bluuebunny/crossref_metadata_2025 huggingface dataset:
Elektrochemische Reduktion von 4‐substituierten 7‐Nitro‐benz‐2,1,3‐oxadiazolderivaten
Authors: Heberer H. , Matschiner H.
Published: December 2004

Electrochemical Reduction of 4‐Substituted 7‐Nitro‐benzo‐furazans

The electrochemical properties of 4‐methoxy‐, hydroxy‐, alkylamino, and arylaminosubstituted 7‐nitrobenzofurazans (1a–1h) are studied between pH 1,7 and 11,6 by use of buffer solutions containing different portions of various organic solvents. Reduction waves which are present in polarograms, are well reproducible and practicable for qualitative and quantitative analysis of amines. A mechanism of reduction is suggested by reason of polarographic and coulometric results. The half wave potentials are correlated with various substituent constants. A value of ϱ = + 0,32 follows from the determination of the reaction constant from the slope of the E 1/2 – σp – relation for the polarographic reduction of each nitro‐function.
Lichtinitiierte Polymer‐ und Polymerisationsreaktionen. 14. Radikalische Photopolymerisation mit Kaliumtrisoxalatocobaltat‐Aryloniumsalz‐Systemen
Authors: Baumann H. , Strehmel B. , Timpe H.‐J. , Lammel U.
Published: December 2004

Light Induced Polymer and Polymerization Reactions. 14. Radical Photopolymerization by Potassium Trisoxalato Cobaltate Arylonium Salts Systems.

The photopolymerization of acrylamide (AA) by trisoxalato cobaltate ([Co(ox)3]3⊖) is inefficient because the produced nucleophilic ·CO2⊖‐radicals are oxidized or they terminate with polymer radicals. If onium compounds are added to this system the initiation efficiency is increased as follows : p‐CH3OC6H4N2⊕>Ph2I⊕>PhCOCH2S(CH3)2⊕>Ph3S⊕. By means of quantum yield measurements a mechanism was proposed including the electron transfer from ·CO2⊖ to onium compounds. The produced radicals also initiate the polymerization of AA. The exponent m of the polymerization rate (vp ≈︁ [AA]m) is decreased from 1.4 to 1.1 in the presence of Ph2I⊕, deciding the decrease of termination reaction between ·CO2⊖ and polymer radicals. In comparison with K3[Fx(ox)3] the corresponding cobalt complex possesses higher polymerization quantum yields for AA.
Synthese und Charakterisierung von Polychlorisobutenen
Authors: Schulze K. , Hartmann S. , Krüger H. , Mühlstädt M. , Richter C. , Richter H.
Published: December 2004

Synthesis and Characterization of Polychlorinated Isobutenes

The preparation of polychlorinated methallylic chlorides by continuous chlorination of isobutene with different ratios of chlorine and following HCl‐elimination is described. The structure is proved by reaction of the polychlorinated isobutenes with sodium thiolacetate and potassium thiocyanate and by spectroscopic methods.
Quantenchemische Untersuchungen zur Farbe und Stereodynamik von acyclischen Azinen. XIV. Zum Chromophorsystem der isomeren Anthraldazine in den niedrigsten Sp(ππ*)‐Zuständen
Authors: Gustav K. , Vettermann S.
Published: December 2004

Quantum Chemical Studies on Colour and Stereodynamics of Acyclic Azines. XIV. On the Chromophoric System of the Isomeric Anthraldazines in the Lowest Sp (ππ*) States

The chromophoric system of the isomeric anthraldazines have been studied quantumchemically by means of the PPP‐CA and LHM‐CI methods. On the basis of a definite substructure being in analogy to the molecular geometries the electronic Sp(ππ*) states of the isomers can be characterized through the corresponding configurations. Taking into account these results an interpretation of the electronic absorption spectra is presented. The conclusions with respect to the chromophoric system are generalized for this class of compounds.
Zur Kenntnis der katalytischen Dimerisation von Acrylsäurederivaten mit Hilfe von Palladiumkomplexen. IV. Zur Dimerisation von Methyl‐methacrylat
Authors: Oehme G.
Published: December 2004

On the Catalytic Dimerization of Acrylic Acid Derivatives by Palladium Complexes. IV. The Dimerization of Methyl Methacrylate.

Methyl methacrylate has been dimerized to a mixture of 2.5‐di(methoxycarbonyl)‐hex‐1‐ene(1) and (E)‐2.5‐di(methoxycarbonyl)‐hex‐2‐ene (2) by catalytic systems containing dichlorobis (nitrile)‐palladium (II) complexes and silver tetrafluoroborate, Codimerization experiments with methyl acrylate show a lower reactivity of methyl methacrylate. Oxidative addition of ß‐chloro methyl methacrylate to tetrakis (triphenylphosphine) palladium (O) gave ß‐polladio methyl methacrylates (8, 9) suitable for model investigations of the catalytic reaction. A proposal is given for a mechanism via pd(IV) intermediates.
Massenspektrometrische Fragmentierung von 4‐substituierten 5‐Hydroxynaphth[2,1‐d]1,3‐oxathiol‐2‐onen
Authors: Lepom P. , Herzschuh R. , Wilde H. , Mann G.
Published: December 2004

Mass Spectrometric Fragmentation of 4‐Substituted 5‐Hydroxynaphth[2,1‐d]1,3‐oxathiol‐2‐ones

The mass spectra of 5‐hydroxynaphth[2,1‐d]1,3‐oxathiol‐2‐ones 1a‐1x have been studied. They show characteristic fragmentations with participation of neighbouring groups. Investigations of isotopically labelled 4‐alkyl and 4‐acyl derivatives give evidence for the formation of cyclic ionic structures.
Zur Cyanethylierung von Hydrochinazolinonen
Authors: Bischoff Christian , Schröder Edith , Gründemann Egon
Published: December 2004

Cyanoethylation of Hydroquinazolinones

By the reaction of acrylonitrile with octahydroquinazolinone‐spirocyclohexane (1), cyanoethyl‐octahydroquinazolinone‐spirocyclohexane (2) is formed. Compound 2 and hydrogen‐peroxide yield 5a‐cyanoethyl‐5‐oxo‐perhydro‐oxaziridino[3,2‐j]‐quinazolin‐2‐spirocyclohexane (5). 2‐Phenyl‐octahydroquinazolinone (7) and acrylonitrile form 3,5a‐biscyanoethyl‐2‐phenyl‐octahydroquinazolinone‐(4) (8). Compound 8 and hydrogenperoxide yield 3‐phenyl‐4,5a‐biscyanoethyl‐4‐oxoperhydro‐oxaziridino[3,2‐j]‐quinazoline (9). Compound 9 rearranges with ferrous sulphate to 3,4a‐bis‐cyanoethyl‐4‐oxo‐8a‐hydroxy‐2‐phenyl‐octahydro‐quinazoline (10).
1H‐kernmagnetische Resonanzspektren der Phenylfulgide
Authors: Ilge H.‐D. , Schütz H.
Published: December 2004

1H‐Nuclear Magnetic Resonance Spectra of Phenylfulgides

The 1H‐chemical shifts are determined in a series of phenylfulgides in order to investigate the steric influences of substituents. The magnetic anisotropy of the carbonyl and the phenyl groups is used for a qualitative discussion of the steric effects introducing different substituents in the fulgide framework. The benzene induced solvent shift supports the conclusions about the bond angle alterations between the different compounds.
Reversible photoisomerizations of sulfonephthalein indicator dyes. III. Kinetic Analysis of the Intermediate Sultone Formation
Authors: Grummt U.‐W.
Published: December 2004

A detailed kinetic analysis is presented of the transient sultone (A2) formation which proceeds thermally from a photogenerated intermediate species after flash excitation of bromo thymol blue and bromo xylenol blue in the presence of quinoline, pyridine and 4‐methyl pyridine in toluene solution. The sultone ring cleavage is a bimolecular reaction with the base resulting in a hydrogen‐bridged molecular complex (A1) which equilibrates consecutively with the most stable rotamer of the ion pair (A3). The rate constants for the latter reaction are controlled essentially by conformational changes rather than by the proper proton transfer.
Spin‐Trapping von Radikalen bei der Zersetzung aromatischer Diazoniumsalze mittels Ultraschall
Authors: Rehorek Detlef , Janzen Edward G.
Published: December 2004

Spin Trapping of Radicals Formed during the Decomposition of Aromatic Diazonium Salts by Ultrasound

The decomposition of aromatic diazonium compounds ArN2⊕X⊖ (Ar = phenyl, 2,5‐diethoxy‐4‐(N‐morpholino)phenyl; X = BF4, PF6, B(C6H5)4, SCN, OCN,N3; 1a, 1c–f, 2b–f) by ultrasonic waves has been studied by e.s.r. The spin trapping technique has been shown to be a suitable method for the detection of free radical intermediates.
10β‐Chlor‐östra‐1,4‐diene als Zwischenprodukte bei der Einführung einer 9(11)‐Doppelbindung in Östra‐1,3,5(10)‐triene
Authors: Kasch H. , Ponsold K.
Published: December 2004

10β;‐Chloro‐estra‐1,4‐dienes as Intermediates of the Introduction of a 9(11)‐Double Bond in Estra‐1,3,5(10)‐trienes

The synthesis of 9(11)‐didehydro‐estra‐1,3,5(10)‐trienes 5 starting from estra‐1,3,5(10)‐trienes 1 is described. 1 can be transformed into the ketals 2 and 3 by means of isocyanuric acid chloride and an alcohol such as methanol or ethylene glycol in the absence of moisture.

The ketals 2 and 3 are sensitive against hydrolysis and react in the presence of water and traces of acid under formation of chlorodienone 4. Dehydrochlorination of 2, 3 and 4 with potassium‐tert.‐butylate in dimethylsulfoxide gives the 9(11)‐didehydro compounds 5. The reaction mechanism of the electrophilic addition of positive chlorine and alcohol to the aromatic A‐ring of 1 is discussed.
Reaktionen einer technischen Butenfraktion mit Trichloracetaldehyd
Authors: Biering H. , Voigtländer R. , Matschiner H.
Published: December 2004

Reactions of a Technical Fraction of Butene with Trichloroacetaldehyde

In pyrolysis plants for gasoline production a C4‐fraction is formed containing isobutene, but‐1‐ene and but‐2‐ene as main products. The reactive separation of this fraction represents an industrial problem. One way to solve this problem is the reaction of trichloroacetaldehyde with these components to form addition products. The favoured reaction is the formation of 1,1,1‐trichloro‐4‐methyl‐pent‐4‐en‐2‐ol (1) and 1,1,1‐trichloro‐4‐methyl‐pent‐3‐en‐2‐ol (2) from iso‐butene. The other isomers react very slowly. The influence of different reaction parameters was investigated to find a method for a reactive separation of the C4‐fraction.
Elektrochemische Carboxylierung von Cinnamoyl‐1,1‐bis(alkylthio)‐ethylenen
Authors: Matschiner H. , Rüttinger H. H. , Austen S.
Published: December 2004

Electrochemical Carboxylation of Cinnamoyl‐1,1‐bis(alkylthio)ethylenes

Cinnamoyl‐1,1‐bis(alkylthio)ethylenes (1a–1h) are reduced electrochemically in the presence of carbondioxide in aprotic media. The attack of CO2 takes place either in 1‐ or 5‐position of cinnamoyl‐1, 1‐bis(alkylthio)ethylenes (1a–1h) depending on the nature of the aryl substituents. If CO2 reacts in position 1 carbonic acids 3 are obtained, reaction of carbondioxide in 5‐ position leads to the acids 2. The effects of different aryl substituents on the halfwave potentials and the preparative electrolyses have been investigated.
Prostaglandins and prostaglandin intermediates. XIV. Synthesis of rac‐9α, 11α, 13α‐trihydroxy‐ and rac‐9α, 11α, 13β‐Trihydroxy‐5(Z)‐prosten‐15‐ynoic Acid
Authors: Mahrwald R. , Schick H. , Schwarz S.
Published: December 2004

Attempts to rearrange a β‐hydroxy‐alkyne with a secondary hydroxy group into an α,β‐unsaturated ketone failed in the case of a potential prostaglandin intermediate. However, it was possible to convert this intermediate into 13‐hydroxy‐5(Z)‐prosten‐15‐ynoic acids, which are interesting prostaglandin analogues with a modified alkyl side chain.
13C‐ und 15N‐NMR‐spektroskopische Untersuchungen an Push‐pull‐butadienen
Authors: Michalik M. , Peseke K. , Radeglia R.
Published: December 2004

13C and 15N N.M.R. Spectroscopic Investigations on Push‐pull Butadienes

13C and 15N n.m.r. spectroscopic investigations show the push‐pull‐character of the investigated butadienes 1 and 2. Linear correlations exist between 13C and 15N chemical shifts and σp‐constants of substituents on the phenyl ring, and between 13C chemical shifts and ΔG≠ values of the C1C2 rotation process in 1, respectively.
EPR‐Untersuchungen kernchlorierter 4‐Dimethylaminophenylkationen
Authors: Fanghänel E. , Kriwanek J. , Mörke W.
Published: December 2004

EPR Investigations of Ring Chlorinated 4‐Dimethylaminophenylcations

The influence of the position and the number of chlorine atoms in the ring of 4‐dimethylaminophenylcations on the zero‐field‐splitting(zfs) parameter Dis investigated. It was found that the π‐donor ability of the chlorine atom(s) ind 2(6)‐position(s) increases the zfs parameter D. In the case of 3(5)‐substitution the value of D decreases because of the steric hindrance of the dimethylamino‐group.
Action of grignard reagents and amines on some N‐(Arylmethyleneamino)phthalimides
Authors: Ismail M. Fekry , El‐Bassiouny F. A. , Enayat E. I. , Kaddah A. M. , Younes H. A.
Published: December 2004

N‐(Arylmethyleneamino)phthalimides (2a–c) carrying an o‐substituent in the aryl group were prepared by the reaction of N‐aminophthalimide with o‐substituted benzaldehydes. The reaction of these compounds with Grignard reagents proceeded either by normal addition to one of the carbonyl groups to give 3a–c or by addition and cleavage to give 4‐arylphthalaz‐1‐ones 5a–c. The steric effect exhibited by either the Grignard reagent or the N‐arylmethylene compound was studied. The reaction of N‐furfurylideneaminophthalimide (2d) with Grignard reagents was also investigated. N‐(Arylmethyleneamino)phthalimides reacted with primary amines to give N,N′‐dialkylphthalamides (7a and b) while the reaction with secondary amines gave (8a and b).
IR‐spektroskopische Untersuchung zur Lösungsmittelwechselwirkung von 1‐Benzylidenpyrazolid‐3‐on‐betainen
Authors: Siegmund Manfred , von Löwis Michael , Geissler Gunther , Menz Irina
Published: December 2004

Investigation of Solvent‐Solute Interactions of 1‐Benzylidenepyrazolidone (3) ‐betaines by I.R. Spectroscopy

The infrared spectra of eight 1‐benzylidenepyrazolidone(3)‐betaines (1–7 and 3 m) have been measured in 22 solvents of different polarity. The carbonyl band of these compounds indicates specific and non‐specific solvent‐solute interactions, which are qualitatively characterized by the electrophilic properties of the solvent (E‐value, acceptor number AN). Intermolecular hydrogen bonds have been detected in protic solvents. The thermodynamic quantities of the associate equilibrium, K,ΔRH,ΔRS were determined in chloroform and deuterochloroform, respectively, by the i.r. intensity method.
Elektrochemische Oxydation organischer Verbindungen in Fluorsulfonsäure. X. Effekt der Aciditätserhöhung auf das anodische Verhalten einiger aromatischer Verbindungen im System HSO3FSbF5
Authors: Rudenko A. P. , Sarubin M. Ja. , Awerjanow S. F. , Pragst F.
Published: December 2004

Electrochemical Oxidation of Organic Compounds in Fluorsulfuric Acid. X. Effect of the Increase in Acidity on the Anodic Behavior of Some Aromatic Compounds in the HSO3FSbF5‐System

The effect of the acidity on the anodic behavior of some aromatic nitrils, nitro compounds, amines, sulfonyl fluorides, carbonyl compounds, hydrocarbons, benzylic acetates and methoxy compounds is investigated by cyclic voltammetry in HSO3F and HSO3FSbF5 (molecular ratio 15:1 and 3:1) at −76°C and in some cases in HSO3FSbF5 (1:1) at −40°C. With increasing content of SbF5 in most cases a positive shift of the anodic half‐peak potentials Δ Ep/2 is found, which depends on the type and on the strength of the interaction with the superacidic solvent. Δ Ep/2 increases from the protonated functional groups in the series NH3⊕ (0.00 V), CN (0.05–0.10 V), SO2F (0.10–0.20 V), COR (0.20–0.40 V), NO2 (0.30–0.60 V), OCH3 (>0.8 V) to benzoylium ions (0.45–0.60 V), benzyl cations (0.60–0.80 V) and arenium ions (1.10–1.30 V). Besides, the anodic behavior depends to a large extent on the deprotonation rate of the substrate, which occurs precedingly to, simultaneously with or subsequent to the electron transfer.
Blitzlichtspektroskopische Untersuchungen an 1‐Phenylazo‐2‐naphtholen
Authors: Grummt U.‐W. , Epperlein J.
Published: December 2004

Flash Spectroscopic Investigations on 1‐Phenylazo‐2‐Naphthols

1‐(p‐R‐Phenylazo)‐2‐naphthols with R = NMe2, OH, OCH3, CH3, H, F, Br, COCH2, NO2, CN show reversible bleaching over the entire visible and near u.v. spectral region upon flash photolysis in ethanol and toluene. It is proposed to interpret this by photochemical formation of the corresponding cis‐azo compound. The thermal relaxation is not an elementary reaction but it involves intermediate tautomerisation. A V‐shaped Hammett correlation is found for the rate constants of the thermal relaxation.
Strukturaufklärung von ausgewählten nitro‐ und sulfonsäuresubstituierten 1,2‐Naphthochinon‐2‐diaziden
Authors: Gey E. , Radeglia R. , Elger J. , Brandtstädter H. , Geissler H. , Hauser A.
Published: December 2004

Structure Determination of Selected Nitro and Sulfonic Acid Substituted 1,2‐Naphthoquinone‐2‐diazides

Selected nitro derivatives of 1,2‐naphtoquinone‐2‐diazide 2 and 5 have been synthesized, the position of the NO2‐group has been unambigously determined by means of 1H and 13C n.m.r. spectroscopy, and the structure of these compounds has been comprehensively determined in relation to unsubstituted 1 and sulfonic acid substituted derivatives 3, 3a, 4 and 4a.

Furthermore, the spectroscopical behaviour, especially in the uv/vis region, was examined in correlation to quantum chemical calculations.
Quantenchemische Untersuchungen zur Farbe und Stereodynamik von acyclischen Azinen. XV. Zum strukturellen Aspekt des Photochromie‐Effektes
Authors: Gustav K. , Vettermann S.
Published: December 2004

Quantum Chemical Studies on Colour and Stereodynamics of Acyclic Azines. XV. On the Structural Aspect of the Photochromic Effect

For the longest‐wavelength colour‐determining electronic transition of selected arylsubstituted acyclic azines the curvature of λ=λ(θcc) has been adapted by means of polynomic and trigonometric functions. On this basis it is possible to discuss the structural aspect of the photochromic and aphotochromic behaviour being observed due to the (E, Z) isomerization.
EPR‐Untersuchungen zur Photolyse halogenierter organischer Verbindungen. I. Reine Phasen halogenierter Verbindungen (CBr4, CHBr3, CCl4, CHCl3)
Authors: Stösser R. , Pritze B. , Abraham W. , Dreher B. , Kreysig D.
Published: December 2004

EPR‐Investigations on the Photolysis of Halogenated Organic Compounds I. Pure Halogenated Compounds (CBr4, CHBr3, CCl4 and CHCl3)

EPR‐spectra of CBr4, CHBr3 and CDBr3, exposed to u.v.‐light and γ‐rays respectively, are presented. They are discussed and compared with the results of the photolysis of CH2Br2, CH3Br and CCl4, CHCl2, CH2Cl2 and CH3Cl. Under stationary conditions at 77K it was possible to identify paramagnetic species like \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CBr}_4\,^{_{\bar.}} $\end{document}, ·CBr3, ·CH3, ·C2H5, ·CCl3 and trapped electrons.
Photoinduzierte Elektronenübertragungsreaktionen zwischen aromatischen Diazoniumkationen und Anionen
Authors: Becker H. G. O. , Israel G. , Oertel Ulrike , Vetter H.‐U.
Published: December 2004

Photoinduced Electron Transfer between Arenediazonium Cations and Anions

Anions X⊖ can act as donors in electron transfer reactions to photoexcited arenediazonium ions. The yield of the arene formed in this reaction increases with decreasing electrochemical oxidation potential E of X⊖ (X⊖ = BPh4⊖, Br⊖, HOOCCOO⊖, Cl⊖, BF4⊖). The oxidized donor X· (Cl·, ·COO⊖) and aryl radicals Ar· benig intermediates of the reductive dediazoniation of ArN2⊖ can be detected by spin trapping with nitrosodurene (ND) and phenyl‐tert‐butylnitrone (PBN). A solvent effect in the electron transfer reaction is interpreted in terms of ion pairing, where the electron transfer is favored by preorientation and a short distance between the electron donor and the acceptor previous to excitation of ArN2⊖ by light.
Substituenteneffekte in den 13C‐NMR‐Spektren von diastereomeren Chalkondihalogeniden. VI. Konfigurationsbestimmung von Chalkonrhodanhydrinen mittels lösungsmittelinduzierter Signalverschiebung in den 13C‐NMR‐Spektren
Authors: Weber Fritz Gerd , Liepert Harald , Radeglia Reiner
Published: December 2004

Substituent Effects in 13C‐N.M.R. Spectra of Diastereomeric Chalcone Dihalogenides. VI. Assignment of Configuration on Chalcone Rhodanohydrins by Solvent Induced Shift of Signals in 13C‐N.M.R. Spectra

The erythro configuration of chalcone rhodanohydrins 1 was determined by comparison of solvent dependent shifts of C‐α and C‐β signals of 1 and both the erythro and threo isomeres of chalcone chlorohydrins 2 as standard in 13C n.m.r. spectra.
Formylation products of thioamides. XIV. Synthesis of Substituted Thiazoles and Thiophenes by the reaction of N, N′‐bis(aminomethylidene)thioureas or N‐(3‐aminothioacryloyl)‐formamidines with alkylating reagents
Authors: Knoll Alexander , Liebscher Jürgen , Radeglia Reiner
Published: December 2004

N, N′‐Bis(aminomethylidene)thioureas 1 react with electron acceptor substituted methyl halides 2 under the formation of 2‐formamidinothiazoles 4. The reaction of N‐(3‐aminothioacryloyl)‐formamidines 5 with substituted methyl halides 2 gives either 2‐formamidinothiophenes 7 or 2‐aminovinylthiazoles 8. The 8 can be hydrolysed to corresponding 2‐hydroxyvinylthiazoles 9. 2‐Aminovinylthiazoles 11 bearing primary amino groups are obtained by transamination of the N‐(3‐aminothioacryloyl)‐formamidines 5 and subsequent reaction of the resulting 10 with substituted methyl halides 2.
Schädigung der Z‐Gruppe und Hydantoinbildung bei der Alkalischen Verseifung von Z‐Peptidestern
Authors: Schwenzer B. , Weber E. , Losse G.
Published: December 2004

Cleavage of Z‐Group and Formation of Hydantoine during Saponification of Z‐Peptide Esters

In the course of alkaline decomposition of the tetrapeptide ester Z‐Arg(NO2)‐Gly‐Phe‐Phe‐OMe one gets a high output of a by‐product. the latter was isolated and identified by 13C‐n.m.r. spectroscopy to be the hydantoine derivative arising from a loss of Z‐group and from a cyclisation. A possibility to suppress the undesired side‐reaction by addition of benzylalcohol is proposed resulting from the discussion of a probable mechanism of reaction.
Photochemie substituierter Cycloheptatriene. XVII. 1‐Aryl‐4‐(p‐dimethylaminophenyl)‐cycloheptatriene
Authors: Abraham W. , Kupfer M. , Kreysig D.
Published: December 2004

Photochemistry of Substituted Cycloheptatrienes. XVII. 1‐Aryl‐4‐(p‐dimethylaminophenyl)‐cycloheptatrienes

The photochemistry of the title compounds is different from that of the isomeric 1‐(p‐dimethylaminophenyl)‐4‐aryl‐cycloheptatrienes. The sigmatropic 1, 7‐hydrogen shift is dominant caused by the arylic substituent in position 1 of the seven‐membered ring. Only strong donor substituents like the p‐methoxyphenyl group in position 1 cause photovalence tautomerism.

The properties of solvents influence both the quantum yields of the photoreactions and the fluorescence quantum yields. The connections between the fluorescing state and the photoreactivity are discussed. Solvent viscosity and polarity are shown to be relevant for the deactivation parameters.
Acetals and ethers. XII. Reaction Products of Prop‐2‐enal with 1,2‐ and 1,3‐Diols
Authors: Piasecki Andrzej , Burczyk Bogdan
Published: December 2004

2‐(Hydroxyalkoxyethyl)‐substituted cyclic acetals (1; 2; 3a‐3d; 4a‐4d), derivatives of 1, 3‐dioxolane or 1, 3‐dioxane have been obtained in a p‐toluenesulphonic acid‐catalysed reaction of prop‐2‐enal with an excess of ethylene, propylene‐1, 2, trimethylene, or butylene‐1, 3 glycol. Respective 2‐vinyl‐1, 3‐dioxolanes or 2‐vinyl‐1, 3‐dioxanes were the intermediate products. The products of the reaction involving propylene‐1, 2 and butylene‐1, 3 glycols were mixtures of cis‐ and trans‐2, 4‐disubstituted‐1, 3‐dioxolanes and cis‐ and trans‐2, 4‐disubstituted‐1, 3‐dioxanes. The structure of HOROCH2CH2‐ substituents at C‐2 atom of 1, 3‐dioxacyclane ring has been proved through 2, 4‐dinitrophenylhydrazone derivatives of the corresponding aldehydes HOROCH2CH2CHO that, however, could not be isolated as individual compounds.
1H‐NMR‐spektroskopische Untersuchungen zur Azo‐Hydrazon‐Tautomerie in substituierten 1‐Phenylazo‐2‐naphtholen
Authors: Haessner R. , Mustroph H. , Borsdorf R.
Published: December 2004

1H‐N.M.R. Spectroscopic Investigations of the Azo‐Hydrazon‐Equilibrium in Substituted 1‐Phenylazo‐2‐naphthols

In substituted 1‐phenylazo‐2‐naphthols an equilibrium between the azoic and the quinoid hydrazone form is observed. It is possible to obtain the equilibrium constants by means of 1H‐n.m.r.‐spectroscopy in CDCl3. Both chemical shifts δH−3 and δH−8 in the naphthalene ring system can be used to determine independently the equilibrium constants. 1‐Phenylazo‐2‐naphthylamine and 1‐(pyrid‐2‐ylazo)‐2‐naphthole were used as reference substances for the pure azoic and hydrazone form, respectively. An appropriate correction is introduced to compare the different influence of OH‐ und NH2‐groups, respectively, on the protons H‐3 and H‐8.

All equilibrium constants measured show a linear correlationship with respect to Hammett‐σ‐constants of the substituents attached to the phenyl ring. The standard reaction entropy for the conversion of the azoic form into the hydrazone form is always negative and of nearly identical magnitude. Obviously, no substituent effect to this value exists. One possibility to interprete these results is to assume that the quinoid hydrazone form shows a higher tendency to aggregation.
Iminoformylierung substituierter Crotonnitrile. I. Synthese neuer N, N‐disubstituierter 4‐Amino‐1,1‐dicyanbuta‐1,3‐diene
Authors: Köckritz P. , Sattler R. , Liebscher J.
Published: December 2004

Iminoformylation Reaction of Substituted Crotonnitriles. I. Synthesis of New N, N‐Disubstituted 4‐Amino‐1, 1‐dicyanobuta‐1, 3‐dienes

A useful and efficient method for the synthesis of 4‐amino‐1, 1‐dicyanobuta‐1, 3‐dienes 10‐20 based on the iminoformylation reaction of crotonnitriles 7‐9 with the system triethyl orthoformate/secondary amine in the presence of an acidic catalyst is described. This novel route to the title compounds yields products which are easy to isolate and to purify and also allows to prepare the hitherto unknown N‐aryl substituted 4‐amino‐1, 1‐dicyanobuta‐1, 3‐dienes. Hence it is advantageous as compared to existing iminoformylation reactions of crotonnitriles using formamide acetals.
Photooxidation von Leukofarbstoffen. X. Untersuchungen zur Photooxidation von Di‐kalium‐anthracen‐9,10‐ylen‐bis‐sulfat
Authors: Langbein H. , Hinzmann G. , Grummt U.‐W. , Koch R. , Fassler D.
Published: December 2004

Photooxidation of Leuco Dyes. X. Investigation of the Photooxidation of Di‐potassiumanthracene 9,10‐ylene‐di‐sulfate

Photolysis of the title compound (DHAE) in water or ethanol produces anthraquinone and anthrone. In deoxygenated solutions 9,10‐dihydroxyanthracene is detected as a long lived intermediate. Laser and conventional flash photolysis reveals three short‐lived transients with lifetimes of 200 ns, 2 and 410 ms. Different temperature dependencies are observed for the fluorescence and the photolysis quantum yields. This is interpreted by two successive thermally activated processes: photohomolysis of OS bond and escape of the radical pair from the solvent cage. The results are discussed with the help of a reaction scheme proposed for the photolysis of DHAE.
Über die Reaktion von Chloranil mit Cyanidionen – eine ESR‐Studie
Authors: Rehorek Detlef , Janzen Edward G.
Published: December 2004

On the Reaction of Chloranil with Cyanide Ions – an ESR Study

The reaction of chloranil 1 with cyanide ions in acetonitrile and methanol solutions has been studied. The ESR Spectra revealed the formation of semiquinone anion radicals 7,8, and 9. The latter has been found as its protonated form in methanol only. In addition, both 1 and 2,3‐dicyano‐5,6‐dichloro‐1,4‐benzoquinone 4 gave tetracyanoethylene anion radicals 6 upon reaction with cyanide ions in acetonitrile. Using 13C‐labelled cyanide 6 was shown to originate from the fragmentation of the cyanide addition product to 4. Using the spin trapping technique it was found that no cyanyl free radicals are formed during the thermal reaction of either 1 or 4 with cyanide ions.
Reactions of 4‐Chloromethyl‐1,3‐dioxolan‐2‐one with Phenols as A New Route to Polyols and Cyclic Carbonates
Authors: Rokicki G. , Pawlicki J. , Kuran W.
Published: December 2004

Reaction of 4‐chloromethyl‐1,3‐dioxolan‐2one (1) with phenol in the presence of potassium carbonate was studied and found to yield 4‐phenoxymethyl‐1,3‐dioxolan‐2one (2) and 3‐phenoxypropan‐1,2‐diol (3). The latter compound 3 was also found to be formed as the main product in the reaction of 1, phenol and sodium hydroxide at a temperature higher than 90°C.

The effect of various factors on the reaction course and the yield of 2 and 3 was examined.

It was found that the reaction studied can be extended to those of difunctional phenols such as 2,2‐di(4‐hydroxyphenyl)‐propane producing the corresponding tetrahydroxyderivative – 2,2‐bis‐[4‐(2,3‐dihydroxypropoxy)phenyl]propane.
Revisitation of Formaldehyde Aniline Condensation. I High Yield Synthesis of 1,3,5‐Triphenylhexahydro‐symtriazine and its X‐Ray Crystal Structure Determination
Authors: Giumanini Angelo G. , Verardo Giancarlo , Randaccio Lucio , Bresciani‐Pahor Nevenka , Traldi Pietro
Published: December 2004

A rapid and efficient preparation of 1,3,5‐triphenylhexahydro‐sym‐triazine (10) using paraformaldehyde is reported. The trimeric nature of the compound and its structure in solid state, where a biaxial chair conformation is favoured, are conclusively shown by X‐ray diffraction analysis. A recent report on a preparation of 1,3‐diphenyl‐1,3‐diazetidine is invalidated.
Sensibilisierte Photooxidation und 13C‐NMR‐spektroskopische Untersuchung von 5,6‐Dihydrodicyclopentadien‐Derivaten
Authors: Fanghänel E. , Keita Y. , Radeglia R. , Schmidt W.
Published: December 2004

Photooxidation and 13C N.M.R. Spectroscopic Investigation of 5,6‐Dihydrodieyelo‐pentadiene Derivatives

The sensitized photooxidation of endo‐5,6‐dihydrodicyclopentadiene (2) by singulet oxygen gives via the corresponding hydroperoxide (10) exo‐1‐hydroxy‐5,6‐dihydrodieyelopentadiene (7a). Starting from exo‐5,6‐dihydrodicyclopentadiene (6) exo‐5,6‐dihydrodicyelopentadien‐1‐one (12) is formed. The 13C n.m.r.spectroscopical data of these compounds and of other hydroxy, alkoxy and acyloxy dihydrodieyclopentadiene derivatives are discussed in relation on their structure.
Elektrochemische Adamant‐1‐ylierungen und Tetrahydro‐exo‐dicyclopentadien‐9‐ylierungen von Azomethinen
Authors: Hess U. , Lieberenz C. , Feuerherd B.
Published: December 2004

Electrochemical Reductive Alkylation of Azomethines with 1‐Bromadamantane and 9‐Bromo‐tetrahydro‐exo‐dicyclopentadiene

Electrochemically generated radical anions of Schiffbases 1a—11 react in DMF and in the presence of bridgeheadhalogenides as 1‐bromoadamantane and 9‐bromo‐tetrahydro‐exo‐dicyclopentadiene to 1‐[α‐(aryl‐ or alkylamino)‐α‐arylmethyl]‐adamantanes and the correspondent 9‐tetrahydro‐exo‐dicyclopentadienes. In the course of SET‐mechanism originating bridgehead radicals couple with the azomethine‐radicalanions at the position of the highest unpaired electron density, which is predominantly the carbon of the C,N‐double bond. Only in cases when this density at the N‐atom is relatively high, or steric hindrance impedes C‐alkylation, N‐hydroalkylated products as N,N‐disubstituted 1‐aminoadamantanes and 9‐amino‐tetrahydro‐exo‐dicyclopentadienes are formed. Product distribution, cyclic‐voltammetric results and quantumchemical data are discussed in terms of mechanism.
Stereochemie der 2‐Aryl‐cyclohexanone. I. Konfigurations‐ und Konformationsanalyse der cis‐trans‐isomeren 2,6‐Dimethyl‐2‐aryl‐cyclohexan‐1‐one über ihre Oxime
Authors: Palitzsch P. , Huneck S. , Fischer F.
Published: December 2004

Stereochemistry of the 2‐Aryl‐cyclohexanones. I. Analysis of the Configuration and Conformation of the cis‐trans‐Isomeric 2,6‐Dimethyl‐2‐aryl‐cyclohexan‐1‐ones by the Aid of their Oximes

Desulfurization of the n‐butylthiomethylene ketone 6 with Raney nickel yields a mixture of trans‐ and cis‐stereoisomers 7 and 8, the conformations of which are 7A and 8B, respectively. While the ketone 7 gives rapidly and quantitatively the oxime 9, the isomer 8 reacts much more slowly to a mixture of 9 and 10. A detailed analysis of the configuration and conformation of the ketones 7 and 8 as well as the oximes 9 and 10 is given.
Zuordnung von Schwingungsspektren organischer Moleküle durch MNDO‐Berechnungen
Authors: Dathe K. , Bögel H.
Published: December 2004

Assignment of the Vibrational Spectra of Organic Molecules by MNDO Calculations

Wavenumbers and intensities of the molecular vibrations can be calculated by the semi‐empirical SCF‐MO method, MNDO. The calculated normal coordinates show the displacements of the atoms in the course of the vibration and provide the assignment of mode and symmetry of the vibrations. This will be shown for the following examples: acetylene, ethylene, substituted and deuterated ethylenes, acetonitrile as well as for EDA complexes. We found a good qualitative agreement between calculated and experimentally observed IR‐data.
Zur Anwendung von Lanthanoid‐Verschiebungsreagenzien bei der NMR‐spektroskopischen Untersuchung von Gemischen monofunktioneller Kohlenwasserstoffe
Authors: Zopf U. , Brunn J. , Radeglia R.
Published: December 2004

Application of Lanthanide Shift Reagents in 1H‐N.M.R.‐Spectroscopic Investigations of Mixtures of Monofunctional Hydrocarbons

The influence of n.m.r. shift reagents on the 1H‐n.m.r.‐spectra of mixtures has been investigated. Hydrocarbons of the type CH3(CH2)nX (X = OH, CHO, COR, COOCH3, COOH, OR with R = Methyl‐, Ethyl‐, n‐Propyl‐, n‐Butyl‐ and n = 1,2) served as model substances. The components of the mixtures compete with the shift reagent. Relative equilibrium constants have been calculated to describe this behavior in mixtures. Several equations have been deduced and tested to describe the induced shifts of the protons in mixtures. These equations are applicable to qualitative and quantitative analysis of unknown mixtures.
Untersuchungen zum UV/VIS‐Spektralverhalten von Azofarbstoffen. XV. Eine Analyse der Absorptionsspektren von 4,4′‐Diaminoazobenzenen
Authors: Haessner C. , Mustroph H.
Published: December 2004

Studies on UV/VIS Absorption Spectra of Azo Dyes. XV. An Analysis of the Absorption Spectra of 4,4′‐Diaminoazobenzenes

In the visible absorption spectrum 4,4′‐bis‐diethylaminoazobenzene shows two absorption maxima (λmax = 426 nm and λmax = 477 nm) with high intensity. Quantum chemical calculations and examination by peak separation of six 4‐substituted azobenzenes and six 4′‐substituted 4‐diethylaminoazobenzenes (1a–k) indicate that the longest wavelength band is due to a n‐π* transition and the other band is due to a π‐π*‐transition.

This is verified using an increment system for n‐π* absorption maxima. A linear relation is found between intensity ratios of the two bands and the HAMMETT‐σ‐constants of the substituents. With increasing electron releasing tendency of the substituents the absorption intensity of the n‐π*‐band increases.
Oxidative Kupplung von 5‐Amino‐pyrazolen mit p‐Phenylendiaminen
Authors: Hennig L. , Hofmann J. , Wilde H. , Mann G.
Published: December 2004

Oxidative Coupling of 5‐Aminopyrazoles with p‐Phenylenediamines

By oxidative coupling of 5‐amino‐3‐methyl‐1‐phenyl‐pyrazole 4 with N,N‐diethyl‐p‐phenylenediamine the 4‐(4‐N,N‐diethylamino‐phenylimino)‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐imin 5 is formed. 5 is oxidized very easily to the 1H‐pyrazolo[3,4‐b]quinoxaline 6a. The Z/E‐isomerism of the azomethine dye is investigated by dynamic n.m.r.‐spectroscopy. 1H‐Pyrazolo[3,4‐b]quinoxalines (6a–d) are also formed by reaction of 1,3‐disubstituted 5‐aminopyrazoles with p‐nitroso‐dialkylanilines.
Zur Reaktion von 5,6‐Dihydro‐1,4‐oxathiin‐4,4‐dioxiden mit Nucleophilen
Authors: Göhmann P. , Schröder L. , Zschunke A.
Published: December 2004

About the Reaction of 5,6‐Dihydro‐1,4‐oxathiin‐4,4‐dioxides with Nucleophilic Compounds

By reactions of 5,6‐dihydro‐1,4‐oxathiin‐4,4‐dioxides (1, 5, 8) with thioles, amines and CH‐acid compounds 2‐substituted ethansulfonylcarbonyl compounds are formed. The structures of the reaction products are determined by elemental analysis, i.r. and 1H‐n.m.r.‐spectroscopy.

5,6‐Dihydro‐1,4‐oxathiin‐4,4‐dioxide sind gut zugänglich durch die Oxidation von 5,6‐Dihydro‐1,4‐oxathiinen mit Wasserstoffperoxid. Besonders zur Darstellung der 5,6‐Dihydro‐2‐methyl‐3‐carboxamido‐1,4‐oxathiin‐4,4‐dioxide, von denen einige im Pflanzenschutz wegen ihrer systemischen fungiziden Wirkung Bedeutung erlangten, wurden verschiedene Methoden beschrieben [1, 2]. In ähnlicher Weise lassen sich auch die entsprechenden Ester und Säuren synthetisieren.
CW CO2‐Laser SF6‐Photosensitized Pyrolysis of Tetralin
Authors: Pola J. , Trka A. , Zimmermann G.
Published: December 2004

CW CO2 laser photosensitized (SF6) pyrolysis of tetralin proceeds mainly via dehydrogenation channel affording 1,2‐dihydronaphthalene and naphthalene. Less important ring cleavage products are indene, styrene, ethylbenzene, toluene, and benzene, together with ethylene and methane. No occurrence of polyaromatics and high yields of ethylene compared to methane are the features differing this process from high temperature conventional pyrolysis.
Synthesis of a Versatile Prostaglandin Intermediate by Ozonization of endo‐cis‐Bicyclo[3.3.0]oct‐6‐en‐2‐ol
Authors: Theil F. , Mahrwald R. , Schick H. , Mel'nikova V. I. , Vasil'eva L. L. , Pivnitsky K. K.
Published: December 2004

The ozonization of endo‐cis‐bicyclo[3.3.0]oct‐6‐en‐2‐ol (1) in methanol followed by reduction with dimethyl sulfide in the presence of traces of an acid yields in a one‐pot procedure an anomeric mixture of 3‐exo‐methoxy‐ and 3‐endo‐methoxy‐2‐oxabicyclo[3.3.0]octane‐6‐endo‐carbaldehyde (3a and 3b) in a ratio of 9:1. This mixture is converted by base catalyzed epimerization in an overall yield of about 65% into a mixture of the anomeric 6‐exo‐aldehydes 5a and 5b, a versatile starting material for the synthesis of prostaglandins of the PG2‐type.
Determination of the main products and intermediates of the Oxidation of Medium Normal Paraffins in dependence on the conversion indirect evidence for the importance of bifunctional intermediates
Authors: Engelmann Eleonore , Just Gerhard , Pritzkow Wilhelm , Rudolf Matthias , Spindler Gerald , Tien Tieu Dung , Voerckel Volkmar , Wittekind Volker
Published: December 2004

The mole numbers of the starting paraffins, of the intermediate alcohols and ketones with the same chain lengths, of the lower alkan‐2‐ones, of the carboxylic acids, and of the esters were determined at different reaction times for the oxidations of n‐tridecane, n‐tetradecane, and n‐pentadecane with molecular oxygen at 140°C in the presence of 0.1% Mn‐stearate. In the stationary region of the oxidation about 1.2 moles of acids and 0.7 moles of esters are formed from 1 mole of paraffin consumed. The relative oxidation rates of alcohols and of ketones with reference to the starting paraffins were estimated from the mole numbers of the starting paraffins, the alcohols and the ketones at the maxima of the alcohols and the ketones. These values are higher than those determined by competitive oxidations, and this discrepancy is an indirect evidence of the formation of bifunctional intermediates from the starting paraffins. The relative rates of the formation of alcohols, ketones, and bifunctional products from normal paraffins were estimated.
Strukturuntersuchungen an einem Produkt der intramolekularen Diels‐Alder‐Reaktion Konfigurations‐ und Konformationsanalyse von 5‐Methyl‐2‐phenyl‐1H‐2,3,3a,4,5,7a‐hexahydroisoindol‐1‐on
Authors: Hauser Andre , Gründemann Egon , Preuschhof Helmut , Schmitz Ernst , Kuban Ralf‐Jürgen
Published: December 2004

Structure Elucidation of a Product of Intramolecular Diels‐Alder‐Reaction: Configurational and Conformational Analysis of 5‐Methyl‐2‐phenyl‐1H,2,3,3a,4,5,7a‐hexahydroisoindol‐1‐one

N‐Allyl‐N‐phenylsorbamide 1 cyclizes at 160°C to give 5‐methyl‐2‐phenyl‐1H,2,3,3a,4,5,7a‐hexahydroisoindol‐1‐one 2. As a result of this intramolecular [4 + 2] cycloaddition four stereoisomeres 2a–2d can exist. The 1H and 13C n.m.r. data are given. The 1H n.m.r. studies demonstrate that the product of Diels‐Alder cyclisation is the result of cis‐fusion of the two rings. The nuclear Overhauser effect data provide further evidence for 2a in which the carbonyl group and methyl one are trans‐arranged. The n.m.r. results are confirmed by X‐ray studies.
Elektrochemische Carboxylierung substituierter Vinylketone
Authors: Rüttinger H.‐H. , Matschiner H. , Gollnow W. D.
Published: December 2004

Electrochemical Carboxylation of Substituted Vinyl Ketones

α‐Chlor‐β‐acyl‐vinylsulphides (1a–f) and keten‐S, N‐acetales (3a,b) are reduced in the presence of CO2 at the cathode to yield the corresponding acids (4a–f resp. 5). Whereas the carboxylation of 1 proceeds via elimination‐addition mechanism, the reduction of 3 is similar to the keten‐S, S‐acetales described earlier an EC (addition) EC (elimination) sequence.
The Structure of 9,9′‐Diethyl‐3,3′‐azocarbazole as elucidated by dipole moment measurements
Authors: Wacławek W. , Kyzioł J. , Frey H. , Fanghänel E.
Published: December 2004

9,9′‐Diethyl‐3,3′‐azocarbazole (2) obtained through the reduction of the nitro derivative with lithium aluminium hydride is the E‐isomer according to dipole moment measurements. The rotational state of 2 is also discussed.
Zur Ring‐Ketten‐Tautomerie und Reaktionen eines bicyclischen 1‐Hydroxy‐3‐imidazolin‐3‐oxids
Authors: Schulz Manfred , Mögel Liena , Römbach Joachim
Published: December 2004

Ring‐Chain Tautomerism and Reactions of a Bicyclic 1‐Hydroxy‐3‐imidazoline‐3‐oxide

The reaction of 8‐hydroxy‐1, 4, 5, 7‐tetramethyl‐6,8‐diaza‐bicyclo[3.2.1]‐oct‐6‐en‐6‐oxide (1), a 2,5‐bridged bicyclic 1‐hydroxy‐3‐imidazoline‐3‐oxide, with NaBH4, dimethyl acetylene dicarboxylate and methylmagnesiumiodide, respectively, yields derivatives of the ring opened isomer 2. Whilst on reaction with phenylisocyanate the bicyclic structure 1 is preserved and the urethane 3 is formed. The ring‐chain tautomerism of 1 is important for the application of 1 as a spin trap or radical scavenger.
Radikalabfang. III [1] ESR‐spektroskopische Untersuchung von Radikalreaktionen eines bicyclischen 1‐Hydroxy‐3‐imidazolin‐3‐oxids [2]
Authors: Reinhardt Michael , Schulz Manfred , Römbach Joachim
Published: December 2004

Spin Trapping. III. Studies of Radical Reactions of a Bicyclic 1‐Hydroxy‐3‐imidazoline‐3‐oxide

Radical addition reactions to the nitrono group and the oxidation of the 8‐hydroxy‐1,4,5,7‐tetramethyl‐6,8‐diazabicyclo[3.2.1]oct‐6‐en‐6‐oxide 2b were investigated by e.s.r.‐spectroscopy. Oxidation of 2b by Ag2O, PbO2, hydrogenperoxide, tert.‐butoxy and benzoyloxy radicals, respectively, yields a bicyclic nitroxide with typical a(N)‐value (1,9 mT). Testing a wide range of carbon‐centered radicals we did not find, however, any spin adducts in contrast to the literature. Only H‐atoms are found to add to the nitrone function of 2b giving a bicyclic nitroxide 4b (R′ = H) with a(N)‐value of 1,4 mT, a(Hax) = 2,4 mT. The relationship between a ring‐chain tautomerism of 2 as previously described and the formation of radicals has been demonstrated by radical reactions of derivatives of ring opened isomers 5b.
Synthese von 5‐Nitro‐2,3‐dihydrobenzo(b)furanen aus 2‐Methylen‐triethyl‐ammonio‐4‐nitrophenolat und 2‐Chlor‐1,3‐dicarbonylverbindungen
Authors: Fanghänel E. , Böckelmann J. , Grossmann N. , Pfeifer D.
Published: December 2004

Synthesis of 5‐Nitro‐2,3‐dihydrobenzo(b)furanes from 2‐Methylenetriethyl‐ammonio‐4‐nitrophenolat and 2‐Chloro‐1,3‐dicarbonyl Compounds

2,2‐Disubstituted 5‐nitro‐2,3‐dihydrobenzo[b]furanes 6a–c were synthezised in a one step procedure starting from 2‐methylene‐triethyl‐ammonio‐4‐nitrophenolat 2 and 2‐chloro‐1,3‐dicarbonyl compounds 4a–c. The structure of 6a–c was determined chemically and by 13C‐n.m.r.‐spectroscopy.
Inkrementsystem zur Beschreibung der Lage von Ionenpaar‐Charge‐Transfer‐Banden in Wasser und nichtwäßrigen Lösungsmitteln
Authors: Hennig Horst , Benedix Roland , Billing Roland
Published: December 2004

Increment System for Predicting of the Position of Ion Pair Charge‐Transfer Bands in Water and Non‐aqueous Solvents

The energy of the absorption maximum of ion‐pair charge‐transfer bands, ΔGCT, occuring in addition to the absorptions of the single ions, is approximately the sum of contributions (increments) of the ions concerned. On the basis of spectroscopic data, an increment system for predicting of ΔGCT in aqueous solution has been proposed. A linear relationship between the increments and the standard electrode potentials of ions has been found, permitting the expansion of the increment system. The difference between calculated and experimental values does not exceed 2500 cm−1. The applicability of the increment system to non‐aqueous solvents has been proved in several cases.
Push‐pull‐Butadiene. VI. Darstellung von substituierten Nicotinonitrilen
Authors: Peseke K. , Michalik M. , Schönhusen U.
Published: December 2004

Push‐pull‐Butadienes. VI. Synthesis of Substituted Nicotinonitriles

2‐Aryl‐4,4‐bis(methylthio)‐1,3‐butadiene‐1,1‐dicarbonitriles 1 react with N‐bromosuccinimide or sulphuryl chloride to give 3‐bromo‐ and 3‐chloro‐butadienedicarbonitriles 3, respectively. Compounds 1 or 3 can be converted with methanethiol in alkaline solution to 4‐aryl‐2,6‐bis(methylthio)nicotinonitriles 2. Butadienedicarbonitriles 3 and sodium alkoxide yield alkoxynicotinonitriles 5. 4‐Aryl‐2,6‐dibromo‐ and 2‐bromo‐5‐chloro‐nicotinonitriles 8, respectively, are prepared by treating 1 or 3 with bromine. Nicotinonitriles 8 react with hydrazine hydrate to yield pyrazolo[3,4‐b]pyridines 12. Treatment of butadienedicarbonitriles 3 with sulphuryl chloride gives 2‐aryl‐3‐bromo‐ and 3‐chloro‐4‐chloromethylthio‐4‐methylthio‐1,3‐butadiene‐1,1‐dicarbonitriles 17, respectively. The structures of the prepared compounds are in agreement with spectroscopic data.
Synthese von B1‐substituierten Peptidyl‐Insulinen
Authors: Losse Günter , Raddatz Heike
Published: December 2004

Synthesis of B1 Substituted Peptidyl Insulins

The peptide derivatives Boc‐Leu‐Tyr(Bzl)‐Gln‐Leu‐OH

Nomenklatur und Abkürzungen nach den Regeln der IUPAC‐IUP‐Commission on Biochemical Nomenclature: Hoppe‐Seyler's Z. Physiol. Chem. 348 (1967) 256 und J. Biol. Chem. 247 (1972) 977. magnified image

of the sequence section 13–16 of the insulin A chain and Boc‐Leu‐Tyr(Bzl)‐Leu‐Val‐Cys(SEt)‐Gly‐OH corresponding to the partial sequence 15–20 of the B chain are condensated with A1, B29‐Boc
2
‐insulin via their pentachlorphenylesters. After removal of the protecting groups by HBr/TFA in the presence of anisole and ethylmercaptan the corresponding insulins elongated in position B1 are isolated and characterized by HPLC.
Intramolekulare 1,3‐dipolare Cycloadditionen von Arylaziden mit Alkinylsubstituenten
Authors: Rudorf W.‐D. , Janietz D.
Published: December 2004

Intramolecular 1,3‐Dipolar Cycloadditions of Aryl Azides with Alkynyl Substituents

Reaction of substituted 4‐chlorobut‐2‐ynes 1 with 2‐acetaminophenol and 2‐aminothiophenol, respectively, leads to the corresponding ethers and thioethers 3 that can be converted into the alkynyl substituted aryl azides 4 by diazotation and reaction with sodium azide. Intramolecular 1,3‐dipolar cycloaddition yields 4H‐[1,2,3]triazolo [5,1‐c] [1,4] benzoxazines and benzothiazines 5. In the same way 1,4‐bis(2‐acetaminophenoxy)but‐2‐yne 6 reacts to a 3‐(2‐azidophenoxy‐methyl)‐triazolobenzoxazine 9. Its thermal decomposition gives the azomethine 11.
Fluoreszenzlöschung aromatischer Verbindungen durch Diazoniumkationen in wäßrigen Lösungen von Natriumpolyvinysulfat
Authors: Becker H. G. O. , Schütz R. , Kuzmin M. G. , Soboleva I. V.
Published: December 2004

Quenching of Fluorescence of Aromatic Compounds by Diazonium Cations in Aqueous Solutions of Polyelectrolytes

The absorption and fluorescence spectra, and lifetimes of sodiumpyrene‐3‐sulfonate, N‐phenylacridone and acridizinium perchlorate have been measured in the absence and in the presence of sodiumpolyvinylsulfate. A study is made of the quenching by diazonium ions of the fluorescence of the aromatic compounds. The results of Stern‐Volmer plots are discussed by a micro‐heterogeneous model and compared with results in homogeneous solutions. It is suggested that contributions of quencher and aromatic compound in both polyelectrolyte and aqueous phases are important.