Hydrogenation polycyclic aromatics

Raney nickel and platinum, palladium, and rhodium catalysts have been used to accomplish the hydrogenation of polycyclic aromatics. Hydrogenation of fused polycyclic arenes leads to the cis- or fran -substituted cyclohexane derivatives. The cis product is usually obtained again this can be understood in terms of the mechanism proposed for aromatic hydrogenation (vide supra). 

Naphthalene and other polycyclic aromatic hydrocarbons show many of the chemical properties associated with aromaticity. Thus, measurement of its heat of hydrogenation shows an aromatic stabilization energy of approximately 250 kj/mol (60 kcal/mol). Furthermore, naphthalene reacts slowly with electrophiles such as Br2 to give substitution products rather than double-bond addition products. 

Major unknowns in the mechanism by which a hydrocarbon fuel bums concern the pyrosynthesis reactions that lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot and the oxidation chemistry of atoms other than carbon and hydrogen (heteroatoms) in the fuel, particularly nitrogen, sulfur, and halogens. 

Most often, these radicals are unstable and can exist only while adsorbed on the electrode, although in the case of polycyclic aromatic compounds (e.g., the derivatives of anthracene), they are more stable and can exist even in the solution. The radicals formed first can undergo a variety of chemical or electrochemical reactions. This reaction type is the analog of hydrogen evolution, where electron transfer as the first step produces an adsorbed hydrogen atom, which is also a radical-type product. 

Jacinto, M.J., Santos, O., Landers, R., Kiyohara, P.K. and Rossi, L.M. (2009) On the catalytic hydrogenation of polycyclic aromatic hydrocarbons into less toxic compounds by a facile recoverable catalyst. Applied Catalysis B Environmental, 90 (3-4), 688-692. 

Ortiz Leon, M. Velasco, L., and Vazquez-Duhalt, R., Biocatalytic Oxidation of Polycyclic Aromatic-Hydrocarbons by Hemoglobin and Hydrogen-Peroxide. Biochemical and Biophysical Research Communications, 1995. 215(3) pp. 968-973. 

Peroxyoxalate-based CL reactions are related to the hydrogen peroxide oxidation of an aryl oxalate ester, producing a high-energy intermediate. This intermediate (l,2-dioxetane-3,4-dione) forms, in the presence of a fluorophore, a charge transfer complex that dissociates to yield an excited-state fluorophore, which then emits. This type of CL reaction can be used to determine hydrogen peroxide or fluorophores including polycyclic aromatic hydrocarbons, dansyl- or fluores-camine-labeled analytes, or, indirectly, nonfluorescers that are easily oxidized (e.g., sulfite, nitrite) and quench the emission. The most widely used oxalate... 

Pure substance RMs pesticides with quoted purities, polycyclic aromatic hydrocarbons with quoted purities and potassium hydrogen phthalate with a quoted purity. 

The UV spectrum (7max 210, 231, 280, and 470 nm) of granulatimide (374), indicated the presence of a polycyclic aromatic framework. The IR spectrum indicated the presence of NH and amide carbonyl groups at v ax 3246 and 1698 cm , respectively. Comparison of the HRFABMS of didemnimide A (373) with that of granulatimide (374) indicated a difference of two hydrogen atoms. The H-NMR... 

All 60 C-atoms of Cjq are incorporated in the CgoHjo polycyclic aromatic hydrocarbon (PAH) 6, for which an efficient synthesis was developed [153], Laser irradiation of 6 at 337 nm induces hydrogen loss and the formation of CgQ, as detected by mass spectrometry (Scheme 1.6). Control experiments with C-labeled material and with the C48H24 homologue of 6 verified that the C50 is formed by a molecular transformation directly from the C50H30 PAH and not by fragmentation and recombination in the gas phase. 

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