Search results for "Radical"
showing 10 items of 1401 documents
Versuche zum Vorgang der Wasserstoffübertragung, XI. Isomerisierung Definiert Deuterierter Alkylbenzole an Raney-Nickel
1964
α-Deutero-toluol. o-, m- und p-Deutero-toluol sowie β-Deutero-athylbenzol isomerisieren schon bei 20° in Beruhrung mit wasserfreiem Raney-Nickel. Der Deuterium-Gehalt des Substrates bleibt dabei annahernd konstant. Beim α-Deutero-toluol wandern mehr als 50% des Deuteriums aus der Seitenkette in den Kern, wobei es sich weitgehend auf die gleichen Positionen verteilt wie beim Austausch von leichtem Toluol mit Deuterium-Gas an Raney-Nickel. Der aromatische Kern wird unter diesen Bedingungen nicht abgesattigt. Mit Hilfe der Massenspektrographie kann gezeigt werden, das Deuterium auch zwischenmolekular ausgetauscht wird. — Im Toluol kernstandiges Deuterium verteilt sich an Raney-Nickel auf samtl…
Polymerisation von acrylnitril, methylmethacrylat und einigen substituierten acrylnitrilen mit anorganischen nitraten. Zur polymerisation von acryini…
1968
Die radikalische Polymerisation von Acrylnitril (AN), Methacrylnitril, α-Chloracrylnitril, Crotonsaurenitril und Methylmethacrylat wird unter Bestrahlung bei 60°C in An wesenheit von AgNo3 untersucht, und die Polymerisationsgeschwindigkeiten werden verglichen. Unterschiede in der Polymerisationsfahigkeit einzelner Monomerer lassen sich teilweise auf Komplexbildung mit AgNO3 zurackfahren. Es werden einige andere anorganische Nitrate als Initiatoren eingesetzt; ihre Aktivitat entspricht der Stellung der Kationen in der Spannungsreihe. Als Teil der Initiierungsreaktion wird eine Reduktion des Metallions angenommen; daher kann eine Abnahme der Kationenkonzentration bei AgNO3 und besonders bei C…
[39] DNA damage induced by ultraviolet and visible light and its wavelength dependence
2000
Publisher Summary DNA damage induced by solar radiation in mammalian cells consists largely of two types of modification: pyrimidine dimers and oxidative modifications. Pyrimidine dimmers that can be subdivided into cyclobutane pyrimidine dimmers, (CPDs) and (6-4) photoproducts are the characteristic and most abundant modifications after direct excitation of DNA, although they can also be formed indirectly by energy transfer from other excited molecules such as carbonyl compounds. Oxidative DNA damage, which includes various pyrimidine and purine modifications, sites of base loss (AP sites), and strand breaks, is generated in only low yield after direct excitation of DNA (except at very sho…
Aryl radicals by copper(II) oxidation of hydrazines: A new method for the oxidative and reductive arylation of alkenes
1989
Abstract A new source of aryl radicals interesting from the preparative point of view has been found in the reaction of arylhydrazines and copper(II) sulfate. The process allows selectively both the reductive and oxidative arylation of alkenes.
Hydroxyl Radical Addition to Thymine and Cytosine and Photochemistry of the Adducts at the C6 Position
2019
Selective C-H Activation of Methoxy Groups in a Three-Component Photoreaction.
2015
Surprisingly, the photocatalytic activation of ethers by H-abstraction and addition of the generated radicals to iminium ions formed in situ from aldehydes and anilines predominantly yielded the products of methoxy activation for dimethoxymethane and 1,2-dimethoxyethane. Various anilines and aromatic as well as aliphatic aldehydes are suitable reaction partners for this three-component photoreaction (Porta-type process) which also provides a simple access to 1,2-aminoalcohols.
ChemInform Abstract: Selective C-H Activation of Methoxy Groups in a Three-Component Photoreaction.
2016
Surprisingly, the photocatalytic activation of ethers by H-abstraction and addition of the generated radicals to iminium ions formed in situ from aldehydes and anilines predominantly yielded the products of methoxy activation for dimethoxymethane and 1,2-dimethoxyethane. Various anilines and aromatic as well as aliphatic aldehydes are suitable reaction partners for this three-component photoreaction (Porta-type process) which also provides a simple access to 1,2-aminoalcohols.
Closer Investigation of the Kinetics and Mechanism of Spirovinylcyclopropyl Oxindole Reaction with 3Σ–g-O2 by Topological Approaches and Unraveling t…
2021
In this investigation at the MN15L/Def2-TZVP level of theory, we present computational evidence indicating that the reaction of 3Σ-g-O2 with spirovinylcyclopropyl oxindole (2) leads to a product called spiro-1,2-dioxolane (2) in its singlet state; this reaction occurs via a stepwise mechanism and its rate-determining step is catalyzed by iodine radicals, which promotes opening of the three-membered ring under dark conditions. The conversion of 2 to 1-benzylindoline-2,3-dione (3) and 2-vinyloxirane (4) takes place via a concerted and slightly asynchronous reaction. Both electron localization function and AIM topological analysis reveal that the step associated with the attack of the 3Σ-g-O2 …
Photo-Crosslinking of Copolymeric Methacrylates Bearing Stilbene Chromophores
2012
Radical polymerization of methyl methacrylate (2) as major component and the methacrylates 1a or 1b, which contain an (E)-stilbene unit fixed by a tether to the ester group, yield easily soluble copolymers 3a, b. Whereas the dominant photoreactions in solution are (E)⇄Z) isomerizations and intra-chain [2π +2π] cycloadditions, cast films of 3a, b give an inter-chain photo-crosslinking on irradiation. Compared to homopolymers, the copolymers are not only better soluble and more easily processible, their films show less undesired light scattering. The cross-linked material is completely insoluble in organic solvents. Thus, it represents the basis for negative photoresists and the corresponding…