Search results for "Benzene"
showing 10 items of 1701 documents
Reibungsverhalten und Trägheitsradien von oligomeren Polypropylenglykolen
1971
Die Ergebnisse von Viskositats- und Diffusionsmessungen an oligomeren Propylenglykolen in Aceton und Benzol werden benutzt, um nach den verschiedenen Theorien die viskosimetrischen und Reibungstragheitsradien zu ermitteln. Ein Vergleich mit direkt durch Streuversuche mit der Rontgenkleinwinkelmethode gefundenen Tragheitsradien zeigt die Gultigkeit der klassischen Viskositatstheorien, wahrend die gleichen Theorien bei der Reibung versagen. Aus [f] = 16,4 · R erhalt man jedoch wie bei Hochpolymeren auch fur Oligomere vernunftige Tragheitsradien. Results of viscometric and frictional measurements on oligomeric propylene glycols in acetone and benzene have been used to calculate the values of v…
<title>Optically induced switching of dicyclohexylamino substituted azobenzene derivatives in thin ordered films</title>
2005
During the last years, there has been an increasing interest in the photoinduced switching effects. Among the objects of concern azobenzene derivatives, isomerizing under UV and visible light, occupy a prominent position. To understand the photoresponse of these materials in the condensed phase, their spectroscopic and electrical properties are studied. It is shown that the photoresponse depends on the orientation of the molecules and their packing. A number of novel azobenzene derivatives containing a N,N-dicyclohexyl sulfonamide moiety is synthesized. The derivatives differ in the length of alkyl chains between the azobenzene moiety and SH or COOH groups. The morphology and the photoinduc…
Die Wirksamkeit verschiedener peroxyde auf die mit Hilfe von Redox-Systemen beschleunigte Lösungspolymerisation von Styrol
1954
Verschiedene Diacylperoxyde, Hydroperoxyde, Dialkylperoxyde und Persaren werden als Komponenten von Eisen-Redox-Systemen zur Polymerisation von Styrol in Benzol bei 50° C benutzt. Die erzielten Umsatze werden mit denen bei peroxydischer Polymerisation verglichen. Bei bromhaltigen Peroxyden kann aus dem Bromgehalt der Polymeren auf die Zahl der eingebauten peroxydischen Bruchstucke geschlossen werden. Dabei Anwendung von Brombenzopersare kein Brom in den Polymeren nachzuweiseu ist, mus angenommen werden, das der Kettenstart durch OH-Radikale erfolgt. Different diacyl peroxides, hydroperoxides, dialkylperoxides and peracids are used as components of Fe··-redox-systems to polymerize styrene in…
Reversible, room-temperature C—C bond activation of benzene by an isolable metal complex
2019
The activation of C-C bonds is of fundamental interest in the construction of complex molecules from petrochemical feedstocks. In the case of the archetypal aromatic hydrocarbon benzene, C-C cleavage is thermodynamically disfavored, and is brought about only by transient highly reactive species generated in situ. Here we show that the oxidative addition of the C-C bond in benzene by an isolated metal complex is not only possible, but occurs at room temperature and reversibly at a single aluminium center in [(NON)Al]- (where NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene). Selectivity over C-H bond activation is achieved kinetically and allows for the generation…
Crystal structure of (E)-4-methoxy-2-{[(5-methylpyridin-2-yl)imino]methyl}phenol
2015
The molecule of the title Schiff base compound, C14H14N2O2, displays anEconformation with respect the imine C=N double bond. The molecule is approximately planar, with the dihedral angle formed by the planes of the pyridine and benzene rings being 5.72 (6)°. There is an intramolecular hydrogen bond involving the phenolic H and imine N atoms.
Crystal structures of isomeric 3,5-dichloro-N-(2,3-dimethylphenyl)benzenesulfonamide, 3,5-dichloro-N-(2,6-dimethylphenyl)benzenesulfonamide and 3,5-d…
2017
The crystal structures of three isomeric compounds of formula C14H13Cl2NO2S, namely 3,5-dichloro-N-(2,3-dimethylphenyl)-benzenesulfonamide (I), 3,5-dichloro-N-(2,6-dimethylphenyl)benzenesulfonamide (II) and 3,5-dichloro-N-(3,5-dimethylphenyl)benzenesulfonamide (III) are described. The molecules of all the three compounds are U-shaped with the two aromatic rings inclined at 41.3 (6)° in (I), 42.1 (2)° in (II) and 54.4 (3)° in (III). The molecular conformation of (II) is stabilized by intramolecular C—H...O hydrogen bonds and C—H...π interactions. The crystal structure of (I) features N—H...O hydrogen-bonded R 2 2(8) loops interconnected via C(7) chains of C—H...O interactions, forming a thre…
(E)-1-(1,3-Benzodioxol-5-yl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one
2017
The molecule of the title compound C19H18O6, adopts anEconformation about the C=C double bond and the C—C=C—C torsion angle is −179.30 (16)°. The molecule is nearly planar, as indicated by the dihedral angle of 6.99 (6)° between the benzene ring and the benzodioxalane ring. In the crystal, molecules are linkedviaweak C—H...O hydrogen bonds, forming zigzag chains propagating along thebaxis.
Cyclic esters of aliphatic diacids with pyrocatechol and hydroquinone
1985
Cyclic esters of adipic acid, suberic acid and sebacic acid were prepared by reaction of the acid dichlorides and pyrocatechol or hydroquinone in benzene under high dilution conditions. While only the cyclic dimers could be obtained from hydroquinone, pyrocatechol formed cyclic monomers as well as cyclic dimers (and also a cyclic dimer with succinic acid). The structure of all compounds was confirmed by1H-NMR- and mass spectra. The crystal structures of the pyrocatechol esters were determined by single crystal X-ray analysis.
Sorption Kinetics of Benzene and p-Xylene on Template Supported Synthesized Gallosilicates
1993
Adsorption equilibria and kinetics of benzene and p-xylene on microporous gallosilicates (Ga-MFI) were measured piezometrically to ascertain the role of Ga in the system and to compare it with Ga-free MFI structures. The intracrystalline mobility of benzene follows a diffusional mechanism throughout the entire concentration range with an energy of activation that considerably exceeds that for the Ga-free species (78 kJmol−1 and 26 kJmol−1, respectively). For p-xylene, the kinetics indicate the existence of three sorption states. Sorbing species become highly immobile at a pore filling of ca n > 4 molecules per unit cell, i.e. in the range of concentration where isotherm hysteresis occurs. T…
ChemInform Abstract: A Simple Procedure for the Oxidation of Alcohols Using [Bis(acetoxy)iodo]benzene and a Catalytic Amount of Bromide Ions in Ethyl…
2015
Primary and secondary benzylic alcohols and secondary aliphatic alcohols were oxidized to the corresponding aldehydes and ketones by using [bis(acetoxy)iodo]benzene (BAIB) and a catalytic amount of bromide ions, from tetrabutylammonium bromide or KBr, in ethyl acetate. The catalytic role of the bromide ions was also highlighted in the oxidation of primary aliphatic alcohols and secondary allylic alcohols carried out in the presence of 1 mol% TEMPO.