Benzene, Toluene and Xylenes


Benzene is the fundamental building block of aromatic compounds. Benzene, Toluene and Xylenes are manufactured from fractions obtained from the distillation of oil and are used as intermediates in the production of a very wide range of chemicals as well as in petrol. They are amongst the most important organic chemicals.

Benzene

About half of the benzene that is manufactured is used to produce ethylbenzene, which in turn is used to make poly(phenylethene) (polystyrene). (1-methylethyl)benzene (cumene) accounts for another quarter, which is used to make phenol and propanone (acetone) which are converted, for example, into a wide range of polymers. Another important use is to make cyclohexane, which is used, in turn, to make hexanedioic acid (adipic acid) and caprolactam, essential intermediates in the manufacture of polyamides. Nitrobenzene is reduced to phenylamime (aniline) used to make azo dyes, methylene diphenyl diisocyanate (MDI) used to make polyurethanes and it is also used in the manufacture of the analgesic, paracetamol. Another use of benzene is in the manufacture of alkylbenzene sulfonates, important surfactants.

Methylbenzene (Toluene)

Over 50% of the methylbenzene (toluene) produced in the refinery is converted into benzene by dealkylation and disproportionation. Methylbenzene is also used to make TDI (toluene diisocyanate or methylbenzene diisocyanate), one of the reagents used to make polyurethanes. It is also widely used as solvent, for example, for alkyd polymers (resins) used in paintsو silicone sealant, chemical reactant, plastic, printing ink, adhesive, varnish and disinfectant and disinfectant. It can also be used to make foam and TNT.

Dimethyl benzenes (Xylenes)


The most widely used dimethyl benzene is 1,4-dimethylbenzene (p-xylene). It is oxidized to benzene-1,4-dicarboxylic acid (terephthalic acid) which reacts with ethane-1,2-diol (ethylene glycol) to form the monomer for the polyester, polyethylene terephthalate (PET).

1,2-Dimethylbenzene (o-xylene) is oxidized to benzene-1,2-dicarboxylic anhydride (phthalic anhydride) which is in turn converted into the esters of benzene-1,2-dicarboxylic acid, for example di-octylbenzene-1,2-dicarboxylate, which are used as plasticizers. It is also used to make alkyd resins.