Chemistry of Naphthalene

Naphthalene (1) is the largest single component of coal tar at 9% and this still remains a source, although it is also produced from petroleum fractions at high temperature. Not all positions on the naphthalene ring are equivalent and the numbering of the ring is as shown in structure 1. The positions 1 and 2 are also called the a- and ( -positions. 

There are many other fused systems, of which pyrene is a more complex example. An interesting system is the Cg carbon allotrope, buckminsterfullerene, which consists of 12 five- and 20 six-membered rings fused together to form the so-caiied buckyball . Many poiycyclic hydrocarbons are potent carcinogens. 

It is incorrect to show the aromatic jc-system in naphthalene with a circle in both rings. This representation of the ji-cloud applies only to six n-electrons. Although one ring of naphthalene has six 7T-electrons, the other has only four -electrons. 

Conversion of the acid into the acyl chloride and subsequent Friedel-Crafts cyclization is an alternative route to the tetralone. 

Finely divided palladium has the ability to adsorb large quantities of hydrogen and is used to catalyse both hydrogenation and dehydrogenation reactions. 

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An important reaction in the chemistry of naphthalenes is the Bucherer reaction,i.e. the conversion of naphthols 1 to naphthylamines 2 as well as the reverse reaction. The reaction is carried out in aqueous medium in the presence of catalytic amounts of a sulfite or bisulfite. Apart from very few exceptions it does not apply to benzene derivatives, which limits the scope of that reaction. 

In a study of the synthesis and chemistry of naphthalene-1,8-diboranes, dihydrodibenzoborepin 51 was prepared by reaction of boron tribromide with l,2-bis(2-trimethylsilanylphenyl)ethane 50, as shown in Equation (10) <2004JCD1254>. 

Sulfonation is of special importance in the chemistry of naphthalene because it gives access to the e/a-substituted naphthalenes, as shown in the next section. 

This chapter is concerned with the chemistry of quinoxalines unsubstituted in the heteroring, and it updates the chapter to be found in Simpson s monograph. For the most part substituents in positions 5, 6, 7, and 8 of the quinoxaline ring behave in a manner that is predictable by analogy with the chemistry of naphthalene. However this generalization is not entirely true, as is seen in the following discussion. 

With perylene, one might have expected either the C-3/C-q dimethyl dihydro isomer, in analogy to the known chemistry of naphthalene, or the C-2/C-3 dimethyl dihydro isomer because of steric constraints at C-q. Yet, the C-l/C-q dimethyl dihydro isomer was obtained overwhelmingly. This result is in accord with the prediction of Minsky et al. (10) that C-l bears the highest electron density (and once C-l picks up an alkyl group in the quench, only one regioisomer can be made). 

Quinoline and isoquinoline, the two possible structures in which a benzene ring is annelated to a pyridine ring, represent an opportunity to examine the effect of fusing one aromatic ring to another. Clearly, both the effect the benzene ring has on the reactivity of the pyridine ring, and vice versa, and comparisons with the chemistry of naphthalene must be made. Thus the regiose-lectivity of electrophilic substitution, which in naphthalene is faster at an a-position, is mirrored in quinoline/isoquinoline chemistry by substitution at 5-... 

Table 9.7 summarizes the most important processes of the industrial chemistry of naphthalene and its derivatives. 

The resonance energy of naphthalene is 255 kj moH. We can compare this with benzene, which has a resonance energy of 157 kJ mohh Effectively, naphthalene is less aromatic than benzene—although the MO theory is beyond the scope of this course, we can see that only one ring at a time can be fully Hiickel compliant with six i-electrons. The consequence for the chemistry of naphthalene is that electrophilic substitution is easier than for benzene—less resonance energy is lost in the initial step to form the Wheland intermediate, as one benzene ring will effectively remain intact and fully aromatic. Electrophilic substitution of naphthalene could, in principle, occur at either the 1- or 2-position. In most cases, we see only the kinetic product, which derives from substitution at the 1-position (Figure 12.43). 

N. Donaldson, The Chemistry and Technology of Naphthalene Compounds, Edward Arnold Pubhshers, London, 1958, pp. 455—473. 

With Orange I [574-69-6] (34) (Cl Acid Orange 20 Cl 14600) the naphthalene moiety was iatroduced to azo chemistry. Basacid Red 340 [1658-56-6] (35) (Cl Acid Red 88 Cl 15620) the first red azo dye of technical value was discovered by BASF ia 1876. Its previous name was Fast Red AV and it is stiU produced ia large amounts ia the United States because of its low cost and good dyeiag and fastness properties. This dye became the prototype of a large number of red azo dyes that were developed simultaneously with the iatroduction of new derivatives of naphthalene. 

The chemistry of dye intermediates maybe conveniendy divided into the chemistry of carbocycles, such as benzene and naphthalene, and the chemistry of heterocycles, such as pyridones and thiophenes. 

Chemistry and Technology of Naphthalene Compounds , E. Arnold, London (1958), 45 55) B.T. Fedoroff et al, Dictionary of Explosives, Ammunition, and Weapons (German Section) , PATR 2510 (1958), Ger 43 56)... 

Wolfe MD, JV Parales, DT Gibson, JD Lipscomb (2001) Single turnover chemistry and regulation of Oj activation by the oxygenase component of naphthalene 1,2-dioxygenase. J Biol Chem 276 1945-1953. 

FIGURE 8.8 Degradation of naphthalene. (From Neilson, A.H. and Allard, A.-S. The Handbook of Environmental Chemistry, Springer, 1998. With permission.)... 

Since Chatt and Davidson13 observed the first clear example of simple oxidative addition of a C—H bond of naphthalene to a ruthenium metal center, Ru(dmpe)2 (dmpe = Me2PCH2CH2PMe2), hydrocarbon activation has been the subject of many transition metal studies.11 c Sometimes, the efforts in this field have ended in findings different from the initial objectives, which have been the starting point for the development of novel organometallic chemistry. 

In another experiment, naphthalene-d8 was used to investigate the chemistry of hydrogen transfer between coal and nondonor solvent at 380°C. An analysis of the recovered naphthalene-d8 showed that approximately 4% of the hydrogen in the coal and in the naph-thalene-d8 exchanged. Most of the protium incorporated in the naphthalene-d8 was found in the a-position. The coal products contained approximately 2 wt % chemically-bound napththalene-d8. 

The main part of this research deals with the reaction of deuterium gas and Tetralin-d12 with a bituminous coal. In a separate experiment, naphthalene-d8 was used for investigating the chemistry of hydrogen transfer between coal and a nondonor solvent. In each experiment, the coal products and spent solvent were analyzed for toal deuterium content and for deuterium incorporation in each structural position. 

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. 

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