Oxidation, anthracene

It may be mentioned briefly that also for other catalytic oxidations, e.g., for those of ethylene and of anthracene, multicomponent catalysts proved to be very effective. For the anthracene oxidation, the following... 

Activation energies and pre-exponential factors for the first-order rate coefficients for anthracene oxidation... 

Figure 8 Schematic representation of binding interactions of aiene oxides at the H site of GST A, (4R,5S -benzo[a]pyrene oxide B, (5S,6R)-benzo[a]anthracene oxide C, (4R,5S)-pyiene oxide D, (7S)-styrene oxide, and E, (7R)-styrene oxide. (Taken from Dostal et al., 1986.)...

While the overall reaction of anthracene oxidation to form anthra-quinone as shown above involves the interaction of three atoms of oxygen per molecule of hydrocarbon, the actual mechanism of the catalysis is more or less obscure. From the observations of Senseman and Nelson86 the vanadium oxide catalysts function by being alternately reduced to a lower oxide by the hydrocarbon and oxidized to the pentoxide by the oxygen of the air used. Thus ... 

Electra-organic synthesis Chlorination of substituted naphthalenes. Toluene and aromatic hydrocarbon oxidation using Ce as a redoxmediator. Anthracene oxidation to anthraquinone using Mn as the redox medi ator. Forsyth et al. (1987) Pletcher Valdez (1988a,b) Chou etal. (1992)... 

The optically active benz[a]anthracene oxides (89) and (90) have been synthesized. Thermal recemization (at 293-322 K, in CDCI3) of the chiral chrysene 3,4-oxide (91) has been shown to occur via first-order kinetics, with an activation energy of 25.2 kcal mol" The results are consistent with a reaction mechanism involving an oxepine intermediate (92), as predicted by theory. 

The increasing importance of electron-transfer reactions with increasing aromatic hydrocarbon size is illustrated in the reaction of bromine with various aromatic compounds. With benzene (with a Lewis acid) and with naphthalene, electrophilic substitution occurs, and with anthracene, oxidative addition occurs (6) however, with graphite, only oxidation to the exclusion of carbon-bromine bond formation occurs, even at a stoichiometry of C8Br (II, 12). 

Methylnaphthalene is commonly used as a feedstock in the production of vitamia K3 (menadione). Methylnaphthalene is oxidized to menadione with chromic or nitric acid, in a similar method to anthracene oxidation. Menadione is used as an intermediate in the production of vitamin Ki.To produce vitamin Ki, menadione is reduced with hydrogen on Pd/activated-carbon catalysts to mena-diol. Esterification of the two hydroxyl groups with acetic anhydride yields mena-diol diacetate, which is converted into the 1-monoacetate with ammonia. Vitamin Ki (phytomenadione) is produced by the reaction of 1-menadiol monoacetate with phytol, using a BF3/ether complex as catalyst, followed by hydrolysis and dehydrogenation. 

Because of adequate availability of anthracene, oxidation is preferred to synthesis, but the latter can, however, be advantageous when substitution is required in specific positions. 

Technically-pure anthracene, containing around 95%, is used as feedstock for anthracene oxidation it is vaporized with the injection of steam and pre-heated... 

SCHEME 14.7 Anthracene oxidation via electron transfer-oxygenation mechanism (Elaborated from Ref. [38]). 

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