In The Field

ACS: Green Grubbs

The theme of this conference is sustainability and green chemistry, loosely speaking. The plenary session this afternoon embraced this theme with gusto and focussed on how green chemistry can save the world.

In case you don’t know what green chemistry is, it’s a field of chemistry that’s all about improving processes by coming up with reaction conditions that use fewer chemicals, in smaller quantities and with less waste. Catalysis is important in orchestrating this change and today’s plenary session featured a giant of catalysis, Robert Grubbs from Caltech.

Grubbs won the Nobel prize in chemistry in 2005, with Robert Shrock and Yves Chauvin, for developing metathesis catalysts. Grubbs also has his very own metathesis catalyst that has brought him additional fame.

Grubbs spoke about the extent at which metathesis catalysts are helping to green the planet, although this goal doesn’t seem to have been his motivation all along: “I didn’t realise I was a green chemist until the Nobel committee made a big thing of it,” he said. But green Grubbs is.

Metathesis is a swapping of constituents on molecules that have carbon-carbon double bonds. Catalysts that speed this process along have been used in myriad places. Grubbs took us hurtling through some applications, starting with pharma, where green chemsitry involving metathesis can take a synthesis of a drug molecule from 20 steps to just 4, and can yield interesting new chemical structures on the way.

Next up was the biodiesel movement, and how metathesis can turn oils from plants into useful, finer, chemicals. This has led to the birth of Materia, a company that Grubbs has set up to exploit olefin metathesis.

But, Grubbs says, despite all these products derived from natural renewable resources, people won’t buy them unless they’re better than the ones that come from petrochemicals. That is apart frmo in the personal care market, where green, organic products are premium best sellers.

What else has metathesis done? It’s helped, or is helping, to replace DDT, the nasty pesticide liberally sprayed in fields worldwide after the second world war, and subsequently banned. Metathesis reactions can be used to recreate insect pheromenes, which can be spread on crops to confuse male bugs and stopping them from sniffing out females to mate with. This is much safer than a kill-all pesticide says Grubbs, becasue it is insect-specific and can be used in low concentrations.

Finally, Grubbs showed us how resins can be made better using metathesis catalysis. So what? Grubbs claims that in future, wind turbines with blades spanning 180 meters will need to be built, and the materials that are needed must be devloped in a sustainable, or more sustainable, manner.

So, all in all Grubbs’s talk was a great hoorah! for green chemistry. Throughout the week I’m sure we’ll see many more examples of chemists trying their best to exploit this area of chemistry. I’ll keep you posted.


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