Furfural as an Extractant

In the applications (a) and (b), the desired product (freed of aromatics) is the raffinate, while in application (c) the desired product (rich in unsaturated compounds) is obtained from the extract. 

Of course, in liquid/liquid extraction, the extractant must form two liquid phases with the feed stock. With lubricating oil, diesel fuel, and soybean oil, furfural is capable of satisfying this condition as its oxygen atoms make it a more polar compound. The spectroscopic polarity index Et [45] of furfural is 0.426 whereas the values of the oils and of diesel fuel are close to zero. 

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