Polynuclear aromatic halides

Very few examples of vinyl substitution with polynuclear aromatic halides have been reported but indications are that they generally react like the halobenzenes. 

A number of biaryl and polynuclear aromatic halides have been electroreduced. Some of these reactions are discussed in a later section (III.B. 10) in connection with the practical problem of detoxification of hazardous chemicals. 

Aryl halides and other simple aromatic hydrocarbons give a deep-orange to dark-red color or precipitate. Polynuclear aromatic hydrocarbons, such as naphthalenes and anthracenes, give brown colors. Aliphatic hydrocarbons give no color, or at most a light yellow tint. 

The isomerization of liquid paraffins such as pentane and hexane proceeds also in the presence of aluminum halides-hydrogen halides. This isomerization, however, is always accompanied by decomposition. It was found that the decomposition can be inhibited by the presence of various substances such as hydrogen, cyclohexane, aromatic mono- and polynuclear hydrocarbons, isobutane, etc. In the case of heptanes and higher molecular weight alkanes the use of hydrogen was not successful in inhibiting the cracking reaction. 

In many cases, the smoke is finely dispersed carbon. It is known from petrochemistry that carbonization of linear hydrocarbons follows the sequence linear hydrocarbon, branched hydrocarbon, cyclic hydrocarbon, aromatization, polynuclear hydrocarbons, char or graphite. In addition, enhanced char formation occurs on addition of halogens, which act as free radical transfer agents, and thus promote branching and cyclization. Since aromatization occurs more readily in the presence of double bonds, halide... 

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