Search results for "Catalysis"
showing 10 items of 5944 documents
Über Serotoninderivate mit cyclisierter Seitenkette, 1. Mitt. Darstellung der isomeren 3-(Piperidylmethyl)- und 3-(Piperidylmethyl)-5-hydroxyindole
1975
Es wird die Synthese der drei isomeren 3-(Pyridylmethyl)- und 3-(Piperidylmethyl)-5-hydroxyindole beschrieben. Die 3-(Pyridilmethyl)-5-benzyloxyindole wurden durch Kondensation von 5-Benzyloxyindolylmagnesiumbromid mit den drei isomeren Chlormethyl-pyridinbasen dargestellt. Katalytische Reduktion ihrer quartaren Salze fuhrte zu den entsprechenden Piperidinverbindungen. Die 5-Benzyloxyindole wurden durch hydrierende Debenzylierung in die 5-Hydroxyindolverbindungen ubergefuhrt. 3-(Pyridylmethyl)- and 3-(Piperidylmethyl)-5-hydroxyindoles The synthesis of the three isomeric 3-(pyridylmethyl)- and the 3-(piperidylmethyl)-5-hydroxyindoles is described. To obtain the 3-(pyridylmethyl)-3-benzyloxyi…
Darstellung eines reinen monomeren formaldehyds durch acidolytische depolymerisation von Trioxan. 22. Mitt. über polyoxymethylene1
1964
Trioxan wird mit nahezu quantitativem Umsatz kontinuierlich in einem Stickstoffstrom bei 200°C an einem Pyrophosphorsaure-Kontakt zu monomerem Formaldehyd depolymerisiert. Durch Vorpolymerisation von ca. 5% des gasformigen Formaldehyds werden die geringfugigen Verunreinigungen wie Methylformiat, Wasser und unumgesetztes Trioxan entfernt, so das das restliche Monomere eine Reinheit von mindestens 99,98% besitzt. Losungen dieses Formaldehyds in Toluol oder Diathylather zeigen zwischen –78 und –50°C eine sehr gute Haltbarkeit. Trioxane is depolymerized almost quantitatively to form monomeric formaldehyde in a flow system at 200°C. using pyrophosphoric acid as catalyst and nitrogen as a carrier…
Photocatalytic oxidation of cyanide in aqueous TiO2 suspensions irradiated by sunlight in mild and strong oxidant conditions
1999
Abstract The photocatalytic oxidation of free cyanide ions was carried out in aqueous aerated suspensions containing polycrystalline TiO2 (anatase) irradiated by sunlight. The influence of the presence of an organic compound (phenol) or of a strong oxidant (H2O2) on the photoprocess was also studied. The dependence of cyanide photo-oxidation rate on the following parameters: (1) cyanide concentration; (2) catalyst amount; and (3) phenol concentration was investigated. At the used experimental conditions, the kinetics of cyanide photo-oxidation is independent of the initial cyanide concentration and of the catalyst amount while it is affected by the phenol concentration and by the presence o…
Palladium-Catalyzed Suzuki Carbonylative Reaction of α-Halomethyl Oxime Ethers: A Regioselective Route to Unsymmetrical 1,3-Oxyiminoketones
2014
Electrochemical Deoxygenation of Aromatic Amides and Sulfoxides
2014
The electrochemical deoxygenation of a broad range of aromatic amides was achieved under mild conditions on lead cathodes. Under the optimized reaction conditions, acetal, thienyl, and ether moieties are tolerated. Furthermore, the reduction protocol can be applied to aromatic and aliphatic sulfoxides to obtain the corresponding sulfides. For both aromatic amides and sulfoxides, the deoxygenation reaction ensues without the use of expensive catalysts or hazardous reducing agents. Owing to the high selectivity of the process, simple extraction is sufficient to isolate the product from the substrate. The straightforward purification protocol, the coformation of water, and the use of electric …
Friessche Verschiebung vonortho- undpara-Methoxyphenylacetaten. Die Bildung von Ketoestern
1980
During theFries rearrangement ofo- andp-methoxy phenyl acetates with AlCl3 in nitromethane at 20°C substitution occurs mainly in thep-position of the phenolic residue to yieldp-acylphenols. Larger quantities ofo-acylphenols are obtained only, if thisp-position is already substituted. Witho-methoxy phenyl acetates the substitution of the acid residue to yield ketoesters is observed as a side reaction. Those ketoesters are obtained as main products if TiCl4 is taken as a catalyst.
Reaction of 2H-1-benzothiete with diazo compounds in the presence of rhodium(II) acetate
1995
2,3-Dihydrobenzo[b]thiophenes (7a-e) were prepared by the Rh2+ catalyzed reaction of 2H-1-benzothiete (1) and diazo compounds (3a-e). α,β-Unsaturated diazo esters (3b,e) and diazo ketones (3d,e) yielded additionally 4,5-dihydro-1-benzothiepins (11b,c) and 5H-4,1-benzoxathiepins (12d,e), respectively.
ChemInform Abstract: Thioetherification of Chloroheteroarenes: A Binuclear Catalyst Promotes Wide Scope and High Functional-Group Tolerance.
2015
The nucleophilic substitution of a variety of chloro- and bromohetarenes with arylthiols is optimized to use [PdCl(allyl)]2 in combination with a ferrocenyltetraphosphane as ligand.
ChemInform Abstract: FeCl3·6H2O-Catalyzed Mukaiyama-Aldol Type Reactions of Enolizable Aldehydes and Acetals.
2015
A general procedure for the title condensation of dimethylacetals derived from enolizable aldehydes with silyl enol ethers is developed using FeCl3 as the catalyst.