9 ms·

> “for the development of asymmetric organocatalysis” The prize is about artificial catalysts. A catalyst is a substance that speeds up a reaction without bein

by aazaa 5y ago

> “for the development of asymmetric organocatalysis” The prize is about artificial catalysts. A catalyst is a substance that speeds up a reaction without being consumed. Another way to speed reactions up is to heat them, but that consumes energy and often leads to by-products that must be removed and disposed of. The "asymmetric" part has to do with one kind of by-product. Some reactions produce 50% of a by-product that must be separated out and disposed of. This happens because some molecules have 3D structure that's different than its mirror image. Think of the way that certain objects like bottle caps and screws only turn one way to tighten. Molecules can have that property (including many drugs you may have taken), and if the handedness is wrong, in many applications, it's a by-product and/or poison. An asymmetric catalyst can make molecules of one handedness selectively, saving material, money, and energy. The "organocatalysis" part has to do with what the catalyst is made of. Prior to the awardee's research, catalysts tended to contain metal atoms. A few Nobels have been awarded for catalytic processes that use metals. So metals are great in principle, but in practice have issues. Some metals are linked to toxicity at trace levels. So when preparing drugs, you need to be very careful about purifying out the metal contaminants. Palladium is an example of a very versatile catalytic metal that causes problems during drug manufacture. Metals can also be quite expensive. Platinum and Rhodium are used in both chemical manufacture and in automobile catalytic converters. The price of Rhodium hit $25,000/oz recently. Not all metals are this expensive, but the cost and availability are often a problem. The awarded work uses catalysts that don't contain metals. Instead, the catalysts contain the elements carbon, hydrogen, oxygen, nitrogen, and possibly some other non-metal atoms. In other words, these catalysts are made of the same kinds of atoms as life. (Enzymes catalyze biological reactions.) So now there's a link between biological catalysis and artificial catalysis that didn't exist before. This work solved a number of practical problems, really went against dogma at the time, and opened up an important area of research that intersects with big questions like the origins of life.

loufe 5y ago
Fantastic summary, thank you for taking the time.
superposeur 5y ago
Thanks for this clear account. This proves that it is possible (at least occasionally) to describe a chemistry project using ordinary language to a non-chemist. By contrast, every single chemistry poster session or talk seems instead to consist of inscrutable walls of long technical terms and impossibly convoluted flow charts. I’ve often wondered whether this really all makes perfect sense to chemists themselves? Like, if I were to surreptitiously change one syllable out of a 10-syllable word, or reverse a couple of the arrows on a flow chart, would anyone in the audience notice? If not, then why is the information being conveyed in this way, seemingly without any effort at comprehensibility? Edit: don’t mean to condescend to chemists. The question is a genuine one. Does it really have to be so inaccessible from start to finish? Maybe yes is the answer, that’s the nature of the thing. Physics is not like that, for instance.
- ampdepolymerase 5y ago
  Would you prefer CS algorithms in papers to be written in English prose rather than pseudo code? Would you notice if your neural network diagram has its arrows reversed? I do not understand HN's superiority complex when it comes to notation. Every thread on music in this forum devolves to complaints about music notation rather than the essence of the art itself. It is disappointing.
  - superposeur 5y ago
    To be clear, despite the slightly snarky tone, I don’t mean to condescend to chemists! Quite the opposite, this is borne out of disappointment when I listen to a whole chem presentation and fail to grasp even one simple idea. I’m a physicist, btw, and could easily fill a presentation with inscrutable equations but what would be the point of that? Instead I make sure that everyone (even a scientifically literate layperson) can stay on board at least the first third of the presentation.
    - ff10 5y ago
      I guess it's alway a question of what audience you speak to. OPs explanation could probably be summarized in 2 sentences when aimed at chemists.
gilleain 5y ago
> So now there's a link between biological catalysis and artificial catalysis that didn't exist before. Not sure I understand that point. There are plenty of enzymatic reactions that rely on metals. Presumably the point is that there exist non-metalloenzymes that catalyse enantiospecific reactions?
- siver_john 5y ago
  I believe the point is more from a relatively "simple" molecule you can have catalytic reactions that don't require metal or complex protein systems. When applied to the observation about life means that random organic compounds could have started selective catalytic reactions which could have given rise to more complex systems which then give rise to the building blocks of life or something. This is me speculating on the meaning of the original comment, my knowledge of abiogenesis is lacking and I know RNA can do some enzymatic reactions which are also organic compounds.
  - gilleain 5y ago
    That makes sense, thanks. With regards to abiogenesis, that is a wonderful area for wild speculation. I say that having done a tiny bit of that myself :) Certainly it would be helpful to have small-molecule catalysts to bootstrap life into having polymer catalysts. I just do not think it matters much about excluding metals, since there were bound to be sufficient dissolved metal ions floating around. Of course, whether they were the 'right' metals and in a suitable oxidation state and so on is a different question.
    - siver_john 5y ago
      I think the importance of organocatalysts besides being potentially less "harsh" is that they can also be more selective in what reactions they allow, which would be important in getting to those polymers. For example most of the amino acids in biology are L-enantiomers. So the reaction in the primordial soup would require catalysts which would bias towards that specific shape, where as a metalocatalyst may be less specific and generate both the L and R enantiomers at equal or near equal rate. Also it could also be that metalocatalysts generate side products at a higher rate such that it consumes say some of your amino acids unhelpfully. So you may be able to think about it as an intermediate step of metals->organocatalysts->polymer catalysts. Full Disclosure: Am not a chemist but work with chemists, one of which follows MacMillan closely. And have sat through a lot of presentations looking at how different catalysts affect selectivity of products.
localhost 5y ago
A bit more detail about how catalysts speed up chemical reactions - to get from products to reactants you need to climb an energy barrier to get to something called the "rate-determining transition state". What catalysts do is stabilize or reduce the amount of energy (called activation energy) required to reach this transition state, and by doing so, the reaction goes faster. The stability is achieved through interactions between the rate determining transition state and the catalyst. Sometimes the catalyst causes a change in the reaction mechanism leading to a different rate-determining transition state as well. EDIT: pretty sure this was Ben List's first paper on this idea: https://pubs.acs.org/doi/10.1021/ja994280y https://pubs.acs.org/doi/10.1021/ja994280y David MacMillan's first paper on this idea: https://pubs.acs.org/doi/abs/10.1021/ja000092s https://pubs.acs.org/doi/abs/10.1021/ja000092s
- hi41 5y ago
  Layperson here. It’s my understanding that energy can neither created not destroyed. So if a reaction needs more energy otherwise, then how do catalysts provide that extra energy needed for the reaction yet not fail energy conservancy law?
  - ace2358 5y ago
    I don’t think they provide the energy, they change the required energy for a reaction to occur. My understanding is that is can happen due to the physical structure of the catalyst changing the electronic configuration of the molecules being reacted. I think often instead of the two molecules coming into contact and reacting, the two molecules and the catalyst come into contact. It’s a whole different reaction, but the catalyst molecule doesn’t change its composition and is left unchanged after the reaction. I guess maybe a terrible analogy would be you’re trying to cross a flat field but there is a large group of animals, say, cows in the way. You’d never be able to get through the crowd of cows without exerting a lot of energy. Then suddenly a dog, catalyst, come over and starts shooing off the cows. Now the cows have moved out of the way and the flat field is clear. You can now make the journey while expending less energy. Hmm maybe someone else can explain it better!
  - infogulch 5y ago
hobofan 5y ago
> This happens because some molecules have 3D structure that's different than its mirror image. I assume that you meant to say that that one possible product _is_ the mirror image of the other product.
- feoren 5y ago
  No, I think they meant what they said: we can encounter the situation where 50% of products need to be separated out only because some molecules are chiral. (Actually their comment was extremely carefully (and well-) worded for a social media comment!) See, in general your statement that reaction products can be mirror images of each other is true for most of the chemical reactions humanity has been able to produce in a lab/factory, yet many reactions don't require separating out 50% of the products because it doesn't matter that they're mirror images if they're non-chiral molecules. Think of the (non-chiral) letter H: a right-handed and left-handed letter H are the same -- one can always be rotated to match the other. The only time it matters that most of our chemical reactions can produce either left- or right-handed molecules is when these molecules are actually different, meaning they cannot be rotated to match each other. Think of the (chiral in 2D) letter L. There's no way I can rotate the letter L in 2D space to make it match its mirror image. (Of course I can if I'm allowed to rotate it through 3D space.)
  - hobofan 5y ago
    I know how enantiomeres work (chemistry background), I just found the quoted sentence really confusing to read for some reason. I think the original press release already expressed it well in an easy to understand way with the classic hand example: > where two different molecules can form, which – just like our hands – are each other’s mirror image
dr_dshiv 5y ago
What a great explanation. Id like to share this old paper on using radio frequency modulation of catalytic activity. Seems like such a neat idea—that chemical catalysts might be emulated through radio waves. Are there better examples or better ways of thinking about this? https://www.sciencedirect.com/science/article/pii/S0009261498010951 https://www.sciencedirect.com/science/article/pii/S000926149...

by aazaa 5y ago

loufe 5y ago

Fantastic summary, thank you for taking the time.

superposeur 5y ago

Thanks for this clear account. This proves that it is possible (at least occasionally) to describe a chemistry project using ordinary language to a non-chemist. By contrast, every single chemistry poster session or talk seems instead to consist of inscrutable walls of long technical terms and impossibly convoluted flow charts. I’ve often wondered whether this really all makes perfect sense to chemists themselves? Like, if I were to surreptitiously change one syllable out of a 10-syllable word, or reverse a couple of the arrows on a flow chart, would anyone in the audience notice? If not, then why is the information being conveyed in this way, seemingly without any effort at comprehensibility? Edit: don’t mean to condescend to chemists. The question is a genuine one. Does it really have to be so inaccessible from start to finish? Maybe yes is the answer, that’s the nature of the thing. Physics is not like that, for instance.

ampdepolymerase 5y ago
Would you prefer CS algorithms in papers to be written in English prose rather than pseudo code? Would you notice if your neural network diagram has its arrows reversed? I do not understand HN's superiority complex when it comes to notation. Every thread on music in this forum devolves to complaints about music notation rather than the essence of the art itself. It is disappointing.
- superposeur 5y ago
  To be clear, despite the slightly snarky tone, I don’t mean to condescend to chemists! Quite the opposite, this is borne out of disappointment when I listen to a whole chem presentation and fail to grasp even one simple idea. I’m a physicist, btw, and could easily fill a presentation with inscrutable equations but what would be the point of that? Instead I make sure that everyone (even a scientifically literate layperson) can stay on board at least the first third of the presentation.
  - ff10 5y ago
    I guess it's alway a question of what audience you speak to. OPs explanation could probably be summarized in 2 sentences when aimed at chemists.

gilleain 5y ago

> So now there's a link between biological catalysis and artificial catalysis that didn't exist before. Not sure I understand that point. There are plenty of enzymatic reactions that rely on metals. Presumably the point is that there exist non-metalloenzymes that catalyse enantiospecific reactions?

siver_john 5y ago
I believe the point is more from a relatively "simple" molecule you can have catalytic reactions that don't require metal or complex protein systems. When applied to the observation about life means that random organic compounds could have started selective catalytic reactions which could have given rise to more complex systems which then give rise to the building blocks of life or something. This is me speculating on the meaning of the original comment, my knowledge of abiogenesis is lacking and I know RNA can do some enzymatic reactions which are also organic compounds.
- gilleain 5y ago
  That makes sense, thanks. With regards to abiogenesis, that is a wonderful area for wild speculation. I say that having done a tiny bit of that myself :) Certainly it would be helpful to have small-molecule catalysts to bootstrap life into having polymer catalysts. I just do not think it matters much about excluding metals, since there were bound to be sufficient dissolved metal ions floating around. Of course, whether they were the 'right' metals and in a suitable oxidation state and so on is a different question.
  - siver_john 5y ago
    I think the importance of organocatalysts besides being potentially less "harsh" is that they can also be more selective in what reactions they allow, which would be important in getting to those polymers. For example most of the amino acids in biology are L-enantiomers. So the reaction in the primordial soup would require catalysts which would bias towards that specific shape, where as a metalocatalyst may be less specific and generate both the L and R enantiomers at equal or near equal rate. Also it could also be that metalocatalysts generate side products at a higher rate such that it consumes say some of your amino acids unhelpfully. So you may be able to think about it as an intermediate step of metals->organocatalysts->polymer catalysts. Full Disclosure: Am not a chemist but work with chemists, one of which follows MacMillan closely. And have sat through a lot of presentations looking at how different catalysts affect selectivity of products.

localhost 5y ago

A bit more detail about how catalysts speed up chemical reactions - to get from products to reactants you need to climb an energy barrier to get to something called the "rate-determining transition state". What catalysts do is stabilize or reduce the amount of energy (called activation energy) required to reach this transition state, and by doing so, the reaction goes faster. The stability is achieved through interactions between the rate determining transition state and the catalyst. Sometimes the catalyst causes a change in the reaction mechanism leading to a different rate-determining transition state as well. EDIT: pretty sure this was Ben List's first paper on this idea: https://pubs.acs.org/doi/10.1021/ja994280y https://pubs.acs.org/doi/10.1021/ja994280y David MacMillan's first paper on this idea: https://pubs.acs.org/doi/abs/10.1021/ja000092s https://pubs.acs.org/doi/abs/10.1021/ja000092s

hi41 5y ago
Layperson here. It’s my understanding that energy can neither created not destroyed. So if a reaction needs more energy otherwise, then how do catalysts provide that extra energy needed for the reaction yet not fail energy conservancy law?
- ace2358 5y ago
  I don’t think they provide the energy, they change the required energy for a reaction to occur. My understanding is that is can happen due to the physical structure of the catalyst changing the electronic configuration of the molecules being reacted. I think often instead of the two molecules coming into contact and reacting, the two molecules and the catalyst come into contact. It’s a whole different reaction, but the catalyst molecule doesn’t change its composition and is left unchanged after the reaction. I guess maybe a terrible analogy would be you’re trying to cross a flat field but there is a large group of animals, say, cows in the way. You’d never be able to get through the crowd of cows without exerting a lot of energy. Then suddenly a dog, catalyst, come over and starts shooing off the cows. Now the cows have moved out of the way and the flat field is clear. You can now make the journey while expending less energy. Hmm maybe someone else can explain it better!
- infogulch 5y ago

hobofan 5y ago

> This happens because some molecules have 3D structure that's different than its mirror image. I assume that you meant to say that that one possible product _is_ the mirror image of the other product.

feoren 5y ago
No, I think they meant what they said: we can encounter the situation where 50% of products need to be separated out only because some molecules are chiral. (Actually their comment was extremely carefully (and well-) worded for a social media comment!) See, in general your statement that reaction products can be mirror images of each other is true for most of the chemical reactions humanity has been able to produce in a lab/factory, yet many reactions don't require separating out 50% of the products because it doesn't matter that they're mirror images if they're non-chiral molecules. Think of the (non-chiral) letter H: a right-handed and left-handed letter H are the same -- one can always be rotated to match the other. The only time it matters that most of our chemical reactions can produce either left- or right-handed molecules is when these molecules are actually different, meaning they cannot be rotated to match each other. Think of the (chiral in 2D) letter L. There's no way I can rotate the letter L in 2D space to make it match its mirror image. (Of course I can if I'm allowed to rotate it through 3D space.)
- hobofan 5y ago
  I know how enantiomeres work (chemistry background), I just found the quoted sentence really confusing to read for some reason. I think the original press release already expressed it well in an easy to understand way with the classic hand example: > where two different molecules can form, which – just like our hands – are each other’s mirror image

dr_dshiv 5y ago

What a great explanation. Id like to share this old paper on using radio frequency modulation of catalytic activity. Seems like such a neat idea—that chemical catalysts might be emulated through radio waves. Are there better examples or better ways of thinking about this? https://www.sciencedirect.com/science/article/pii/S0009261498010951 https://www.sciencedirect.com/science/article/pii/S000926149...