bluuebunny/crossref_metadata_2025_split huggingface dataset:
Friedel‐Crafts‐Acylierungen aliphatischer Verbindungen. VII. Friedel‐Crafts‐Acylierungen von Carbonsäurechloriden mit Maleinsäureanhydrid ‐ ein neuartiger Zugang zu Tetronsäuren
Authors: Schick H. , Gründemann E. , Ballschuh D. 
Published: December 2004

Friedel‐Crafts‐Acylations of Aliphatic Compounds. VII. Friedel‐Crafts‐Acylations of Carboxylic Acid Chlorides with Maleic Acid Anhydride — a New Access to Tetronic AcidsReaction of succinic acid with propionyl chloride under Friedel‐Crafts‐reaction conditions yields 2‐methyl‐cyclopentan‐1,3‐dione. The related reaction of maleic acid anhydride with propionyl chloride does not yield 2‐methyl‐cyclopent‐4‐en‐1,3‐dione 7, but a E/Z‐mixture of the lactones 5 and 8. By treating with hydrogen chloride in methanol or with thionylchloride in methanol the lactone mixture is converted to dimethyl (2Z, 4E)‐3‐hydroxy‐2‐methyl‐hexa‐2,4‐diendioate 10. By reaction with excessive sodium hydroxide the mixture of lactones is transformed into tetronic acid 11. Structure determinations are based on u.v.‐, i.r.‐, m.s.‐ and n.m.r.‐spectroscopy and on further chemical transformations. This tetronic acid synthesis represents an intramolecular addition of a carboxylate anion to an α, β‐unsaturated carbonyl compound.
Syntheses and spectroscopic characterisation of some new 3,5‐Bisaryl‐2‐pyrazoline Derivatives. II
Authors: Sayed G. H. , Kjøsen H. 
Published: December 2004

Synthese und spektroskopische Charakterisierung einiger neuer 3,5‐Bisarylierter‐2‐pyrazolinderivate. IIDurch Kondensation von Hydrazin bzw. substituierten Hydrazinen mit Chalkonen wurden einige neue 3,5‐bisarylierte‐2‐pyrazoline 4, 7–18 dargestellt.Bromierung des Pyrazolins 4 liefert das 4‐Brompyrazol 20.Die Verbindungen wurden durch hochauflösende Massenspektrometrie, UV‐, IR‐ und H‐NMR‐Spektroskopie charakterisiert.
1H‐NMR‐Untersuchungen zur innermolekularen Beweglichkeit in substituierten 1,3‐Diazabutadienen
Authors: Michalik M. , Evers R. 
Published: December 2004

1H‐N.M.R. Spectroscopic Investigations on Innermolecular Mobility of Substituted 1,3‐DiazabutadienesTwo isomerization processes in substituted 1,3‐diazabutadienes can be observed by the method of dynamic n.m.r. spectroscopy. From coalescence phenomena the free activation enthalpies ΔG± are determined and discussed with regard to substituent effects and solvent dependency.
Reaktionen von Difluordichlormethan mit Kohlenwasserstoffen
Authors: Schmidt H. , Burtzlaff Ch. , Masuhr H. , Ohl J. , Pehle W. , Schmoz G. , Suppan R. , Tetzner W. 
Published: December 2004

Reactions of Difluoridichloromethane with HydrocarbonsThe reaction of difluordichloromethane with different hydrocarbons between 150°C and 250°C yields the CFCl2‐substituted hydrocarbons. Beside it the corresponding chlorides are formed. For the hydrocarbons studied the following sequence of reactivity against difluordichloro‐methane was found. n‐paraffins < isoparaffins ≅ cycloparaffins < alkylaromatics < olefines.
Dreikomponentenreaktionen. XI. Bromchlorierung von Cyclopenten in Gegenwart von Alkoholen
Authors: Beger J. , Thielemann C. 
Published: December 2004

Three Component Reactions XI. Bromochlorination of Cyclopentene in the Presence of AlcoholsThe product composition of reaction mixtures after the addition of bromochlorine to cyclopentene in the presence of several alcohols was determined by GLC in dependence of the molar relations, the temperature and the order of addition. A comparison with the chlorination and bromination is given.The yields of three component products increase in the order bromination‐bromochlorination‐chlorination and decrease from primary to tertiary alcohols.
Über die Autoxidation einiger monocyclischer Olefine
Authors: Blau K. , Müller U. , Pritzkow W. , Schmidt‐Renner W. , Sedshaw Z. 
Published: December 2004

Studies on the Autoxidation of Some Monocyclic OlefinsThe autoxidations of cyclopentene, cyclohexene, cycloheptene, cyclooctene, cycloocta‐1,5‐diene, 1‐methylcyclopentene, 1‐methylcyclohexene, 1‐methylcycloheptene, 1‐methylcyclooctene, methylene cyclopentene, and methylene cyclohexene with pure oxygen under normal pressure were studied. The epoxides formed were determined gaschromatographically. In most cases also the products of allylic oxidation were analyzed and their structures elucidated after reduction to the corresponding allyl alcohols. The portions of high boiling or polymeric products which could not be detected gaschromatographically and also the real yields of epoxides were determined by balance experiments in the presence of inert internal standards.
Polymerisation von Vinylverbindungen in Gegenwart von Titan(III)‐chlorid
Authors: Moszner N. , Hartmann M. 
Published: December 2004

Polymerization of Vinyl Compounds in the Presence of Titanium(III)ChlorideThe polymerization of styrene, acrylonitrile and some methacrylates initiated by a titanium(III) chloride dichloroacetic acid redox system was studied. The monomer selectivity of the polymerization in the presence of titanium(III) chloride was found to be affected by a reductive termination reaction. Titanium(III) chloride acts as a retarder in the polymerization of styrene initiated by azobisisobutyronitrile (AIBN). The polymerization of polar monomers like acrylonitrile, methyl, ethyl and propyl methacrylate by AIBN is inhibited by titanium(III) chloride.
Partialsynthesen von Cardenoliden und Cardenolid‐Analogen. III. Synthese von Cardenolid‐analogen β‐Steroidyl‐crotonsäuremethylestern
Authors: Theil Fritz , Lindig Claus , Repke Kurt 
Published: December 2004

Partial Syntheses of Cardenolides and Cardenolide Analogues. III. Synthesis of Cardenolide‐Analogous Methyl β‐Steroidyl‐crotonatesStarting with 14‐hydroxy‐5β, 14β‐pregnan‐3β‐yl‐acetate (2) the synthesis of the cardenolide analogues methyl 3β‐acetoxy‐14, 15β‐epoxy‐24‐nor‐5β, 14β‐chol‐20(22)‐en‐23‐oate (7) via Reformatskij synthesis and methyl 3β, 14‐dihydroxy‐5β, 14β‐chol‐20(22)‐en‐23‐oate (11) via addition of lithium ethoxyacetylide to 2 are described.The activity of 11 in the ATPase‐test is about the same as that of digitoxigenin.
Substituierte 4‐Amino‐thieno[2,3‐c]isothiazole und 4‐Amino‐thieno[3,2‐d]isothiazole
Authors: Gewald K. , Radke W. , Hain U. 
Published: December 2004

Substituted 4‐Amino‐thieno[2,3‐c]isothiazoles and 4‐Amino‐thieno[3,2‐d]isothiazolesThe alkylation of disodium‐(4‐cyanisothiazole‐3,5)‐dithiolate 1 with α‐chloro carbonyl compounds followed by THORPE‐ZIEGLER‐cyclization yields the substituted 4‐amino‐thieno[3,2‐d]isothiazoles 3, which can be converted into the thieno‐isothiazolo‐1,4‐thiazepine derivatives 4, 5. The successive alkylation of 1 with dimethylsulfate and α‐chloro carbonyl compounds yields the 5‐methylthio‐isothiazole‐4‐carbonitriles 11 which are cyclized to form the substituted 4‐amino‐3‐methylthio‐thieno[3,2‐d]isothiazoles 13. The inverse alkylation procedure leads to the isomeric 4‐amino‐3‐methylthio‐thieno[2,3‐c]isothiazoles 20. Successive alkylation of the 3‐hydroxy‐5‐mercapto‐4‐cyanoisothiazoles 14 with α‐chloro carbonyl compounds and diazomethane followed by cyclization yields the 4‐amino‐3‐methoxy‐thieno[3,2‐d]isothiazoles 17. From 13 and 20 the isothiazole‐thieno‐pyrimidines 21, 22 and the isothiazolo‐thieno‐oxazinone 25 are synthesized.
NMR‐Spektroskopische Untersuchungen an Push‐pull‐Butadienen
Authors: Michalik M. , Peseke K. , Radeglia R. 
Published: December 2004

N.M.R. Spectroscopic Investigations on Push‐pull Butadienes1H‐ and 13C‐n.m.r. spectroscopic investigations show the preference of s‐trans configuration and the push‐pull character of the investigated butadienes 1 and 2.
Zur Bromierung des Cyclohexanon‐2‐carbonsäureamids
Authors: Bischoff Christian , Schröder Edith 
Published: December 2004

The Bromination of Cyclohexanone‐2‐carboxamideCyclohexanone‐2‐carboxamide with bromine forms 6‐bromo‐cyclohexanone‐2‐carboxamide (2) or 2‐bromo‐cyclohexanone‐2‐carboxamide (3). Via Faworski‐rearrangement the reaction of 2 and ammonia or amines gives trans‐cyclopentanedicarboxamides (5a–f). 3 and thiourea form the aminothiazole derivative 6. Pyridinium salt 7 is formed by reaction of 2 and pyridine. 7 and phenylhydrazine form the phenyl‐indazolonoyl‐hydrazine 8. 1 and sodiumhypochlorite yield 2‐hydroxy‐cyclohexanone‐2‐carboxamide (9).
Massenspektroskopie von Naturstoffen. XIII. Massenspektroskopische Untersuchungen von A‐nor‐Allobetulanen
Authors: Schmidt J. , Huneck S. 
Published: December 2004

Mass Spectroscopy of Natural Products. XIII. Mass Spectroscopic Investigations of A‐nor‐AllobetulanesThe mass spectroscopic fragmentation behaviour of A‐nor‐allobetulanes with several substituents at C‐2 is discussed. The skeleton fragmentation is comparable to that of C‐3‐substituted allobetulanes. The nature of the substituent at C‐2 influences both the abundance of typical skeleton fragments and the formation of specific ions.
Ein neuer synthetischer Zugang zu Ergot‐Peptidalkaloiden des N‐(d‐Lysergyl‐aminoacyl)‐lactam Types
Authors: Losse G. , Wehrstedt Kl.‐D. 
Published: December 2004

A General Synthetic Pathway to Ergot Peptide Alkaloides of the N‐(d‐Lysergyl‐aminoacyl)‐lactam TypeThe structure and configuration of the novel ergot alkaloid from Claviceps purpurea N‐(d‐Lysergyl‐valyl)‐phenylalanyl‐D‐prolin‐lactam (2) has been proved by synthesis. In addition, a general synthetic pathway to N‐(d‐Lysergyl‐aminoacyl)‐lactams of this type is opened, which are possible key intermediates in the biogenesis of ergot peptide alkaloides.
Elektrosynthese cyclischer Hydroxamsäuren mit anschließender analoger Bamberger‐Umlagerung
Authors: Matschiner H. , Tanneberg H. , Maschmeier C.‐P. 
Published: December 2004

The Electrochemical Synthesis of Cyclic Hydroxamic Acids Followed by Bamberger‐RearrangementThe electrochemical reduction of 2‐(o‐nitro‐phenylthio)acetic acid 1a results in the expected cyclic hydroxamic acid 3a and a rearranged product 4a by consuming 4 electrons. The analogous reduction of 2‐(o‐nitro‐phenoxy)acetic acid 1b leads only to a rearranged product 4b. This fact has been explained by the Bamberger‐rearrangement of the hydroxylamine intermediate 2a, b. Now the rearrangement of the expected products was shown as a new aspect to explain the formation of the products.
Photooxidation von Arylazonaphtholen mit Singulett‐Sauerstoff
Authors: Becker H. G. O. , Franze J. 
Published: December 2004

Photooxidation of Arylazo‐Naphtholes with Singlet OxygenThe reaction of p‐substituted 4‐arylazo‐1‐naphtholes 1 and 1‐arylazo‐2‐naptholes 5 with singlet oxygen (produced by methylene blue‐sensitized photolysis) has been studied spectroscopically in methanol as a solvent. The rate constants of dye bleaching are the same, irrespective whether the extinctions of the azo or the hydrazone forms of the tautomeric systems are measured. Both reaction series 1 and 5 afford linear Hammett plots, which is discussed in the light of the azohydrazone equilibrium of the dyes and an „ene”︁ mechanism of the reaction with singlet oxygen. It could be shown by short‐time spectroscopy that the azo‐hydrazone isomerization proceeds much faster than the attack of singlet oxygen on the hydrazone form, which explains all observed facts.
Synthese von Heterocyclen durch CC‐Knüpfung. V. Eine neue Pyridonsynthese
Authors: Schmitz Ernst , Schramm Siegfried 
Published: December 2004

Synthesis of Heterocyclic Compounds by CC‐bond Closure. V. A Novel Pyridone SynthesisUnder the action of alkali two moles of N‐primary alkyl cyanoacetamides 5 condense to form 1‐alkyl‐5‐alkylaminocarbonyl‐4,6‐diamino‐pyridone‐2 (6)
Chemische Synthese des Dodecanucleotids dCACAAGCTTGTG
Authors: Weiss R. , Birch‐Hirschfeld E. 
Published: December 2004

Chemical Synthesis of the Dodeecanuceleotide. dCACAAGCTTGTGFor studies of some sequence dependent structural factors the self‐complementary dodecanucleotide dCACAAGCTTGTG was required. Its chemical synthesis is reported according to the diester approach starting with the monomers dC, dpA, dpG, dpC and dpT.
Lichtinitiierte Polymer‐ und Polymerisationsreaktionen. III. Photoinduzierte Zersetzung von Aryldiazoniumsalzen durch Benzoinderivate
Authors: Baumann H. , Müller U. , Pfeifer D. , Timpe H.‐J. 
Published: December 2004

Light Induced Polymer and Polymerization Reactions. III. Photoinduced Decomposition of Arene Diazonium Salts by Benzoin DerivativesThe combination benzoin derivate/arene diazonium salt is suitable as a bivalent photoinitiator system for radicalic and cationic photopolymerization. By means of product analysis, quantum yield measurements and photo‐CIDNP‐studies a mechanism was proposed including the electron transfer from α‐substituted benzyl radicals formed by benzoin derivate photolysis to arene diazonium salts. The quantum yields for diazonium salt decomposition in acetonitril were about 0.65. They show only a small dependence on substituents of diazonium salt but are strong influenced by the solvent. In methanol or dioxane quantum yields were found from 11 to 460. 13C‐photo‐CIDNP‐measurements agree with a mechanism of benzoin ether photolysis on the triplet state.
Heterocyclisch substituierte Cumarine aus β‐Chloropropeniminiumsalzen
Authors: Czerney Peter , Hartmann Horst 
Published: December 2004

Heterocyclic Substituted Coumarines from β‐Chloropropeniminium Salts3‐Chloro‐3‐coumar‐3′‐yl‐propeniminium salts 7 or the derived aldehydes 10 are versatile synthons for the preparation of heterocyclic substituted coumarines 5. The transformation of the starting materials into the coumarines 5 can be carry out in more steps or in one step directly.
Theoretical description of solvent effects. V. The medium influence on the lactim‐lactam tautomerism of hydroxyazines
Authors: Krebs C. , Förster W. , Weiss C. , Hofmann H.‐J. 
Published: December 2004

Theoretische Beschreibung von Lösungsmitteleffekten. V. Der Mediumeinfluß auf die Lactim‐Lactam‐Tautomerie von HydroxyazinenDer Lösungsmitteleffekt auf die Tautomeriegleichgewichte der Titelverbindungen wird mit Hilfe klassischer und quantenchemischer Versionen der Solvatonen‐ und der Reaktionsfeldtheorie berechnet. In Übereinstimmung mit dem Experiment ergeben alle getesteten Verfahren eine Gleichgewichtsverschiebung zugunsten der Lactamform. Zur quantitativen Beschreibung dieses Effektes ist jedoch das Reaktionsfeldmodell besser geeignet.
Desaktivierung angeregter Singulettzustände von N‐Arylurethanen durch intra‐ und intermolekulare Energieübertragung auf Salicylsäureester und ‐amide
Authors: Stumpe J. , Schwetlick K. 
Published: December 2004

Quenching of Excited Singlet States of N‐Arylurethanes by Intra‐ and Intermolecular Resonance Energy Transfer to Salicylic Acid Esters and AmidesFluorescence and photo‐Fries reactions of N‐arylurethanes are quenched by energy transfer to salicylic acid esters and amides. Quenching of photo reaction and fluorescence obeys the Stern‐Volmer equation and is accompanied by sensitization of salicylic acid ester fluorescence.The rate constants of energy transfer are greater than the diffusion rate constants and show that resonance energy transfer occurs.The influence of solvent viscosity, donor lifetime, and spectral overlap is discussed. The rate constants of energy transfer are slightly decreased by increasing the solvent viscosity.The results are in good agreement with the treatment of POVINELLI.
Flüssigphasenoxydation von Cyclohexen in Gegenwart von Kombinationen von Verbindungen verschiedener Metalle
Authors: Boeden H.‐F. , Dahlmann J. , Hamann H.‐J. , Höft E. 
Published: December 2004

The Liquid Phase Oxidation of Cyclohexene in Presence of Combinations of Compounds of Different MetalsThe oxidation of cyclohexene (1) with molecular oxygen in chlorobenzene solution at 80°C has been studied using cobalt, manganese and copper compounds, respectively in combination with molybdenum complexes. The selectivity has been determined of cyclohex‐2‐en‐1‐hydroperoxide (2), epoxycyclohexane (3), cyclohex‐2‐en‐1‐ol (4), cyclohex‐2‐en‐1‐one (5), 2,3‐epoxy‐cyclohexane‐1‐ol (6) and cyclohexane‐1,2‐diol (7), formed from reacted 1. Investigation of the consecutive reactions showed that 3 and especially 4 can react in different ways and moreover 4 inhibits the oxidation of 1. From these results conclusions were drawn on the mechanism of oxidation of 1.
α‐Substituierte Phosphonate. 40. 1‐Trimethylammonium‐1‐diethylphosphono‐1‐cyanomethylid, ein stabiles N‐Ylid
Authors: Costisella B. , Gross H. 
Published: December 2004

α‐Substituted Phosphonates. 40. 1‐Trimethylammonium‐1‐diethylphosphono‐1‐cyanomethylid, a Stable N‐YlidDiethyl‐1‐dimethylamino‐1‐cyanomethanephosphonate 4 can be alkylated on nitrogen to the quarternary ammoniumsalts 5, which by C‐deprotonation gives the stable N‐ylid 8. The N‐ylid 8 behaves inert against carbonyl compounds and acylating agents, but can be C‐alkylated and — involving an ester‐dealkylation — C‐chlorinated.
Synthese von Heterocyclen durch CC‐Knüpfung. IV. Heterocyclensynthesen durch intramolekulare Dien‐Reaktion
Authors: Schmitz Ernst , Heuck Uwe , Preuschhof Helmut , Gründemann Egon 
Published: December 2004

Synthesis of Heterocyclic Compounds by CC‐bond Closure. IV. Synthesis of Heterocyclic Compounds by Intramolecular DienreactionN‐2‐Cyclohexenyl‐N‐isopropylcinnamamide 8 cyclizes at 230°C to give the decahydronaphthindolone 9. N‐Alkyl‐N‐allylcinnamamides 10 analogously form 1 H‐hexahydrobenzisoindolones 11. N‐Alkyl‐N‐allylsorbamides 14 cyclize at 150°C to 1 H‐hexahydroisoindolones 15. 15b yields the cyclic enamide 16 by alkali catalyzed shift of the double bond. Tricyclic lactames 19 and 20 are formed by thermal isomerization of N‐cycloalkenylsorbamides 18a and 18b, respectively.
NMR‐Untersuchungen an Dicyclopentadien‐Derivaten. VII. Zur Abhängigkeit des γ‐gauche Effektes von der sterischen Kompression eng benachbarter Protonen bei exo/endo‐Isomerieumkehr
Authors: Kleinpeter E. , Kühn H. , Mühlstädt M. , Jancke H. , Zeigan D. 
Published: December 2004

N.M.R. Investigations of Dicyclopentadiene Derivatives. VII. Dependence of the γ‐Gauche Effect on the Steric Compression of Closely Neighbouring Protons during the Reversal of Exo/Endo‐IsomerismThe 13C‐chemical shifts of the carbon atoms C1, C6, C7, C8 and C10 of different substituted exo/endo‐isomeric dicyclopentadiene derivatives are highly depending on the configuration of these compounds. The observed shift effects are discussed within the concept of the steric γ‐gauche effect and are not only explained by nonbonding interactions of steric closely neighbouring protons.
Untersuchungen zum Verlauf der Cyclisierung von Alkylmalonsäure‐ und β‐Amino‐crotonsäureestern zu alkylierten Hydroxypyridincarbonsäureestern
Authors: Schrötter E. , Niedrich H. , Schick H. 
Published: December 2004

Investigations on the Cyclization of Alkylmalonic Acid Esters with β‐Aminocrotonic Acid Esters to Alkylated Hydroxypyridine Carboxylic Acid EstersThe cyclization of substituted malonic esters with β‐aminocrotonic acid alkyl esters yields 2,4‐ or 4,6‐dihydroxy‐3‐pyridinecarboxylic acid esters, respectively, in dependence on the reaction conditions and the nature of the substituent in the malonic esters. In the presence of alcoholate malonic acid alkyl esters and alkylmalonic acid alkyl esters form 2,4‐dihydroxy‐3‐pyridinecarboxylic acid esters. Under the same conditions nitromalonic acid alkyl esters lead to 4,6‐dihydroxy‐3‐pyridinecarboxylic acid esters, which also arise in the thermal cyclization of malonic acid 2,4,6‐trichlorophenyl ester. The structure of the reaction products is determined by the relative nucleophilicity of the cyclization components.
Darstellung und Reaktionen von β‐Oxosulfenylchloriden. II. Direkte Chlorsulfanylierung von disubstituierten Acetaldehyden mit Schwefeldichlorid
Authors: Mühlstädt Manfred , Meinhold Hansjürgen , Martinetz Dieter , Neumann Eberhard 
Published: December 2004

Preparation and Reactions of β‐Oxosulfenyl Chlorides. II. Direct Chlorosulfenylation of Disubstituted Acetaldehydes by Sulfur DichlorideThe reaction of dialkylacetaldehydes (1a, b) with sulfur dichloride yields the corresponding β‐oxosulfenylchlorides (2a, b). Examples for addition‐ and substitution‐reactions of 2a, b are described.
Nucleophile Substitutionen an funktionellen Kohlensäurederivaten. XVI. Kinetik und Mechanismus der Hydrolyse von Kohlensäure‐ N,N,N′‐triphenylchloramidin
Authors: Bacaloglu R. , Bacaloglu I. , Chicu A. 
Published: December 2004

Nucleophilic Substitution to Carbonic Acid Derivatives. XVI. Kinetics and Mechanism of N,N,N′‐Triphenylchloroformamidin HydrolysisFirst order rate constants of N,N,N′‐triphenylchloroformic amidine hydrolysis in dioxane‐water have been determined by u.v.‐spectroscopy. The effects of water concentration, addition of KClO4, LiCl, HgCl2, and AgNO3 or nucleophilic agents (piperidine) as well as isotopic effects have been investigated. Activation entropy and enthalpy have been determined. According to the data obtained the reaction takes place in two steps – chlorionization and reaction of the formed cation with the nucleophilic agent. Both steps have rates of the same order of magnitude, but can become slow steps in specific conditions.
The Complexes of Dipicolinic Acid and Related Compounds in oxidation of organic substrates
Authors: Achremowicz Lucjan , Młochowski Jacek , Mora Czesław , Skaržewski Jacek 
Published: December 2004

Komplexe der Dipicolinsäure und verwandter Verbindungen zur Oxidation organischer SubstrateDie Oxidation von methylierten Hydrochinonen zu Chinonen und von α,β‐ungesättigten Alkoholen zu Aldehyden in Gegenwart verschiedener Oxidationsmittel wurde untersucht.Günstige Ergebnisse wurden bei der Anwendung des MnO2‐Dipikolinsäure‐Systems für d'e Oxidation von Allyl‐ und Benzylalkoholen und des AgO‐Dipikolinsäure‐Systems für die oxidative Demethylierung von methylierten Hydrochinonen erreicht.Der Einfluß der Struktur von 4‐substituierten Dipicolinsäuren auf die katalytischen Eigenschaften wurde untersucht.
Untersuchungen zum UV/Vis‐Spektralverhalten von Azofarbstoffen. VI. Zum Einfluß von Substituenten auf die Farbe von Derivaten des 1‐Phenylazo‐2‐naphthols
Authors: Mustroph H. , Bartel R. 
Published: December 2004

Studies on UV/Vis Absorption Spectra of Azo Dyes. VI. The Effect of Substituents on the Color of Derivatives of 1‐Phenylazo‐2‐naphtholsThe absorption spectrum of 1‐(4′‐diethylaminophenylazo)‐2‐naphthol has been examined, and it has been found that the absorption band at 510 nm corresponds to the azo form and the shoulder at 610 nm corresponds to the hydrazone tautomeric form. Substituents in 3‐position of 2‐naphthol which have a free proton (e.g. OH, COOH, CONHR) stabilize the hydrazone tautomeric form by an intramolecular hydrogen bonding between substituent and hydrazone oxygen. Substituents which have not a free proton (e.g. OCH3, COOCH3, CONR1R2) have little influence on the absorption spectrum.The relative intensities of the two bands of the tautomeric forms are dependent on:
— the electron attracting or electron releasing effect of the substituent R in CONHR
— the hydrogen bonding acidity of the substituents in 2′‐position if R in CONHR is a phenylring
— the hydrogen bonding acidity of the solvent.

The effect of substituents in the phenylazo subsystem is also discussed.
Elektrochemische Darstellung von organischen Diseleniden
Authors: Jeroschewski P. , Ruth W. , Strübing B. , Berge H. 
Published: December 2004

Electrochemical Preparation of Organic DiselenidesBy the method of electrosynthesis a number of organic diselenides can be prepared simply and without danger. The cathodic polarisation of a special selenium electrode in aprotic solutions gives rise to polyselenideanions, which react with electrophilic compounds to the corresponding diselenides of the general formula RSeSeR (2a–e) with R = benzyl, 2‐nitrophenyl, cyclohexyl, isopropyl, 4‐cyanophenyl.