Aug 9 2016
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 unique and useful invention has been developed by chemical engineers and chemists from Rice University and China’s Dalian Institute of Chemical Physics. However, these engineers and chemists are yet to confirm it's worth.
The journal Green Chemistry presents a paper in which a group, headed by Rice’s Michael Wong, explains a new method to develop extremely pure levoglucosan (LGA), which is a naturally occurring organic compound that is both expensive and rare that even chemical engineers and drugmakers have yet to consider using it.
A couple of years ago, we got to thinking about chemistries that could turn biomass into something of greater value than heat or biofuels. 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.
Michael Wong, Professor, Rice University
Wong stated that LGA’s value is obtained from the options it presents to chemical engineers and drugmakers who are experts in chemical synthesis, which is a branch of chemistry that exists in the center of some of the world’s largest industries, including polymers, plastics, petrochemicals and pharmaceuticals.
The complex chemicals produced by these industries are developed from smaller chemicals, similar to a Lego model constructed from individual bricks. LGA is an organic precursor chemical, which is an organic brick that a chemist uses in a synthesis reaction.
LGA, according to Wong, is specifically useful as it has several chiral carbons. This highlights the fact that the carbons are obtained in left-handed and right-handed forms that are not mirror images of one another. In comparison to Lego bricks that are custom shaped and rare but handy to construct unique structures, LGA molecules are capable of opening new avenues to synthetic chemists, he stated. Glucose has chiral carbons, but it lacks the stability to do chemistry with.
Wong and co-lead scientist Conrad Zhang of China’s Dalian Institute of Chemical Physics collaborated with graduate student Li Chen to plan a number of experiments in order to analyze the possibility of finding an ideal method for developing 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. 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.
Michael Wong, Professor, Rice University
Wong further stated that the team’s process should be even more economical and simpler to execute compared to the existing small-scale route for developing LGA.
Today, producers begin with starch and apply extreme heat under oxygen-free conditions. Heating needs an increasing amount of energy, and the result is a chemical soup that contains a small percentage of LGA. Further treatment of this soup is required in order to separate the waste and yield LGA that is highly pure.
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.
Li Chen, Graduate Student, Rice University
LGA was placed among the 30 most valuable chemicals identified as possible products of biorefineries in a 2004 Department of Energy analysis. These biorefineries are “green” chemical facilities capable of competing with chemical plants that develop products from nonrenewable gas and oil.
Wong said LGA’s unique properties can be used for producing “green” plastics, plastics made solely from biomass, if quantity was no longer considered to be an issue. He stated that drugmakers have focused on using LGA as a building block for developing a dozen drugs, also including some of the commonly type 2 diabetes drugs referred to as SGLT2 inhibitors.
The study was supported by a National Science Foundation grant, which recently resulted in Wong and Chen receiving an NSF Innovation Corps grant to investigate potential markets for LGA together with other anhydrosugar compounds. I-Corps grants allowed academic researchers to examine the commercial possibilities of a promising discovery. Each I-Corps team attends a seven-week process, which includes interviews with about 100 potential customers and online training with business mentors.
“The experience has been invaluable,” Chen said. “It’s intense, but instructive.”
Wong said he and Chen may develop 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.
Process for making pure LGA
Video Credit: Rice University/Youtube.com