Helvetica Chimica Acta

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Microbial Transformation of Sesquiterpenes, (−)‐Ambrox® and (+)‐Sclareolide
Helvetica Chimica Acta - Tập 87 Số 10 - Trang 2685-2694 - 2004
M. Iqbal Choudhary, Syed Ghulam Musharraf, Amtul Jamil Sami, Atta‐ur Rahman
AbstractThe microbial transformation of (−)‐Ambrox® (1), a perfumery sesquiterpene, by a number of fungi, by means of standard two‐stage‐fermentation technique, afforded ambrox‐1α‐ol (2), ambrox‐1α,11α... hiện toàn bộ
Untersuchungen in der Benztropylium‐Reihe XII. Absorptionsspektrum und Acidität benzologer Tropylium‐Kationen
Helvetica Chimica Acta - Tập 43 Số 5 - Trang 1221-1243 - 1960
G. Naville, Hansruedi Strauss, E. Heilbronner
AbstractThe series of benzologue tropylium cations up to C15 has been completed by the preparation of 1,2; 3,4‐dibenzo‐tropylium cation (III), of (1′,2′‐naphtha)‐tropylium cation (V) and of (2′,3′‐naphtha)‐tropylium cation (IV). The absorption spectra and the relative acidities of these compounds are described.
Novel Naamidine‐Type Alkaloids and Mixed‐Ligand Zinc(II) Complexes from a Calcareous Sponge, Leucetta sp., of the Coral Sea
Helvetica Chimica Acta - Tập 78 Số 5 - Trang 1178-1184 - 1995
Ines Mancini, Graziano Guella, Cécile Debitus, Francesco Pietra
AbstractAs compounds from a calcareous sponge, Leucetta sp., of the Coral Sea, we isolated a series of novel naamidine‐type alkaloids, 6–10, which are oxidized at a single benzylic position. We also report on the first marine, mixed‐ligand metal complex 5 and on the firs...... hiện toàn bộ
Über den Mechanismus der enzymatischen Verseifung von Pektinstoffen
Helvetica Chimica Acta - Tập 38 Số 1 - Trang 321-329 - 1955
J. Solms, H. Deuel
AbstractEs wird die Kinetik der enzymatischen Verseifung von verschiedenen Pektinstoffen durch Orangenpektinesterase untersucht. Die enzymatische Verseifung erfolgt stets unvollständig bis zu einem Veresterungsgrad von ca. 10%.
Über Toxine II. Zur Kenntnis des Crotins
Helvetica Chimica Acta - Tập 8 Số 1 - Trang 384-392 - 1925
P. Karrer, Fritz Gerd Weber, J. van Slooten
Zum Mechanismus der Photoreduktion von Wasser mit Ruthenium‐trisbipyrazil als Sensibilisator
Helvetica Chimica Acta - Tập 66 Số 8 - Trang 2652-2655 - 1983
Heinz Dürr, Gisela Dörr, Klaus Zengerle, Jean‐Marc Curchod, André M. Braun
On the Mechanism of the Photoreduction of Water with Ruthenium‐trisbipyrazil as SensitizerOxidative and reductive primary steps can be differentiated in using Ru(bipy) hiện toàn bộ
Ein präparatives Analogon zur Trennung an dünnen Schichten: Horizontale Säulenchromatographie im Cellophanschlauch
Helvetica Chimica Acta - Tập 45 Số 1 - Trang 261-270 - 1962
H. Dahn, Harald Fuchs
AbstractThe authors describe a technique which allows the direct transfer of the results of thin‐layer chromatography or paper chromatography to preparative scale separations: a horizontal column is made using finely powdered adsorbents (silica gel, alumina, or cellulose powder) in a cellophane tube which can be cut into slices after development.
Quelques apercus concernant l'oxydation du soufre organique chez les animaux supérieurs
Helvetica Chimica Acta - Tập 29 Số 5 - Trang 1279-1283 - 1946
Claude Fromageot, M. A. Royané
AbstractL'injection intraveineuse d'acide cystéine‐sulfinique chez le lapin provoque un accroissement important de la quantité de thiosulfate excrété par l'urine. D'autre part, l'acide cystéine‐sulfinique, mis en contact avec du foie broyé de lapin, est scindé avec formation de sulfite, par suite d'une réaction fermentaire dont le mécanisme n'est pas encore élucidé...
Glycosylidene Carbenes a new approach to glycoside synthesis. Part 1. Preparation of glycosylidene‐derived diaziridines and diazirines
Helvetica Chimica Acta - Tập 72 Số 6 - Trang 1371-1382 - 1989
Karin Briner, Andrea Vasella
AbstractA new approach towards the synthesis of glycosides based upon a (formal) insertion of glycosylidene carbenes into OH bonds is presented. The synthesis and characterization of the glycosylidene‐derived diazirines 25–28, precursors of glycosylidene carbenes, are described. The diazirines were prepared by the rapi...... hiện toàn bộ
Nachbarǵruppeneffekte bei der Hydrolyse von Acetonyl‐Estern
Helvetica Chimica Acta - Tập 46 Số 6 - Trang 2418-2424 - 1963
Elsbeth Schätzle, Hans Urheim, M. Thürkauf, Max Rottenberg
AbstractKinetic studies revealed that esters of hydroxyacetone undergo alkaline hydrolysis with participation of neighbouring groups, its rate being higher by a factor of at least 20 than could have been anticipated on the basis of inductive effects alone. The mechanism is discussed in terms of either nucleophilic or electrophilic intra‐molecular catalysis.
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