bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterocyclen aus o‐Aminoketonen. XXIII [1]. Umsetzung von o‐Aminoketonen mit Dicarbonsäuren
Authors: Kempter G. , Rehbaum D. , Schirmer J.
Published: December 2004

Aus gesättigten aliphatischen Dicarbonsäuren (C4–7 und C10) werden mit 2‐Aminobenzophenonen in Polyphosphorsäure (PPS) substituierte Vertreter des partiell hydrierten Benzo[b][1,8]naphthyridin‐Systems 2a–d sowie substituierte 2‐Anilino‐chinolin‐3‐alkansäuren 5a–h gebildet. Die Glutarsäure‐Analoga, die an Stelle der β‐CH2‐Gruppe Heteroatome (–S‐ oder –O‐) besitzen, reagieren mit den Aminoketonen zu Thiazino‐ und Oxazino [3,2‐b]chinolinen 2e–h. Aromatische o‐Dicarbonsäuren mit einer –CH2CO‐Gruppierung können mit Aminoketonen zu anilino‐substituierten 5i bzw. pyrano[b]kondensierten Chinolinen 6 umgesetzt werden. –N,N′‐Bis‐(2‐benzoyl‐phenyl)‐dicarbonsäurediamide 3 lassen sich leicht mit Ammoniak in die entsprechenden α,ω‐Bis‐(4′‐phenyl‐chinazolinyl‐(2′))‐alkane 4 überführen.
Zur Einwirkung starker Basen auf quartäre Methallyl‐ammoniumverbindungen. IV [1]. Die basen‐initiierte Umlagerung von Dimethyl‐benzyl‐methallyl‐ammoniumjodid
Authors: Dietrich W. , Schulze K. , Mühlstädt M.
Published: December 2004

Es wird die Konkurrenz von STEVENS‐ und SOMMELET‐Umlagerung bei der Einwirkung von Natriumamid, Methylsulfinyl‐carbanion und Butyllithium auf Dimethyl‐benzyl‐methallyl‐ammoniumjodid untersucht. Mit allen 3 Basensystemen wurden ein SOMMELET‐ und zwei STEVENS‐Umlagerungsprodukte erhalten. Mit Natriumamid überwog das Produkt der [3, 2]‐SOMMELET‐Umlagerung, mit Methylsulfinyl‐carbanion das der [1, 2]‐ und mit Butyllithium das der [3, 2]‐ STEVENS‐Umlagerung.
Desaktivierungsverhalten von Arenen und Heteroarenen. II. Fluoreszenzlöschung des Acridiziniumions durch äußeren Schweratomeffekt
Authors: Bendig Jürgen , Helm Siegrun , Kreysig Dieter
Published: December 2004

Die Geschwindigkeitskonstanten der durch Alkyl‐ bzw. Arylbromide und ‐jodide verursachten Fluoreszenzlöschung des Acridiziniumions werden außer von der Kernladungszahl des Schweratoms von den Donatoreigenschaften der Löscher bestimmt. Das zeigen die entsprechenden Zusammenhänge der nach STERN‐VOLMERermittelten Geschwindigkeitskonstanten mit den Ionisierungspotentialen der Elektronendonatoren und den TAFT‐Konstanten. Für niedrige Ionisierungspotentiale der Löcher ist eine Beteiligung von Triplettzuständen des Löschers bzw. die Bildung eines strahlungslos desaktivierenden Exciplexes anzunehmen.
N‐Substituted Aziridine Reaction with Sodium Carbonate and Trithiocarbonate
Authors: Giumanini Angelo G. , Plessi Laura
Published: December 2004

N‐substituierte Aziridinreaktion mit Natriumcarbonat und Trithiocarbonat
Zur Analytik von Kohlenwasserstoffen mit Hilfe der Massenspektrometrie. IV. Die quantitative Bestimmung von Paraffinen bei schonender Anregung durch Elektronenstoß
Authors: Herzschuh R. , Seidlitz W.
Published: December 2004

Analysis of Hydrocarbons by Means of Mass Spectrometry. IV. The Quantitative Determination of Paraffins by Low Voltage Electron Impact

The exactness of the quantitative determination of paraffins by means of electron impact mass spectrometry on the basis of the molpeak methodes can be much improved by reducing the ion‐source temperature.

The time for carrying out the analysis in order to determine calibrated values is reduced by using the ion‐source of the mass spectrometer as a pressure measuring‐instrument.

The determination of the amount of iso‐paraffines is possible by the sum of molpeak‐intensities with a relative deviation of 2–3%.
Darstellung, Konfigurationen und NMR‐Daten der Säuren CH3(SR)  CHCOOH (R  C6H5, CH2C6H5, CH2COOH)
Authors: Larsson Erik
Published: December 2004

Preparation, Configurations and N.M.R. Dates of the Acids CH3(SR)CHCOOH (R  C6H5, CH2C6H5, CH2COOH)

The cis and trans isomers of the acids CH3(SR)CHCOOH (R  C6H5, CH2C6H5, CH2COOH) were prepared by addition of HSR to CH3CCCOOH in alkaline water solution and by alkaline hydrolysis of CH3C(SR)2CH2COOC2H5 (R  C6H5, CH2C6H5, CH2COOC2H5). The oxidation products CH3C(SO2R)  CHCOOH (R  C6H5, CH2COOH) were also prepared. The n.m.r. dates of the acids were obtained and some relations between them were discussed.
α‐Substituierte Phosphonate. XXXI. Zur Reaktion von N,N,N′,N′‐Tetramethylchlorformamidiniumchlorid mit P‐III‐Verbindungen
Authors: Riesel L. , Franke U. , Costisella B. , Gross H.
Published: December 2004

α‐Substituted Phosphonates. XXXI. The Reaction of N,N,N′,N′‐Tetramethyl Chloroformamidinium Chloride with P(III) Compounds

N,N,N′,N′‐Tetramethyl chloroformamidiniumchloride (4) does not react with triethyl phosphite (TEP) or isopropyl diphenylphosphinate to give the expected bisphosphoryl derivatives 7 and 11, respectively, but primarily the monophosphorylated amidinium salts 6 and 10 respectively. The phosphine oxide 10 is stable, while 6 undergoes an elimination of ethyl chloride to the betain 8. Even under more drastic conditions the reaction of 4 or 8 with TEP does not lead to the expected bis(dimethylamino)bisphosphonate 7, but to the monoaminated bisphosphonate 1, involving a reduction step. Similar reduction has been observed under mild conditions in Michaelis‐Arbusov reaction of dichloromethylenimonium chloride, yielding the expected trisphosphonate 2 and the bisphosphonate 1 as a by‐product.
Pyrazolonderivate. IV [9]. Zur Tautomerie und Stereochemie von 4‐Aminomethylen‐Δ2‐pyrazolinonen‐(5)
Authors: Freyer Wolfgang
Published: December 2004

Pyrazolone Derivatives. IV. Tautomerism and Stereochemistry of 4‐Aminomethylene‐Δ2‐pyrazolinones‐(5)

Tautomerism and stereochemistry of compounds of type 1 were investigated by 1H‐n.m.r.‐ and i.r.‐spectroscopy. Dynamic 1H‐n.m.r. study with 15N‐labelled compounds shows, that 1 exist in solution as 4‐aminomethylene‐Δ2‐pyrazolinones‐(5) with strong intramolecular hydrogen bonds. Compared to 4‐unsubstituted Δ2‐pyrazolinones‐(5) polar solvents do not change the tautomeric equilibrium of 1. The N‐aryl‐substituted compounds have a higher NH‐acidity than N‐alkyl‐substituted derivatives.

In crystalline state the N‐alkyl‐substituted compounds 1g, h exist in the E‐configuration as 4‐aminomethylene‐Δ2‐pyrazolinones‐(5) with intermolecular hydrogen bond. At higher temperatures or in solution the Z‐isomer is formed spontaneously.
Pyrazolonderivate. V [1]. UV‐spektroskopisches und photochemisches Verhalten von N‐mono‐ und N,N‐disubstituierten 4‐Aminomethylen‐Δ2‐pyrazolinonen‐(5)
Authors: Freyer Wolfgang
Published: December 2004

Pyrazolone Derivatives. V. U.V.‐Spectroscopical and Photochemical Behaviour of N‐mono and N,N‐disubstituted 4‐Aminomethylene‐Δ2‐pyrazolinones‐(5)

U.V.‐spectra of N‐mono and N,N‐disubstituted 4‐Aminomethylene‐Δ2‐pyrazolinones‐(5) 1a–j and their dependence on solvent and temperature are discussed. N,N‐disubstituted and N‐monosubstituted 4‐aminomethylene‐3‐methyl‐1‐phenyl‐Δ2‐pyrazolinones‐(5) show a Z‐/E‐isomerization of the exocyclic CC‐double bond at low temperatures. Compared to the N‐monosubstituted compounds the compound 1j exhibits a strong interaction in the E‐configuration between the aminomethylene‐substituent and the methyl‐group at the parazolone‐ring.

The Z‐/E‐isomerization depends on solvent polarity. With increasing solvent polarity the energy of activation of thermic E‐/Z‐isomerization is decreased.

A low temperature cell is described.
Electronic Absorption Spectra of Some Quinoneanils
Authors: Issa I. M. , El‐Shafei A. K. , Etaiw S. H. , El‐Kashef H. S.
Published: December 2004

Absorptionsspektren einiger Chinonanile

Elektronenabsorptionsspektren einiger Chinonanile wurden in organischen Lösungsmitteln unterschiedlicher Polarität untersucht. Die Spektren werden in Abhängigkeit von Mediumeffekten und der Molekularstruktur diskutiert. Die pK‐Werte der Verbindungen wurden durch Spektralmessungen in Pufferlösungen durch Veränderung des pH‐Wertes bestimmt. Die wichtigsten IR‐Banden werden bezüglich der Molekularstruktur diskutiert.
Selektive Umsetzungen von Kohlenhydraten mit Phenylisothiocyanat
Authors: Zinner H. , Langer T.
Published: December 2004

Selective Reactions of Carbohydrates with Phenyl Isothiocyanate

D‐Galactose dialkyl dithioacetals, o‐nitrophenyl‐β‐D‐galactopyranoside and 1,2‐O‐trichloroethylidene β‐D‐glucofuranose react by treatment with phenyl isothiocyanate in pyridine only at the primary hydroxyl group to form the corresponding 6‐O‐phenylthiocarbamoyl compounds 2a–d, 4 and 6.
Über einige Zusammenhänge zwischen Elektronenstoßfragmentierung und Eigenschaften organischer Moleküle
Authors: Hottmann K. , Kriegsmann H.
Published: December 2004

About Some Correlations between Electron‐Impact‐Induced Fragmentations and Properties of Organic Molecules

The most important theoretical conceptions in organic mass‐spectrometry are discussed and compared. By consideration of special cases of single, competitive and consecutive reaction models and their graphical presentation it is possible to demonstrate some consequences of the QET useful for the qualitative interpretation and the understanding of the formation process of a mass‐spectrum. The validity and the limits of the physical‐organic theory of mass‐spectra is examined from the point of view of the QET. A method to estimate the relative strength of chemical bonds in ions from fragmentation behaviour, including rearrangement, is proposed.
Bestimmung der Dimerisationskonstanten kationischer Farbstoffe in festen Schichten von Polyvinylalkohol durch Eigenlöschung der Fluoreszenz
Authors: Marx Jörg , Schiller Kurt
Published: December 2004

Determination of Dimerization Constants of Cationic Dyes in Solid Layers of Polyvinyl Alcohol by Means of Fluorescence Self‐Quenching

The concentration‐dependent quenching of the fluorescence of cationic dyes (acridine orange, methylene blue, rhodamine B, and rhodamine 6G, respectively) has been used to evaluate the monomerdimer equilibrium constants of these dyes.
Über die Verwendung von Nitrosomesitylen als Spin‐Trap
Authors: Rehorek Detlef
Published: December 2004

On the Use of Nitrosomesitylene as a Spin Trap

2, 4, 6‐Trimethylnitrosobenzene (nitrosomesitylene) has been tested for spin trapping of radicals. The rate constant for trapping of tert. butyl radicals by nitrosomesitylene has been estimated to be (1.2 ± 0.3) · 108mole−1dm3s−1.
Elektronenstruktur konjugierter Sulfone SCF‐π‐Elektronenberechnungen mit expliziter Berücksichtigung der d‐Orbitale
Authors: Sauer J. , Grohmann I. , Stösser R. , Wegener W.
Published: December 2004

Electronic Structure of Conjugated Sulfones SCF‐π‐Electron Calculations Explicitly Taking into Account d‐Orbitals

The model proposed by DE JONG and JANSSEN in order to treat the interaction between the sulfon group and adjacent π electron centers within the HÜCKELapproximation is extended to the PPP method. Parameters are given which are consistent with those known for other substituents. Charge distributions and electronic spectra are calculated for some substituted phenylsulfones and styrylsulfones and compared with the corresponding experimental data (13C n.m.r. chemical shift and u.v. spectra, respectively).
Synthesekontrolle und Charakterisierung höherer Peptide durch Anwendung der 13C‐NMR‐Spektroskopie
Authors: Schwenzer B. , Scheller D. , Losse G.
Published: December 2004

Control of Synthesis and Characterization of Higher‐Molecular Peptides by Means of 13C n.m.r. Spectroscopy

The 13C n.m.r. spectra of the C‐terminal bovine insulin decapeptide derivative Boc‐Glu(OBzl)‐Arg(H+)‐Gly‐Phe‐Phe‐Tyr(Bzl)‐Thr(Bzl)‐Pro‐Lys(Z)‐Ala‐OBzl as well as the amino acid and peptide intermediates used in its synthesis, have been measured and assigned as extensively as possible. The use of 13C n.m.r. spectroscopy as a method for controlling the synthesis and for the characterization of higher‐molecular peptides is discussed.
Massenspektroskopie von Naturstoffen. I. Vergleichende Anionen‐Kationen‐Massenspektroskopie von 2,3,4,6‐Tetra‐O‐acetyl‐β‐D‐glucopyranosylestern
Authors: Voigt D. , Lehmann H.
Published: December 2004

Mass Spectroscopy of Natural Compounds. I.

Comparative Investigation of Anion‐Cation Mass Spectra of 2,3,4,6‐Tetra‐O‐acetyl‐β‐D‐glucopyranosyl Esters

The electron attachment mass spectra (anion mass spectra) of 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosyl esters with different structures of the acids are discussed and compared with the corresponding electron impact spectra. In contrast to the cation mass spectra the molecular ion peak appears in all the anion mass spectra.
Folgeprodukte halogenierter Aldehyde. XVI [1]. Untersuchungen über Chloralammoniak
Authors: Schnell M. , Erfurt G. , Zinner H.
Published: December 2004

Derivatives of Halogenated Aldehydes. XVI. Investigations of Chloralammonia

N‐(1,2,2,2‐Tetrachloroethyl)trichloroacetaldimine 8 is formed by heating of chloral‐ammonia 2 with thionyl chloride. The reaction of 2 with phosphorus pentachloride in ether leads to a mixture of aldimine 8, 1,2,2,2‐tetrachloroethyl‐phosphorodichloridate 5, N‐(1,2,2,2‐tetrachloroethyl)‐phosphorimidic acid trichloride 6 and N‐(1,2,2,2‐tetrachloroethyl)‐phosphoramidic acid dichloride 7. From compound 7, the phosphoramidic acid ester 9, the substituted phosphoric acid triamide 10 and the N‐dichlorophosphoryl trichloroacetaldimine 11 are obtained on treatment with methanol, isopropyl amine or triethyl amine, respectively. Compound 9 is also formed from 6 by reaction with methanol. The data of i. r. spectra are concordant with the assigned structures of the compounds 6–11.
Synthese von Triorgano‐amido‐arsen‐, ‐antimon‐ und ‐wismut‐halogeniden
Authors: Dahlmann J. , Winsel K.
Published: December 2004

Synthesis of Triorgano‐amido‐arsenic‐, ‐antimony‐ and ‐bismuthhalides

The preparation of some triorgano‐amido‐metalhalides by addition of various N‐haloamides to organometallic compounds of the type R3M (M  As, Sb, Bi) in polar aprotic solvents under mild conditions is described. The properties of these derivatives are studied. In solution equilibriums of triorgano‐amido‐antimonyhalides, the corresponding dihalides, and diamido compounds are existing, as we proved by 1H‐n.m.r.
Cyansäureester, 27 [1]. Triazino‐benzimidazole aus 2‐Amino‐benzimidazol‐1‐imidsäureestern und carbonylanalogen Verbindungen
Authors: Martin Dieter , Graubaum Heinz
Published: December 2004

Cyanic Acid Esters. 27. Triazino‐benzimidazoles from 2‐Amino‐benzimidazole‐1‐imid‐esters and Carbonyl Analogic Compounds

The Cyclocondensation of 2‐amino‐benzimidazole‐1‐imid‐esters with aldehydes, carbonic acid anhydrides and isocyanates has been investigated. With aldehydes in the presence of piperidine 4‐aryloxy‐1,2‐dihydro‐1,3,5‐triazino[1,2‐a]benzimidazoles 3 and with carbonic acid anhydrides 4‐aryloxy‐1,3,5‐triazino[1,2‐a]benzimidazoles 5 are formed. Isocyanates react with the imid esters to the corresponding 3‐substituted ureas 8 which on heating undergo acyl migration of the carbamoyl group followed by cyclocondensation to 4‐imino‐2‐oxo‐1,2,3,4‐tetrahydro‐1,3,5‐triazino[1,2‐a]benzimidazoles 12.
Synthese und biochemische Aktivität perfluoralkylierter Derivate des 5′‐Desoxy‐5′‐fluor und 2′,5′‐Didesoxy‐5′‐fluor‐uridins
Authors: Cech D. , Herrmann G. , Staske R. , Langen P. , Preussel B.
Published: December 2004

Synthesis and Biochemical Activity of Perfluoroalkylated Derivatives of 5′‐Deoxy‐5′‐fluoro‐, and 2′, 5′‐Dideoxy‐5′‐fluorouridine

5‐Perfluoroalkylated 5′‐deoxy‐5′‐fluoro‐, and 2′,5′‐dideoxy‐5′‐fluorouridine are obtained by the reaction of 5′‐fluorouridine or 2′,5′‐dideoxy‐5′‐fluorouridine, respectively, with a perfluoroalkyl‐coppercomplex in DMSO under inert conditions, and at temperatures of about 100 °C. Analogously 5‐perfluoroethyl, 5‐perfluorobutyl, and 5‐perfluorohexyl derivatives of uridine, and 5‐perfluoroethyl, and 5‐perfluorobutyl derivatives of 2′‐deoxyuridine could be isolated. It is shown either by mass spectroscopy or by1H‐n.m.r. spectroscopy that the substitution always takes place at the 5‐position of the pyrimidine. The 5‐perfluoroethyl derivatives are particularly effective as cytostatics.
Molekül‐ und KristallStruktur des Dioxano‐bis(2,4‐dichlorphenoxyacetato)‐kupfer(II) Cu2(2,4‐D)4 · 5 Dioxan
Authors: Reck G. , Jähnig W.
Published: December 2004

Molecular and Crystal Structure of Dioxano‐bis(2,4‐dichlorophenoxyacetato)‐copper (II) Cu2(2,4‐D)4 · 5 Dioxan

The cupric salt of 2,4‐D crystallizes from dioxane solution in the space group P 1 with 2 formula units C16H10O6Cl4Cu and 5 dioxane molecules in the unit cell. The lattice constants are a = 12.557 Å, b = 14.391 Å, c = 9.537 Å, α = 112.56°, β = 99.62° and γ = 92.77°. By X‐ray structure analysis the coordination around the Cu atoms was especially investigated.
Gasadsorptionschromatographie höherer Kohlenwasserstoffe. Normalparaffinbestimmung durch temperaturprogrammierte Segregations‐Gaschromatographie an 5A Molekularsieb
Authors: Eppert G. , Ludwig H. , Schinke I.
Published: December 2004

Gas Adsorption Chromatography of Higher Hydrocarbons. Determination of Normal Paraffins by Temperature‐Programmed Segregation Gas Chromatography on 5A Molecular Sieve

A fast temperature program makes it possible to determine the normal paraffins up to C 20 in the concentration range between 0.1 and 99.9 percent (molecule type analysis). From the group peak of the normal paraffins we can obtain on line the distribution of the carbon numbers.

As the normal paraffin selectivity of the molecular sieve S ≈ 1 can be assumed. Isoparaffin memory could not be detected.

The new method makes it possible to perform analysis with great accuracy within three minutes or less. Connected to a computer it is excellently suitable for large series of samples.

Under the standard conditions of this method only a little paraffin cracking has been found. Type and quantity of the cracked products proved to be independent of the chain length of the individual normal paraffin.
Zur Reaktion von Bis‐(dimethylglyoximato)‐nickel(II) mit Hexamethyldisilazen
Authors: Uhle Klaus , Schubert Harald
Published: December 2004

On the Reaction of Bis‐(dimethylglyoximato)‐nickel(II) with Hexamethyldisilazane

The reaction of bis‐(dimethylglyoximato)‐nickel(II) with hexamethyldisilazane was investigated. Some reactions of the formed nickel(II) dimethylglyoximate are described.
Der kristallin‐flüssige Zustand als Kriterium zur Konstitutionsermittlung von Derivaten tautomeriefähiger heterocyclischer Systeme. I. Kristallin‐flüssige Benzoesäure‐ und Thiobenzoesäure‐pyrimidinyl‐(2)‐ester
Authors: Zaschke H. , Isenberg A. , Schubert H.
Published: December 2004

The Liquid Crystalline State as a Criterion in Determination of Structure. I. Crystalline Liquid Benzoic Acid and Thiobenzoic Acid Pyrimidinyl‐(2)‐esters

The acylation of subst. 1H‐pyrimidinethiones‐(2) 3 and 4, as well as of subst. 1H‐pyrimidinones‐(2) 7 is investigated. Due to the tautomeric equilibrium in the starting materials the reactions may lead to N‐, S‐, or O‐esters. The liquid crystalline properties of the reaction products formed prove that S‐ and O‐acylated esters 5, 6, and 8 had been formed only. Spectroscopic data confirm this.
Kristallin‐flüssige Thiazole
Authors: Dölling K. , Zaschke H. , Schubert H.
Published: December 2004

Liquid Crystal Thiazoles

The synthesis of 2,4‐ and 2,5‐disubstituted thiazoles is described and their melting and clearing points are investigated. The influence of the thiazole ring system on the formation of crystalline‐liquid phases is discussed.
Massenspektren alicyclischer Verbindungen. VI. Massenspektrometrisches Fragmentierungsverhalten von Chloressigsäurediestern des trans‐1,4‐Cyclohexandiols
Authors: Borsdorf R. , Remane H. , Arnold M.
Published: December 2004

Mass Spectra of Alicyclic Compounds. VI. Mass Spectrometric Fragmentation of Chloroacetic Esters of the trans‐1,4‐Cyclohexanediol

The electron impact mass spectra of some chloroacetic esters of trans‐1,4‐cyclo‐hexanediol and of cyclohexanol are discussed.

It was found that the fragmentation process in these compounds is determined by the number of chlorine atoms in the acid and the interactions between the two functional groups.
Nα‐Acetyl‐aminosäure‐methylamide als Modellverbindungen zur Interpretation der 13C‐NMR‐Spektren geschützter Peptide
Authors: Schwenzer B. , Scheller D. , Losse G.
Published: December 2004

Nα‐Acetyl‐methylamides of Amino Acids as Model Compounds for Interpretation of 13C‐NMR‐Spectra of Protected Peptides

Nα‐Acetyl‐methylamides of differents amino acids have been synthesized as model compounds for amino acid residues in peptides, and 13C‐n.m.r. spectra have been measured.

The three derivatives of peptides Boc‐Glu(OBzl)‐Arg(H+)‐Gly‐Phe‐Phe‐Tyr(Bzl)‐Thr(Bzl)‐Pro‐Lys(Z)‐ Ala‐OBzl (B 21–30). Boc‐Leu‐Tyr(Bzl)‐Leu‐Val‐Cys(SEt)‐Gly‐OH (B 15–20) and Boc‐Ser(Bzl)‐His(Trt)‐Leu‐Val‐Glu(OBzl)‐Ala‐OH (B 9–14) used for the synthesis of insulin B chain are an illustration for the fact that chemical shifts of characteristic amino acid carbon atoms obtained by corresponding model compounds, allow a simple and correct interpretation of peptide derivative spectra.
Derivate des Phosphorsäure‐o‐phenylenesters. XIX. Zum Ablauf der Bromierung von Phenyl‐o‐phenylenphosphit
Authors: Gloede Jörg , Gross Hans
Published: December 2004

Derivatives of o‐Phenylene Phosphates. XIX. Bromination of Phenyl o‐Phenylene Phosphite

The bromination of phenyl o‐phenylene phosphite does not yield the expected penta‐coordinated phosphorus dibromide 3 but phosphorus tribromide, phenoxy‐bis‐(o‐phenylendioxy)‐phosphorane and tetraphenoxyphosphonium bromide. The mechanism of the reaction is discussed.
Zur Analytik von Kohlenwasserstoffen mit Hilfe der Massenspektrometrie. V. Abhängigkeit der elektronenstoßinduzierten Fragmentierung monocyclischer Kohlenwasserstoffe von der Ringgröße
Authors: Herzschuh R. , Epsch K.
Published: December 2004

Analysis of Hydrocarbons by Means of the Mass Spectrometry. V. Fragmentation of Monocyclic Hydrocarbons as a Function of the Ring Size

The E.I.‐spectra of the cycloalkanes CnH2n (n = 5 – 14) and of the cycloalkenes CnH2n‐2 (n = 5 – 12) exhibit strongly influence of the ring strain energies on the stability of molecular ions. Medium‐sized cycloalkanes and cycloalkenes (n = 9 – 11) show exceptional behaviour under the conditions of the electron impact ionization, which is discussed on the base of ring strain effects.
Zur Analytik von Kohlenwasserstoffen mit Hilfe der Massenspektrometrie. VI. Der Einfluß von Ringgröße und Konfiguration auf die Fragmentierung der Bicyclo(n.1.0)alkane und ihrer Halogenderivate beim Elektronenstoß
Authors: Herzschuh R. , Epsch K.
Published: December 2004

Analysis of Hydrocarbons by Means of the Mass Spectrometry. VI. The Influence of the Ring Size and the Konfiguration on the Fragmentation of Bicyclo(n.1.0)alkanes and their Halogen Derivatives by Electron Impact

The mass spectra of cis and trans bicyclo(n.1.0)alkanes and their halogen derivatives are discussed. The ring strain energies of these compounds influence the stability of their molecular and fragment ions.
Dipolmomente und Konformation von 3‐ und 4‐Brom‐ und Chlorheteracyclohexanen
Authors: Remane H. , Borsdorf R. , Scholz M. , Dölle E. , Loock P.
Published: December 2004

Dipole Moments and Conformation of 3‐ and 4‐Bromo and Chloro Heteracyclohexanes

The dipole moments of some 3‐ and 4‐bromo and chloro heteracyclohexanes are measured by the method of Debye and calculated both by the quantum‐mechanical method CNDO/2 and vector addition method.

The determination of conformational free energy is made on the basis of measured dipole moments μ of the conformation mixture and the calculated dipole moments μe and μa of the pure conformers. The results are discussed in relation to n.m.r.‐results.
Zur Berechnung der kritischen Mizellbildungskonzentration isomerer und substituierter Alkansulfonate
Authors: Sowada Rudolf
Published: December 2004

Concerning the Calculation of Values of the Critical Concentration of Mizellization for Isomeric and Substituted Alkane Sulphonates

Based on Lin's approach hydrophobicity indices I have been calculated for the isomeric dodecane sulphonates and some substituted alkane sulphonates from published cK data. These I values are useful for estimating cK values of new surface active alkane sulphonates.
Dreikomponentenreaktionen. IX. Methoxychlorierung von Butadien. 1. Produktverteilung bei Chlorunterangebot und Chlorüberangebot
Authors: Beger J. , Schiefer H. , Movsumzade M. M. , Gurbanov P. A.
Published: December 2004

Three‐Component Reactions. IX. Methoxychlorination of Butadiene. 1. Composition of Reaction Mixtures Obtained Using Either an Excess of Butadiene or an Excess of Chlorine

Methoxychlorination of butadiene with 2 mol chlorine gives saturated secondary addition products 5–15, which were found identical with methoxychlorination products of unsaturated primary addition products 1–4 (investigated by capillar GLC). 1, 2 and 3 add chlorine and methanol with high regioselectivity (80–90%); meso and erythro isomer predominate in Markovnikov products from 1 and 2 (87% diastereoselectivity). 5–7 and 11–15 were separated by preparative GLC for structural analysis.
d‐NMR‐Untersuchung der behinderten Rotation am NC(X)‐Bindungsfragment. XII. Substituenteneffekte auf die CN‐Rotationsbarriere in unterschiedlich N‐substituierten Carbamidsäure‐O‐ethylestern
Authors: Kleinpeter E. , Kretschmer M. , Borsdorf R. , Widera R. , Mühlstädt M.
Published: December 2004

d‐N.M.R.‐Investigation of the Restricted Rotation at the NC(X)‐Bonding Fragment. XII. CN‐Rotational Barrier in Different N‐Substituted Carbamic Acid O‐ethyl Esters

The 1H‐n.m.r. spectra of a series of different N‐substituted urethanes R1R2N‐C(O)OC2H5 are studied at various temperatures. At low temperatures the syn/anti rotamers are assigned by using the LIS‐values of the protons. The thermodynamic parameters ΔGC± of the restricted rotation about the partial C‐N double bond are determined and discussed with regard to inductive, conjugative and homoconjugative effects of the N‐substituents.
Chemistry and application of organic isocyanates. II. Application of tolylene‐2,4‐diisocyanate for the Syntheses of New Surface‐Active Urethanes of poly(oxyethylene)‐sucrose and poly(oxyethylene)glucose
Authors: Lesiak T. , Iwaszkiewicz‐Nowak J.
Published: December 2004

Chemie und Anwendung von organischen Isocyanaten. II. Verwendung von Toluylen‐2,4‐diisocyanat für die Darstellung von neuen grenzflächenaktiven Poly(oxethylen)saccharose‐ und Poly(oxethylen)glucoseurethanen

Durch Synthese von 3‐Isocyanato‐4‐methyl‐phenylcarbaminsäurealkylestern 1–5 mit Poly(oxethylen)sacchariden entstehen bisher unbekannte, grenzflächenaktive Poly(oxethylen)saccharose‐ und Poly(oxethylen)glucoseurethane 6–23.

In Abhängigkeit von der Konzentration wurden die Oberflächenspannung und die Schaumfähigkeit dieser Verbindungen bestimmt und mit den Standards Na‐Dodecylsulfat und K‐Oleat verglichen.
Aldehyde, tert. Amine bzw. Acetale aus Amidacetalen und Grignardverbindungen
Authors: Walther H. , Haase L. , Gross H. , Costisella B. , Keitel I.
Published: December 2004

Aldehydes, tert. Amines or Acetales from Amidacetales and Grignard‐Compounds

Amidacetales1or ‐mercaptales9respectively react with Grignard‐agents dependent on molar ratio by exchange of methoxy‐ or methylthio group via not isolable O,N‐ or S,N‐acetales to the corresponding aldehydes4or the tert. amines3. Starting from bicyclic amidacetales6aldehydes or bis‐β‐hydroxyethylamines8are formed. By quaternisation of the amidacetal‐nitrogen followed by reaction with Grignard‐agents the corresponding O,O‐acetales are formed.
Interpretation von Moleküldiagrammen freier π‐Radikalkationen — Naphthalen, Butadien, Styren, 1‐Methylstyren, 1,1′Diphenylethylen
Authors: Helmstreit W. , Hanschmann G.
Published: December 2004

Interpretation of the MO‐diagrams of Free π‐Radical Cations — Naphthalene, Butadiene, Styrene, 1‐Methyl‐styrene, 1,1′‐Diphenylethylene

The reactive and spectroscopic behaviour of the radical cations of the title compounds is discussed on the basis of general structural principles by means of molecular diagrams calculated with the PPP‐LHP‐SCF‐MO‐CI‐method. The greater reactivity of the monomer radicals compared with the dimers is due to the character of polymethene‐like compounds, whereas the lower reactivity of the dimer radicals cations can be ascribed to the more aromatic state of these species. The experimentally determined optical absorption maxima of the radical cations can be interpreted by the same classification.
Umsetzungen substituierter 1‐Thiochromone und 4(1H)‐Chinolone mit Nucleophilen
Authors: Rudorf W.‐D. , Augustin M.
Published: December 2004

Reactions of Substituted 1‐Thiochromones and 4(1H)‐Quinolones with Nucleophiles

1‐Thiochromone 1a and 4(1H)‐quinolone 1b react with nucleophiles to substitute the methylthio group. Compounds of type 1 are suitable C3‐fragments for the synthesis of novel heterocycles. Hydroxylamine leads to 2‐amino‐1‐thiochromone‐3‐carboxamide 7, whereas 1c gives 2‐methylthio‐1‐thiochromone‐oxime 8.
1H‐, 13C‐ und 15N‐NMR‐Untersuchungen an substituierten Thiadiazolen
Authors: Preiss A. , Walek W. , Dietzel S.
Published: December 2004

1H‐, 13C‐ and 15N‐N.M.R.‐Studies on Substituted Thiadiazoles

A number of substituted 1,2,4‐thiadiazoles, unlabelled and 15N‐labelled, were studied by 1H‐, 13C‐ and 15N‐ n.m.r. spectroscopy. The obtained n.m.r. data, especially the nitrogen‐15 chemical shifts and the 15N‐1H and 15N‐13C coupling constants allow to distinguish between isomeric forms and to determine the correct structure of each compound. So it was possible to come to conclusions about the formation mechanism of the investigated compounds.
Untersuchungen zum UV/Vis‐Spektralverhalten von Azofarbstoffen. V [16]. Quantitative Beschreibung der Absorptionsmaxima mehrfach substituierter Azobenzene mit einem Inkrementsystem
Authors: Mustroph H. , Epperlein J.
Published: December 2004

Studies on U.V./vis Absorption Spectra of Azo Dyes. V. Quantitative Prediction of the Absorption Maxima of Polysubstituted Azobenzenes with an Increment System

The effect of substituents on the long‐wave band of azobenzenes can be described by using an increment system. Absorption increments which specifically characterize the substituents are derived from the difference in excitation energy between azobenzene and monosubstituted azobenzenes. Analysis of about 350 polysubstituted azobenzenes with absorption maxima between 320 nm and 650 nm showed that the differences between observed and calculated values are generally ±5 nm.

Therefore, this increment system permits absorption maxima of azobenzenes to be deduced not as yet prepared or spectroscopically investigated.
Oxidative Kupplung CH‐acider Verbindungen mit p‐Phenylendiaminen. VII [1]. Synthese und oxidative Kupplung von 5‐Hydroxy‐naphth[2,1‐d]1,3‐oxathiol‐2‐onen
Authors: Mann G. , Wilde H. , Hauptmann S. , Naumann M. , Lepom P.
Published: December 2004

Oxidative Coupling of CH‐acid Compounds with p‐Phenylenediamines. VII. Synthesis and Oxidative Coupling of 5‐Hydroxy‐naphth[2,1‐d] 1,3‐oxathiol‐2‐ones

5‐Hydroxy‐naphth[2,1‐d]1,3‐oxathiol‐2‐ones with different substituents 1–21 were synthesized using the following procedures: Condensation of substituted naphthoquinones‐1,4 with thiourea (A); electrophilic substitution of 5‐hydroxy‐naphth[2,1‐d]1,3‐oxathiol‐2‐one (B); Fries‐reaction of 5‐acyloxy‐ and 5‐N‐phenylcarbamoyloxy‐naphth[2,1‐d]1,3‐oxathiol‐2‐ones (C). Oxidative coupling of the compounds with N,N‐diethyl‐quinone‐1,4‐diimine yielded thiazine dyes.
Cyclisierungsreaktionen β,γ‐ungesättigter Kohlensäurederivate. V . Reaktionen β,γ‐ungesättigter Carbamidsäureester mit Sulfenylchloriden ‐ Synthese von 3,5,5‐trisubstituierten Oxazolidin‐2‐onen
Authors: Mühlstädt M. , Widera R. , Olk B.
Published: December 2004

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. V. Reactions of β,γ‐Unsaturated Carbamic Acid Esters with Sulfenyl Chlorides — Synthesis of 3,5,5‐Trisubstituted Oxazolidine‐2‐ones

N,N‐Disubstituted β,γ‐Unsaturated urethanes 1 have been cyclized to 3,5,5‐trisubstituted oxazolidine‐2‐ones 3 by aromatic sulfenyl chlorides in methylene chloride. The same oxazolidine‐2‐ones 3 were obtained by reaction of 5‐bromomethyloxazolidine‐2‐ones 8 with thiophenols.
A new ester component in the stobbe condensation. I. The condensation of some aromatic aldehydes with diethyl β,β‐dimethylglutarate
Authors: El‐Newaihy M. F. , Salem M. R. , Enayat E. I. , El‐Bassiouny F. A.
Published: December 2004

Eine neue Esterkomponente in der Stobbe‐Kondensation. I. Kondensation einiger aromatischer Aldehyde mit Diethyl‐β,β‐dimethylglutarat

Kondensation von Benzaldehyd und p‐Anisaldehyd mit Diethyl‐β,β‐dimethylglutarat in Gegenwart von Natriumhydrid ergibt die kristallinen (Z)‐Halbester (1a und b) und ölige Halbesterfraktionen, die die E‐Isomeren 2a und b enthalten.

Im Falle von p‐Chlorbenzaldehyd werden die (Z)‐ und (E)‐Halbester (1c und 2c) in reiner kristalliner Form erhalten. Die Konfiguration wurde durch Cyclisierung der entsprechenden Anhydride 3 zu den Oxoindenylcarbonsäuren 5 bestimmt.
Epoxid‐Reaktionen. V. Untersuchung von Teilreaktionen der Epoxidharz‐ Vorprodukt‐bildung durch chromatographische Methoden
Authors: Fedtke M. , Tänzer W.
Published: December 2004

Epoxide Reactions. V. Chromatographic Studies of Some Reactions Involving Epoxide Formations

A reverse phase liquid chromatographic method has been applied for the quantitative determination of some products in epoxide forming reactions. The reaction of chlorohydrinethers of bisphenol A with aqueous sodium hydroxide has been studied quantitatively under different conditions.

The influence of side products originating from epichlorohydrin on the course of the main reaction is discussed.

In addition preparative liquid chromatographic methods have been developed to separate epoxide oligomers and some chlorohydrinethers of bisphenol A.
Zur heterogenkatalytischen Oxydation und Ammoxydation von Isobuten. IV. Über die Beeinflussung der heterogenkatalytischen Oxydation von Isobuten zu Methacrolein durch n‐Buten
Authors: Freiberg J. , Herrmann J. , Seeboth H.
Published: December 2004

On the Heterogeneous‐Catalytic Oxidation and Ammoxidation of Isobutene. IV. Influence of n‐Butene on the Heterogeneous‐Catalytic Oxidation of Isobutene to Methacroleine

The influence of n‐butenes 2 on the oxidation of isobutenes 1 to methacroleine 3 has been investigated in presence of a catalyst containing Bi, Mo, P, Fe, Mg, Mn, Si and O. Addition of 2 to the gas mixture increase the selectivity and yield of 3. This fact can be correlated by decrease of oxygen partial pressure in consequence of the dehydrogenation of 2 to butadiene 4.
Massenspektrometrische Fragmentierung cis/trans‐isomerer tert. Butylcycloheptanole
Authors: Herzschuh R. , Borsdorf R. , Strüber F.‐J.
Published: December 2004

Mass Spectrometric Fragmentation of cis‐trans Isomeric tert. Butylcycloheptanols

The mass spectra of six cis‐trans isomeric tert. butylcycloheptanole 1–6 are discussed The fragmentation of the tert. butylcycloheptanols is similar to that observed for the corresponding cyclohexanes. The quotient \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{[{\rm M \hbox{---} M}_{\rm 2} {\rm O}]^{+ _ \bullet}}}{{{\rm M}^{{\rm +}_ \bullet}}} $\end{document} is found to be characteristic for the different geometric isomers. But the differences observed between flexible tert. butylcycloheptanols are much smaller than those calculated for the rigid tert. butylcyclohexanols.
Solvolysis of cis‐ and trans‐2‐Phenylcyclohexyl‐p‐bromobenzene Sulphonate
Authors: Youssef Abdel‐Hamid A. , Sharaf Saber M. , El Hegazy Fatma M.
Published: December 2004

Solvolyse von cis‐ und trans‐2‐Phenylcyclohexyl‐p‐brombenzen‐sulfonaten

Die Solvolyse von cis‐ and trans‐2‐Phenyl‐cyclohexyl‐p‐brombenzensulfonaten wurde in Essigsäure, wäßrigem Dioxan und wäßrigem Ethanol untersucht und mit der des Cyclohexylsulfonatesters verglichen. In Essigsäure liegt die Geschwindigkeit des cis‐Isomeren gegenüber dem trans‐Isomeren um den Faktor 5 höher, in wäßrigem Dioxan und wäßrigem Alkohol dagegen um den Faktor 10 bzw. 12.

Produkte der Acetolyse sind hauptsächlich Eliminierungsprodukte (1‐ und 3‐Phenylcyclohexen 75%) und cis‐ und trans‐Acetate (25%). In wäßrigen Lösungsmitteln entstehen vorwiegend Eliminierungsprodukte (98%).

Die Erhöhung der Geschwindigkeit des cis‐Isomeren gegenüber der trans‐Verbindung ist auf eine sterische Beschleunigung zurückzuführen.

Ein solvatisiertes Ionenpaar wurde als Zwischenprodukt postuliert; für eine Phenylnachbargruppenwirkung ergab sich kein Hinweis.
Photochemie substituierter Cycloheptatriene. XV. Zur Charakterisierung der Elektronischen Übergänge in 1‐Aryl‐4‐(p‐dimethylaminophenyl)‐cycloheptatrienen
Authors: Abraham W. , Kupfer M. , Kreysig D.
Published: December 2004

Photochemistry of Substituted Cycloheptatrienes. XV. About the Characterization of the Electronic Transitions in 1‐Aryl‐4‐(p‐dimethylaminophenyl)‐cycloheptatrienes

The absorption spectra of the title compounds are discussed in dependence on polarity of the solvent and its ability to form hydrogen bonds. The results suggest a hybridization of the N‐atom of the dimethylamino group between sp3 and sp2 in the ground state. Contrary to this, the nitrogen has sp2‐hybridization in the short wavelength (SE) fluorescing state. In a second fluorescence state the geometry of the seven‐membered ring should change. Therefore the viscosity of the solvents influences both the position and the quantum yield of this long wavelength emission (LE). The influence of polarity and viscosity of the solvents is described by multiple regression. The temperature dependence of fluorescence quantum yields is discussed, as well.
Bestimmung der Nullfeldparameter optisch angeregter 3(π,π*)‐Zustände ausgewählter aromatischer Systeme
Authors: Stösser R. , Thurner J.‐U. , Hanke T. , Sarodnick G.
Published: December 2004

Determination of the Zero Field Parameters Optically Excited 3(π,π*)‐States in Selected Aromatic Systems

Experimental zero field parameters of optically excited naphthalene and quinoxaline derivatives are presented. The (D*), (D) and (E) parameters are determined by the position of the transitions by means of simple approximation formula, magnetophotoselection and simulation of spectra. Possibilities of comparison of the zero field parameters of optically excited 3(π,π*)‐states with parameters of ground state for simple aromatic hydrocarbones are presented.
1,2,3‐Triazabutadiene. XV. Einfluß der Substituenten auf die 15N‐ und 13C‐chemischen Verschiebungen in Triazabutadienen und Azobenzenen
Authors: Simova S. , Radeglia R. , Fanghänel E.
Published: December 2004

1,2,3‐Triazabutadienes. XV. Substituent Effects on the Nitrogen‐15 and the Carbon‐13 Chemical Shifts of Triazabutadienes and Azobenzenes

Nitrogen‐15 and carbon‐13 chemical shifts are reported for 15N‐enriched p‐substituted triazenes 1, triazenium salts 2 and azobenzenes 3. Linear correlations between substituent induced shifts for various 15N‐ and 13C‐atoms and σ‐Hammett constants was found and discussed. The sensitivity of the chemical shifts of both nuclei to substituent effects in analogously constituted compounds are compared.
The aminolysis of carbamates. I. The Kinetics of the Aminolysis of Benzyl N‐phenylcarbamate with Ethanolamine
Authors: Löcsei Vasile , Facsko Otilia , Chirila Traian
Published: December 2004

Aminolyse von Urethanen. I. Kinetik der Aminolyse des Benzyl‐N‐phenylurethans mit Monoethanolamin

Die Kinetik der Aminolyse des Benzyl‐N‐phenylurethans im Bereich von 135 bis 165°C in Gegenwart eines Überschusses an Monoethanolamin mit und ohne Lösungsmittel (Benzylalkohol) konnte als Folgereaktion erster Ordnung erfaßt werden:

.

Die Abhängigkeit der Geschwindigkeitskonstante k1 von der Monoethanolaminkonzentration weist auf eine Reaktion 2. Ordnung hin, und es wurde eine lineare Abhängigkeit der relativen Reaktivität R = k1/k2 von der Konzentration festgestellt. Der Einfluß der Temperatur auf R und die Aktivierungsenergien der beiden Reaktionsschritte wurden ermittelt.

Die Analyse der Reaktanten und Zwischenprodukte erfolgte mit Hilfe der Hochdruckflüssigkeitschromatographie.

Mögliche Mechanismen werden besprochen.
Untersuchungen zur Verseifung aromatischer Sulfochloride
Authors: Beck H. , Doerffel K.
Published: December 2004

Studies on the Hydrolysis of Aromatic Sulfochlorides

The hydrolysis of aromatic sulfochlorides can bei described by a second‐order law. Due to the strength of the base the constants of velocity are between 10−6 (H2O) or 103 (OH−) 1 mol −1 s−1 respectively. The reaction of benzensulfochlorides proceeds according to an addition‐elimination mechanism, whereas benzylic sulfochlorides, reacting with a strong base, proceed to an elimination‐addition mechanism.
Vinyloge Acylverbindungen. XX. Reaktivität und Toxizität arylsubstituierter β‐Chlorvinylketone, β‐Chlorvinylaldehyde und β‐Chlorvinylmethyleniminiumsalze
Authors: Fischer Gerhard W. , Jentzsch Renate , Riemer Fritz
Published: December 2004

Vinylogous Acyl Compounds. XX. Reactivity and Toxicity of Aryl‐substituted β‐Chlorovinyl Ketones, β‐Chlorovinyl Aldehydes, and β‐Chlorovinyl Methyleniminium Salts

Based on kinetic measurements, the nucleophilic replaceability of the chlorine in aromatic β‐chlorovinyl ketones ArCO‐CH  CH‐Cl (1), isomeric β‐chlorovinyl aldehydes OCHCHC(Cl)Ar(2), and corresponding β‐chlorovinyl methyleniminium salts Me2N⊕;CHCHC(Cl)Ar X⊖ (3) is compared and related to toxicological findings. The chemical reactivity of these important synthetic building blocks increases in the order 2<1<3, the acute toxicity (24 h LD50 i. p. in the mouse) shows the graduation 2<3<1. Compounds of type 1 prove to be relatively toxic (LD50 24–42 mg/kg) and display a marked necrotic action after percutaneous absorption, whereas the aldehydes 2 have not only a minor acute toxicity (LD50 158–298 mg/kg) but also a somewhat less marked skin damaging activity. In addition, the LD50 values of selected β‐chlorovinyl carbonyl compounds are compared with those of corresponding halogen‐free compounds as well as of vinylogous carbonamidium salts ArCOCHCHN⊕R3X⊖. The latter, which can be used as synthetic equivalents of 1, differ in both the reduced acute toxicity and missing skin damaging properties.
Azomethinimine. VI. Zum thermischen Verhalten des Photochromiesystems Azomethinimin/Diaziridin, untersucht an Pyrazolidon‐(3)‐azomethiniminen und deren Photoprodukten
Authors: Geissler G. , Menz I. , Angermüller K. , Tomaschewski G.
Published: December 2004

Azomethineimine. VI. On the Thermic Behaviour of the Photochromic System Azomethineimine/Diaziridine, Investigated by Means of the Photoproducts of Pyrazolidone‐(3)‐Azomethineimines

The photochemically obtained cycloproducts 2 of pyrazolidone‐(3)‐azomethineimines 1 react thermically to 1 in aprotic solvents. This backreaction was investigated by following up the growth of the intensive long wave absorptionband of 1. The kinetic analysis was carried out according to SWINBOURNE [5, 6]. The thermic backreaction is accelerated by factors favouring a polarization of the CN(2)‐bond (Cδ+  Nδ−) of diaziridine 2. Such factors are polar solvents, donors in the substituent R and extensive, easily polarizable π‐electronic systems in R. The influence of substituents on the backreaction can be correlated by means of the σ+‐Hammett‐constants. For most compounds the values of EA ≈ ΔH≠, Δ≠ and ΔG≠ were determined. The possible reaction mechanism is discussed. The influence of steric factors on the thermic backreaction is regarded as a first indication of an exo‐form of the bicyclic diaziridines 2.
Azomethinimine. VII. Photochemisches und thermisches Verhalten azarylsubstituierter Pyrazolidon‐(3)‐azomethinimine
Authors: Geissler G. , Fust W. , Krüger B. , Tomaschewski G.
Published: December 2004

Azomethineimines. VII. Photochemical and Thermic Behaviour of Azarylsubstituted Pyrazolidone‐(3)‐Azomethineimines

In principle the photochemical behaviour of azarylsubstituted pyrazolidone‐(3)‐azomethineimines 1 does not differ from other pyrazolidone‐(3)‐azomethineimines. Except for the acridyl‐(9)‐substituted compound in aprotic solvents they react to bicyclic diaziridines 2. The quantum yield of this reaction has a value of nearly 0.3. For two of the diaziridines 2 the photochemical backreaction was realized. Results of the investigation of the thermic backreaction show the expected stability of the bicyclic diaziridines 2a–d. All the investigated compounds have a pronounced tendency towards several irreversible side reactions.
Eine einfache Methode zur quantitativen Bestimmung von Silanolgruppen
Authors: Welsch T. , Frank H.
Published: December 2004

A Simple Method for Quantitative Determination of Silanol Groups

Die Bestimmung der Konzentration von Hydroxylgruppen auf Kieselgeloberflächen ist von großem analytischen Interesse, da diese die chromatografischen oder katalytischen Eigenschaften des Kieselgelmaterials maßgeblich beeinflussen. Dazu wurden bisher sowohl spektroskopische als auch chemische Bestimmungsmethoden angewendet [1–7], die uns jedoch aufgrund des apparativen Aufwandes bzw. der benötigten Zeit für Routineuntersuchungen als ungeeignet erschienen. Die von GALLEI [3]vorgeschlagene, gut reproduzierbare aber apparativ anspruchsvolle Variante der chemischen Umsetzung der Silanolgruppen mit Lithiummethyl und anschließender gaschromatografischer Bestimmung des gebildeten Methans wurde von uns wesentlich vereinfacht, wobei die Bestimmung der gebildeten Methanmenge volumetrisch erfolgte.
α‐Substituierte Phosphonate. 43. Synthese und Reaktivität von 1,2,3,4‐Tetrahydroisochinolin‐1‐phosphonaten
Authors: Gross H. , Ozegowski S.
Published: December 2004

α‐Substituted Phosphonates. 43. Synthesis and Reactivity of 1,2,3,4‐Tetrahydroisochinolin‐1‐phosphonates

N‐Alkyl‐ and N‐arylsubstituted 1,2,3,4‐tetrahydroisochinolin‐1‐phosphonates 1 have been synthesized from the corresponding 3,4‐dihydroisochinoliniumbromides 7 and triethyl‐phosphite. The N‐unsubstituted 1,2,3,4‐tetrahydroisochinolin‐1‐phosphonate 10 is available starting from the 1,2,3,4‐tetrahydroisochinolin‐1‐phosphonic acid by esterification with triethylformate and splitting off the formyl group of the primarily formed N‐formyl derivative 14. – N‐Quarternated tetrahydroisochinolines 19 and the 1‐phosphorylated derivatives 17, respectively react with triethyl‐phosphite in an unexpected way by dealkylation and not by splitting off the isochinolinring. – By Horner‐synthesis with 1 the 1‐aralkylidene‐isochinolines 23 are available in moderate yields.
Prostaglandine und Prostaglandinvorstufen. VIII. Synthese von (1S, 5S)‐5‐Methyl‐2‐oxa‐bicyclo[3.3.0]octan‐3,6‐dion, einem wichtigen Zwischenprodukt für 8‐Methyl‐prostaglandin C2
Authors: Schick H. , Welzel H.‐P. , Schwarz S.
Published: December 2004

Prostaglandins and Prostaglandin Intermediates. VIII. Synthesis of (1S, 5S)‐5‐Methyl‐2‐oxa‐bicyclo[3.3.0]octane‐3,6‐dione, an Important Intermediate for 8‐Methylprostaglandin C2

The bicyclic lactone 5 is prepared by Meerwein‐Ponndorf‐Verley‐reduction of the chiral cyclopentyl acetic acid 3. The stereoselectivity of this reaction is compared with that of complex metal hydride reductions.
Elektrochemische Oxidation organischer Verbindungen in Fluorsulfonsäure. VI. Voltammetrische Untersuchungen zur Oxidierbarkeit heterocyclischer Kationen
Authors: Rudenko A. P. , Pragst F.
Published: December 2004

Electrochemical Oxidation of Organic Compounds in Fluorosulfuric Acid. VI. Voltammetric Investigation about the Oxidability of Heterocyclic Cations

The anodic behavior of a series of pyridinium, quinolinium, isoquinolinium, pyrylium, tropylium, pyrazolium and imidazolium cations and of some of their benzoderivatives was investigated by cyclic voltammetry in HSO3F at −76°C. Because of the available very positive potential region under these conditions almost all cations were oxidized, and in many cases relatively stable dication radicals could be detected. The oxidation potential decreases with decreasing acceptor ability of the heterocyclic ring, increasing extension of the π‐electron system and increasing donor effects of substituents. There was no significant difference between the curves obtained from the N‐alkylated and the corresponding N‐protonated heterocyclic compounds, which showed that the oxidation is not coupled with the N‐deprotonation. The voltammograms of phenylsubstituted pyrylium and pyrazolium ions as well as of benzimidazolium ions display typical marks of the anodic aromatic dimerization, which hitherto seemed to have been restricted to donor substituted benzenes and π‐excess heterocycles.