Search results for "Alko"
showing 10 items of 423 documents
The Reactions of Electron-Rich Heterocycles with Derivatives of Orthocarboxylic Acids; VIII. Proton Acid-Catalyzed Acylation of Indoles by 2-Alkoxy-1…
1987
In acid-catalyzed reactions with 3-unsubstituted indoles 1, 2-alkoxy-1,3-dioxolanes 2a-c behave as acyl equivalents. Depending on the substitution patterns of the reaction partners, the 1,3-dioxolanium ions 3a-c, generated in situ from the cyclic ortho esters by the action of sulfosalicylic acid, react to form tris-(3-indolyl)alkanes 6 and 9, bis-(3-indolyl)ethenes 7, or 3-benzoylindoles 8. Analogous reactivity was observed with related acyclic ortho esters. Reaktionen elektronenreicher Heterocyclen mit Orthocarbonsaure-Derivaten; VIII. Protonsaurekatalysierte Acylierung von Indolen mit 2-Alkoxy-1,3-dioxolanen 2-Alkoxy-1,3-dioxolane 2a-c reagieren als Acylaquivalente mit 3-unsubstituierten …
New sensing devices part 1: indole-containing polyamines supported in nanosized boehmite particles
2005
The synthesis, characterisation and optical properties of new sensing systems made by attaching different polyamine chains functionalised with an indole fluorophore to a boehmite matrix is reported for the first time. Firstly, a family of tri(alkoxy)alkylpolyaminosilanes have been reacted with indole-3-carboxaldehyde to form the corresponding Schiff bases which were reduced with sodium borohydride. The anchoring to the surface of the boehmite nanoparticles was carried out by reacting the precursors with the hydroxyl groups available in the surface of the support. The characterisation of the materials by elemental microanalysis, X-ray powder diffraction, CP-MAS 29Si NMR and electron microsco…
Veresterung und Veretherung sterisch gehinderter Kohlenhydrat‐Hydroxylfunktionen mit dem System Triphenylphosphan/Azodicarbonsäureester
1979
Die 6-0-Benzoyl-3-0-Benzyl-1,2-0-isopropyliden-α-D-glucofuranose (11) reagiert unter der Einwirkung von Azodicarbonsaure-diethylester (2) (DEAD) und Triphenylphosphan (1) mit p- Nitro benzoesaure, Benzoesaure, p-Toluolsulfonsaure- und Mesitylensulfonsaure-methylester sterisch nicht einheitlich. Es bildet sich das erwartete Substitutions-(L-ido)-Produkt (unter Inversion an C-5), aber daneben auch das D-gluco-Epimere; fur dessen Bildung wird ein Acylierungsmechanismus diskutiert. – Die Reaktion der 1,2:5,6-Di-O-isopropyliden α-D-glucofuranose(7) mit dem Reagenzsystem 1/2 und Arylsulfonsaure-methylesters bleibt auf der Alkoxyphosphoniumsalze 8 stehen. Durch Umsetzung mit Alkoholat erhalt man a…
Heterometallic Pentanuclear [Ni 4 Ln] (Ln III = Gd, Tb, Dy, Ho) Complexes: Accidental Orthogonality Leading to Ferromagnetic Interactions
2014
The reaction of 6-formyl-2-(hydroxymethyl)-4-methylphenol (LH2) with NiII and LnIII salts afforded a series of heterometallic pentanuclear compounds [Ni4Ln(L)4(OAc)2(MeOH)4](NO3)(MeOH) [LnIII = Gd (1), Dy (2), Tb (3), Ho (4)]. Four dianionic L2– ligands and two acetate anions hold together four NiII and one LnIII ion to form a Ni4Ln core possessing a distorted tetrahedral geometry. All the NiII ions are hexacoordinate (6 O) with a distorted octahedral geometry whereas the LnIII ion is octacoordinate (8 O) with a distorted square-antiprism geometry. All the NiII ions are connected to the central LnIII ion through μ2 bridging of one deprotonated phenolic oxygen and two deprotonated alkoxy oxy…
Triphenanthro‐anellierte [18]Annulene mit Alkoxy‐Seitenketten — Eine neue Klasse discotischer Flüssigkristalle
1994
Triphenanthro-Anellated [18]Annulenes with Alkoxy Side Chains - A Novel Class of Discotic Liquid Crystals Two different types 6 and 16 of [18]annulenes condensed with phenanthrene systems were prepared by cyclocondensation reactions (Schemes 2 and 3). The central 18-membered rings do not show a macrocyclic diamagnetic ring current. Conformational analyses and X-ray analyses in the solid state reveal non-planar structures in which aromatic “islands” are connected by (E)-configurated olefinic bridges. The introduction of long alkoxy side chains yields a new class of discotic liquid crystals; either ND or hexagonal columnar phases are generated, which were characterized by DSC, microscopy with…
Darstellung und Zerfall von tertiären Hyponitriten
1971
Dicumylhyponitrit (1a), substituierte Dicumylhyponitrite (1b1f) (p-Br, p-Cl, p-CH3, m-CH3, p-CH3O), Bis-[1.1-diphenyl-athyl]-hyponitrit (1h) und Bis-[1.1-dimethyl-pentyl]-hyponitrit (1g) wurden dargestellt. Die tertiaren Hyponitrite zerfallen bereits rasch bei-40 in Stickstoff und freie Alkoxyradikale, die dann zu den entsprechenden Alkoholen und Ketonen weiter reagieren. Die relativen Reaktivitaten von tert.-Butyloxy-und Cumyloxyradikalen hinsichtlich Wasserstoffabstraktion und β-Spaltung wurden fur verschiedene Losungsmittel bestimmt; Cumyloxyradikale neigen starker zur β-Spaltung als tert-Butyloxyradikale. Die freien Alkoxyradikale konnen Polymerisations- und Autoxydationsreaktionen init…
Photochemie elektronenreicher 1,3‐Distyrylbenzole
1988
Die 1,3-Distyrylbenzole 3 mit bis zu sieben Alkoxygruppen werden der oxidativen Photocyclisierung unterworfen. Bei der Bildung der Produkte 6, 7 und 8 konnen als Konkurrenz- bzw. Folgeprozesse die Abspaltung von Methanol (3bb 7bb, 3bf 7bf) und die Chinonoxidation (3cf 8) auftreten. Die eigensensiblisierte Erzeugung von Singulettsauerstoff kann bei 6bf zur Endoperoxidbildung fuhren (6bf 11). Photochemistry of Electron-Rich 1,3-Distyrylbenzenes The 1,3-distyrylbenzenes 3, containing up to seven alkoxy groups, are subjected to the oxidative photocyclization. Elimination of methanol (3bb 7bb, 3bf 7bf) and quinone oxidation can occur as competitive or consecutive reactons in the formation of the…
Novel route in the synthesis of MCM-41 containing framework aluminum and its characterization
1999
Abstract Mesoporous molecular sieve MCM-41 with incorporated structural aluminum (Al-MCM-41) was prepared by hydrolysis of a solution of tetraethoxysilane and aluminum isopropoxide in the presence of ammonia as a catalyst. This method provides Al-MCM-41 of different Si/Al ratios from 13 to 297 corresponding to 0.3–7 mol% Al within an hour. X-ray diffraction and nitrogen adsorption measurements showed that the Al-MCM-41 prepared by this method had a highly ordered structure of pore arrays. Most Al atoms in these samples were incorporated tetrahedrally in the MCM-41 structure, which gave rise to cationic sites in the framework.
Di-n-butyltin(IV)-catalyzed dimethyl carbonate synthesis from carbon dioxide and methanol: An in situ high pressure 119Sn{1H} NMR spectroscopic study
2011
The reactivity of five di-n-butyltin(IV) complexes, n-Bu2Sn(OR)(2) (1), n-Bu2SnO (3), [n-Bu2Sn(OR)](2)O (4), (n-Bu2SnO)(2)(CO2) (6) and (n-Bu2SnO)(6)[(n-Bu2SnOR)(2)(CO3)](2) (7) (R = CH3), with CO2, suggested as possible catalyst precursors and key-intermediates for the direct synthesis of dimethyl carbonate from carbon dioxide and methanol, has been investigated using high-pressure Sn-119{H-1} NMR (HP-NMR) spectroscopy. Four of the five precursors studied, i.e. 3, 4, 6 and 7 give rise to an identical Sn-119{H-1} NMR pattern which can be explicitly attributed to the fingerprint of the dimeric form of the 1-methoxy-3-methylcarbonatotetrabutyldistannoxane {5}(2). However, with 1, a new pair o…
2-Tetrahydrofurfuroxo-vanadium-(III) and -(IV) complexes. Synthesis, structures and reactivities of [V2Mg2(μ3,δ2-thffo)2(μ,δ2-thffo)4Cl4]· 2CH2Cl2 an…
1997
Vanadium complexes of 2-tetrahydrofurfuroxide (2-tetrahydrofurylmethoxide) (thffo) with the metal in oxidation state III and IV have been prepared and characterized. The reaction of [VCl3(thf)3] with 1.5 equivalents of [Mg(thffo)2] in tetrahydrofuran (thf) or CH2Cl2 led to the formation of [V2Mg2(µ3,η2-thffo)2(µ,η2-thffo)4Cl4]· 2CH2Cl21. Its structure consists of centrosymmetric tetranuclear molecules and CH2Cl2 of crystallization. Two Mg and two V atoms have distorted octahedral geometry and form a nearly regular Mg2V2 rhombus. The V · · · V distance is 3.266(2) A. The reaction of [VOCl2(thf)2] with Na(thffo) in thf yielded [V2(µ,η2-thffo)2Cl2O2] 2. Two VOCl units are linked by alkoxide ox…