bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fotosensibilisierte Ausbleichung von Azomethinfarbstoffen
Authors: Grossmann N. , Wehner V. , Weise A. , Winnig B. , Fanghänel E. 
Published: December 2004

Fotosensitized Fading of Azomethine DyesThe quantum yields of photofading of the azomethine dyes 1a—h were determined in the presence of the sensitizers benzophenone (B), michler's ketone (MK) and anthracen (A), in isopropanol and benzene. In isopropanol, excluding oxygen, the leuco dyes 5 are formed by benzophenone in high quantum yield (Φ = 0.4). Photofading also takes place using Michler's ketone (Φ ≅ 3 · 10−3) and anthracene (Φ ≅ 1 · 10−4), but 5 was not found. With benzophenone (Φ
≅ 7 · 10−3), Micher's ketone (Φ ≅ 1 · 10−3) and anthracene (Φ ≅ 1 · 10−4) as sensitizers the chromophore of 1a—h were destroyed, when oxygen was present. The photofading with benzophenone and Michler's ketone is a result of radicalic processes.Radical scavangers 8 and 9, therefore, give a strong decrease of the quantum yield of photofading. The photofading in benzene corresponds to the results in isopropanol considering the lower potential of this solvent for photoreduction processes.
Photochemie diarylsubstituierter 2H‐Tetrazole. VI. Quantenausbeuten der Photolyse diarylsubstituierter 2H‐Tetrazole
Authors: Lohse V. , Leihkauf P. , Csongar Ch. , Tomaschewski G. 
Published: December 2004

Photochemistry of Diarylsubstituted 2H‐Tetrazoles. VI. Quantumyields of the Photolysis of Diarylsubstituted 2H‐TetrazolesThe photoexcitation of diarylsubstituted 2H‐tetrazoles in ethanol in the presence of methylmethacrylat (MMA) yields quantitatively 1,3‐diaryl‐Δ2‐pyrazolines. The photoreactions investigated are spectroscopically uniform. The influence of the substituents on the quantum yields of the photolysis of 2H‐tetrazoles (1a—1x) is discussed.
Pyrazolinon‐Ringschluß unter Alkoxywanderung
Authors: Kirschke Klaus , Kuban Ralf‐jürgen , Schulz Burkhard 
Published: December 2004

Pyrazolinone Ring Closure with Alkoxy MigrationAlkyl 3‐(4‐nitro‐phenylazo)‐2‐brom‐2‐butenoates (1a, b) with morpholine undergo substitution of the bromo group and ring closure connected with a migration of the alkoxy group forming 4‐alkoxy‐3‐methyl‐4‐morpholino‐1‐(4‐nitro‐phenyl)pyrazolin‐5‐ones (2a, b).
Synthesis, characterization, spectral and antifungal properties of some 5‐Substituted‐1,3,4‐oxadiazole‐2‐thiones and their mannich bases
Authors: Holla B. Shivarama , Kalluraya Balakrishna , Nath S. C. 
Published: December 2004

AbstractA series of 5‐substituted aryloxymethyl‐1,3,4‐oxadiazole‐2‐thione (3a–e) and their Mannich bases 4–8 are synthesized and subjected to fungitoxic screening. The structures of these compounds are established on the basis of elemental analysis 1H‐n.m.r. and mass spectral data. The mass spectral fragmentation pathways of these compounds are discussed.
Solvatochromic Behaviour and Prototropic Studies of some oxazolones of electron donor‐acceptor type
Authors: Antonious M. S. , Habashy M. M. , El‐Sayed Y. A. 
Published: December 2004

AbstractSolvatochromic and halochromic behaviour in the u.v.‐vis absorption spectra of some substituted 4‐arylidene‐2‐aryloxazol‐5‐ones (1–5) are studied. Positive and negative solvatochromism, depending on the substituent present, are observed in different hydrogen bonding donoracceptor (HBD‐A) and hydrogen bonding acceptor (HBA) solvents. However, in non hydrogen bonding (NHB) solvents all compounds show a positive solvatochromism. A considerable intramolecular charge transfer interaction, between the donor and acceptor parts in the oxazolones studied, is observed. Small fluorescence quantum yields are observed for the oxazolones. In triethanolamine‐acetone mixtures, the visible absorption spectra of the hydroxy substituted oxazolone shows an additional long‐wavelength band suggesting the existance of prototropic equilibria. The prototropic equilibrium constants at different temperatures are determined.
Wasserlösliche disulfonierte aromatische Ketone — Photophsikalische und photochemische Eigenschaften
Authors: Kronfeld K.‐P. , Timpe H.‐J. 
Published: December 2004

Water Soluble Disulphonated Aromatic Ketones — Photophysical and Photochemical PropertiesBy the sulphonation of benzophenone, xanthone, thioxanthone, acridone, and methylacridone the disulphonated derivatives BPS, XS, TXS, AcS and MAcS are produced. Their disodium salts are well soluble in water. The absorption and the emission spectral data of these ketones are similar to those of the respective parent compounds. The S1 state of BPS alone is of n — π* type, in all the other cases it possesses mainly π — π* character. The S1 states can serve as donors in electron transfer reactions with iodonium salts. The kinetic curves of flash photolysis of these ketones in water show two decay processes, which are attributed to the triplet state and the long living ketyl radical. The triplet absorption spectra of the disulphonated ketones are very close to those of the unsubstituted ketones, but the life times of the former are much higher. The T1 are quenched through onium salts by electron transfer reactions. Acryl amide, too, acts as a quencher for the triplets.
Zur Pyrolyse von 3‐Ethylpent‐2‐en – Ein weiterer Hinweis auf eine Homoallyl‐Umlagerung
Authors: Bach G. , Zychlinski W. , Kopinke F.‐D. , Zimmermann G. 
Published: December 2004

Pyrolysis of 3‐Ethylpent‐2‐ene — a Further Evidence for a Homoallylic‐RearrangementThe pyrolysis of 3‐ethylpent‐2‐ene has been studied under conditions of steam cracking in the temperature range 600—700°C in a laboratory scale tubular reactor. The main products of decomposition were methane, 2‐ethylbutadiene and isoprene. The majority of products obviously arose from H abstraction and radical addition, typical for radical chain reactions in olefins decomposition including phenomena resulting from allylic resonance. The formation of isoprene, however, could only be explained by a reaction network including a homoallylic rearrangement.
Zur Kinetik der photoinduziertenRadikalpolymerisation mit Elektronendonator/Elektronenakzeptor‐Initiatorsystemen
Authors: Timpe H.‐J. , Oertel U. , Zücker I. , Müller G. 
Published: December 2004

Kinetics of Photoinduced Radical Polymerization with Electron Donor/Electron Acceptor Initiator SystemsBy means of benzyltriphenylphosphonium tetrafluoroborate (P⊕) and anthracene (An) as photoinitiator system and methylmethacrylate (MMA) as monomer the influences of several reaction parameters on the polymerization quantum yield Φp, were studied. The following principal reactions proceed: electron transfer between excited An (1An) and P⊕salt (kq= 2,5 · 109M−1s−1), quenching of1An by MMA (k= 1,3 · 107M−1s−1), reaction between a1An…P⊕salt complex and MMA. The last reaction is assumed, since from the disappearance of An and the formation of An cation radical, respectively, rate constants k> 108M−1s−1have been calculated. Furthermore, it is assumed, that only the quenching of1An by MMA (Φp= 3,8) and the addition of free radicals, produced by the photoinduced electron transfer, lead to polymer formation. Kinetic equations were developed, which can explain the effect of P⊕‐salt concentration, light intensity and MMA concentration on Φpdata. The quotient obtained for kp/kis in the range of 0,053 to 0,087 M−0,5s−0,5, depending on the used experimental parameters. Polymerization degrees Pnof 260–590 were found, which also depend on the experimental parameters.
Zur Reaktion von atomarem Wasserstoff mit Cyclopenten und Cyclohexen in der Gasphase
Authors: Gebhardt J. , Scherzer K. 
Published: December 2004

About the Reaction of Hydrogen Atoms with Cyclopentene and Cyclohexene in the Gas PhaseThe reaction of hydrogen atoms with cyclopentene and cyclohexene has been investigated in an isothermal flow‐system (298 K) at a pressure of 130 Pa. 12 products of the cyclopentene reaction and 17 products of the cyclohexene reaction were identified by gas chromatography. The quantitative studies show, that the main reactions of the cyclopentene system are the hydrogenation to cyclopentane and the chemical activated decay to methane; cyclohexene reacts especially by hydrogenation to cyclohexane and ring‐isomerisation to methylcyclopentane.
2,3‐Heterokondensierte Thiophene aus substituiertem 2‐Aminothiophen‐3‐thiol
Authors: Gewald K. , Hain U. , Madlenscha M. 
Published: December 2004

2,3‐Heterocondensed Thiophenes from Substituted 2‐Aminothiophen‐3‐thioleEthyl 5‐amino‐4‐mercapto‐3‐methyl‐thiophen‐2‐carboxylate (2), obtainable from the appropriate thienylthiocyanate 1 by reduction, undergoes reactions in analogy to the 2‐aminobenzenthiole. Thus, with formic acid or trimethylorthoacetat the thieno [2,3‐d]thiazoles 4 and 5 are formed. Aromatic aldehydes yield the thieno[2,3‐d]thiazolines (6) which can be dehydrogenated by sulphur to form 9. From carbon disulfide and 2 the thieno[2,3‐d]thiazol‐2‐thione (7) is formed. With phenacylbromide or ethyl bromoacetate 2 can be converted into the thieno[3,2‐b] thiazine derivatives 11 or 12. Diazotation of 2 yields the thieno[2,3‐d]1,2,3‐thiadiazole derivative (14).
Photochemie von Bis‐2H‐tetrazolen. III. Nachweis von Bisnitriliminen durch Tieftemperatur‐UV‐Spektroskopie und thermische Folgereaktionen durch Photolyse von Bis‐2H‐tetrazolen
Authors: Weinberg P. , Csongar Ch. , Gessner M. , Tomaschewski G. 
Published: December 2004

Photochemistry of Bis‐2H‐tetrazoles. III. Detection of Bisnitrilimines through Low‐Temperature‐UV‐Spectroscopy and Thermic Consecutive Reactions through Photolysis of Bis‐2H‐tetrazolesThe photolysis of 2H‐tetrazoles (1) leads to nitrilimines. Bis‐2H‐tetrazoles form correspondingly bisnitrilimines 2. They were detected directly by the photolysis of bis‐2H‐tetrazoles (1) in an ethanol/ether glass at 95 K. The absorption maxima are depend in an expected manner on the substituents. In the presence of dipolarophiles the reaction of bis‐2H‐tetrazoles (1) at room temperature gives bis‐Δ2‐pyrazolines (3). These reactions can also be explained by a photoreaction of bis‐2H‐tetrazoles (1) to bisnitrilimines 2 at 95 K and subsequent cycloaddition above 150 K. Some bis‐Δ2‐pyrazolines (3) are described.The photolyses of bis‐2H‐tetrazoles (1) to the bisnitrilimines 2 proceed as one step eliminations of two molecules of nitrogen.
Tetrazolverbindungen. 3. Modifizierung von (1‐Aryl‐1H‐tetrazol‐5‐yl)‐acetaldehyd‐Enaminen durch säurekatalysierte Umaminierung
Authors: Fischer G. W. 
Published: December 2004

Tetrazole Compounds. 3. Modification of 1‐Aryl‐1H‐tetrazole‐5‐acetaldehyde Enamines by Acid‐Catalyzed TransaminationThe acid‐catalyzed transamination of tetrazole‐5‐acetaldehyde enamines proves to be a useful synthetic method for preparing specially N‐substituted enamines of this series not accessible directly from 3‐chloro‐propeniminium salts 3 and sodium azide. Thus, starting from (E)‐1‐aryl‐5‐(2‐dimethylamino‐vinyl)‐1H‐tetrazoles 5 transamination with dialkylamines yields tertiary enamines of types 6 and 7. Analogously, acid‐catalyzed reaction of 5 with N‐alkylanilines leads to 1‐aryl‐5‐[2‐(N‐alkylanilino)‐vinyl]‐1H‐tetrazoles 8. Bifunctinal secondary amines such as N,N′‐dimethylethylenediamine result in systems of type 9 with two linked tertiary tetrazolyvinylamino groups. All the transaminations with secondary amines proceed with retention of configuration. According to the same reaction scheme transamination of 5 (Ar = Ph) with primary alkyl‐, aralkyl‐, and arylamines affords secondary tetrazolylvinylamines 10; however, here the formation of Z‐configurated products dominates. Bifunctional primary amines like ethylenediamine and 1,2‐phenylenediamine react with 5 to give the N,N′‐linked systems 11 and 12 possessing two secondary tetrazolylvinylamino groups. – Characteristic i.r., u.v., and 1H‐n.m.r. spectroscopic data of the novel tetrazole‐5‐acetaldehyde enamines are reported.
Preparation of 2‐Aroyl‐3‐methyl‐1H‐1,4‐benzothiazines. ESR Study of 2‐benzoyl‐1,3‐dimethyl‐1H‐1,4‐benzothiazine
Authors: Isakander George M. , El Shiekh El Khawad Ibrahim , Zahran Hassan B. , Schlemper Elmer O. 
Published: December 2004

Abstract2‐Aroyl‐3‐methyl‐1 H‐1,4‐benzothiazine ylids (2a–k) were prepared by alkylation of the corresponding 4H‐benzothiazines 1. The ylids 2 are labile at room temperature; proper analytical and 1H‐n.m.r. data were obtained for their picrates. E.s.r. studies of u. v. irradiated polycrystalline form of (2; R1 = Me, R2 = H) gave evidence for a long‐lived benzothiazinyl radical with the odd electron residing on nitrogen 6.
Studies of tertiary amine oxides. 11. Rearrangement of Acetylenic Amine Oxides
Authors: Khuthier Abdul‐Hussain , Sheat Mohammed Ali 
Published: December 2004

AbstractSixteen acetylenic amine oxides (5a–p) were prepared by the oxidation of the corresponding tertiary amines (4a–p) with m‐chloroperbenzoic acid. The N‐oxides are thermally unstable and undergo a rearrangement when stirred in an inert solvent yielding O‐allenyl hydroxylamines (6). The rearrangement proceeds by an intramolecular cyclic mechanism.
Pyryliumverbindungen. 42. Benzocycloalkenone und Dihydro‐2H,7H‐1‐benzopyranone aus 2,4,6‐Triaryl‐pyryliumsalzen und Cycloalkan‐1,2‐dionen
Authors: Zimmermann T. , Fischer G. W. , Olk B. , Findeisen M. 
Published: December 2004

Pyrylium Compounds. 42. Benzocycloalkenones and Dihydro‐2H,7H‐1‐benzopyranones from 2,4,6‐Triarylpyrylium Salts and Cycloalkane‐1,2‐diones2,4,6‐Triarylpyrylium salts 1 react with cycloalkane‐1,2‐diones 2 in the presence of an appropriate condensing agent to yield benzocycloalkenones 3. Thus, sodium acetate and cyclo‐hexane‐1,2‐dione (2a) lead to the dihydro‐2H‐naphthalenones 3a–i, whereas with cycloheptane‐1,2‐dione (2b) and piperidine acetate, triethylamine or sodium acetate the tetrahydro‐5H‐benzo‐cyclohepten‐5‐ones 3j–r are formed. As shown for the example 3a, j → 4a, b, benzocycloalkenones of type 3 can be converted into phthalazines 4 on heating with hydrazine in ethanol. By reaction of the dione 2a and an equimolar mixture of triethylamine and acetic acid or morpholine acetate with the salts 1 5,6‐dihydro‐2H,7H‐1‐benzopyran‐8‐ones 5 are obtained as a result of a new type of ring transformation. The pyrans 5 can be cleaved with perchloric acid in ethanol to 5,6,7,8‐tetrahydro‐8‐oxo‐1‐benzopyrylium perchlorates 6. If the pyrans 5 are heated with sodium acetate in ethanol, a conversion to benzocycloalkenones 3 is achieved (cf. 5a → 3a). The structure of the new compounds was established by spectroscopic methods.
Protonierung und Solvation schwacher organischer Basen. VII. 1H‐NMR‐spektroskopische Bestimmung der Basizität von cyclischen Ketonen
Authors: Freiberg W. , Roth H. , Rautenberg Ute , Kröger C.‐F. 
Published: December 2004

Protonation and Solvation of Weak Organic Bases. VII. 1H‐N.M.R. Spectroscopic Determination of the Basicity of Cyclic KetonesFrom protonation ratios for cycloalkanones of ring size C4‐C7 in the acid system H2OH2SO4HSO3F, determined by 1H‐n.m.r. spectroscopy, basicity and solvation parameters are estimated by application of extrapolation procedures based on the Hammett acidity function H0 or the excess acidity X. The frequency shifts of the n̈OH stretching vibrations of phenol in hydrogen bonded complexes with cycloalkanones have been measured. The ΔνOH values are related to the basicity parameter (H0)1/2.
Condensation of 4‐phenyl‐3,5‐dicarboethoxycyclopentane‐1,2‐dione with primary amines
Authors: Afsah A. M. , Osman A. I. , Sofan M. 
Published: December 2004

AbstractCondensation of the title compound (1) with primary aromatic amines gave the dianilides (2), which cyclized to cyclopenta[1,2‐c:4,3‐c′]diquinolines (3). Treatment of 1 with o‐phenylenediamine or 2,3‐diaminopyridine afforded cyclopenta[2,1‐b:3,4‐b′]bis[1,5]benzodiazepine (4) and bis[1,5]pyrido[b]diazepine derivative (5), respectively. Whereas, with o‐aminophenol a mixture of 2c and cyclopenta[2,1‐b:3,4‐b′]bis[1,5]benzoxazepine (7) was obtained. Pechmann reaction of 1 with m‐cresol gave the bis[1]benzopyrane (9). Mannich reaction of 1 with benzylamine afforded the 3‐azabicyclo[3.2.1]octane system (10).
Tetrathiafulvalene. XXIV. Gewinnung von cis‐ und trans‐ Isomeren bei Tetrathiafulvalenen (TTF)
Authors: Fanghänel E. , van Hinh L. , Schukat G. , Patzsch J. 
Published: December 2004

Tetrathiafulvalenes. XXIV. Isolation of cis‐ and trans‐Isomers of Tetrathiafulvalenes (TTF)The synthesis of naphthylsubstituted TTF permits in the case of the α‐naphthyl‐methylsubstituted TTF the isolation of the cis‐ and trans‐isomer by reason of differences in the solubility. The spectroscopical and electrochemical properties of naphthylsubstituted TTF are described.
Tetrazolverbindungen. 4 [1]. Alkylierung von 1‐Aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazolen
Authors: Fischer G. W. 
Published: December 2004

Tetrazole Compounds. 4. Alkylation of 1‐Aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazolesAlkylation of 1‐aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazoles 1 with dialkyl sulfates or alkyl iodides yields mainly 4‐alkyl‐1‐aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazolium salts which can be isolated free from isomers by separation as perchlorates 2. The reaction proceeds with retention of the E configuration of the vinyl group. In contrast to 1 the methyl groups of the dimethylamino substituent in 2 are magnetically non‐equivalent indicating restricted rotation of this residue. On heating 2 with aqueous mineral acids the dimethylaminovinyl moiety undergoes degradation to a methyl group affording 4‐alkyl‐1‐aryl‐5‐methyl‐1 H‐tetrazolium salts 4, the structure of which was confirmed by independent synthesis. With hot aqueous alkali hydroxide 2 reacts under ring cleavage to give aryl azide. — 1H n.m.r. and u.v. spectroscopic data of the tetrazolium salts 2 and 4 are reported.
Chemotherapeutic agents. XII [1]. Synthesis of Pyrimidines and Fused Pyrimidines as leishmanicides and herbicides
Authors: Ram Vishnu Ji 
Published: December 2004

AbstractVarious bicyclic (2, 3) and tricyclic (4, 5) heterocycles were prepared by the reaction of 1a, c with dihaloalkanes and polynitrohalobenzene separately. Electrophilic substitution on 1a–c with different alkyl halides yielded mono and dialkyl pyrimidiens (6–20). Nucleophilic substitution reactions on 18 and 21 with amine and hydrazine separately yielded 22–31, 21a, b and 41c. Reaction of 25a with ethyl ethoxymethylenecyanoacetate and chloroacetyl chloride separately provided bicyclic compounds 32 and 33. Condensation‐cyclization of 25a with formic, acetic and nitrous acid separately yielded 34a, b and 35. Reaction of 26a with ethylthiocylycolate and thiourea separately provided 36a and 39. The latter was alkylated with methyl iodide to 40. An attempt to cyclize 29a and 30a with thionyl chloride provided bicyclic compounds 37a, b and an uncyclic product 38. Some of the compounds were screened for leishmanicidal and herbicidal activities and a few of them exhibited significant activity.Leishmaniasis is considered to be one of the most devastating diseases and is ominous to tropical countries. The high toxicity of leishmanicidal drugs in current use, aroused considerable interest to develop new safer and effective chemotherapeutic agents. The only drug pyrimethamine [2] is the representative of pyrimidine derivatives, known as leishmanicides but low order of activity at high dose failed to retain in the clinic. Based on our past experiences in rational designing of leishmanicidal pyrimidine analogs, incorporation of levamisole pharmacophore either in flexible or rigid forms is indispensable for potential activity [1,3] against visceral leishmaniasis. These observations induced an impetus to synthesize pyrimidine analogs as potential leishmanicides.
Kinetics and isotope effects of the Dehydrochlorination of 1,1‐dichloro‐2,2‐bis‐(4‐nitrophenyl) ethane with 1,5‐diazabicyclo [4.3.0] non‐5‐ene in aprotic solvents
Authors: Schroeder Grzegorz , Jarczewski Arnold 
Published: December 2004

AbstractThe kinetics of the reaction of 1,1‐dichloro‐2,2‐bis‐(4‐nitrophenyl)ethane (1) with 1,5‐diazabicyclo‐[4.3.0]non‐5‐ene(DBN) in acetonitrile (MeCN), dichloromethane (DCM), tetrahydrofuran (THF), isopropylether (IPE) and hexane (Hex) solvents are reported. The reaction is a simple β‐elimination forming 1‐chloro‐2,2‐bis‐(4‐nitrophenyl)ethane (2) (100% conversion). The rate constants are similar for MeCN, THF, IPE, but lower by a factor of 2 and 7 for DCM and Hex respectively. The deuterium kinetic isotope effects kH/kD are between 10 and 6 for MeCN and Hex solvents. The entropies of activation (ΔS≠) are negative and large and show no correlation with the polarity of the solvents. The free enthalpies of activation (ΔG≠) are rather small (about 68 kJ mol−1). The results are interpreted in terms of E2H with a contribution of (E1cB)I mechanism.
Synthesis of Condensed 4H‐Pyrans: The reaction of 1,1‐dimethyl‐3,5‐diketocyclohexane with cinnamonitriles
Authors: Elnagdi Mohamed Hilmy , Abdel Aal Fatma Abdel Maksoud , Yassin Youssef Mahfouz 
Published: December 2004

AbstractCyclohexano‐4H‐pyrans could be prepared by reaction of 1,1‐dimethyl‐3,5‐diketo‐cyclohexane 2 with cinnamonitriles 1 and converted into 2‐amino‐4‐aryl‐1,4‐dihydro‐7,7‐dimethyl‐5‐oxocyclohexanopyridin‐3‐carbonitrile 7a, b; 7,7‐dimethyl‐2,5‐dioxo‐4‐phenyl‐1,2,3,4‐tetrahydro‐cyclohexanopyridin‐3‐carbonitrile 8, 5‐aryl‐1,1‐dicyano‐2‐phenyl‐8,8‐dimethyl‐1,2,3,4,6,7,8,9‐octahydro‐3‐azaacridin‐4,6‐dione 12a, b and 2‐thioxo‐4‐amino‐5‐aryl‐3‐benzoyl‐2,3‐dihydro‐9,9‐dimethylcyclohexano‐[g]‐4H‐pyrano[2,3‐d]pyrimidin‐7‐one 14a, b.
Zur Gasphasenpyrolyse von α, ω‐Phenylalkenen – Gesetzmäßigkeiten und Besonderheiten
Authors: Ondruschka B. , Zychlinski W. , Bach G. , Zimmermann G. 
Published: December 2004

On the Gas Phase Pyrolysis of α, ω‐Phenylalkenes — Regularities and Special FeaturesThe thermal conversion of the α, ω‐phenyl alkenes 1 to 4 was studied in the presence of a molar excess of Ar or steam at 500 to 875°C in a labscale tubular reactor. Detailed GC analyses did not establish significant evidences for such molecular rearrangements like, e.g., Di‐π‐methane rearrangement of 2, Ene and Carbo‐Claisen reaction of 3. The decomposition obviously occurs via radical chain processes in the main. Besides them, however, radical cyclizations, Neophyl rearrangements and Retro‐Ene reactions are parts of the complex reaction.
Studies on UV/Vis Absorption Spectra of Azo Dyes. 24. The different effect of a 2‐methoxy and a 3‐methoxy group in 4‐N.N‐diethylaminoazobenzenes on colour
Authors: Mustroph Heinz , Gussmann Frank 
Published: December 2004

AbstractA number of 2‐ and 3‐methoxy‐substituted‐4‐N.N‐diethylaminoazobenzenes have been prepared and their absorption maxima in ethanol and toluene compared with the corresponding 4‐N.N‐diethylaminoazobenzenes. Both the 2‐ and 3‐methoxy groups cause a bathochromic shift, but the bathochromic shift of a 3‐methoxy group depends on the substituents in the diazo component. With increasing electron‐withdrawing strength of the substituents in the diazo component a progressive enhancement of bathochromic shift appears. In toluene all 3‐methoxy‐substituted dyes absorb at longer wavelengths compared with the 2‐methoxy‐substituted dyes.
Azobrücken aus Azinen. X. Ein neuer Weg zu Carbocyclen mit parallel benachbarten NN/CC‐Brücken
Authors: Hünig Siegfried , Kraft Petra 
Published: December 2004

Azo‐bridges of Azines. X. A New Way to Carbocyclic with Parallel Neighbouring NN/CC‐BondsNitrogen extrusion from the easily accessible triazoline 11 on acidic solid phases results in the formation of aziridine 13 together with 14, a new system with parallel NN/CC‐bonds. By irradiation 14 undergoes smoothly [2 + 2]‐cycloaddition forming the cage compound 15. Photolysis of 11 does not yield 13 or 14. Instead by loss of the azo‐group either triazoline 16 or aziridine 17 are formed, depending on the band width of the UV‐sources.