bluuebunny/crossref_metadata_2025 huggingface dataset:
Das biologische Verhalten von Fettsäuren mit Dreifachbindung II: Behenolsäure
Authors: Bernahard K. , Yekundi K. , Greub H. R.
Published: December 2004

Behenolic acid fed to rats as a triglyceride is incorporated into depot fat but not into liver lipids. From urine the same metabolite as after feeding of stearolic acid, i. e. 5‐decyne‐dicarboxylic acid, was isolated.
Alkaloide aus vinca herbacea W.K. VIII. Mitteilung Isolierung und struktur von Hervin
Authors: Ognyanov I. , Pyuskyulev B. , Bozjanov B. , Hesse M.
Published: December 2004

Aus Vinca herbacea W. K. WURDE ein neues Alkaloid, Hervin, isoliert, für das im wesentlichen auf Grund spektroskopischer Befunde die Struktur 1 abgeleitet wurde.
Magnetische Kernresonanz‐ und «Molecular Orbital»‐ untersuchungen über die struktur von MEISENHEIMER‐komplexen 8. Mitteilung über nucleophile aromatische Substitutionsreaktionen [1]
Authors: Caveng P. , Fischer P. B. , Heilbronner E. , Miller A. L. , Zollinger H.
Published: December 2004

(1) The NMR. spectra of the stable methoxide addition complexes of 2,4‐dinitro‐, 2,4,6‐trinitro‐ and 2,4‐dinitro‐6‐cyano‐anisole, and the intramolecular (spiro) reaction product of 1‐(2′‐hydroxyethoxy)‐2,4,6‐trinitrobenzene demonstrate that these products are MEISENHEIMER (σ−) complexes (addition of base in position 1).
Kupferkomplexe von Bisamiden: Struktur und Stabilität I
Authors: Zuberbühler A. , Fallab S.
Published: December 2004

Complex formation between Cu2+ and several ligands, each containing two amino and two amide groups, has been studied potentiometrically and spectrophotometrically. A digital computer was used to determine the composition of the complex species formed and to calculate their stability constants. N,N′‐diglycyl‐1, 2‐diaminoethane and its homologues form 5‐, 6‐, 7‐, 8‐ and 9‐membered rings between the two amide groups, respectively. No tendency towards formation of binuclear species has been observed.
Recherches sur la formation et la transformation des esters LXXIII Sur la préparation d'acides ω‐[aryl (ou aralcoyl ou alcoyl) carbamylamino]‐alcoylphosphoriques et sur leur vitesse de scission à divers pH
Authors: Cherbuliez Emile , Behler B. R. , Espejo O. , Frankenfeld E. , Jaccard S. , Rabinowitz J.
Published: December 2004

N‐Aryl(or aralkyl or alkyl)carbamoyl‐aminoalkyl phosphoric monoesters have been prepared by the reaction of isocyanates R′‐NCO on the corresponding amino‐alkylphosphoric monoesters H2NROPO3H2 in the presence of 2 equivalents of NaOH. The rates of scission of the phosphoric monoester group and occasionally of the phenylcarbamoylamino group of these monoesters have been studied at 100°, in solutions 0.1M in ester and at various pH.
Fonte zonale et analyse de pureté dans les iodures alcalins
Authors: Ecklin Daniel
Published: December 2004

Die Alkalijodide KI, RbI und CsI wurden durch Zonenschmelzverfahren bis zu einem Gesamtrestgehalt an zweiwertigen Ionen von höchstens 1 ppm gereinigt. Die Kristalle wurden dann auch mit Mg++, Ca++, Sr++, Eu++ oder Mn++ genau dotiert.
Gas‐chromatographische und massenspektrometrische Untersuchung der Trimethylsilyläther von Vitamin A und einigen seiner Isomeren
Authors: Vecchi M. , Vetter W. , Walther W. , Jermstad S. F. , Schutt G. W.
Published: December 2004

Vitamin A and some of its isomers are separated and quantitatively determined as trimethylsilylethers by gas liquid chromatography. The identity of the different fractions is proved by mass spectrometry.
Darstellung und strukturelle Eigenschaften von Ni(CN)2, 2H2O und Ni(CN)2, 11/2 H2O
Authors: Ludi A. , Hügi R.
Published: December 2004

Ni(CN)2,2H2O is prepared as a powder of a very light violet color by slow addition of very dilute sulfuric acid to a boiling aqueous solution of K2[Ni(CN)4], H2O. It has a cubic unit cell with a cell edge of 10.10 Å. The nickel ions form a cubic face‐centered lattice analogous to the structure of Prussian Blue.
Über die Chemie des Vitamins E. 8. Mitteilung [1]. Die Stereochemie von natürlichem γ‐Tocotrienol (Plastochromanol‐3), Plastochromanol‐8 und Plastochromanol‐8
Authors: Mayer H. , Metzger J. , Isler O.
Published: December 2004

The stereochemistry of γ‐tocotrienol (plastochromanol‐3) from latex of Hevea brasiliensis (rubber tree), plastochromanol‐8 from leaves of Hevea brasiliensis, and plastochromenol‐8 from tobacco is reported.
Die Bestimmung von Nanogramm‐Mengen Quecksilber aus Lösungen durch ein flammenloses atomares Absorptionsverfahren
Authors: Brandenberger H. , Bader H.
Published: December 2004

A flameless atomic absorption method for the determination of small amounts of mercury in solutions is described. The mercury is amalgamated quantitatively on a copper wire and subsequently vaporized in an absorption cell which is placed in the light path of a commercial atomic absorption instrument. The mercury vapor can be quantitatively determined by its absorption of the 253.7 nm mercury line. The method has a detection limit of 0.2 ng and is therefore about 10000 times more sensitive than atomic absorption analysis using flame atomization.
Synthèses dans la série des bis‐indéno‐fluorénes III [1]. Dihydro‐14, 15‐13H‐bis‐indéno[2,1‐a;1′,2′,‐i]fluorène et dihydro‐14, 15‐8H‐bis‐indéno [2, 1‐a;2′,1′‐h]fluorène
Authors: Hammer Wolfgag , Chardonnens Louis
Published: December 2004

Starting from 2‐bromo‐9‐oxo‐fluorene‐1‐carboxylic acid the biangular bis‐indenofluorene 14, 15‐dihydro‐13H‐diindeno[2, 1‐a; 1′, 2′‐1]fluorene (VIII) and the monoangular 14, 15‐dihydro‐8H‐diindeno[2, 1‐a; 2′, 1′‐h]fluorene (XI) have been synthesised in 6 resp. 7 steps (overall yield 22% resp. 18%). As intermediate compounds the 14‐oxoderivatives of VIII and XI were also obtained.
Sur la composition de l'arôme de thé noir II
Authors: Bricout J. , Viani R. , Müggler‐Chavan F. , Marion J. P. , Rwymond D. , Egli R. H.
Published: December 2004

Trans‐2‐penten‐1‐ol, 1‐ethyl‐2‐formyl‐pyrrole, 2‐trans, 4‐cis‐heptadienal, phenyl‐acetonitrile, methyl benzoate, 2‐phenyl‐but‐2‐enal and the lactone of 2,6,6‐trimethyl‐2‐hydroxy‐cyclohexylidene acetic acid have been separated from black tea aroma by gas‐liquid chromatography, and identified by infra‐red and mass spectrometry.
11‐Amino‐5H‐dibenzo[b, e]‐1, 4‐diazepine. 10. Mitteilung über siebengliedrige Heterocyclen
Authors: Hunziker F. , Fischer E. , Schmutz J.
Published: December 2004

11‐Amino‐5H‐dibenzo[b,e]‐1, 4‐diazepines V, several of which possess neuroleptic properties, have been prepared using three methods:

Aminolysis of either iminothioethers IV (X = methyl or an activating group such as cyanomethyl and p‐nitrobenzyl) or the iminochlorides III.

Bischler‐Napieralski type cyclodehydration of o‐anilinophenyl‐ureas IX (only applicable for the synthesis of compounds V where R is other than hydrogen).

Cyclodehydration of amino‐amides VII by various condensing agents.
Konformation und Circulardichroismus der Sesquiterpene vom Trichothecan‐Typ und deren makrocyclischen Estern
Authors: Snatzke G. , Tamm C. H.
Published: December 2004

The circular dichroism of keto derivatives with trichothecane skeleton and some of their rearrangement products has been measured. The sign (and sometimes even the magnitude) of all COTTON effects can be explained by applying the respective rules for the cyclohexanone, cyclopentanone, enone and ene‐ester chromophores. Thus conformations could also be determined in those cases which did not follow unambiguously from conformational analysis. The conformation of the muconic acid moiety of the macrocyclic ring of verrucarin A is the same in dioxane solution as in the crystalline state.
Darstellung und Charakterisierung einige Thiocyanat‐ und Selenocyanat‐Komplexe von Übergangsmetallen
Authors: Schmidtke Hans‐Herbert , Garthoff Dieter
Published: December 2004

Some 6:1 thiocyanate complexes of FeIII, MoIII, RuIII, OsIII, IrIII and some 6:1 or 4:1 selenocyanate complexes of FeII, FeIII, MoIII, RhIII, PdII, PtII, and AuIII have been prepared as salts of large organic cations. The compounds are characterized by their infra‐red spectra and by conductance measurements. In particular the linkage property of the thiocyanate and selenocyanate ligand is discussed together with the consequences it has on the AHRLAND‐CHATT‐DAVIES‐PEARSON classification of the central ions.
Organische Phosphorverbindungen XXVIII. Die α‐Aminoalkylierung von elementarem weissem Phosphor. Eine einfache Methode zur Darstellung von tertiären Phosphinoxiden, Phosphinsäuren und Phosphonsäuren [1]
Authors: Maier Ludwig
Published: December 2004

White phosphorus reacts with N‐hydroxymethyl‐dialkylamines to give mainly three products, i.e., tris(dialkylaminomethyl) phosphine oxides, bis(dialkylamino‐methyl) phosphinic acids, and dialkylaminomethyl phosphonic acids, according to the equation:

The yield of the various products depends mainly upon the ratio of the reactants, the pH, and the solvents used.
Pyrazines. 1re communication. I. Synthèse de méthyl‐2‐pyrazines alcoylées en 3, par condensation de l'éthylènediamine avec les dioxo‐2,3‐alcanes
Authors: Flament I. , Stoll M.
Published: December 2004

The synthesis of eight 2‐methyl 3‐alkyl pyrazines by catalytic dehydrogenation of condensation products of ethylenediamine with 2,3‐diketoalkanes is described.
Synthese funktionell abgewandelter Flavocoenzyme: 3‐Alkyl‐ und 2‐Alkylimino‐flavin‐mononucleotide und ‐flavin‐adenin‐dinucleotide. Studien in der Flavinreihe, 14. Mitteilung
Authors: Föry W. , Hemmerich P.
Published: December 2004

Functional derivatives of flavo‐coenzymes, altered in position 2 or 3, have been synthesized in order to check the coenzyme specificity of flavo‐apoproteins. Phosphorylation and phosphate separation methods have been adapted to the synthesis of 2‐imino‐,2‐thio‐ and 3‐alkyl‐flavin mono‐ and di‐nucleotides.
Über die strukturellen Probleme des Di‐cyclopentadienyl‐titans
Authors: Salzmann J.‐J. , Mosimann P.
Published: December 2004

On the basis of spectral and chemical evidence it is shown that bis(cyclopentadienyl)titanium is not a sandwich‐π‐type compound. The most probable structure in solution is that of a dimer containing metal‐metal bond and π‐and σ‐bonded cyclopentadienyl rings.
Über die Ringspannung in pentacyclischen Azofarbstoff‐Chrom(III)‐Komplexen
Authors: Schetty G.
Published: December 2004

In pentacyclic chromium‐azo dyestuff complexes in which two azo dyestuffs in a vertical position to each other are so linked that a metal‐containing hetero ring
magnified image
is formed, the number of members of this hetero ring was systematically increased. The alterations occurring in the electron spectra express the change in the position of the two azo dyestuff residues or the change in tension occurring in the hetero ring. When the number of ring atoms is sufficiently large, which in this series of compounds was 15 (n = 10), the electron spectrum is identical with that of the «open» form, i.e. with that of the corresponding 1:2 complex devoid of this particular ring. The position of the two azo dyestuff residues, therefore, must be identical in both complexes, and this is only possible when the adjoining ring is completely free from tension. The phenomenon of ring tension can, therefore, be visibly followed in these examples.
Die Koordinationstendenz des Murexid‐Ions
Authors: Geier G.
Published: December 2004

The stability constants of the murexide complexes with various metal ions were determined spectrophotometrically. The coordination tendencies of the tridentate ligands iminodiacetate, dipicolinate and murexide are compared. In terms of basicity and charge, the murexide complexes exhibit a stability which is remarkably high and most of all pronounced with A‐metal ions. The possible reason for this fact is discussed.
ψ‐Bufarenogin, ein neues Bufadienolid aus Ch'an Su und Umlagerungsprodukt des Arenobufagins sowie Bemerkung zur Konfiguration des Bufarenogins. Über Krötengifte 32. Mitteilung
Authors: Huber Kurt , Linde Horst , Meyer Kuno
Published: December 2004

Aus der chinesischen Krötengiftdroge Ch'an Su konnte ein bisher unbekanntes Bufogenin isoliert werden, das sich bei den chromatographischen Auftrennverfahren wie Bufarenogin verhält, weshalb wir es ψ‐Bufarenogin 5 nennen. −5 und Arenobufogin (3) gehen bei der vorsichtigen Dehydrierung in dasselbe 3,11,12‐Trioxobufadienolid über, unterscheiden sich somit lediglich in ihrer Ketolstruktur an C‐11/C‐12. Der aus der Acetylverbindung von 5 durch Abbau erhaltene Ätiansäure‐methylester 17 war mit den vier möglichen, bereits bekannten C‐11/C‐12‐Acetoxy‐ketonen der Ätiansäure‐Reihe nicht identisch. Auf Grund chemischer und vor allem spektroskopischer Befunde dürfte der aus 5 erhaltene Abbauester 17βH‐Konfiguration besitzen, die sich im Laufe des Abbaus durch Umlagerung ausgebildet hat. ψhyphen;Bufarenogin ist 3β, 12α,14‐Trihydroxy‐11‐oxo‐5β‐bufa‐20,22‐dienolid entsprechend Formel 5. Bufarenogin besitzt 12β‐Hydroxy‐11‐oxo‐Struktur; die Stereochemie an C‐17 ist noch nicht abgeklärt.
Zur Kenntnis der Benzylpenicilloinsäure
Authors: Schneider C. H. , De Weck A. L.
Published: December 2004

The molar penamaldate value of benzylpenicilloic acid and the influence of large amounts of benzylpenicillin on the estimation of penamaldate values and penamaldate stabilities of benzylpenicilloic acid and ε‐(benzylpenicilloyl‐α‐amido)‐caproic acid have been determined. The molar penamaldate values of purified benzylpenicilloate and of benzylpenicillin hydrolyzed in alkali were equal, indicating that benzylpenicillin upon alkaline hydrolysis is converted to penicilloic acid exclusively, with no side reactions occurring to any considerable degree. Benzylpenicilloate mutarotates in neutral solution as well as in alkali, the reaction being unaffected by metal ion complexing with ethylene diamine tetraacetate. ε‐(Benzylpenicilloyl‐α‐amido)‐caproate also mutarotates in alkali; no mutarotation occurs however in neutral solution. Different mechanisms of epimerisation have therefore to be considered for the mutarotations of penicilloates and of α‐amides of penicilloic acid respectively.
Löslichkeitsprodukte von Metalloxiden und ‐hydroxiden. 11. Mitteilung [1]. Die Löslichkeit von α‐GaO(OH) bei 60°C in perchlorsauren Lösungen konstanter Ionenstärke
Authors: Gamsjäger H. , Schindler P.
Published: December 2004

The solubility equilibrium of α‐GaO(OH) has been investigated at 60°C in solutions of perchloric acid having a constant ionic strength I = 3 m (Na, H)ClO4. The hydrogen ion concentration of the equilibrated solutions was measured with a glass electrode and the concentration of the dissolved GaIII was determined by chelometric titration. The experimental data can be explained by assuming the equilibrium

.
Trypsinhemmstoffe aus Ascaris lumbricoides var. suum I. Herstellung von reinen Trypsininhibitoren
Authors: Portmann P. , Fraefel W.
Published: December 2004

The purification of a trypsin inhibitor from Ascaris lumbricoides var. suum is described. The electrophoretically pure preparation which inhibits trypsin in a specific manner is a relatively small peptide containing 5 Asp, 4 Thr, 1 Ser, 11 Glu, 6 Pro, 6 Gly, 5 Ala, 2 Val, 10 (Cys)1/2, 3 Ile, 2 Phe, 7 Lys, 3 Arg and 1 Try.
Versuche zur Strukturermittlung der Cardenolide F, H, I, T und U aus Glossostelma carsoni (N. E. BR.) BULLOCK. Glykoside und Aglykone 298. Mitteilung
Authors: Reichstein P. , Stöcklin W. , Reichstein T.
Published: December 2004

Physical data and a few chemical reactions have been used to try to elucidate some of the structural features of a few cardenolides which are present in small quantities in the roots of Glossostelma carsoni (N.E. BR.) BULLOCK. The glycoside F is probably a derivative of xysmalogenin‐β‐D‐sarmentoside, whereas fermentative degradation of glycoside U yielded the genin H which was identified through paper chromatography. The genins H, I and T are possibly O‐acetyl‐cardenolides which, however, do not correspond to any known compounds.
Über den pentacylischen Chrom (III)‐Komplex aus 1,6‐Di‐(2‐amino‐benzolsulfonamido)‐hexan ⇉β‐Naphtol
Authors: Schetty G.
Published: December 2004

A five‐ or six‐membered ring in pentacyclic azo‐dyestuff‐chromium complexes with the sandwich arrangement, having sulphonamido groups as complex formers, was extended into a nine‐membered ring. This altered not only the electron spectrum but also the stability of the complex. Whilst the five‐ and six‐membered pentacycles are very stable, the corresponding nine‐membered ring complex is considerably less stable. Its stability approaches that of the corresponding 1:2‐Cr complexes which, because of deformed valency angles, are very strained and, therefore, are also very unstable. This tension is counteracted in pentacycles having a lower number of members (5 and 6), and so the system is stabilised. If the number of ring members is increased, this counteraction is reduced and, therefore, the stabilising effect is lessened.
Photoisomerisierung von Pyrazolen und Indazolen zu Imidazolen bzw. Benzimidazolen und 2‐Amino‐benzonitrilen
Authors: Tiefenthaler H. , Dörscheln W. , Göth H. , Schmid H.
Published: December 2004

It is shown that pyrazoles and indazoles undergo photochemical bond‐switching.
6‐Desoxy‐L‐idose, 6‐Desoxy‐L‐sorbose und 6‐Desoxy‐L‐psicose. Desoxyzucker, 41. Mittelung [1]
Authors: Kaufmann Heinz , Reischstein T.
Published: December 2004

Although crystalline 6‐deoxy‐L‐idose (2) and crystalline 6‐deoxy‐L‐sorbose (3) have similar melting points and specific rotations, they can be conclusively differentiated from one another through paper chromatography and paper electrophoresis. 6‐Deoxy‐L‐idose cannot be converted into 6‐deoxy‐L‐sorbose on short heating in very dilute aequeous mineral acids. The synthesis of amorphous 6‐deoxy‐L‐psicose (17), through oxidative fermentation of 6‐deoxy‐L‐allitol with Acetobacter suboxydans, has been described.
Steroide und Sexualhormone 233. Mitteilung [1]. Synthese von 4 stereoisomeren 1, 4‐Oxido‐3‐oxa‐A‐homo‐androstan‐Derivaten
Authors: Eggart Fr L. G. , Wehrli H.
Published: December 2004

A synthesis of the four stereoisomeric 1,4‐oxido‐3‐oxa‐A‐homo‐androstane‐derivatives 3, 9, 13, and 19 is described, starting from the lactones 1, 11, and 15.
Photochemische Reaktionen 42. Mitteilung [1]. Photoisomerisierung von α, β‐Epoxyketonen II Der sterische Verlauf der Umlagerung von 3‐Oxo‐4, 5‐oxido‐Steroiden
Authors: Wehrli H. , Lehmann C. , Iizuka T. , Schaffner K. , Jeger O.
Published: December 2004

The photorearrangement previously described [3] of saturated and Δ1‐unsaturated 3‐oxo‐4,5‐epoxy‐10β‐steroids to 3,5‐dioxo‐10(5 →4)‐abeo compounds proceeds most likely via a radical 1,2‐alkyl shift (Chart 1). The similar rearrangements of the related 10α‐epoxyketone 10 and the 4‐methyl‐epoxyketones 13, 15, 16, 20 and 21 to the corresponding 3,5‐diketones occurred without epimerization at the migrating carbon atom (C‐10) and the site of substitution (C‐4) (Chart 3). The stereochemical control of the rearrangement is in agreement with the earlier proposed mechanism of a concerted alkyl radical shift in these alicyclic systems.
Synthese der Dl‐Form eines natürlichen Prostaglandins. Vorläufige Mitteilung
Authors: Hardegger E. , Schenk H. P. , Broger E.
Published: December 2004

Ausgehend vom bekannten, leicht zugänglichen Cyclopentenon‐Derivat I wird ein präparativ gangbarer Weg skizziert, der zur Racemform des natürlichen Prostaglandins E1‐278 und zu rac‐Prostaglandin E1‐237 führt.
Spektroskopische Eigenschaften alkylsubstituierter Diazulyle (Die photochemische Darstellung des 3,3′ und des 2,2′ ‐Di‐guaj‐azulyls)
Authors: Hagen R. , Heilbronner E. , Straub P. A.
Published: December 2004

Irradiation with light of 366 nm wave‐length of guay‐azulene‐2‐sulfonic acid (IV) or of guay‐azulene‐3‐sulfonic acid (I) dissolved in concentrated sulfuric acid yields 2,2′‐di‐guayazulyl (VI) or 3,3′‐di‐guay‐azulyl (III) respectively. The nmr and electronic spectra of III and VI and of their conjugate acids are recorded. The essential features of the electronic spectra of III and VI can be understood in terms of a model based on SIMPSON'S «independent system approach».
Über primäre Disazofarbstoffe mit Aminonaphtol‐sulfonsäuren
Authors: Schneider L.
Published: December 2004

Disazo dyes from 6‐amino‐1‐hydroxy‐naphthalene‐3‐sulfonic acid (J acid) were synthesized by coupling ortho‐hydroxy monoazo dyes with different diazonium compounds in acid medium (dyes No 3–14. A second coupling to the ortho position of the amino group was also possible with the copper complexes of o,o' ‐dihydroxy monoazo dyes from 8‐amino‐1‐hydroxynaphthalene‐3,6‐disulfonic acid (H acid) dyes No 19–22). This is a reversal of the well known rule that the formation of disazo dyes with aminonaphthol‐sulfonic acids is only practicable when an acid coupling is followed by an alkaline one. 5‐Amino‐1‐hydroxy‐naphthalene‐3‐sulfonic acid (M acid), which is said to form no disazo dyes, could be coupled twice with several diazonium compounds to yield disazo dyes (dyes No 24, 26, 27, 29).
Drevogenin A und Drevogenin B, zusätzlicher Strukturbeweis. Glykoside und Aglykone, 306. Mitteilung
Authors: Bhatnagar Ajay S. , Stöcklin W. , Reichstein T.
Published: December 2004

Drevogenin B is shown to be 11‐O‐acetyl‐drevogenin P. The earlier derived structure for drevogenin A (11‐O‐acetyl‐drevogenin P) is further confirmed by conversion of 3‐O‐acetyl‐drevogenin A.
Cycloaddition von N‐Phenylmaleinimid an (1,2,3,6‐Tetrahydropyridyl)‐indole
Authors: Beck D. , Schenker K.
Published: December 2004

1‐Methyl‐2‐and 1‐methyl‐3‐(1‐methyl‐1,2,3,6‐tetrahydro‐4‐pyridyl)‐indole undergo 1,4‐cycloaddition (formally of the DIELS‐ALDER‐type) with N‐phenyl‐maleimide, leading to the pentacyclic compounds III and IV.
Die Fraktionierung von Serumproteinen mit flüssigen Phasenpaaren. 3. Mitteilung [1] Eine Zentrifuge für Gegenstromverteilung
Authors: Tavel P. V. , Bolliger W.
Published: December 2004

Eine Zentrifuge zur schrittweisen Gegenstromverteilung ist gebaut worden, mit welcher die Phasentrennung nach jedem Verteilungsschritt beschleunigt werden kann. Sie eignet sich für multiplikative Verteilungen mit nahezu kritischen Phasenpaaren und andern Systemen, deren Phasen sich nur langsam trennen. Die Zentrifuge enthält 40 Verteilelemente zu 27 ml und arbeitet voll automatisch auch im Kaltraum. Sie ermöglicht 3 Arbeitsweisen: Schrittweiser Transport der spezifisch leichteren order der schwereren Phase, oder alternierender Transport beider Phasen im Gegenstrom. Ihre Trennschärfe ist geringer als die eines CRAIG'schen Apparates, da sich die überführten Phasenvolumina jeweils in die nächsten Elemente verdrängen. Versuche mit einer Komponente zeigen, dass die Verteilungen den berechneten Werten nahezu entsprechen, wenn pro Verteilungsschritt weniger als ¾ des Volumens an mobiler Phase in einem Element verschoben werden. Die Trennschärfe eines CRAIG'schen Apparates wird mit der Zentrifuge erst nach einer höheren Schrittzahl erreicht.

Polyäthylenglykol von M̄w 30000 wurde in Fraktionen verschiedener Viskosität, d. h. verschiedenen mittleren Molekulargewichts, zerlegt. Ein als einheitlich angesehenes Human‐Serumalbumin zeigte eine kleine Nebenkomponente, die auch elektrophoretisch nachzuweisen war.
Synthese und Eigenschaften von 2‐(α‐Hydroxyalkyl)‐und 2‐(α‐alkoxycarbonyl)‐substituierten 4‐Methyl‐5‐(β‐hydroxyäthyl)‐thiazolen und ‐thiazoliumsalzen
Authors: Kiss J. , D'Souza R. , Spiegelberg H.
Published: December 2004

Condensation of the tetrahydropyranyl ether of the α‐hydroxyalkyl‐thioamides with 3‐bromo‐4‐hydroxy‐2‐pentanones yields DL‐2‐(α‐hydroxyalkyl)‐4‐methyl‐5‐(β‐hydroxyethyl)‐thiazoles. By oxidation with chromic anhydride 2‐hydroxymethyl‐4‐methyl‐5‐(β‐acetoxyethyl)‐thiazole yields the corresponding 2‐formyl derivative. The latter compound reacted with GRIGNARD complexes gives the homologous DL‐2‐(α‐hydroxyalkyl)‐4‐methyl‐5‐(β‐hydroxyethyl)‐thiazoles. This is a general method for the synthesis of the thiazole part of the «active aldehydes».

2‐Acetyl‐4‐methyl‐5‐(β‐hydroxyethyl)‐thiazole is also obtained by chromic oxidation of the suitable methylthiazol‐2‐yl‐carbinol.

The condensation of the thioamides obtained from the α‐ethoxycarbonyl‐nitriles with 3‐bromo‐5‐acetoxy‐2‐pentanone results in the DL‐2‐(α‐ethoxycarbonyl‐alkyl)‐4‐methyl‐5‐(β‐acetoxyethyl)‐thiazoles. The α‐hydroxyl function is introduced into the 2‐(α‐ethoxycarbonyl‐alkyl) group by chlorination with sulfuryl chloride and replacement of the introduced chlorine by acetate. The latter compounds are the esters of the thiazole part of the «active α‐oxo‐carboxylic acids» (e.g. active pyruvate, etc.).

The reaction of 2‐(α‐hydroxyalkyl)‐4‐methyl‐5‐(β‐hydroxyethyl)‐thiazoles and 2‐(α‐ethoxycarbonyl‐α‐acetoxy‐alkyl)‐4‐methyl‐5‐(β‐acetoxyethyl)‐thiazoles, respectively, with alkyl, alkenyl and aralkyl haloids, or with 2‐methyl‐4‐amino‐5‐bromomethyl‐pyrimidine hydrobromide results in the quaternary thiazolium compounds belonging to the group of the active aldehydes, active α‐oxo‐carboxylic acids, etc. According to this method 2‐hydroxymethyl‐thiamine bromide hydro‐bromide has been synthesized, which can be considered as the pyrophosphate‐free «active formal‐dehyde».

The 2‐α‐hydrogen atom in 2‐(α‐hydroxyalkyl)‐thiazolium compounds cannot be replaced by deuterium under conditions similar to those used for the H → D exchange in thiamine.

The main peaks in the mass spectra of 2‐(α‐hydroxyalkyl) substituted thiazoles and thiazolium quaternary salts are listed.
Die Elektronen‐ und Infrarotspektren von Hydraten und Clathraten des Nickelcyanids
Authors: Ludi A. , Hügi R.
Published: December 2004

The infrared and diffuse reflectance spectra in the visible and ultraviolet region of the following compounds have been measured: Ni(CN)2, 2 H2O, Ni(CN)2, 1½ H2O, Ni(CN)2, NH3, ¼ H2O, Ni(CN)2, NH3, R (R = C6H6, C6H5NH2, C6H5OH). The structural units of these compounds are shown to be the square planar [NiC4] and the pseudo‐octahedral [NiN4L2]‐group (L = H2O, NH3) with Ni‐C‐N‐Ni‐bridges. Additional water is present as zeolitic water. The magnetic data give a 1:1 relation of the paramagnetic pseudo‐octahedral to the diamagnetic square planar co‐ordination polyhedra.

The nitrogen of the cyanide ion is close to ammonia in the spectrochemical as well as in the nephelauxetic series, the values of Dq and B being ˜1000 and ˜900 cm−1 respectively.

The absorption bands of the aromatic molecules in the clathrates are shifted towards lower wave numbers compared to the corresponding solution spectra.
Über die sterische Anordnung von Chrom(III)‐ und Kobalt(III)‐1:2‐Azofarbstoff‐Komplexen mit annellierten 5/5‐ und 5/6‐Chelatringen, gebildet mit Azofarbstoffen aus 4,5‐Diphenylimidazol als Kupplungskomponente
Authors: Schetty G.
Published: December 2004

On cuppling 4,5‐diphenylimidazole with a diazotised o‐aminophenol or with a diazotised anthranilic acid, tridentate ligands are produced which, on co‐ordination with the metal atom, form ortho‐condensed 5/5‐ or 5/6‐membered rings. Both ligand systems can form 1:2 chromium (III) and 1:2 cobalt (III) complexes having the DREW‐PFITZNER arrangement. The dimensions of the o‐carboxyazo dyestuff fit well, those of the o‐hydroxyazo dyestuff fit badly into the octahedral crystal lattice. In the same way, on co‐ordination one dyestuff is not deformed but the other is very greatly deformed, as can be concluded from a comparison of the electron spectra of the metal‐free dyestuff with those of the complexes.
Charakterisierung einer neuen organo‐metallischen Titan‐Zink‐ Verbindung
Authors: Salzmann J.‐J.
Published: December 2004

A new organo‐metallic titanium‐zinc compound [Ti(C5H5)2Cl]2ZnCl2 has been isolated. Its structure has been characterised by means of spectroscopic, susceptibility and dipole measurements.
Zum chemischen Verhalten des Antiphlogisticums «Azapropazon» (Mi 85) = 3‐Dimethylamino‐7‐methyl‐1,2‐(n‐propylmalonyl)‐1,2‐dihydro‐1,2,4‐benzotriazin
Authors: Mixich G.
Published: December 2004

The chemical properties of the new antiphlogistic substance Mi 85 (generic name ‘Azapropazone’), which contains a 1,2,4‐benzotriazine ring condensed to a 3,5‐dioxo‐pyrazolidine ring, were investigated. It is shown that this molecule is relatively easily attacked by various chemical reactants (scheme) mainly in the 3,5‐dioxo‐pyrazolidine ring and on the dimethylamino group. There are essential differences between Azapropazone and Phenylbutazone concerning their stability towards hydrolyzing and oxidizing agents.
Beiträge zur Chemie der Si‐N‐Bindung XV [1]. α,ω‐Dimethylchlorsilyl‐substituierte Cyclodisilazane
Authors: Fink Walter
Published: December 2004

α,ω‐Dimethylchlorosily‐substituted monomeric and oligomeric cyclodisilazanes were prepared by the reaction of dimethyl‐dichlorosilane with hexamethylcyclotrisilazane in the molar ratios 1:1 to 1:3. The mechanism of these reactions was investigated.
Synthese des Thyreocalcitonins
Authors: Guttmann St. , Pless J. , Sandrin Ed. , Jaquenoud P.‐A. , Bossert H. , Willems H.
Published: December 2004

A total synthesis of hog thyrocalcitonin is described. A protected C‐terminal tridecapeptide amid (20–32) was coupled with a protected central decapeptide (10–19), and the resulting protected tricosapeptide amide (10–32) was reacted with the N‐terminal protected nonapeptide (1–9). After elimination of the protective groups, a free dotriacontapeptide amide was obtained whose physical, chemical and biological behaviour was indistinguishable from that of the natural hormone.
Steroide und Sexualhormone. 235. Mitteilung [1] Über eine neue ergiebige Synthese von A‐nor‐Testosteron und dessen 6‐Dehydro‐Derivat sowie von 7β‐Methyl‐A‐nor‐testosteron
Authors: Pfister J. , Lehmann [2] C. , Wehrli H.
Published: December 2004

A novel synthetic approach to 2‐oxo‐Δ3‐A‐nor‐steroids is described. The photochemical ring contraction of epoxyketones, cf. 4 → 5, serves as the key step of this procedure, which gives notably higher yields than the previously published syntheses (e.g., overall yield 6 → 10 40%).
Echange d'oxygène lors de la substitution électrophile des phénols
Authors: Dahn H. , Aubort J.‐D.
Published: December 2004

In the bromodesulfonation of sodium 2, 6‐dibromophenol‐4‐sulfonate (I) and similar compounds, the relatively stable quinoloid intermediate II exchanges its carbonyl oxygen with that of H218O by an addition‐elimination process. The exchange is slower than the formation of the product III; it is roughly comparable to the exchange velocity of quinones of similar structure. By reversibility of the electrophilic additon step, 18O is incorporated into the starting phenol I. In electrophilic substitutions with shorter life‐time of the quinoloid intermediate, the oxygen exchange is difficult or impossible to observe.
Zur Kenntnis des Kohlenstoffringes. 80. Mitteilung [1]. 1,1,6,6‐Tetramethyl‐cyclodecan und seine Derivate
Authors: Cordes C. , Prelog V. , Troxler E. , Westen H. H.
Published: December 2004

1,1,6,6‐Tetramethyl‐cyclodecane and various of its derivatives have been synthesized. The influence of geminal methyl groups on the properties of cyclodecane derivatives, especially on their n.m.r. spectra, has been investigated.
Propriétés thermodynamiques des mélanges binaires Énergie libre et entropie de formation des solutions de l'hexadécane dans les isomères de l'hexane
Authors: Fernández‐Garcia J. G. , Guillemin M. , Boissonnas Ch. G.
Published: December 2004

Vapour pressures were measured at 20°C for the systems composed of hexadecane and the isomers of hexane. Activities and free energies were deduced. From previous measures of the heat of mixing values of the entropy of mixing were obtained. The excess free energies are negative. The excess entropies are positive.
Massenspektrometrie und ihre Anwendung auf strukturelle und stereochemische Probleme CLXVII Langkettige Wasserstoffverschiebung in der Massenspektrometrie
Authors: Brandt R. , Djerassi Carl
Published: December 2004

The mass spectral fragmentation behavior of various α‐substituted tetrahydrofuran derivatives and their deuterium labeled analogs has been examined. It was established that the ester and hydroxy derivatives undergo ring fragmentation associated with long range hydrogen transfer. The mass spectra of the deuterium labeled samples provided evidence that direct hydrogen transfer takes place from positions as far as thirteen or more carbon atoms away from the oxygen function in preference to the McLafferty rearrangement. Examination of the spectra of the deuterium labeled derivatives shed further light on the mechanism of the loss of water from the molecular ion and various fragment ions.
Synthesen in der Isochinolinreihe Synthesen von 7‐Hydroxy ‐6‐methoxy‐2‐methyl‐ 1‐(4‐hydroxy‐3, 5‐dimethoxy‐phenäthyl)‐1, 2, 3, 4‐tetrahydro‐isochinolin, einem wichtigen Zwischenprodukt zur Synthese von Homoapomorphin‐Alkaloiden
Authors: Brossi A. , Van Burik J. , Teitel S.
Published: December 2004

Polymethoxylated 1‐phenethyl‐3, 4‐dihydro‐ and ‐1, 2, 3, 4‐tetrahydro‐isoquinolines were selectively demethylated by varying the mineral acid treatment. Under these conditions, the 6‐methoxyl was the most stable, while the 4′‐methoxyl was the most labile. Based on this study and by employing an unprotected phenolic intermediate in the Bischler‐Napieralski cyclization, an efficient, simple and technically feasible synthesis of the diphenol 1, an important intermediate in the synthesis of homoapomorphine alkaloids, was achieved.
Lösungsmittel‐sensibilisierte strahlungschemische Reaktionen II FRIES‐Umlagerungen von Arylestern und Arylamiden [1]
Authors: Belluš D. , Schaffner K. , Hoigné J.
Published: December 2004

In a series of screening experiments p‐tolyl acetate (1a), phenyl benzoate (1b), p‐tolyl benzoate (1c), acetanilide (1d), and 2‐naphthyl acetate (5) have been subjected to γ‐radiolysis in aromatic and saturated hydrocarbon solutions. Qualitatively, the products formed correspond to those observed also with the respective photo‐FRIES reactions, i.e., hydroxy‐ and amino‐aryl ketones due to rearrangements, and products due to homolytic fission into aryloxy and aniline radicals, respectively, were produced.

The relatively high G values of conversion in dilute solutions indicate that energy transfer from the solvent is operative. E.g., 0,1 M p‐tolyl acetate (1a) in benzene has a G value of over 0.3 for ortho‐rearrangement to 2a, and of 0.55 for cresol (4a) formation. Kinetic evidence points to different energy requirements of the ortho‐rearrangement and the phenol formation, and to more than one excited state of benzene acting as energy donor. The ratio of the observed rate constants of the energy transfer to self‐quenching in benzene is about 80 1 · mole−1 for the ortho‐rearrangement to 2a. The over‐all reaction is strongly quenched upon addition of p‐terphenyl.

A comparison of the quantitative data obtained in this work with available published data reveals differences between benzene‐sensitized runs with γ radiation and photochemical experiments. Thus, the ratios of ortho vs. para and amphi rearrangement, and of homolytic fission vs. rearrangements are higher in the solvent‐sensitized radiolyses.
Synthese und Eigenschaften von [n] (2,5) Pyridinophanen und ihren Derivaten
Authors: Gerlach H. , Huber E.
Published: December 2004

[n] (2,5) Pyridinophanes (I) have been synthesized by acid catalyzed cyclization of bis‐(β‐aminovinyl)‐diketones to [n] (2,5) pyridinophan‐n‐ones (V), followed by WOLFF‐KISHNER reduction. The conformational stability of the lower members (n < 12) of the series is shown by reduction of V to diastereomeric [n] (2,5) pyridinophan‐n‐ols (XI). In addition [9] (2,5) pyridinophane (I, n = 9) has been resolved into enantiomers.
(4‐phenyl‐2‐thiazolyl)‐acetone and its enamines: Synthesis and NMR. Spectra
Authors: Govindachari T. R. , Rajappa S. , Nagarajan K.
Published: December 2004

The synthesis of (4‐phenyl‐2‐thiazolyl)‐acetone and its enamines is reported. Their NMR. spectra are discussed.
Zerfall von Diazoniumsalzen in homogener Lösung I: Arylierung von Aromaten mit Benzoldiazonium‐ und p‐Nitrobenzoldiazonium‐fluoroborat in Dimethylsulfoxid Vorläufige Mitteilung
Authors: Kaul B. L. , Zollinger H.
Published: December 2004

The decomposition of two aryldiazonium tetrafluoroborates in homogeneous solution in a mixture of dimethylsulphoxide and benzene or nitrobenzene has been studied quantitatively. The isomer ratios for the arylation of benzene and of nitrobenzene respectively are consistent with a heterolytic substitution mechanism for benzenediazonium tetrafluoroborate, and a homolytic mechanism for p‐nitrobenzenediazonium tetrafluoroborate. The latter compound gives astonishingly high arylation yields under the conditions mentioned.
Abschätzung von Reaktivitäts‐Parametern von Nucleophilen auf Graund der Kern‐Spin‐Spin‐Kopplungskonstanten J1H‐199Hg ihrer Methylquecksilberkomplexe
Authors: Scheffold R.
Published: December 2004

The value of the nuclcear‐spin‐coupling‐constant J1H‐199Hg of methylmecury compounds CH3HgL is related to:

(a) the electrode potential for oxidative dimerisation of L,

(b) the interatomic distances C‐Hg in CH3HgL,

(c) the interatomic distances Hg‐Hg in L‐Hg‐Hg‐L,

(d) the energy of dissociation of CH3HgL into CH3 and HgL,

(e) the logarithms of the stability constants of CH3HgL,

(f) the logarithms of the relative nucleophilic reactivites of L in SN2 reactions at a saturated carbon atom

(g) the proton‐bascicity of L (in series of structurally similar ligands, possessing the same ligating atom, as for example carboxylate anions).

Approximately linear correlations were found between J1H‐199Hg and the values of (a), (e), (f), and (g). It is suggested that the value of the nuclear‐spin‐spin‐coupling‐constant J1H‐199Hg of CH3HgL provides a measure of the relative energy of the occupied frontier orbital of the nucleophile L.
Ein neuer Abbau des Indolalkaloids Kopsin; chemische Korrelierung der Alkaloide vom Kopsin‐ und Pleiocarpin‐Typ mit Minovincin
Authors: Guggisberg A. , Gorman A. A. , Bycroft B. W. , Schmid H.
Published: December 2004

A new chemical degradation of (–)‐kopsine is described which completely confirms the structure of this alkaloid. Correlation of (–)‐aspidofractinine, (–)‐pleiocarpine and (–)‐kopsine with (–)‐minovincine establishes the absolute stereochemistry of these bases. It appears that, in contrast to the aspidospermine group, all alkaloids containing the aspidofractinine skeleton possess the same absolute stereochemistry.
Umwandlung von Krötengiften (Bufadienoldien) durch Mikroorganismen IV. 7β‐Hydroxybufalin, 7β‐Hydroxyresibufogenin und 12α‐Hydroxyresibufogenin. 16. Mitteilung über Reaktionen mit Mikroorganismen [1]
Authors: Gsell L. , Tamm Ch.
Published: December 2004

Bufalin (1) was transformed to 7β‐hydroxybufalin (2) by an aqueous suspension of the mycelium of Absidia orchidis VUILL. (HAGEM.). Incubation of resibuforgenin (9) under the same conditions yielded 12α‐hydroxyresibufogenin (7) and, under changed conditions, another monohydroxylated derivative which possesses most likely the structure of 7β‐hydroxyresibufogenin (10). The corresponding cardenolide 3‐O‐acetyl‐14β, 15β‐epoxy‐14‐anhydro‐digitoxigenin (17) gave both the 7β‐ and the 12α‐monohydroxylated derivatives 18 and 22 and another monohydroxylated product 21 of unknown structure. All microbial transformation products are new.
Notiz über Radikal‐Ionen des 3,6‐Dimethyl‐1,2,4,5‐tetrazins und seines 1,4‐Dihydroderivats
Authors: Gerson F. , Skorianetz W.
Published: December 2004

Paramagnetic solutions of 3,6‐dimethyl‐1,2,4,5‐tetrazine and its 1,4‐dihydroderivative in aqueous bases and acids have been investigated by ESR. spectroscopy.
Niederdruck‐Oligomerisation von Mono‐Olefinen mit löslichen Nickel/Aluminium‐Bimetallkatalysatoren Teil III. Reaktionskinetische Untersuchungen über die Dimerisation und Trimerisation des Áthylens
Authors: Onsager Olav‐Torgeir , Wang Hagbarth , Blindheim Ulf
Published: December 2004

The kinetics of the di‐ and trimerization of ethylen in organic solvents under the influence of a homogeneous catalyst containing π‐tetramethylcyclobutadiene‐nickeldichloride and a prereacted mixture of ethylaluminiumdichloride and tri‐n‐butylphosphine are reported. The primary reaction product is 1‐butene, which is isomerized to 2‐butene (cis/trans) during the reaction. The C6‐Olefins are formed by the reaction of ethylene with 1‐butene and with the 2‐butenes. The following primary reaction products are obtained: 3‐hexene (cis/trans), 1‐hexene, 2‐ethyl‐1‐butene, 3‐methyl‐1‐pentene and 3‐methyl‐2‐pentene (cis/trans).

The effect of other phosphines on the reaction was also studied. The relative composition of the reaction product is strongly dependent upon the amount and the LEWIS base strength of the phosphine present. The results are in accordance with a coordinative mechanism on nickel.
Über die Wirkungsweise löslicher Nickel‐/Aluminium‐Bimetallkatalysatoren auf der Basis von π‐Cyclobutadien‐Nickel‐(II)‐Verbindungen beider Niederdruck‐Oligomerisation von Mono‐Olefinen
Authors: Onsager Olav T. , Wang Hagbarth , Blindheim Ulf
Published: December 2004

Mixtures of π‐cyclobutadiene‐nickeldihalides and LEWIS acids such as Al(R)nCl3‐n,, n = 1–2, represent very active homogeneous catalysts for dimerization of mono‐olefins. As active cocatalyst may be used LEWIS bases, in particular compounds containing three‐coordinated phosselectivity of the catalytic system has been investigated. The kinetics of the dimerization‐reaction is outlined.

The mechanisms of the olefin‐dimerization is best characterized as a «double‐cis‐insertionreaction». The main catalytic activity is thought to be connected either to free positively charged nickel cations or to bimetallic nickel‐aluminium‐complexes, depending on theconditions of reaction, in particular the amount and chemical nature of the cocatalyst.
Untersuchungen über das Verhalten organischer Mischphasen 7. Mitteilung. Dampfdrücke, Dichten und thermodynamische Mischungsfunktionen des binären Systems Cyclohexan‐ Tetrahydrofuran bei 25°
Authors: Arm H. , Bánkay D.
Published: December 2004

The total vapor pressures and the heats of mixing of the system cyclohexane‐tetrahydrofuran were measured at 25°C. The density was used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.
Zur Synthese von 3‐Desoxy‐aldulosonsäuren
Authors: Baschang Gerhard , Fritz Hans
Published: December 2004

The condensation of 2.4‐ethylidene‐erythrose with the sodium salt of diethyl‐phosphono‐piperidino‐ethylacetate yields an enamino‐lacton V which is converted under mild conditions into an α‐keto ester, 2‐oxo‐3‐desoxy‐gluconic acid, and its quinoxaline derivative.
Synthèse et purification de l'acide (trifluorométhyl‐3‐phénylamino)‐2‐nicotinique (acide niflumique) à Carboxyle [14C], d'activité spécifique élevée
Authors: Colombini C. , Deganello G. , Benakis A. , Strolin‐Benedetti M.
Published: December 2004

On décrit la synthèse de l'acide (trifluoroéthyl‐3‐phénylamino)‐2‐nicotinique (acide niflumique) à carboxyle‐[14C], d'activité spécifique élevée (11 mCi/mmole), et sa purification par chromatographie qui permet d'obtenir une pureté de 99,9%.
Über 1,4‐Di‐äthoxycarbonyl‐cyclohexandion‐(2,3) und daraus erhaltene Phenazinderivate
Authors: Schweizer H. R.
Published: December 2004

Das bisher unbekannte 1,4‐Di‐äthoxycarbonyl‐cyclohexandion‐(2,3) wurde durch Kondensation von Diäthyladipat mit Diäthyloxalat in 10% Ausbeute erhalten. Von den beiden Ketogruppen des Dions reagiert im allgemeinen nur die eine. Mit o‐Phenylendiamin bildet sich 1,4‐Di‐äthoxycarbonyl‐2,3,5,10‐tetrahydrophenazin, das sich über die 5, 10‐Dihydroverbindung zum 1,4‐Di‐äthoxycarbonyl‐phenazin dehydrieren lässt. Die Verseifung des letzteren führt zur bisher unbekannten Phenazin‐1,4‐dicarbonsäure. Die Umsetzungen lassen sich auf substituierte o‐Phenylendiamine ausdehnen.
Bemerkung zur vorstehenden Notiz [1] von H. REMBOLD
Authors: Viscontini M.
Published: December 2004

Der von Herrn Dr. REMBOLD beanstandete Satz aus meiner Veröffentlichung mit PROVENZALE [2] ist tatsächlich nicht glücklich formuliert. Ich wollte keinesfalls eine polemische Mitteilung schreiben, sondern nur eine génstige Synthese von analysenreinen und stereospezifisch einheitlichen 6‐Polyhydroxyalkyl‐pterinen bekanntgeben. Da ich bis dahin auf viele Schwierigkeiten bei der chromatographischen Reinigung dieser synthetisch hergestellten Substanzen stiess, fasste ich meine Erfahrungen in diesem zu allgemein formulierten Satz zusammen, ohne auf irgendeinen bestimmten Kollegen bezugnehmen zu wollen. Ich habe keinerlei Grund zu bezweifeln, dass Herr Dr. REMBOLD seine biologischen Experimente immer mit ganz reinen Pterinen durchgeführt hat.
Zur Stereochemie der aromatischen CLAISEN‐Umlagerung
Authors: Fráter Gy. , Habich A. , Hansen H.‐J. , Schmid H.
Published: December 2004

The possible transition state conformations (chair (S), boat (W), and twist (T), respectively cross (K) forms) and methods for their determination in the thermal ortho‐CLAISEN rearrangement of allyl aryl ethers are discussed.

Crotyl 3,5‐dimethylphenyl ether (11) gives a mixture of 2‐(α‐methylallyl)‐3,5‐dimethyl‐phenol (12) and 4‐crotyl‐3,5‐dimethyl‐phenol (13) on heating in N, N‐diethylaniline. Values of 3 and 31 were obtained for the ratio of 12/13 for trans‐11 and cis‐11, respectively. It therefore follows that both ethers rearrange steroselectively ( > 90%) by the S or W forms of the activated complex.

αMethylallyl 6‐alkylphenyl ethers rearrange on heating in various solvents to a mixture of trans‐and cis‐2‐crotyl‐6‐alkyl‐phenols. The amount of the cis‐phenols in the rearrangement products decreases with the increasing bulk of the 6‐alkyl substituent. This result is only obvious if the chair form of the transition state during the rearrangement of these ethers is highly favoured.

trans‐Crotyl 2,6‐dimethylphenyl ether (trans‐33) rearranges highly steroselectively (94%) on heating to trans‐4‐crotyl‐2,6‐dimethyl‐phenol (trans‐34). In the case of the corresponding cis ether 33, the rapid cis → trans isomerisation of this ether and the cis/trans ratio of the phenol 34 indicate that the reverse rearrangement of the intermediate ortho‐dienone to the ether 33 and the further rearrangement to 4‐crotyl‐2,6‐dimethyl‐phenol (34) has little stereoselective character.
Assoziation in Lösung. Eine graphische Methode zur Bestimmung von Gleichgewichtskonstanten aus kolligativen Eigenschaften
Authors: Wachter A. H. , Simon W.
Published: December 2004

A graphical procedure for the evaluation of association equilibria in solution is given. It consists of families of master plots that are superimposed on a diagram of experimental values (namely practical osmotic coefficient vs. concentration). Different models (dimerisation, multimerisation, chain association) can be tested, and the values of up to two association constants can be read off. Tables of the normalized variables and various examples are presented.
Reaktionen mit Blei(IV)‐acetat, XVI. Eine neuartige Umwandlung von 2‐Acetoxy‐3‐oxo‐4,5‐epoxy‐steroiden
Authors: Mihailović M. Lj. , Foršek J. , Lorenc Lj. , Maksimovic Z. , Fuhrer H. , Kalvoda J.
Published: December 2004

Treatment of 3‐oxo‐4, 5‐oxido steroids with lead tetraacetate results in acetoxylation in the 2α‐position as could be shown by independent synthesis of the acetoxylated compounds. The products of this reaction rearrange even under very mild conditions (chromatography on silicagel or alumina) to the corresponding 2,3‐dioxo‐Δ4 compounds. The influence of structure and conformation of the various intermediates on their NMR.‐spectra is discussed. A mechanism for this new transformation is proposed.
Theviridosid, ein Iridoid‐glucosid aus Thevetia peruviana (PERS.) K. SCHUM. (Thevetia neriifolia JUSS.). Vorläufige Mitteilung
Authors: Sticher O. , Schmid H.
Published: December 2004

From stem bark of Thevetia peruviana a new iridoid glucoside, theviridoside was isolated. Its structure II was established by chemical degradations and spectroscopic methods.
Sur la composition de l'arôme de thé. III. Identification de deux cétones apparentées aux ionones
Authors: Müggler‐Chavan F. , Viani R. , Bricout J. , Marion J. P. , Mechtler H. , Reymond D. , Egli R. H.
Published: December 2004

La triméthyl‐2, 6, 6‐hydroxy‐2‐cyclohexanone et l'époxy‐5, 6‐ionone ont été identifiées dans l'arǒme de thé noir.