Catalytic hydrogenation of naphthalene

Obtained by the catalytic hydrogenation of naphthalene. Owing to the presence of one aromatic ring it can be nitrated and sulphon-ated. It is non-toxic and is used as a solvent for fats, oils and resins. 

The catalytic hydrogenation of naphthalene produces 80.0 kcal/mol (335 kJ/mol) of heat. Calculate the resonance stabilization of naphthalene. Do you think naphthalene should be termed aromatic ... 

Catalytic hydrogenation of benzene under pressure by using Raney Ni as a catalyst results in the addition of three molar equivalents of hydrogen. First, benzene is converted into cyclohexadiene, which is reduced to cyclohexene. The hydrogenation of cyclohexadiene and cyclohexene is faster than the hydrogenation of benzene (aromatic compound). Similarly, catalytic hydrogenation of naphthalene in the presence of a Ni catalyst gives tetralin and then decalin. 

Naphthalene is reduced to 1,4-dihydronaphthalene by sodium and alcohol. Isomerization of this product to 3,4-dihydronaphthalene occurs with sodamide in liquid ammonia. Tetrahydronaphthalene (tetralin) is formed from naphthalene by sodium in amyl alcohol or by reduction with nickel-aluminum alloy and aqueous alkali. Catalytic hydrogenation of naphthalene can be stopped at the tetralin stage over copper chromite, Raney nickel, or alkali metal catalysts. cis-Decahydronaphthalene is produced by high-pressure hydrogenation of tetralin over Adams catalyst, whereas a mixture of cis- and trans-decalins is obtained from naphthalene under the same conditions. ... 

Catalytic hydrogenation of naphthalene over Pd-C results in rapid addition of 2 moles of H2. Propose a structure for this product. 

Tetrahydronaphthalene is produced by the catalytic treatment of naphthalene with hydrogen. Various processes have been used, eg, vapor-phase reactions at 101.3 kPa (1 atm) as well as higher pressure Hquid-phase hydrogenation where the conditions are dependent upon the particular catalyst used. Nickel or modified nickel catalysts generally are used commercially however, they are sensitive to sulfur, and only naphthalene that has very low sulfur levels can be used. Thus many naphthalene producers purify their product to remove the thionaphthene, which is the principal sulfur compound present. Sodium treatment and catalytic hydrodesulfuri2ation processes have been used for the removal of sulfur from naphthalene the latter treatment is preferred because of the ha2ardous nature of sodium treatment. 

Isopropylnaphthalenes can be prepared readily by the catalytic alkylation of naphthalene with propjiene. 2-lsopropylnaphthalene [2027-17-0] is an important intermediate used in the manufacture of 2-naphthol (see Naphthalenederivatives). The alkylation of naphthalene with propjiene, preferably in an inert solvent at 40—100°C with an aluminum chloride, hydrogen fluoride, or boron trifluoride—phosphoric acid catalyst, gives 90—95% wt % 2-isopropylnaphthalene however, a considerable amount of polyalkylate also is produced. Preferably, the propylation of naphthalene is carried out in the vapor phase in a continuous manner, over a phosphoric acid on kieselguhr catalyst under pressure at ca 220—250°C. The alkylate, which is low in di- and polyisopropylnaphthalenes, then is isomerized by recycling over the same catalyst at 240°C or by using aluminum chloride catalyst at 80°C. After distillation, a product containing >90 wt % 2-isopropylnaphthalene is obtained (47). 

Figure 1.1 Variations in catalytic activity as a function of the degree of leaching with NiAb (O) and C02AI9 ( ) (a) hydrogenation of cyclohexanone (1 ml) in f-BuOH (10 ml) at40°C and atmospheric hydrogen pressure over 0.08 g of catalytic metal (b) hydrogenation of naphthalene (3 g) to tetrahydronaphthalene in cyclohexane (10 ml) at 60°C and 8.5 1.5 MPa H2 over 0.08 g of catalytic metal (c) hydrogenation of benzene (15 ml) in cyclohexane (5 ml) at 80°C and 7.5 2.5 MPa H2 over 0.08 g of catalytic metal. (From Nishimura, S. Kawashima, M. Inoue, S. Takeoka, S. Shimizu, M. Takagi, Y.Appl. Catal. 1991, 76, 26. Reproduced with permission of Elsevier Science.)...

In the preparation of Ni/Hp catalysts by the deposition-precipitation method (DP), nickel hydrosilicates are formed mainly but not exclusively in the external surface of the Hp zeolite. The strong metal-support interaction induced by the DP preparation method prevents the Ni metal particles from sintering during the activation of the catalysts (calcination and reduction) and a homogeneous distribution of small nickel particles is obtained. The catalyst prepared by DP showed better catalytic activity in the hydrogenation of naphthalene than the catalyst prepared by cationic competitive exchange. 

Naphthalenes can be reduced by catalytic hydrogenation, either to the corresponding tetralins or the fully saturated decalins. The selectivity in partial saturation depends on both the substrate structure and the catalyst. The following order of selectivity for the hydrogenation of naphthalenes to decalins is observed for the noble metal catalysts14 ... 

Hydrogenation. Hydrated NiCl2 and Li with a catalytic amount of naphthalene form a reducing agent for alkenes and alkynes. ... 

Tetralin. ItitSrt Tetrahyclronaphthalene Tetransp. CioHu mol. wt. 132.20. C 90.85%, H 9.16%. Prepd. by catalytic hydrogenation of purified naphthalene. See ref. under Decalin. 

Eriedel-Crafts reaction of naphthalene or tetrahydronaphthalene derivatives with those of styrene or alkylbenzenes has been used in the preparation of high viscous fluids for traction drive (195). Similarly, Eriedel-Crafts reaction of tetraline and a-methylstyrene followed by catalytic hydrogenation provided l-(l-decalyl)-2-cyclohexyl propane, which is used as a highly heat resistant fluid (196). 

H-acid, l-hydroxy-3,6,8-ttisulfonic acid, which is one of the most important letter acids, is prepared as naphthalene is sulfonated with sulfuric acid to ttisulfonic acid. The product is then nitrated and neutralized with lime to produce the calcium salt of l-nitronaphthalene-3,6,8-ttisulfonic acid, which is then reduced to T-acid (Koch acid) with Fe and HCl modem processes use continuous catalytical hydrogenation with Ni catalyst. Hydrogenation has been performed in aqueous medium in the presence of Raney nickel or Raney Ni—Fe catalyst with a low catalyst consumption and better yield (51). Fusion of the T-acid with sodium hydroxide and neutralization with sulfuric acid yields H-acid. Azo dyes such as Direct Blue 15 [2429-74-5] (17) and Acid... 

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