Toluene (methylbenzene) is similar to benzene as a mononuclear aromatic,
but it is more active due to presence of the electron-donating
methyl group. However, toluene is much less useful than benzene
because it produces more polysubstituted products. Most of the toluene
extracted for chemical use is converted to benzene via dealkylation or
disproportionation. The rest is used to produce a limited number of petrochemicals.
The main reactions related to the chemical use of toluene
(other than conversion to benzene) are the oxidation of the methyl
substituent and the hydrogenation of the phenyl group. Electrophilic
substitution is limited to the nitration of toluene for producing mononitrotoluene
and dinitrotoluenes. These compounds are important synthetic
intermediates.
The 1994 U.S. toluene production (of all grades) was approximately
6.8 billion pounds. Hydrodealkylating toluene to benzene was the largest
end use in United States and West Europe, followed by solvent applications.