The chemical industry generates significant amounts of waste. Now, in a new study published April 27 in the journal Nature, scientists reveal that powerful algorithms may help find ways to recycle such waste products into useful goods such as medication.
Scientists have long sought to devise "circular chemistry" techniques to reuse chemical wastes that might otherwise prove toxic or expensive to store or dispose of. However, even a small number of such wastes can generate millions of possible molecules within a few chemical reactions. Investigating all these potential synthesis routes and finding practical ones to implement has proven extraordinarily challenging.
In the new study, researchers used computers to help synthesize valuable chemicals from waste. They previously used their platform to shed light on the origins of life on ancient Earth.
"What I thought the machine should attack are some real-world problems, those related not to this or than specific synthesis but to a global problem relevant to industry — and hence, the current project was born," study senior author Bartosz Grzybowski, an organic chemist and co-founder of Allchemy in Highland, Indiana, tells Inverse.
WHAT DID THE SCIENTISTS DO? — The scientists developed a computer model to analyze what chemicals might get synthesized from nearly 200 waste molecules common in chemical industries, including pharmaceuticals, agriculture, flavors, and fragrance. It also ranked these synthesis reactions by how sustainable they might prove — for instance, whether they needed a lot of energy or involved hazardous compounds.
"The difficulties have been two-fold — you have to teach the machine a lot of expert-level knowledge before it starts thinking like a chemist, and you need very efficient algorithms to examine all the possibilities and fish out those that make industrial sense," Grzybowski says. This new study alone examined nearly 1 billion molecules and billions of routes to synthesize them, he notes.
WHAT DID THEY FIND? — The computer model suggested it was possible to synthesize roughly 300 important drugs and farming chemicals from these 200-plus waste compounds. These include some of the world's most prescribed medicines, such as the asthma drug salbutamol and the blood pressure drug carvedilol.
"There are so many productive ways in which we could convert industrial chemical wastes into useful products," Grzybowski says. All in all, it's "incredible how much less wasteful the chemical industry could become if they started using more rational planning tools."
The scientists confirmed several of these synthesis routes in experiments, including what they say could be a "pharmacy on demand" platform that was fed waste streams to potentially generate chemicals urgently sought for ventilated Covid-19 patients, such as the muscle relaxant cisatracurium, the sedative midazolam, and the anesthetic propofol.
WHAT'S NEXT? — "This should not be a tool only we and a few of our partner companies use, but an industry-wide system in which someone reports some surplus waste, the machine calculates if this and some other wastes can be starting points for making something useful — say, a life-saving drug — and then some other companies bid online for a contract to execute this synthesis," Grzybowski says.