Hydrogenation, catalytic aromatic hydrocarbons

The y -phenylenediamiaes are easily obtained by dinitrating, followed by catalyticaHy hydrogenating, an aromatic hydrocarbon. Thus, the toluenediamiaes are manufactured by nitrating toluene with a mixture of sulfuric acid, nitric acid, and 23% water at 330°C which first produces a mixture (60 40) of the ortho and para mononitrotoluenes. Further nitration produces the 80 20 mixture of 2,4- and 2,6-dinitrotoluene. Catalytic hydrogenation produces the commercial mixture of diamiaes which, when converted to diisocyanates, are widely used ia the production of polyurethanes (see Amines, aromatic, DIAMINOTOLUENES) (22). 

S. Siegel and N. Garti, The effect of pressure on the catalytic hydrogenation of aromatic hydrocarbons on rhodium, in Catalysis in Organic Syntheses 1977 (G.V Smith, ed.). Academic Press, New York, 1977, p. 9. 

The cyclo-paraffins, with the exception of cyclopropane, which behaves as an unsaturated hydrocarbon toward bromine (but not towards KMnOi), are similar in reactions to the normal paraffins. This class of compounds is becoming of increasing importance because of the develojjment of the catalytic nickel method for the hydrogenation of aromatic hydrocarbons. 

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. 

Acyl chlorides, Aromatic hydrocarbons EfFenberger, F. et al., Angew. Chem. (Intern. Ed.), 1972, 11, 300 Addition of catalytic amounts (1%) of the acid (stronger even than perchloric acid) to mixtures of acyl chlorides and aromatic hydrocarbons causes more or less violent evolution of hydrogen chloride, depending on the reactivity of the Friedel-Crafts components. 

Aroflning A process for removing aromatic hydrocarbons from petroleum fractions by catalytic hydrogenation to naphthenes. Developed by Labofina, France, and licensed by Howe-Baker Engineers. 

Aromatic hydrocarbons with side chains containing double bonds can be easily reduced by catalytic hydrogenation regardless of whether the bonds are isolated or conjugated. Double bonds are saturated before the aromatic ring is reduced. Hydrogenation of styrene to ethylbenzene is one of the fastest catalytic hydrogenations [14],... 

Catalytic hydrogenation over Raney nickel converted benzenesulfonates of both alcohols and phenols to parent hydroxy compounds, benzene and nickel sulfide. p-Toluenesulfonates of alcohols are reduced similarly while p-tolu-enesulfonates of phenols gave nickel p-toluenesulfinates and aromatic hydrocarbons. The yields of the hydroxy compounds range from 25 to 96% [698]. 

Catalytic reforming92-94 of naphthas occurs by way of carbocationic processes that permit skeletal rearrangement of alkanes and cycloalkanes, a conversion not possible in thermal reforming, which takes place via free radicals. Furthermore, dehydrocyclization of alkanes to aromatic hydrocarbons, the most important transformation in catalytic reforming, also involves carbocations and does not occur thermally. In addition to octane enhancement, catalytic reforming is an important source of aromatics (see BTX processing in Section 2.5.2) and hydrogen. It can also yield isobutane to be used in alkylation. 

The addition of hydrogen across multiple bonds is one of the most widely studied of catalytic reactions. Alkenes and alkynes, as well as di- and polyunsaturated systems can all be hydrogenated, provided the suitable experimental conditions are used. Studies on the ways in which these compounds react with hydrogen have revealed very complex reaction patterns. Because of their resonance stabilization, carbocyc-lic aromatic hydrocarbons are more difficult to hydrogenate than are other unsaturated compounds. 

In contrast to the aforementioned binary oxides, V2Os has a stronger oxidation power and is able to attack hydrogen attached to the aromatic nucleus. Sometimes attention is drawn to the importance of a layer structure in the catalyst or to geometric factors (e.g. Sachtler [270]). Unexpectedly, however, very effective vanadium-based catalysts exist which operate in the molten state, indicating that a fixed structure is not important. The catalytic activity of molten oxide phases seems to occur exclusively in the oxidation of aromatic hydrocarbons over V2Os-based catalysts, such systems have not been reported for the selective oxidation of olefins. 

Catalytic dehydrocyclisation. This is a reaction in which an alkane is converted into an aromatic hydrocarbon and hydrogen, for example,... 

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