Another brick in the molecule

David Ruth
713-348-6327
david@rice.edu

Jade Boyd
713-348-6778
jadeboyd@rice.edu

Another brick in the molecule

Rice University chemical engineers explore market for pure levoglucosan

HOUSTON — (Aug. 8, 2016) — Chemical engineers and chemists from Rice University and China’s Dalian Institute of Chemical Physics have made something so useful and unusual they aren’t yet sure how much it’s worth.

In a new paper in the journal Green Chemistry, a team led by Rice’s Michael Wong describes a new process for making extremely pure levoglucosan (LGA), a naturally occurring organic compound that has been so rare and expensive that drugmakers and chemical engineers typically haven’t considered using it.

Rice University’s Li Chen (left) and Michael Wong and colleagues in Dalian, China, have discovered a new way to make extremely pure levoglucosan, a rare sugar compound that drug makers and synthetic chemists can use to build larger molecules. (Photo by Jeff Fitlow/Rice University)

“A couple of years ago, we got to thinking about chemistries that could turn biomass into something of greater value than heat or biofuels,” said Wong, professor and chair of Rice’s Department of Chemical and Biomolecular Engineering and professor of chemistry. “Most chemicals are made from oil and gas, but you can’t make LGA from petrochemicals. LGA has a very interesting structure that makes it a much better starter molecule than sugar, but it’s been hard for researchers to work with LGA when quantities are limited. LGA is so difficult and inefficient to make that whatever small amounts were commercially available were very expensive.”

Wong said LGA’s value derives from the options it presents to drugmakers and chemical engineers who specialize in chemical synthesis, a branch of chemistry that lies at the center of some of the world’s largest industries, including pharmaceuticals, petrochemicals, plastics and polymers. The complex chemicals these industries produce are built up from smaller chemicals, much like a Lego model is built from individual bricks. LGA is an organic precursor chemical, one of the organic “bricks” that a chemist could use in a synthesis reaction.

Wong said LGA is particularly handy because it contains a number of chiral carbons, which means the carbons come in left-handed and right-handed forms that are not mirror images of one another. Just as specially shaped Lego bricks are rare but useful to build unique structures, LGA molecules could open new avenues to synthetic chemists, he said. Glucose also contains chiral carbons, but it is less stable to do chemistry with.

Rice University researchers Michael Wong (left) and Li Chen are exploring the commercial possibilities for their levoglucosan manufacturing process with an Innovation Corps grant from the National Science Foundation. (Photo by Jeff Fitlow/Rice University)

Wong and co-lead scientist Conrad Zhang of China’s Dalian Institute of Chemical Physics worked with graduate student Li Chen to design a series of experiments to see if an efficient method could be found for making pure LGA in bulk.

“We’ve shown that we can make LGA that is at least 95 percent pure, and possibly much more pure, from three different feedstocks — cellulose, glucose and starch,” Wong said. “This comes from our much better understanding of sugar chemistry at high temperatures, which we summarize in our paper as the ring-locking concept. We like to think we solved the purity problem, and now we’re focusing on the quantity problem.”

Wong said the group’s process should be far more economical and operationally simpler than the current small-scale route for making LGA. Producers today begin with starch and apply intense heat under oxygen-free conditions. Heating requires lots of energy, and the result is a chemical soup that contains a few percent LGA. That soup must further be treated to separate the waste and yield highly pure LGA.

Chen, lead author of the new study, said, “Our approach is fundamentally different. We use a few chemical tricks to prepare our feedstocks in order to produce extremely pure LGA. So we’ve gone from 10 steps to two steps, which drastically cuts down the cost.”

In a 2004 Department of Energy analysis, LGA was among the 30 most valuable chemicals identified as possible products of biorefineries, “green” chemical facilities that could compete with chemical plants that make products from nonrenewable oil and gas. Wong said LGA’s unique properties could be useful for making “green” plastics (plastics made solely from biomass) if quantity were no longer an issue. He said some drugmakers have looked at using LGA as a building block for making at least a dozen drugs, including some of the widely prescribed type 2 diabetes drugs known as SGLT2 inhibitors.

The work was initiated with a National Science Foundation grant, which recently led to Wong and Chen receiving an NSF Innovation Corps grant to explore potential markets for LGA and other anhydrosugar compounds. I-Corps grants let academic researchers explore the commercial possibilities of a promising discovery. Each I-Corps team goes through an immersive seven-week process that includes online training with business mentors and interviews with at least 100 potential customers.

“The experience has been invaluable,” Chen said. “It’s intense, but instructive.”

Wong said he and Chen may form a startup company if the I-Corps process reveals a significant market.

Additional co-authors include Jin-mo Zhao, Sivaram Pradhan, Bruce Brinson and Gustavo Scuseria, all of Rice. Additional support was provided by the Chinese Academy of Sciences International Partnership Program for Creative Research Teams.

-30-

VIDEO is available at:
https://youtu.be/ukZk3O41d5w
High-resolution IMAGES are available for download at:
http://news.rice.edu/files/2016/08/0808_GREEN-lga-tw43-lg-1785cg6.jpg
CAPTION: Rice University’s Li Chen and Michael Wong and colleagues in Dalian, China, have discovered a new way to make extremely pure levoglucosan, a rare sugar compound that drugmakers and synthetic chemists can use to build larger molecules. (Photo by Jeff Fitlow/Rice University)

http://news.rice.edu/files/2016/08/0808_GREEN-lga-pr50-lg-1qx5za7.jpg
CAPTION: Rice University chemical engineers Li Chen and Michael Wong display a model of a levoglucosan molecule, a rare type of sugar that could be useful for chemical synthesis. (Photo by Jeff Fitlow/Rice University)

http://news.rice.edu/files/2016/08/0808_GREEN-lga-ov36-lg-ra9v0f.jpg
CAPTION: Rice University researchers Michael Wong and Li Chen are exploring the commercial possibilities for their levoglucosan manufacturing process with an Innovation Corps grant from the National Science Foundation. (Photo by Jeff Fitlow/Rice University)

The DOI of the Green Chemistry paper is: 10.1039/C6GC01600F

A copy of the paper is available at:
http://pubs.rsc.org/en/content/articlehtml/2016/gc/c6gc01600f

More information is available at:

Catalysis and Nanomaterials Laboratory home page
http://www.ruf.rice.edu/~wonglab/index.html

Related research from Rice:

Water-cleanup catalysts tackle biomass upgrading — June 26, 2014
http://news.rice.edu/2014/06/26/water-cleanup-catalysts-tackle-biomass-upgrading/

Rice scientists ID new catalyst for cleanup of nitrites — Nov. 25, 2013
http://news.rice.edu/2013/11/25/rice-scientists-id-new-catalyst-for-cleanup-of-nitrites/

Chloroform cleanup: just the beginning for palladium-gold catalysts — April 15, 2013
http://news.rice.edu/2013/04/15/chloroform-cleanup-just-the-beginning-for-palladium-gold-catalysts/

Rice uses light to remotely trigger biochemical reactions — Dec. 13, 2012
http://news.rice.edu/2012/12/13/rice-uses-light-to-remotely-trigger-biochemical-reactions/

This release can be found online at news.rice.edu.

Follow Rice News and Media Relations via Twitter @RiceUNews

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for best quality of life and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to http://tinyurl.com/RiceUniversityoverview.