Anthracene partial hydrogenation

Anthracene and phenanthrene are converted to their 9,10-dihydro derivatives in high yield. Other partially hydrogenated intermediates formed by further stepwise hydrogen addition can also be isolated under suitable experimental conditions.10 18 Platinum and palladium exhibit different selectivities in the partial hydrogenation of polycyclic aromatics under mild conditions 108... 

It was found that the Et3SiH and boron trifluoride monohydrate (a strong acid compatible with Et3SiH) ionic hydrogenation system produces partially hydrogenated anthracene [Eq. (11.77)] and naphthacene in excellent yield under mild conditions 240... 

Almost exclusive formation of the corresponding tetrahydro derivatives in the partial hydrogenation of naphthalene and anthracene are observed with all-cw addition of the hydrogens. 

Feedstocks - The vapors from the carbonization of a bituminous, low-rank coal, an anthracene oil, and a coal extract in anthracene oil were diluted with nitrogen and cracked their product yields were compared with those from the cracking of a partially hydrogenated anthracene oil and coal extracts hydrogenated to various extents. The coal was Linby (National Coal... 

Four model compounds, n-undecane, tetralin, cis/trans decalin and mesitylene, and a natural gas condensate from the North Sea were also cracked. Analyses and the reference code key of the coal-based feedstocks and the gas condensate are given in Table 1. Paraffin, naphthene, and aromatic-type analyses were calculated from gas chromatographic analyses of the partially hydrogenated anthracene oil and gas condensate whereas, mass spectrometric analysis was performed on the two coal extract hydrogenates and their further hydrogenated products. 

The yields from the partially hydrogenated anthracene oil (Cl), also given in Table 2, are relatively low, little more than 10% BTX and ethylene being obtained. 

Feedstock Linby coal A Anthracene Oil Extract of Linby coal B Anthracene oil C Partially hydrogenated anthracene oil Cl... 

Even cyclophanes containing large aromatic units such as pyrene, anthracene, or benzophenanthrene units or partially hydrogenated annulated systems can easily be desulfurized via sulfone pyrolysis, as Staab et al. have shown in a series of works on such compounds [49 53],... 

With nickel(II) 2-ethylhexanoate and triethylaluminum, tetralin (59) is obtained by hydrogenation of naphthalene (55). Polycyclic aromatics, such as anthracene (57 equation 8), 9-methylanthracene and 9-trifluoroacetylanthracene, are partially hydrogenated to 1,2,3,4-tetrahydroanthracene derivatives by use of [Rh(DPPE)(arene)]+ in methanol and by ruthenium hydride complexes having triphenylphosphine ligands... 

Partial hydrogenation of aromatic rings can also be accomplished with catalysts such as [Co2(CO)g] under an atmosphere of carbon monoxide and hydrogen, but the isolated benzene nucleus cannot be re-duced. ° Anthracene (57), naphthacene, perylene (61) and pyrene (63) are converted to 9,10-dihydroan-thracene (60), 5,12-dihydronaphthacene, 1,2,3,10,11,12-hexahydroperylene (62) and 4,5-dihydropyrene (64), respectively. 

In the partial hydrogenation of benz[a]anthracene (35) palladium promotes the regioselective production of the internally saturated dihydroarene, 36, while a platinum catalyst saturates a terminal ring to give the tetrahydroarene, 37, as... 

Partial hydrogenation of benzene to cyclohexene is possible on supported Ru catalyst, or on an unsupported Ru catalyst poisonned by FeCl3, FeS04, TiC, or O-i-Ruthenium catalysts allow selective reduction of anthracene derivatives bridged by a... 

This new zeolite-catalyzed ring-shift isomerization could provide a new route to anthracene and its derivatives [Song, 1996], which are valuable chemicals in demand, from phenanthrene, which is rich in liquids from coal. Selective partial hydrogenation of phenanthrene would be needed as the first step. Possible applications of sym-OHAn include the manufacturing of anthracene (for dyestuffs and fine chemicals), anthraquinone (pulping agent), and pyromellitic dianhydride (the monomer for polyimides such as Du Pont s Kapton) [Song and Schol rt, 1993]. Fundamental research is needed to clarify the mechanisms and reaction pathways. 

Hypervalent iodine species were demonstrated to have a pronounced catalytic effect on the metalloporphyrin-mediated oxygenations of aromatic hydrocarbons [93]. In particular, the oxidation of anthracene (114) to anthraquinone (115) with Oxone readily occurs at room temperature in aqueous acetonitrile in the presence of 5-20 mol% of iodobenzene and 5 mol% of a water-soluble iron(llI)-porphyrin complex (116) (Scheme 4.57) [93]. 2-ferf-Butylanthracene and phenanthrene also can be oxygenated under similar conditions in the presence of 50 mol% of iodobenzene. The oxidation of styrene in the presence of 20 mol% of iodobenzene leads to a mixture of products of epoxidation and cleavage of the double bond. Partially hydrogenated aromatic hydrocarbons (e.g., 9,10-dihydroanthracene, 1,2,3,4-tetrahydronaphthalene... 

A particularly active catalyst for the hydrogenation of polycylic arenes has been generated from the anionic hydridoruthenium precatalyst in Figure 15.18, discovered by Grey and Fez. This system catalyzes the hydrogenation of antliracene to 1,2,3,4-tetrahydroanthracene under relatively mild conditions with a turnover frequency of > 50 h" and a turnover number of > 100 (Equation 15.96). Both anthracene and naphthalene are partially hydrogenated in the presence of tlais catalyst, but monocyclic arenes do not react. 

Naively, we might have anticipated that dehydration (Figure 9) of dideoxykohnkene (14) would afford a hydrocarbon 15 containing two anthracene and two benzene units. However, in the knowledge [7, 8] that partially hydrogenated polyacenes reshuffle their aromatic rings to maximise their resonance... 

Fused Systems.—Naphthalene and Derivatives. A new method of aromatization of partially hydrogenated aromatic hydrocarbons overcomes the difficulty of the competing Diels-Alder reaction of reactive arenes. The method is based on deprotonation-hydride elimination in which potassium fencholate (277) serves as the base and fenchone (278) as the hydride acceptor, catalytic amounts only of fencholate being required since it is regenerated in the aromatisation step. In this way, the conversion of 1,2-dihydronaphthalene into naphthalene and of 9,10-dihydroanthracene into anthracene proceeds almost quantitatively. 

The direct synthesis of anthraquinone from phthalic anhydride and benzene has been reported to proceed over zeolite Beta [50] in a shape selective manner. In a conventional anthraquinone synthesis, anthracene is used as a feedstock for oxidation. Once there is a shortage of it in the market, additional anthracene could be produced by isomerization of its isomer, viz. phenanthrene. This, however, is not possible by direct isomerization of the trinuclear aromatic system but involves the partially (symmetrically) hydrogenated species. Consequently, isomerization of symmetrical octahydrophenanthrene to symmetrical octahydro-anthracene was studied by Song and Moffatt [51]. As sketched in Figure 3, a high yield of symmetrical octahydroanthracene can be obtained over zeolite H-mordenite (ngj/nyy = 8) at 250 °C (liquid phase, decalin as solvent). These examples show that (shape selective) catalysis on zeolites is more and more expanding into the conversion of polycyclic aromatics, and we foresee continued interest and success in this field of zeolite catalysis. 

Catalytic hydrogenations over CojfCOjg (using Hj and CO) or with stoichiometric quantities of preformed hydridocarbonyl complex CoH(CO)4 are useful for the partial selective reductions of polycyclic aromatic compounds. Isolated benzene rings are not affected. Naphthalene is reduced to tetralin, at 200°C under a pressure of 20 X 10 kPa and anthracene to 9,10-dihydroanthracene (99%). The substituted phenanthrene nucleus is stable under these conditions as illustrated by hydrogenation of perylene 1 and pyrene 2. ... 

With polycyclic aromatic compounds, it is often possible, by varying the conditions, to obtain either partially or completely reduced products. Naphthalene can be converted into the tetrahydro or decahydro compound over Raney nickel depending on the temperature. With anthracene and phenanthrene, the 9,10-dihydro compounds are obtained by hydrogenation over copper chromite although, in general,... 

The acidic chloroaluminate IL [EMIMJCl-AlClj (5c = 0.67), combined with electropositive metals (Al, Zn, and li) and a proton source, has been applied to the stereoselective hydrogenation of aromatic compounds [62]. Anthracene, pyrene, and 9,10-dimethyIanfhracene were partially or completely hydrogenated, and the selectivity appears to be a function of the proton source. It was found, for example, that anthracene could be converted to dihydroanthracene in [EMIM]C1—AICI3 [x = 0.67) containing lithium and water, whereas in the presence of zinc and HCl gas complete hydrogenation was possible as shown in Scheme 2. 

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