Aromatic hydrocarbon

About: Aromatic hydrocarbon is a research topic. Over the lifetime, 5814 publications have been published within this topic receiving 55499 citations. The topic is also known as: arene & arenes.

Preparation of ethylene copolymers in fluid bed reactor

Abstract: Ethylene copolymers having a density of ≧0.91 to ≦0.96 and a melt flow ratio of ≧22 to ≦32 are readily produced in a low pressure gas phase process at a productivity of ≧50,000 pounds of polymer per pound of Ti with a particulate catalyst diluted with an inert carrier material and formed from selected organo aluminum compounds and a precursor composition of the formula: Mg.sub.m Ti.sub.1 (OR).sub.n X.sub.p [ED].sub.q wherein ED is a selected electron donor compound. m is ≧0.5 to ≦56 n is 0 or 1 p is ≧6 to ≦116 q is ≧2 to ≦85 R is a C 1 to C 14 aliphatic or aromatic hydrocarbon radical, or COR' wherein R' is a C 1 to C 14 aliphatic or aromatic hydrocarbon radical, and X is selected from the group consisting of Cl, Br, I, or mixtures thereof.

Electron-transfer and complex formation in the excited state

Abstract: FLUORESCENCEt Some years ago, while investigating fluorescence quenching of aromatic hydrocarbons (A) by typical electron donors (D), like anilines, we observed1 a broad structureless emission band about 5000 cm1 to the red of the fluorescence of the aromatic hydrocarbon of normal structure. This anomalous fluorescence, as shown in Figure 1, increases in intensity with increasing donor concentration at the expense of the fluorescence intensity of the hydrocarbon, thereby following the same Stern—Volmer-type relation as does the well known excimer fluorescence, e.g. in the case of pyrene2. Extrapolation to infinite donor concentration gives the dashed spectrum (cf. Figure 1) which

Stimulating the anaerobic degradation of aromatic hydrocarbons in contaminated sediments by providing an electrode as the electron acceptor.

Abstract: The possibility that electrodes might serve as an electron acceptor to simulate the degradation of aromatic hydrocarbons in anaerobic contaminated sediments was investigated. Initial studies with Geobacter metallireducens demonstrated that although toluene was rapidly adsorbed onto the graphite electrodes it was rapidly oxidized to carbon dioxide with the electrode serving as the sole electron acceptor. Providing graphite electrodes as an electron acceptor in hydrocarbon-contaminated sediments significantly stimulated the removal of added toluene and benzene. Rates of toluene and benzene removal accelerated with continued additions of toluene and benzene. [(14)C]-Toluene and [(14)C]-benzene were quantitatively recovered as [(14)C]-CO(2), demonstrating that even though the graphite adsorbed toluene and benzene they were degraded. Introducing an electrode as an electron acceptor also accelerated the loss of added naphthalene and [(14)C]-naphthalene was converted to [(14)C]-CO(2). The results suggest that graphite electrodes can serve as an electron acceptor for the degradation of aromatic hydrocarbon contaminants in sediments, co-localizing the contaminants, the degradative organisms and the electron acceptor. Once in position, they provide a permanent, low-maintenance source of electron acceptor. Thus, graphite electrodes may offer an attractive alternative for enhancing contaminant degradation in anoxic environments.

Reaction mechanisms in aromatic hydrocarbon formation involving the C5H5 cyclopentadienyl moiety

Abstract: The quantum chemical BAC-MP4 and BAC-MP2 methods have been used to investigate the reaction mechanisms leading to polycyclic aromatic hydrocarbon (PAH) ring formation. In particular we have determined the elementary reaction steps in the conversion of two cyclopentadienyl radicals to naphthalene. This reaction mechanism is shown to be an extension of the mechanism occurring in the H atomassisted conversion of fulvene to benzene. The net reaction involves the formation of dihydrofulvalene, which eliminates a hydrogen atom and then rearranges to form naphthalene through a series of ring closures and openings. The importance of forming the -CR(·)-CHR-CR′=CR″- moiety, which can undergo rearrangement to form three-carbon atom ring structures, is illustrated with the C4H7 system. The ability of hydrogen atoms to migrate around the cyclopentadienyl moiety is illustrated both for methyl-cyclopentadiene, C5H5CH3, and dihydrofulvalene, C5H5C5H5, as well as for their radical species, C6H7 and C5H5C5H4. The mobility of hydrogen in the cyclopentadienyl moiety plays an important role both in providing resonance-stabilized radical products and in creating the -CR(·) CHR-CR′=CR″- moiety for ring formation. The results illustrate the radical pathway for converting five-membered rings to aromatic six-membered rings. Furthermore, the results indicate the important catalytic role of H atoms in the aromatic ring formation process.