Model aromatic compound hydrogenation

Hydrogenation of model aromatic compounds All the hydrogenation experiments were carried out in 500 cm capacity spinning/falling basket autoclaves manufactured by Baskerville Scientific Ltd. Detail of the autoclaves is provided elsewhere in this book (Harrison, Doughty and Ali). Apart from further experiments with phenanthrene, all the... 

Another possibility is based on a model of active sites proposed by Hubaut et al. (138), which derives from a previous investigation by the same group (139) (Fig. 40). In this model, the reactions involved in hydro-treating on Mo/Al catalysts are associated with the CUS configuration. Hydrogenation of aromatic compounds (toluene, pyridine, etc.) and isomerization of dienes require a or site, whereas sites... 

Despite the fact that synthetic peroxovanadium complexes do not model satisfactorily the active centre of the VHPOs in the sense outlined above, most of them are effective oxidants under mild conditions, or even catalysts for, or active intermediates in the catalysis of, oxygenation reactions using hydrogen peroxide as the oxo transfer agent. Examples of 0X0 transfer reactions to organic substrates carried out via peroxovanadium complexes -the hydroxylation of alkanes, alkenes and aromatic compounds by the picolinato complex 22 (Figure 4.21) - are depicted in Scheme 4.8. 

Zinc oxide, an inexpensive and commercially available inorganic solid, can be utilized as an efficient catalyst in the Friedel-Crafts acylation of activated and unactivated aromatic compounds with acyl chlorides at room temperature for 5 to 120 min (Table 4.14). Acylation is claimed to occur exclusively at the para-position of the monosubstituted aromatic compounds. The catalyst can be recovered and reused, after washing with methylene chloride, for at least two further cycles, showing quite similar high yield (-90%) in the model benzoylation of anisole. Mechanistically, it seems that zinc chloride can be the true catalyst, generated in situ by the reaction of zinc oxide with hydrogen chloride. 

The first model proposed for the drug monooxygenase stem in liver microsomes was described by Udenfnend et al. ) and since then referred to as the Udenfriend system . It consists of ferrous iron, EDTA and ascorbate which are incubated aerobically in an aqueous buffer of pH 5—8. Aromatic compounds were hydroxylated in this mixture to phenols and the substitution pattern pointed to an electrophilic mechanism. Breslow and Lukens argued that the Udenfriend system was not different from the Fenton stem since the autoxidation of ascorbate provides hydrogen peroxide, which by the reduction with ferrous ions forms hydroxyl radicals as hydroxylating agent ... 

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