Sweet synthesis: fructose product could replace chemicals from oil.

The production of many chemicals starts with petroleum, but as worldwide oil supplies wane, scientists are looking for renewable building blocks. A Wisconsin team describes the efficient use of fructose toward making one starting material. The strategy could lead to sugar-based polyesters and other products.

The Department of Energy (DOE) has identified 12 high-value chemicals that can be made from sugars. On the list is furandicarboxylic acid (FDCA), which the agency pegs as a possible replacement for terephthalic acid, a petrochemical found in polyesters.

One pathway to FDCA contains hydroxymethylfurfural (HMF), a fructose product. Previous HMF-synthesis routes, however, were plagued by either energy-intensive separation steps or low yields, both of which would make for high production costs, says James A. Dumesic, a chemical engineer at the University of Wisconsin-Madison.

"We tried to tweak the process," he says, to "combine good yield with easy separation."

Dumesic and his colleagues put fructose and an acidic catalyst in a continually stirred mix of water and the solvent called methylisobutylketone. After the conversion, they stopped stirring, and the water and organic solvent separated into two layers, as oil and vinegar do.

The water at the bottom retained the catalyst and any remaining fructose, while the organic solvent held the HMF, which could then be easily isolated by evaporation, Dumesic says.

The group found that spiking the organic solvent with the alcohol 2-butanol "more efficiently pulls HMF up to the organic layer where you want it to be," Dumesic adds.

This and other adjustments improved the reaction's yield. At its best, the technique converted 80 percent of the fructose to HMF and made only 10 percent of the sugar into by-products. The team describes its procedures in the June 30 Science.

Chemicals made from renewable materials have the potential to become new and useful molecules, according to the DOE. Sugar-inspired chemistry could form the basis for a biorefinery--the renewable equivalent of a petrochemical refine--that could turn HMF and other key' chemicals into any of thousands of different products.

"When you look at the literature for converting renewables into chemicals, HMF always shows up as one of the usual suspects," says Joseph J. Bozell, an organic chemist at the University of Tennessee in Knoxville. "But no one has been able to produce it in a high yield that you could isolate easily."

Dumesic's system, he says, "may be a first step in that path."