As oil supplies dwindle, there is a growing
need to develop new routes to chemical intermediates that
utilize alternative feedstocks. We report here a synthesis of
para-xylene, one of the highest volume chemicals derived
from petroleum, using only ethylene as a feedstock.
Ethylene is an attractive alternative feedstock, as it can be
derived from renewable biomass resources or harnessed
from large domestic shale gas deposits. The synthesis relies
on the conversion of hexene (from trimerization of
ethylene) to 2,4-hexadiene followed by a Diels−Alder
reaction with ethylene to form 3,6-dimethylcyclohexene.
This monoene is readily dehydrogenated to para-xylene
uncontaminated by the ortho and meta isomers. We report
here a selective synthesis of para-xylene, uncontaminated
by the ortho or meta isomers, using ethylene as the sole
feedstock.