The most common reactions of<unk>  involve substitution of a proton<unk> y other groups. Electrophilic aromatic substitution is a general method of derivatizing<unk> .<unk>  is sufficiently nucleophilic that it undergoes substitution<unk> y acylium ions and alkyl carbocations to give substituted derivatives. :Electrophilic aromatic substitution of<unk>  The most widely practiced example of this reaction is the ethylation of<unk> . ::320 px Approximately 24,700,000 tons were produced in 1999. Highly instructive<unk> ut of far less industrial significance is the Friedel-Crafts alkylation of<unk>  (and many other aromatic rings) using an alkyl halide in the presence of a strong Lewis acid catalyst. Similarly, the Friedel-Crafts acylation is a related example of electrophilic aromatic substitution. The reaction involves the acylation of<unk>  (or many other aromatic rings) with an acyl chloride using a strong Lewis acid catalyst such as aluminium chloride or Iron(III) chloride. Friedel-Crafts alkylation of<unk> <unk> y acetyl chloride Sulfonation, chlorination, nitration Using electrophilic aromatic substitution, many functional groups are introduced onto the<unk>  framework. Sulfonation of<unk>  involves the use of oleum, a mixture of sulfuric acid with sulfur trioxide. Sulfonated<unk>  derivatives are useful detergents. In nitration,<unk>  reacts with nitronium ions (NO2+), which is a strong electrophile produced<unk> y combining sulfuric and nitric acids. Nitrobenzene is the precursor to aniline. Chlorination is achieved with chlorine to give chlorobenzene in the presence of a Lewis acid catalyst such as aluminium tri-chloride. Hydrogenation Via hydrogenation,<unk>  and its derivatives convert to cyclohexane and derivatives. This reaction is achieved<unk> y the use of high pressures of hydrogen in the presence of heterogeneous catalysts, such as finely divided nickel. Whereas alkenes can<unk> e hydrogenated near room temperatures,<unk>  and related compounds are more reluctant substrates, requiring temperatures >100 °C. This reaction is practiced on a large scale industrially. In the absence of the catalyst,<unk>  is impervious to hydrogen. Hydrogenation cannot<unk> e stopped to give cyclohexene or cyclohexadienes as these are superior substrates.<unk> irch reduction, a non catalytic process, however selectively hydrogenates<unk>  to the diene. Metal complexes<unk>  is an excellent ligand in the organometallic chemistry of low-valent metals. Important examples include the sandwich and half-sandwich complexes, respectively,RuCl2(C6H6)2.
Benzene
Nitrobenzene
Naphthalene
Vinyl chloride
Coal tar
Methanol
Alkylphenol
Triphenylchloroethylene