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Student creates powerful catalyst from potassium (phys.org)
86 points by jonbaer on Apr 22, 2015 | hide | past | web | favorite | 34 comments

The read cube link doesn't work for me.

I kind of get the weirdness of the result and the usefulness of silanes. But nothing explains what you have to do with potassium tert-butoxide to get this to work. That may be why some comments remark on the irritation -- no specifics.

If I could access the paper I probably still could not understand the process but maybe someone could translate it into lay speak.

Also the potential for new chemistry seems extremely interesting but again the specifics are missing. I guess we are talking about the same old quantum mechanics, so what would be new -- some larger scale effect that no one every realized was implied by the physics? Or what?

OK, found a library with the subscription, and the key sentence in the paper seems to be:

We observed that the combination of a bulky basic anion (that is, Ot-Bu, trimethylsilanolate or bis(trimethylsilyl)amide) and, importantly, a potassium countercation led to the desired C–Si bond formation.

But I don't understand it at all. Lay speak translation needed.

Hi there, I'm Kerry - one of the researchers who wrote the paper. Basically, you have a molecule with a bunch of carbons bonded to hydrogens - like R-C-H (where R is the rest of your molecule). Then you mix in our catalyst (K-OtBu, the potassium tert-butoxide catalyst) and a silicon compound (let's say Si-H) and then stir it up, and you get your final product: R-C-Si-H! A very simple explanation for what is no doubt an extremely complex mechanism.

A bit about the specifics of that quote - so we don't know the specific way this catalyst works, just that it works (we're working on finding it out!!) But we've observed several important things - and one of them is that the potassium ion in that potassium tert butoxide salt is absolutely necessary for the reaction to go. Analagous ions like Sodium or Lithium (going up the periodic table) don't work AT ALL. You NEED this potassium ion - which has never been seen before in chemistry, really. You'd expect sodium and lithium to maybe work less well, but to not work at all? Something weird's going on.

Let me know if I didn't answer your question - I can probably get a bit too technical sometimes, habit really :(

That really helps. Thanks very much.

The interviews are helpful but only deepen the mystery. They say that the reactions are so easy they can be carried out at room temperature in introductory college chemistry (albeit at Cal Tech). And potassium tert-butoxide is apparently cheap and common.

So what exactly did this team discover? Apparently the basic recipe can be varied to cover a huge range of applications. What are the key new ideas common to all these recipes that make them work?

So as some other comments say, we discovered that this reaction was a thing at all! Once you put everything together, it happens very simply, in an easy setup, but no one had put together this setup because it's so unlikely and, according to old chemical knowledge, impossible. It's hard to describe just how much this goes against the grain of 100 years of chemical history, which all tell us that precious (transition) metal catalysts are absolutely necessary for these types of seemingly difficult transformations. This is like - to make a complicated pastry with layers and bubbles and flakes, it's a crazy bakery process, right, complicated and most people can't do it. But what if I told you to make the most complicated pastry, all you had to do was add salt and stir it up in a big bowl and poof - your pastry would be there? You'd laugh at me and say I didn't know anything about pastry-making.

The thing is, in this case, it's right - a potassium salt can indeed do this, which goes against this big assumption that chemists have been making for a very long time: that transition metal catalysts (the middle block of the periodic table) are the ONLY things that can do this type of chemistry.

So to answer your last question, the key new idea is "earth-abundant catalysis" - or the fact that we can do these complicated reactions with very, very simple, cheap, and common reagents - maybe the way that Nature itself does chemistry!

To answer the previous comment, there is no special preparation of the potassium t-butoxide necessary. The reaction itself is indeed quite simple to carry out. (In fact, this is one of the things that makes the research significant.) The achievement of the researchers was simply to find this reaction, which they did in part by paying attention to some early results that others may have not noticed or chosen to ignore.

Right now, the "key new idea" is simply that this is possible. But because the reaction is so general (i.e. it works on a wide variety of substrates) and so unexpected, it's clear that some new unifying ideas are just around the corner.

Not being a bench chemist I have no sense of what "the reaction" is, even looking at the paper. Could you describe it?

Heteroaromatic silanes (rings made mostly of carbon but also include a non-carbon atom like nitrogen) are useful synthetic intermediates (you can use them to make other molecules).

In the past, you usually made them using precious metal catalysts (really expensive metals like rhodium; the reactions are easy to screw up). The metal atom basically inserts between the ring and a hydrogen (the outside of the rings are covered in hydrogens). You then added a silane source and it would displace the metal complex (through a pretty complex pathway) to get your desired product (the original ring with a silicon atom where a hydrogen used to be).

This new method creates the exact same product. However, instead of using a precious metal catalyst, you can just add this really common base (potassium t-butoxide) and your silicon source and "poof!" the reaction is complete. No expensive reagents!

What makes this so science-news worthy is that I don't think anyone would have guessed this would have worked.

A good analogy would be a really complex math problem. Folks can solve it, but it's a lengthy and complex proof. Suddenly someone comes by and says "just take the cosine and divide by 9" and you realize that this super simple approach works better than anything else.

Sounds a bit like how Feynman diagrams changed finding solutions to quantum problems from lengthy, complex math equations into simple doodles.

Thanks! The description of the old complex way was helpful.

These replies are great and the picture is getting clearer, but now I wonder... The linked article describes Anton Toutov as struggling to get the basic reaction figured out, being ready to give up, finally getting it to work well, etc. But this doesn't fit the underlying simplicity of the reaction. Kudos to Anton for noticing the oddity and figuring out what was going on, but was there really a heroic struggle or was that journalistic license?

Does anyone have insight into what type of silicon product they were creating and it's usefulness (if any)? I'm not sure if I missed it in the article or if it just wasn't there.

An organosilane is basically any molecule with a Si-C bond. This reaction step creates the Si-C bond, so you could (in theory) use it to prepare any organosilane by starting with the correct Si- and C- containing fragments. Organosilanes currently find wide use in industry as hydrophobic coatings, adhesion promoters, and as useful intermediates in drug synthesis.

It's a little hard to describe just how unbelievable this discovery is. Before this, if you were to propose research in this area, you would most likely be laughed at. It's a bit like if you discovered a hard drive could also be used as a microprocessor. In both cases, there seem to be very good reasons why it could never work. In this case, however, those reasons just happened to be wrong.

EDIT: Free access to the original paper here: http://rdcu.be/cmm5

Don't know if you were thinking of this with your reference, but you CAN use your hard drive as a microprocessor, even a whole new computer!


Thanks for that link, it's an interesting read. One particular story there is so great it bears posting:

"what I found was a thread from a guy called Dejan on the HDDGuru forums. Dejan had managed to corrupt the internal flash of his hard disk in some way and wanted to know if there's a way to either boot the controller from external flash, or a method to re-write the flash. For five days, he doesn't get a reponse, but the guy is inventive: the next thing he posts is the message that he has found the pinout of the JTAG-port. That's a major find: the JTAG-port can be used to control a controller like a puppet. You can stop it, restart it, modify memory, set breakpoints etc with it. Dejan then figures out how to dump the boot ROM of the controller, figures out there's a serial port on one of the hard disk headers and manages to restore his flash ROM. He then dumps a few more bits and pointers about the flash update process before finally disappearing into the mists of the Internet again. "

So what will happen now ? since we no longer know how (some) catalysts work, will this start a race of scanning materials(i.e. combinatorial chemistry) to find catalysts ?

> since we no longer know how (some) catalysts work

It's not like we ever knew exactly how things work at the molecular level. Chemistry is still an expanding field, there are theories to explain molecular combinations in most cases but there is not fixed, absolute theory behind it that explains everything in every single case.

> race of scanning materials(i.e. combinatorial chemistry) to find catalysts

What for ? There's tons of literature already available (more than you can absorb in a single lifetime), and experiments need to be carefully planned and understood, and not just randomly thrown at multiple targets.

>experiments need to be carefully planned and understood, and not just randomly thrown at multiple targets.

Well, if you automated the process...

> Well, if you automated the process...

Problem is, the understanding cannot be automated at this stage. Combinatorial experiments are great to optimize an existing process, it's not that great at finding new stuff or new insights.

Makes me want to build a real life GLaDOS

> [...] will this start a race of scanning materials(i.e. combinatorial chemistry) to find catalysts ?

It will be like the race to find high-temperature superconductors all over again :-)

Thank you!

I have to say, I'm all for making science articles more accessible, and I like that science journalism is more widely reported, but it really annoys me when an article both doesn't go into the technical details in any depth, and doesn't provide a noticeable link to the primary source.



Potassium tert-butoxide (affectionately "KOtBu") isn't any sort of special potassium compound. Basically KOtBu is a really, really strong base, which is called a "non-nucleophilic base" because it doesn't undergo certain kinds of reactions (generally bad ones). In fact according to the patent it isn't required at all; you could use the non-metallic (but very expensive) BEMP or something.

The patent concerns the "silylation" of "aromatic" compounds, which is sort of involved but in essence normally one would silylate -> react -> desilylate in order to achieve a reaction that would normally be outcompeted by a faster reaction. It's rare (but not unheard of) that the silylated compound is actually the target, so while I expect such a reaction to be useful, it doesn't seem transformative on its own. However using KOtBu instead of Pd certainly makes anything a lot cheaper, and maybe somebody had every wrinkle ironed out but this one in some process somewhere.

>Coauthor Brian Stoltz, professor of chemistry at Caltech, says the reason for this strong response is that while the chemistry the catalyst drives is challenging, potassium tert-butoxide is so seemingly simple. The white, free-flowing powder—similar to common table salt in appearance—provides a straightforward and environmentally friendly way to run a reaction that involves replacing a carbon–hydrogen bond with a carbon–silicon bond to produce molecules known as organosilanes.


Looks like it's for organosilanes (of which I have no clue about)

However, the video for this discovery was pretty cool

The Caltech student newspaper interviewed some of the researchers involved: http://loridajose.com/?p=249

A very inspiring story of perseverance and the ultimate payoff. I wonder if it will take off the way the discovery and subsequent development of the transistor (which had a similarly difficult birth process) did for electronics.

I wonder how will this impact the rare-metal industries around the world, especially the ones in China.

What an incredibly irritating article to read.

Can someone find a more normal article on this, that just says what the catalyst does, and leaves out the "birthing story" and other nonsense.

I didn't find it irritating at all, but perhaps you would prefer this article: http://phys.org/news/2015-02-cheap-abundant-chemical-outperf...

Thank you!

The article is so much better I'm stunned that both are located on the same website.

It's like finding kindergarten stories and college age stores in the same book.

Not really, more like finding both in the same book store. Different audiences like different formats, so if you can have both you get more viewers.

Personally I hate the narrative form of news reporting, I like just the facts.

That is indeed somewhat more informative. More centered around the findings and potential applications instead of telling a people-story.

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