Alkane Dehydroaromatization

Project Details

As global demand for chemicals grows, so does that for aromatics, which constitute a large fraction of the major building blocks of the chemical industry. As petroleum is displaced by natural gas, and as decreased gasoline refining (in favor of diesel) limits production of aromatic by-product, the synthesis of aromatics from alkanes becomes increasingly attractive.

In work that has grown out of the alkane metathesis project, we have devised new methods by which n-alkanes can be "dehydroaromatized". First, we reported in 2011 that n-alkanes can be dehydroaromatized by pincer-iridium catalysts to alkylbenzes by successive dehydrogenation to linear trienes, which cyclize to cyclohexadienes that can be further dehydrogenated to aromatics. ¹ We have also developed a selective, economic synthesis of one of the most valuable aromatics, para-xylene, using ethylene as the sole feedstock. ² Ethylene can be trimerized to hexane, which can then be disproportionated to 2,4-hexadiene. The 2,4-hexadiene can then undergo a Diels-Alder reaction with ethylene, and subsequent dehydrogenation to para-xylene. We are continuing to explore the mechanisms of these processes and developing routes to addition valuable aromatic products.