A major disadvantage of the reforming
of naphtha is that the proportions of methylbenzene and dimethylbenzene
produced do not match the demands Ð there is too much methylbenzene,
and not enough dimethylbenzene.
Many sites therefore incorporate a disproportionation
plant, which converts methylbenzene into the dimethylbenzenes
All three isomers of dimethylbenzene are produced,
though it is the 1,4-dimethylbenzene isomer (shown in the equation)
that is most useful.