 7 yielded 1‐phenylamino‐3‐oxo‐4‐cyano‐cycloalkenoisoquinoline 8.
Desaktivierungsverhalten von Arenen und Heteroarenen. XLI [1b]. Struktur‐ und Umgebungseinflüsse auf die intramolekulare [π4s + π4s]‐photo‐cycloaddition von α,ω‐Bis‐(9‐acridiziniumyl)‐alkanen
Authors: Wagner J. , Bendig J. , Kreysig D. 
Published: December 2004

Deactivation Behaviour of Arenes and Heteroarenes. XLI. Structural and Environmental Effects on the Intramolecular [π4s + π4s]‐ Photocycloaddition Reaction of α, ω‐Bis‐(9‐acridiziniumyl) ‐ alkanes.Fluorescence characteristics, including quantum yields and decay times, and quantum efficiencies for the reversible intramolecular [π4s + π4s]‐ photocycloaddition reaction for a series of α, ω‐bis‐(9‐acridiziniumyl)‐alkanes have been measured in several solvents and they have been compared with those of the model compounds acridizinium‐ion. and 9‐methyl‐acridizinium‐ion. These parameters of the bichromophores depend on the number of CH2‐groups of chromophor linkage. The title compounds investigated were divided into groups of common behaviour, and differences are due to increasing bond angle strain and coulomb‐repulsion in the photocyclomer state.
Polarographic study of the Reduction of Cadmium(II) and Lead(II) in DL‐norleucine media
Authors: Saxena R. S. , Dhawan S. K. 
Published: December 2004

AbstractIn continuation of our earlier work on the electrochemical behaviour of amino acids and their metal complexes [1–3], the present investigation reports the polarographic behaviour of Cd(II) and Pb(II) in presence of DL‐norleucine, formation and composition of their complexes, determination of stability constants by DEFORD and HUME'S method [4] and MIHALLOV'S mathematical approach [5] at 20° and 30°C and also thermodynamic parameters accompanying complexation reactions at 20°C.
Reaktionen von Cyclanyl‐Radikalen in der Gasphase. II. Cyclohexyl‐Radikale aus Azomethan‐Cyclohexan‐Gemischen
Authors: Ondruschka B. , Zimmermann G. , Anders G. 
Published: December 2004

Reactions of Cyclanyl Radicals in the Gas Phase. II. Cyclohexyl Radicals from Mixtures of Azomethane and CyclohexaneCyclohexane‐azomethane mixtures in argon as diluent were converted by temperatures between 400 and 480°C in a stirred flow system. All products were analytically determined in a comprehensive way. In this way not only isomeric C6H11‐radicals, which were already known from former investigations, but also hitherto unknown C6H11‐radicals, especially the 3‐methylcyclopentyl radical, could be detected as a recombination product with methyl radicals or as the corresponding olefinic compounds. From the results the stationary concentrations of important radical species were estimated and mechanistic consequences discussed.
Photooxidation von Leukofarbstoffen. VIII. Kurzzeitspektroskopische Untersuchungen zum Mechanismus der Photooxidation von Leukokristallviolett
Authors: Hinzmann G. , Grummt U.‐W. , Paetzold R. 
Published: December 2004

Photooxidation of Leuco Dyes. VIII. Time Resolved Investigations of the Mechanism of the Photooxidation of Leucocrystal VioletThe photooxidation of leucocrystal violet has been reexamined by means of conventional and laser flash photolysis as well as spin trap experiments. Three radical transients have been observed and assigned to the cation radical (λmax ≈ 490, 530 nm), the neutral radical with oneNCH3CH2 moiety (λmax ≈ 480 nm) and the triphenyl methyl radical derivative (λmax ≈ 400 nm).
Palladium‐katalysierte Addition von Methanol an Isopren
Authors: Gaube W. , Stegemann H. 
Published: December 2004

Palladium‐Catalyzed Addition of Methanol to IsopreneThe soluble systems containing palladium(II)‐compounds and tri‐n‐butylphosphine as a ligand catalyze the addition of methanol to isoprene to give methoxyisopentenes in goodyields. Activity and selectivity of the reaction are dependent on the ligand, the ratio ligand to palladium and in a surprising manner on the concentration of methanol.
Photokatalytische Systeme. LXIV. Theoretische Untersuchungen zum Ladungstransfer und zur Photoreaktivität von π‐Akzeptorligandkomplexen mit d6‐Übergangsmetallen
Authors: Benedix R. , Hennig H. 
Published: December 2004

Photocatalytical Systems. LXIV. Theoretical Investigations of the Charge Transfer and of the Photochemical Reactivity of d6 Transition Metal Complexes with π Acceptor LigandsQuantum chemical investigations concerning the charge transfer interactions between a d6 complex fragment and heterocyclic nitrogen ligands are reported. The influence of inductive, mesomeric and steric effects on the π acceptor ability of the isolated ligand and on the electronic structure of the pentacyano‐ferrate(II) mixed ligand compounds has been investigated and possibilities to sensitize spectrally the Fe(CN)5L3− system (L= pyridine‐type ligand) with regard to their photochemical reactivity are discussed.
Eine neue Methods zur Einführung von CF3‐ und C2F5‐Gruppen in Pyrimidinderivate und die Anti‐Herpes‐Aktivität der Verbindungen
Authors: Schwarz B. , Cech D. , Reefschläger J. 
Published: December 2004

A New Method of the Introduction of CF3‐ and C2F5‐Groups into Pyrimidine Derivatives and their Antiherpes ActivityA new method of the perfluoroalkylation of uracil derivatives is described. The irradiation of aqueous solutions of uracil and uracilnucleosides with bis‐(perfluoroalkyl) mercury (CnF2n+1)2Hg n = 1, 2 under the exclusion of oxygen in the presence of catalytic amounts of azo‐bis‐isobutyronitril at 254 nm for several hours gave new 5‐perfluoroalkylated compounds. In this way we obtained 5‐trifluoromethyluracil (5a), 5‐pentafluoroethyluracil (5b), 5‐trifluoromethyl‐2′‐deoxyuridine (6a), 5‐pentafluoroethyl‐2′‐deoxyuridine (6b) and 1‐(ß‐D‐arabinofuranosyl)‐5‐trifluoromethyluracil (7a) in different yields. The perfluoroalkylated compounds were tested against HSV‐1 and HSV‐2 viruses on human lungefibroblasts. The compounds are markedly less potent than other known nonfluorinated compounds.
Photochemie von Aminoketonen. VII. Eine diastereoselektive Synthese von 3‐Hydroxy‐prolinen
Authors: Haber H. , Buchholz H. , Sukale R. , Henning H.‐G. 
Published: December 2004

Photochemistry of Aminoketones. VIII. Diastereoselective Synthesis of 3‐Hydroxy‐prolinesGlycine esters react in two steps (aminoalkylation and N‐acylation) to N‐acyl‐N‐(β‐benzoylethyl)‐glycine ester 3. In less polar solvents these ketonic compounds are n,π*‐excited by 300 nm irradiation. In ether 3* yield mixtures of aminocyclopropanoles 4, hydroxyprolines 5 and products of additions and cleavages. In benzene and cyclohexane/benzene, respectively, the regioselective photocyclization to 5 is favoured. Furthermore this hydroxyproline synthesis has the advantages of high diastereoselectivity yielding the (2,3) E–5 and of high overall‐yields in connection with the one pot method. The influence of solvents and substituents on the regio‐ and diastereoselectivity are explained using a model with stabilization of special conformations of intermediates by dipol‐dipol interactions.
Untersuchungen zum UV/Vis‐Spektralverhalten von Azofarbstoffen. XII. Eine Analyse der Korrelationen zwischen Absorptionsmaxima und den Hammett‐σ‐Konstanten der Substituenten
Authors: Mustroph H. 
Published: December 2004

Studies on UV/Vis Absorption Spectra of Azo Dyes. XII. An Analysis of the Correlations between Absorption Maxima and Hammett‐σ‐Constants for the SubstituentsPreviously claimed relationships between wavelength shifts and Hammett‐σ‐constants for the substituents are mostly unfounded. In certain cases, good linear correlations are found, but in other cases the plots deviate appreciably from linearity.We have examined such correlations on the basis of the classification scheme of organic dyes suggested by Fabian (charge transfer‐(CT)‐chromophores, locally excited‐(LE)‐chromophores) respectively Griffiths (donor‐acceptor chromogens, cyanine‐type chromogens).It was shown that good linear correlations should be obtained by LE‐chromophores (cyanine‐type chromogens). In CT‐chromophores (donor‐acceptor chromogens) however, an electron withdrawing substituent in the acceptor fragment causes a bathochromic displacement of the absorption maxima, and in the donor fragment it has little influence. A reversed behaviour was assumed for electron releasing substituents. Thus in CT‐chromophores V‐type correlations should be obtained.These rules are equally applieable to interpret the linear relationships between σ‐constants and the difference between the absorption maxima of two different, equilibrating species.
Folgeprodukte aus Sulfonamiden. VI. Darstellung und Cyclisierung von N‐Allyl‐N′‐arylsulfonyl‐thioharnstoffen
Authors: Hans M. , Dehne H. 
Published: December 2004

Consecutive Products of Sulphonamides. VI. Synthesis and Cyclization of N‐Allyl‐N′‐arylsulphonyl‐thioureasN‐Allyl‐N′‐arylsulphonyl‐thioureas 3a–e are synthesized by addition reaction of substituted arensulphonamides 2a–e and allylisothiocyanate 1. The thioureas 3a–e react with hydrogen bromide in acetic acid or bromine in chloroform to 2‐(arylsulphonylimino)‐5‐methyl‐(or bromomethyl)thiazolidines 8a‐j. The mechanism of reaction and the structures are discussed by means of i.r., m.s. and 1H‐n.m.r. data.
Synthesis, Spectroscopy and Tautomeric Study of Thiazoles substituted in positions 2 and 4 by hydroxy, mercapto and amino groups
Authors: Valls N. , Segarra V. M. , Alcalde E. , Marin A. , Elguero J. 
Published: December 2004

AbstractThiazoles substituted in positions 2 and 4 by hydroxy, mercapto and amino groups were synthesized, as well as its carbamate derivates and formylhydrazones. The research of the reaction of the formylhydrazide with 4‐imino‐2‐thiazolidinone has not given the pyrazolo [3,4‐d]‐ thiazol‐2‐one, but the 4‐formylhydrazono‐2‐thiazolidine. The detailed tautomeric study of each of the heterocyclic compounds has been carried out by infrared spectroscopy, nuclear magnetic resonance of proton and of 13‐carbon, and of masses.
Molecular geometry and excited electronic states. XII. Equilibrium Geometries of 9‐Phenyl Anthracene in different electronic states and its electronic spectral behaviour
Authors: Gustav K. 
Published: December 2004

AbstractWithin the framework of a complete geometry‐optimization the molecular geometries of 9‐phenyl anthracene in the S0, S1and T1states have been determined by means of the Warshel‐Karplus method. In all cases twisted structures have been found. In addition to this, for the excited electronic states the presence of the anthracene ring acoplanarity has to be emphasized. Taking into account the theoretical molecular geometries the electronic transition energies and oscillator strengths have been calculated and used for the interpretation of the electronic spectral behaviour in absorption and fluorescence. The theory‐experiment comparison performed is satisfactory and confirms the calculated structures of 9‐phenyl anthracene indirectly.