Search results for "Reaction"
showing 10 items of 6134 documents
Redox-Responsive Host-Guest Chemistry of a Flexible Cage with Naphthalene Walls
2020
“Naphthocage”, a naphthalene-based organic cage, reveals very strong binding (up to 1010 M–1) to aromatic (di)cationic guests, i.e., the tetrathiafulvalene mono- and dication and methyl viologen. Intercalation of the guests between two naphthalene walls is mediated by C–H···O, C–H···π, and cation···π interactions. The guests can be switched into and out of the cage by redox processes with high binding selectivity. Oxidation of the flexible cage itself in the absence of a guest leads to a stable radical cation with the oxidized naphthalene intercalated between and stabilized by the other two. Encapsulated guest cations are released from the cavity upon cage oxidation, paving the way to futur…
Searching for signatures around 1920 MeV of a N-* state of three hadron nature
2009
We provide a series of arguments which support the idea that the peak seen in the gamma p -> K+ Lambda reaction around 1920 MeV should correspond to the recently predicted state of J(P) = 1/2(+) as a bound state of K(K) over bar N with a mixture of alpha(0)(980)N and f(0)(980)N components. At the same time we propose polarization experiments in that reaction as a further test of the prediction, as well as a study of the total cross-section for gamma p -> K(+)K(-)p at energies close to threshold and of d sigma/dM(inv) for invariant masses close to the two-kaon threshold.
Asymmetric Organocatalytic Wittig [2,3]-Rearrangement of Oxindoles
2016
A highly enantioselective organocatalytic [2,3]-rearrangement of oxindole derivatives is presented. The reaction was catalyzed by squaramide, and this provides access to 3-hydroxy 3-substituted oxindoles in high enantiomeric purities.
Chemie von Aerosolen
2007
Atmospharische Aerosolpartikel sind keine chemisch inerten Teilchen, deren Bildungsmechanismen, Verweildauer oder Funktion in der Atmosphare lediglich von mechanischen oder physikalischen Prozessen abhangen. Sowohl bei der Bildung von Aerosolpartikeln als auch im Verlauf ihres Verbleibs in der Atmosphare spielen chemische Reaktionen eine wesentliche Rolle. Chemische Reaktionen laufen an der Oberflache und im Inneren von Aerosolpartikeln ab und konnen sowohl die atmospharische Gasphasenchemie beeinflussen, z.B. indem sie sowohl als Reaktionsmedium fur ansonsten langsam verlaufende Gasphasenreaktionen dienen, als auch die Eigenschaften der Partikel, beispielsweise ihre Funktion als Kondensati…
Pyrosequencing survey of intestinal microbiota diversity in cultured sea bass (Dicentrarchus labrax) fed functional diets.
2014
The routine use of chemotherapy to control bacterial diseases in aquatic populations has resulted in the development and spread of antibiotic resistance. The inclusion of immunostimulants in fish diets (functional diets) is one of the main strategies to solve this threat. This study aimed to analyse the intestinal microbiota of cultured European sea bass (Dicentrarchus labrax) fed two functional diets applying pyrosequencing of PCR-amplified 16S rRNA gene. Quality-filtered reads were assigned to family and genus taxonomic levels using the Ribosomal Database Project classifier. The autochthonous intestinal microbiota of sea bass consisted of two dominant bacterial genera: Dysgonomonas (Bacte…
Ultrasound accelerated esterification of bile acids
2004
In this study power ultrasound accelerated esterification reactions of some model substances and bile acids were done. In the model reactions the best result was 19-fold increase in the reaction rate when using ultrasound and the temperature was allowed to rise during the irradiation. In the case of bile acid methyl esters a clear increase in the reaction rates was also observed by ultrasonic irradiations.
Organocatalytic Enantioselective Functionalization of Hydroxyquinolines through an Aza-Friedel-Crafts Alkylation with Isatin-derived Ketimines
2018
[EN] A highly enantioselective addition of hydroxyquinolines to isatin-derived ketimines has been realized using a quinine-derived thiourea organocatalyst. The reaction affords chiral 3-amino-2-oxindoles bearing a quinoline moiety with a quaternary stereocenter in high yields (up to 98%) and excellent enantioselectivities (up to 99%). Moreover, we can extend this methodology for the enantioselective functionalization of 5-hydroxyisoquinoline. This methodology represents, to the best of our knowledge, the first enantioselective addition of hydroxyquinolines to imines.
New oxygenated eudesmanolides from artemisia herba-alba
1990
Abstract The aerial parts of Artemisia herba-alba Asso subsp.valentina Lam. (Asteraceae) yielded the new eudesmanolides 1-11 and the new sesquiterpene-monoterpene adducts 12-13. The absolute configuration of compound 6 was confirmed with the aid of X-ray diffraction analysis. Some aspects of the thermal and photochemical reactivity of 2,4-cyclohexadienones are discussed.
Antimykotische Wirkstoffe, Mitt. Chlor-(1-piperazinyl)-1,3,5-triazine
1988
Aus der Umsetzung von Cyanurchlorid (1) mit den Piperazinderivaten 2a–c bei –20 bis 10° gehen die Dichlor-(1-piperazinyl)-1,3,5-triazine 3a–c hervor. Bei der erhohten Reaktionstemperatur von 40° erfolgt aus 1 und den Piperazinderivaten 4a–b Bildung der 2-Chlor-4,6-bis(piperazinyl)-1,3,5-triazine 5a–b. Zu gemischt substituierten Chlor-1,3,5-triazinen 9 fuhrt die nacheinander erfolgende Umsetzung von 1 mit 2 verschiedenen cyclischen sekundaren Aminen (6 und 8). Die Strukturtypen 3, 5 und 9 zeigen in den 1H-NMR-Spektren zwei fur Piperazinringe charakteristische Signalgruppen im Bereich 2.4–4.0 ppm. Unter den neu entwickelten Verbindungen finden sich Vertreter mit sehr starker antimykotischer W…
Usutu virus activity in Austria, 2001–2002
2003
Usutu virus (USUV), a member of the mosquito-borne clade within the Flaviviridae family, was responsible for avian mortality in Austria in 2001. In 2002, the virus continued to kill birds, predominantly blackbirds. High numbers of avian deaths were recorded within the city of Vienna and in surrounding districts of the federal state of Lower Austria, while single die-offs were noticed in the federal states of Styria and Burgenland. A total of 72 birds were submitted for laboratory examination, 30 of which tested positive for USUV by immunohistochemistry and/or polymerase chain reaction. Laboratory-confirmed cases of USUV infection originated from the federal states of Vienna and Lower Austri…