Terpenes are a class of lightly oxygenated organic compounds produced in large quantities in nature which are currently greatly underutilized. Global biogenic emissions of monoterpenes are estimated at around 100 million tonnes annually and by far the largest source of terpenes produced is crude sulfate turpentine, a by-product of the Kraft paper milling process. In an effort to simultaneously reduce waste and lower the use of non-renewable petroleum feedstocks, crude sulfate turpentine was investigated as a cheap and renewable feedstock for the production of terephthalic acid. This monomer used in the synthesis polyethylene terephthalate is currently produced from aerobic oxidation of para-xylene on a multi-million tonne scale annually. Due to the scale on which this commodity chemical is produced, replacing it with a biorenewable alternative would be both challenging and high-impacting. By using sustainable catalytic methods involving cheap and abundant reagents, the complex mixture of terpenes found in crude sulfate turpentine was initially transformed to a common aromatic intermediate, para-cymene, via ring opening and aromatisation steps. Oxidation was then carried out using a combination of transition metal salts with molecular oxygen from the air as the terminal oxidant to yield terephthalic acid. Through further optimization of the reactions it is hoped that this process can be developed in to a viable route to biorenewable commercial terephthalic acid.

Sustainable route to bio-based terephthalic acid from crude sulfate turpentine

2019 Spring National Meeting

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