Halogenation of naphthalene

Problem 11.18 Account for (a) formation of the a-isomer in nitration and halogenation of naphthalene, (f>) formation of a-naphthalenesulfonic acid at 80°C and -naphthalcnesulfonic acid at 160°C. -4... 

There are few but very interesting examples in the literature concerning the synthesis of large molecules with functional groups. Shape-selective halogenation of naphthalene is claimed to proceed over non-acidic zeolites, e.g. the selective monochlorination in the liquid phase with zeolite KL [48], usually carried out with typical Lewis acid catalysts, and the oxyiodination on zeolite KX to 2-iodo and 2,6-diiodonaphthalene [49]. 

Nitration and halogenation of naphthalene occur almost exclusively in the 1-position. Chlorination or bromination takes place so readily that a Lewis acid is not required for catalysis. 

Nitration and halogenation of naphthalene take place almost exclusively in the a-position. Is this orientation of substitution what we might have expected ... 

Reactions other than those of the nucleophilic reactivity of alkyl sulfates iavolve reactions with hydrocarbons, thermal degradation, sulfonation, halogenation of the alkyl groups, and reduction of the sulfate groups. Aromatic hydrocarbons, eg, benzene and naphthalene, react with alkyl sulfates when cataly2ed by aluminum chloride to give Fhedel-Crafts-type alkylation product mixtures (59). Isobutane is readily alkylated by a dipropyl sulfate mixture from the reaction of propylene ia propane with sulfuric acid (60). 

Polychloiinated naphthalenes (PCNs) are halogenated aiomatic hydiocaibons that are no longer produced. They can be synthesized by the chlorination of naphthalene. The commercial products were graded and sold according to their chlorine content (wt %), and used as waxes and impregnants (for... 

The activated nickel powder is easily prepared by stirring a 1 2.3 mixture of NiL and lithium metal under argon with a catalytic amount of naphthalene (1(7 mole % based on nickel halide) at room temperature for 12 h in DME. The resulting black slurry slowly settles after stirring is stopped and the solvent can be removed via cannula if desired. Washing with fresh DME will remove the naphthalene as well as most of the lithium salts. For most of the nickel chemistry described below, these substances did not affect the reactions and hence they were not removed. The activated nickel slurries were found to undergo oxidative addition with a wide variety of aryl, vinyl, and many alkyl carbon halogen bonds. 

A different synthetic route involves halogenation (bromination, chlorination) of pyrene 77, which is thus converted to the tetrahalogen derivative. Oxidation with sulfuric acid to form a diperinaphthindandione with subsequent oxidation, once again in a sodium hydroxide solution [7], yields the tetra sodium salt of naphthalene tetracarboxylic acid 78 ... 

Halogenation of perimidines, perimidinones, and dihydroperimidines occurs at an ortho- or /) 7ra-position in the naphthalene system, that is, the 4-, 6-, 7-, 9-positions in the perimidine system, where the donor effects from the nitrogens operate <1981RCR816, 1995AQ151>. 

The synthesis of organozinc compounds by electrochemical processes from either low reactive halogenated substrates (alkyl chlorides) or pseudo-halogenated substrates (phenol derivatives, mesylates, triflates etc.) remains an important challenge. Indeed, as mentioned above, the use of electrolytic zinc prepared from the reduction of a metal halide or from zinc(II) ions does not appear to be a convenient method. However, recent work reported by Tokuda and coworkers would suggest that the electroreduction of a zinc(II) species in the presence of naphthalene leads to the formation of a very active zinc capable of reacting even with low reactive substrates (equation 23)11. 

In addition to oxidation and reduction reactions, naphthalene readily undergoes substitution reactions such as nitration, halogenation, sulfonation, and acylation to produce a variety of other substances, which are used in the manufacture of dyes, insecticides, organic solvents, and synthetic resins. The principal use of naphthalene is for the production of phthalic anhydride, CgbLO,. 

Substituents have considerable influence on emission characteristics of aromatic compounds. Heavy atom substituents tend to reduce the fluorescence quantum yield 4>f in favour of phosphorescence emission f. In halogen series the effect increases in the order F < Cl < Br < I. In Table 5.1 are recorded experimental data for halogen substituted Naphthalenes. 

The critical separation distance calculated from the quenching data was found to be 13 A which is of the same order as the van der Waals separation. The critical separation distance remained unchanged when halogen substituted naphthalenes were used. The halo-substitution is expected to increase T1A SoA transition probability in naphthalenes. Since oscillator strengths / (naphthalenes /(iodonaphthalenes) is as 1 1000, no increase in transfer efficiency is clear indication of the lack of dependence on the oscillator strength. 

Goldstein JA, Safe S. 1989. Mechanism of action and structure-activity relationships for the chlorinated dibenzo-p-dioxins and related compounds. In Kimbrough RD, Jensen AA, eds. Halogenated biphenyls, naphthalenes, dibenzodioxins and related compounds, 2nd ed. Amsterdam Elsevier Science Publishers B.V., 239-293. 

The halogen attacks the e-position to the tune of about 95%. XVI-2 Nitration of naphthalene... 

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