Search results for "Reactivity"
showing 10 items of 880 documents
Über die copolymerisation des acroleins und des methacroleins in homogener lösung. Polymere acroleine. 25. Mitt.
1962
Die Copolymerisation des Acroleins und des Methacroleins in Dimethylformamid sowie in Dioxan wird beschrieben. Die Parameter folgender Systeme wurden bestimmt: Acrolein/Acrylnitril (r1 = 1,60; r2 = 0,52); Acrolein/Acrylamid (r1 = 1,69; r2 = 0,21); Acrolein/Methacrylnitril (r1 = 0,72; r2 = 1,20); Acrolein/2-Vinylpyridin (r1 = 4; r2 = 0) und Methacrolein/Methacrylnitril (r1 = 1,78; r2 = 0,40). Die Berechnung der Q-und e-Werte bzw. der q- und ϵ-Werte ergab fur Acrolein: Q = 0,64; e = 0,61; q = -2,8 kcal/Mol; ϵ = 0,19 = 10−10 elektrostatische Einheiten und fur Methacrolein: Q = 1,59; e = 0,36; q = −3,4 kcal/Mol; ϵ = 0,11 = 10−10 elektrostatische Einheiten. The copolymerisation of acrolein and m…
Reaktivitäut und reaktionswege von methylsubstituierten bisindolylcarbenium-ionen
1987
Methyl substituted bisindolylcarbenium ions 1 react with some O- and C-nucleophiles regioselectively. The cations 1b, 1c yield with hydroxide ions the tetraindolyldimethyl ether 4 and with methoxide ions the bisin-dolylmethoxymethanes 5. Compounds 1a, 1b, 1c react with several methylindoles to isomeric bis- and trisin-dolylmethanes. An electrophilic reactivity order of cations 1 can be derived supporting on the experimental results.
Preparation, reactivity and tautomeric preferences of novel (1H-quinolin-2-ylidene)propan-2-ones
2006
1,1-Difluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1a, 1,1,1-trifluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1b, 1,1,1-trifluoro-3-(4-chloro-1H-quinolin-2-ylidene)propan-2-one 1c and 1,3-dibromo-1,1-difluoro-3-(2-quinolyl)propan-2-one 2 are prepared and characterized by various spectroscopic techniques. The crystal structure of 1a is determined by X-ray diffraction. Furthermore, a series of previously known non-halogenated (1H-quinolin-2-ylidene)propan-2-ones 1d-1h are oxidized with AgBrO3 in the presence of AlCl3. In all cases, 2-(1-bromo-1-chloromethyl)quinoline 3 is obtained in high yield. The bromination order and sites of 1a are analyzed based on ab initio MP2 and DFT calculations for …
1983
The kinetics of the electrophilic bromination of 17 oligonuclear phenolic compounds with molecular bromine in acetic acid were studied at 22°C. Some of these compounds, consisting of up to 6 phenolic units, which are linked in ortho-position by methylene bridges, and having only one (or two) reactive ortho-position(s) at the end of the molecule, were synthesized for the first time. It could be shown, even for hexanuclear compounds, that the variation of substituents at one end of the molecule leads to a change in the reactivity at the other end, that means over a distance of 22 nonconjugated covalent links. So far, this can be explained only by a chain of intramolecular hydrogen bonds betwe…
1972
ChemInform Abstract: Heterocycles from α-Aminonitriles
2014
Owing to their various modes of reactivity, α-aminonitriles represent versatile building blocks for the construction of a wide range of nitrogen heterocycles. The present Concept article focuses on synthetic methodologies using their bifunctional nature which is the basis of their reactivity as α-amino carbanions and as iminium ions. Reactions exclusively taking place on either the amine or on the nitrile moiety will not be considered.
Azomethin-imine durch Umsetzung von Diphenylketen mit Azodicarbonsäureestern
1981
Die Umsetzung von Diphenylketen mit Azodicarbonsaureester fuhrt zu den Azomethin-iminen 4, die 1,3-dipolare Reaktivitat zeigen: Addition von Diphenylketen liefert das Addukt 8, von Phenylisocyanat ergibt 7 und Dimerisierung fuhrt zu 5. Azomethine Imines by Reaction of Diphenylketene with Azodicarboxylates1) The reaction of diphenylketene with azodicarboxylates yields azomethine imines 4 which show 1,3-dipolaric reactivity: addition of diphenylketene yields the 2:1-adduct 8, addition of phenyl-isocyanate produces 7, and dimerization leads to 5.
Synthesis, Characterisation, and Reactivity of 1-(1-Methylimidazol-2-yl)ethenes
1990
Abstract Thermally labile 1-(1-methylimidazol-2-yl)-ethenes, synthesised using the Wittig reaction, have been characterised as stable picrate or N-phenacyl salts. The free bases can be regenerated from the picrates on treatment with triethylamine and their reactivity with dienophiles is described.
Highly Enantio- and Diastereoselective Inverse Electron Demand Hetero-Diels-Alder Reaction using 2-Alkenoylpyridine N-Oxides as Oxo-Heterodienes
2008
A general catalytic inverse electron demand hetero-Diels Alder reaction for 2-alkenoylpyridine N-oxides is presented. 2-Alkenoylpyridine N-oxides react very efficiently with alkenes in the presence of bisoxazolidine-copper(II) [BOX-Cu(II)] complexes to give chiral dihydropyrans bearing a pyridine ring at the 6-position with very high yields and excellent diastereo- and enantioselectivity. These heterodienes exhibited higher reactivity and enantioselectivity than the corresponding non-oxidized 2-alkenoylpyridines.
ChemInform Abstract: Fluorous TBAF: A Convenient and Selective Reagent for Fluoride-Mediated Deprotections.
2010
A fluorous analogue of TBAF has been developed for its use in the clean removal of silicon-derived protecting groups. Purification of the crude mixtures by fluorous solid-phase extractions allowed alcohols, amines, and carboxylic acids to be obtained in high purity, with no need of chromatographic separations. The moderate reactivity of fluorous TBAF was exploited in selective deprotections of several bifunctional molecules.