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Science

Why Chemists Can't Quit Palladium (nature.com) 87

A retracted paper highlights chemistry's history of trying to avoid the expensive, toxic -- but necessary -- catalyst. From a report: It's hard to find a place on Earth untouched by palladium. The silvery-white metal is a key part of catalytic converters in the world's 1.4 billion cars, which spew specks of palladium into the atmosphere. Mining and other sources add to this pollution. As a result, traces of palladium show up in some of the most remote spots on Earth, from Antarctica to the top of the Greenland ice sheet. Palladium is also practically indispensable for making drugs. That's because catalysts with palladium atoms at their core have an unmatched ability to help stitch together carbon --carbon bonds. This kind of chemical reaction is key to building organic molecules, especially those used in medications.

"Every pharmaceutical we produce at some point or another has a palladium-catalysed step in it," says Per-Ola Norrby, a pharmaceutical researcher at drug giant AstraZeneca in Gothenburg, Sweden. Palladium-catalysed reactions are so valuable that, in 2010, their discoverers shared a Nobel prize. But despite its versatility, chemists are trying to move away from palladium. The metal is more expensive than gold, and molecules that contain palladium can also be extremely toxic to humans and wildlife. Chemical manufacturers have to separate out all traces of palladium from their products and carefully dispose of the hazardous waste, which adds extra expense. Thomas Fuchb, a medicinal chemist at the life-sciences company Merck in Darmstadt, Germany, gives the example of a reaction to make 3 kilograms of a drug molecule for which the ingredients cost US$250,000. The palladium catalyst alone adds $100,000; purifying it out of the product another $30,000.

Finding less-toxic alternatives to the metal could help to reduce environmental harm from palladium waste and move the chemicals industry towards 'greener' reactions, says Tianning Diao, an organometallic chemist at New York University. Researchers hope to swap palladium for more common metals, such as iron and nickel, or invent metal-free catalysts that sidestep the issue altogether. Several times in the past two decades, researchers have reported finding palladium-free catalysts. But in what has become a recurring pattern for the field, each heralded discovery turned out to be a mistake.

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Why Chemists Can't Quit Palladium

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  • My wedding band is made of palladium. Is it going to kill me?

    • My wedding band is made of palladium. Is it going to kill me?

      https://chemistry.stackexchang... [stackexchange.com]

    • It will recombine your DNA into the original twelve-stranded Atlantean DNA that only a lucky few humans possess today.

      Have you been for a swim recently? It may not have taken full effect yet.

      https://jean-paulblommaert.com... [jean-paulblommaert.com]

    • by PPH ( 736903 )

      No. But eventually you might find yourself yearning for the sweet release that death can bring.

    • by Tablizer ( 95088 )

      No, but marriage will.

    • by gweihir ( 88907 )

      Not unless you grind it into a fine powder and eat it. And even then it is not sure it would do harm.

    • by Luckyo ( 1726890 ) on Thursday June 16, 2022 @08:24PM (#62626640)

      This is the standard alarmist/catastrophist writing that is so popular with modern journalists. It gives you a view that palladium is very dangerous and toxic to humans. It's done by writing in a way that gives that impression unless you really pay attention to specific details of writing:

      "molecules that contain palladium can also be extremely toxic to humans and wildlife."

      This formulation is satisfied if there are two very rarely encountered molecules that include palladium out of a billion potential variants. But if you read it within the context of the whole post, it gives you an idea that palladium is very toxic.

      In reality, its toxicity to humans is very low. There are some compounds however that include palladium that are very toxic indeed. Just like there are many compounds that include carbon that are very toxic. While we use activated coal to detoxify things.

      And the real reason why there have been many attempts to find alternatives to palladium is costs. It's exceedingly expensive because of extreme demand and relatively low supply.

      • Yep. It's a bit like mercury.

        Mercury salts and mercury vapor can be incredibly dangerous, less than a gram can kill you. Even if you don't die it's really, really bad.

        A blob of mercury in your hand? Safe.The mercury in your teeth fillings? No known link to health problems.

        Eating tuna? There's EPA guidelines for that. How many people know them...?

        • It all about physical and chemical state. The blob on your hand is indeed safe as long as you're not breathing it in. The mercury in your filling isn't pure mercury, it's an amalgam for which the mercury vapor pressure is very low.

          Alkyl mercury (eg methyl mercury) is insanely toxic. So chemical state really does matter here. The same is true of palladium. It's not the palladium metal itself, it's the palladium-ligand complexes that are so dangerous.

        • We also don't have hard evidence that amalgam does *not* cause health problems.

          We do have reasons to suspect it. Some does get released as vapor. I don't believe it's known yet how much, or whether that is affected by things like drinking hot coffee or tea. We also don't know whether some foods could leach it out, or, worse, form toxic organomercury compounds which could be dramatically more toxic than elemental mercury, and in dramatically smaller amounts.

          This has led some countries to ban it, and I thi

      • This is a fine example of a "weasel phrase". You can recognize it if the phrase remains true/plausible even when you inverse it:

        "molecules that contain palladium can also be extremely toxic to humans and wildlife"

        Sounds plausible...

        "molecules that contain palladium can also NOT be extremely toxic to humans and wildlife"

        Also sounds true: some molecules with palladium are extremely toxic, some aren't.

        There is also the comparison to gold used in the article: The price of gold is used as a reference p

      • by Junta ( 36770 )

        The writers really need to latch onto the dangers of Dihydrogen Monoxide. It contains an element that is highly flammable, which is dangerous enough, but the rest is highly explosive. And yet the government and big companies are perfectly content to let huge amounts of it be stockpiled right near where people live.

        • It can also be harmful if swallowed in large quantities, or when inhaled! Why do people swim in this stuff!?

      • I thought palladium is a noble metal, like gold and platinum, so it does not tend to form compounds.

        However, palladium and platinum both catalyse many chemical reactions, so they must have significant chemical activity. I will admit that I do not understand how this works. Do these metals make temporary compounds, which break down and release the reactive payload, and unchanged catalyst?

        • by crunchygranola ( 1954152 ) on Friday June 17, 2022 @09:57AM (#62627976)

          I will admit that I do not understand how this works. Do these metals make temporary compounds, which break down and release the reactive payload, and unchanged catalyst?

          Your intuition is correct. Since these elements do not form substitution (permanent) compounds readily their surface bonds remain available to make temporary bonds with things like (famously, and especially) hydrogen. Since all organic compounds have C-H bonds, this makes them targets for precious metal catalysis.

    • My wedding band is made of palladium. Is it going to kill me?

      There's this one guy named "The State of California" who you should ask.

      He will know.

      • There's this one guy named "The State of California" who you should ask.

        He will know.

        I try to avoid "State of California" as much as possible since being physically there can be harmful to your health.

        • I try to avoid "State of California" as much as possible since being physically there can be harmful to your health.

          Yep. Everything gives you cancer in California.

    • by OldBus ( 596183 )
      Doubt it. Have a palladium wedding ring myself. We went for palladium as well cos it was cheaper than platinum. Palladium has tripled in price since then.
      Consider it an investment!
  • As much as we might want to wish away the need for a bunch of mined metals (especially precious metals), it turns out there are a lot of uses for elements that you just can't substitute something else...

    But because mining has fallen into disfavor the last decade or so, a lot of mined stuff is going to be coming up short not too long from now, and remain expensive as a result for quite a while.

    • by Anonymous Coward

      Our "purification" processes are sloppy. I blame the financial system that demands it be that way

    • Could be worse. Food is likely to come up short in the next year or so. Especially in Sri Lanka.

    • Thomas Fuchb, a medicinal chemist at the life-sciences company Merck in Darmstadt,

      Speaking of real things, if you want to read the real version of that you'll have to wait until it appears on The Other Site, whose character set isn't stuck in 1963.

  • by Anonymous Coward

    I wonder if that might be because it was utter bullshit?

  • Retracted? (Score:4, Insightful)

    by Roger W Moore ( 538166 ) on Thursday June 16, 2022 @06:42PM (#62626432) Journal

    A retracted paper highlights chemistry's history of trying to avoid the expensive, toxic -- but necessary -- catalyst.

    Quoting a paper that you know has been retracted is really not a good idea because papers are only retracted if they are seriously flawed.

    • That’s what big palladium wants you to think.

      • by haruchai ( 17472 )

        "Ronald Reagan and the NRA canceled open carry in 1967. Google Mulford Act
        "
        Ronald Reagan and the NRA canceled open carry in 1967 because some black people in California armed themselves.
        FTFY

    • TFA makes it clear that the fact that it's retracted is why it's interesting. They're citing the retracted article as an example of how hard it is to replace Pd catalysts, and how easy it is to fall into experimental traps that result in flawed research and retracted papers.

    • Quoting a paper that you know has been retracted is really not a good idea because papers are only retracted if they are seriously flawed.

      Yes but you don't know what the flaw was. The summary here references only the fact that chemistry has a history of trying to avoid palladium as a catalyst, and that is objectively true. Palladium is a woefully expensive catalyst so it would be more a major scientific discovery if someone wasn't trying to replace it with something cheaper.

      We've be trying to avoid using palladium since we first started using palladium. You don't need to trust a redacted paper for that story, that is common knowledge in the c

  • Liquid metal catalysis, such as is being done with platinum catalysts [sciencealert.com], could reduce the amount necessary -- probably won't help the hard work to remove it from the final product, though.
  • The article says we thought we had discovered palladium-free catalyst reactions in the past but it turned out to be a mistake.

    How could that be a mistake?
    Did they forget that they had added some Palladium? After they add something, does someone only then check the label for Palladium?
    Did they think they made something, but turned out not to? Wow, I thought this was insulin, but it turns out to only be adenaline?

    • by Ailicec ( 755495 )
      Whenever I see the word "spew" in the summary, I know I'm looking at a constructed environmental outrage piece.
      • Let's examine that sentence.

        Constructed means it was made on purpose by a thinking being.
        All articles are constructed. That word is meaningless for the sentence's actual content, but used to imply a belief in falseness. It's like putting air quotes around something. It tells us about you, not the topic.

        Environmental means it is a discussion of a topic that liberals thinks is important and conservatives dismiss as unimportant.

        Outrage piece means that the speaker is wanting to change the way the current w

    • by Cyberax ( 705495 )

      How could that be a mistake?

      Quite easily.

      Did they forget that they had added some Palladium?

      They did not. Minute quantities of palladium that got stuck on the glassware even through repeated washes were enough. It is REALLY hard to get rid of all of it.

    • RTFA. It gets better than its introductory material. One worker got good results in the UK, but bad results in the US. A UK sourced reagent was found to have ppb quantities of Pd, whereas a US sourced reagent was Pd-free and failed. A worker in China had results that could not be reproduced, and again Pd contamination was found; the original assay method was defeated by the surrounding chemistry. A second worker in China was also unable to reproduce results and lamented the waste of effort. The retrac
      • by Junta ( 36770 )

        But I've read very credible people online telling me that science is just liberal elites in labcoats saying what they want and declaring 'science' to give themselves authority. Who am I to believe, well researched articles citing specific examples of how science includes attempts to reproduce and thoughtful exploration, or my Uncle Jim on Facebook?

  • I remember a YouTube video made a few years back about a couple of guys who swept a few hundred yards of road shoulder. They brought back the grit, smelted it and assayed it for precious metals. They found platinum, palladium, and some others. They claimed that their yield exceeded that from some commercial mines.

    Makes you wonder about all those vacuum sweeper trucks.

  • Palladium (Score:5, Insightful)

    by Retired Chemist ( 5039029 ) on Thursday June 16, 2022 @07:07PM (#62626488)
    The toxicity of palladium is controversial at best. The more critical practical issue is that it and rhodium and the other metals used in catalysis are are expensive and mostly available from unpleasant countries. I worked for a chemical company, which spent a vast amount of effort trying to find ways to replace platinum group metals with very limited success. Electric cars would appear to be the long-term solution to the catalytic converter issue, but the other issues are harder to deal with.
    • I wondered about that, is there any evidence palladium in the environment is poisoning anything or any one?

      People wear palladium jewelry, I'd be very interested in a single proven case of an allergy or other poisoning.

  • I never knew you could snort that stuff.

  • by gweihir ( 88907 )

    Are we now citing known-to-be-flawed research? Can we at least get some information as to _why_ that paper was retracted?

    • maybe it's because palladium actually isn't poisonous? must say I was quite puzzled by the claim of it poisoning the world; first I've ever seen the claim

    • by Junta ( 36770 ) on Friday June 17, 2022 @07:47AM (#62627488)

      The paper that was retracted thought they found a way to *not* use palladium. The article was about how they were mistaken. They said that they determined there was palladium contamination explaining the results. So they indeed say why it was retracted.

      It was 'citing' the paper to demonstrate how scientific results can be initially flawed and the scientific community methodology to double check each others findings and amend mistakes.

  • by Gravis Zero ( 934156 ) on Thursday June 16, 2022 @08:05PM (#62626608)

    If you're getting serious about reducing the cost of producing drugs then there is no escaping the simple fact that monocular organisms are the kings of chemical production. What they should be looking at is how to either mimic how these molecular masters modify chemical compounds or how to harness them to make the compounds they need most. We always seems to be trying to poorly copy what nature has mastered with billions of years of evolution.

    • The advantage of non biological chemical processes is that we can vastly increase production and greatly lower cost by increasing temperatures and pressures that biological systems cannot survive.

      A perfect example is nitrogen fixing. It can be done biologically but is not practical at the scale we have with the Haber-Bosch process without which our world would starve. Read a book called the Alchemy of Air to learn more about Haber-Bosch.

      Nature does not use the wheel and does not travel into space. We ha
      • The advantage of non biological chemical processes is that we can vastly increase production and greatly lower cost by increasing

        That's fine so long as you have a lot of excess energy to use on keeping it a closed loop. If you fail to keep it a closed loop then your process is unsustainable.

        temperatures and pressures that biological systems cannot survive.

        Well that is a bold assertion.

        Nature does not use the wheel and does not travel into space

        Nature doesn't use the wheel because it's a shit design for survival as wheels get stuck. Furthermore, going into space isn't advantageous for survival. Hell, most of the sats we've put in orbit are now merely debris because the environment is so unforgiving.

        • Bold assertion challenge accepted :-)

          We cannot feed our existing population without Haber-Bosch for making nitrogen fertilizer. For commercial production, the reaction is carried out at pressures ranging from 200 to 400 atmospheres and at temperatures ranging from 400 to 650 C (750 to 1200 F). Biological equivalents would be absurdly impractical.

          Haber-Bosch actually does use energy from its reactions in a somewhat closed loop and is quite energy efficient for what it produces.

          You cannot increase prod
          • The highest temperature known for extremophiles is roughly 121 C so high temperatures are impossible due to the breakdown of organic chemistry.

            You wrote that biological systems cannot survive but in doing so you excluded all undiscovered organisms, yet to evolve organisms, extraterrestrial organisms, and possibly even non-carbon based lifeforms. It's best to qualify such assertions with the prefix "known" as there is much we don't know about.

            Don't get me wrong, I'm a big believer in using bioengineered organisms, (I like to make beer) but they cannot be universally applicable and are not always the best solution to a problem.

            What specifically is impeding it from being used as such?

            Furthermore, I started off by stating we should understand and mimic how it's done biologically OR utilize biology to do it.

  • Chemical manufacturers have to separate out all traces of palladium from their products and carefully dispose of the hazardous waste, which adds extra expense. Thomas Fuchb, a medicinal chemist at the life-sciences company Merck in Darmstadt, Germany, gives the example of a reaction to make 3 kilograms of a drug molecule for which the ingredients cost US$250,000. The palladium catalyst alone adds $100,000; purifying it out of the product another $30,000.

    Seems like there'd be a cost benefit to finding a way to separate, recycle and re-use the palladium rather than using it, separating it out and disposing of it.

  • Something can't be inert and harmless and a good catalyst at the same time.

    I take that back. Something can be a good catalyst at high temperatures and mostly harmless at body temperature. But if you need something to happen at higher temperatures, chances are that either your inputs or outputs won't survive it.

    I guess we have to put on our big bou pants and come to terms with the fact that dangerous chemicals are a necessary part of technoligical civilization.

    Reality is a stubborn bitch.

    • I guess we have to put on our big bou pants and come to terms with the fact that dangerous chemicals are a necessary part of technoligical civilization.

      Yes we definitely should stop scientific research along these lines because it personally offends your politics.

      • Magical thinking offends my politics. Magical thinking of the following variety in particular:

        "Here's something that works (at best) on a lab bench, or maybe only in theory. And either way, only some of the time. Let's predicate national industrial/energy/transportation policy on the assumption that the Something in question can scale up and totally replace cars/oil and gas/synchronous grid power/basic foodstuffs, and do so in the next ten years!"

        Statements like this are sometimes made by crooks trying to

        • blah-de-blah

          but you didn't say that. You said we should "just accept" it. No, we are not going to stop scientific research because you are offended by it.

          All this blah is post-hoc whining. also you have very peculiar opinions as to that is likely to be pointless and fruitful.

          • Remember that old cartoon with a scruffy professor type at a blackboard full of equations and at the end, the words "and then a miracle happens" that leads to the solution?

            Real life doesn't work like that at all.

            Opining about how great it would be if we could just vaguely "science" a solution to a physics-based limitation or tradeoff into existence is exactly that sort of sloppy thinking.

            So are the apologies for it.

            Shit either works right here and right now or it doesn't exist. Sometimes new and better thin

            • Remember that old cartoon with a scruffy professor type at a blackboard full of equations and at the end, the words "and then a miracle happens" that leads to the solution?

              No.

              Real life doesn't work like that at all.

              Yeah no shit sherlock. Real life is a bunch of research. Fortunately everyone who counts is going to thoroughly ignore you and continue to research things rather than putting on their big boy pants and just accepting it, as you put it.

              I mean I know you want the world to bend to your angry right w

              • You clearly don't understand the difference between a knowledge limit and a physics limit. Here's an example: 50 years ago, no one knew how to manufacture semiconductors with ~10 nanometer scale features. Today, no one knows how to manufacture with 10 picometer scale features. The former was a knowledge limit. Since a silicon atom is about 100 pm across, the latter is a physics limit.

                • you don't know remotely enough chemistry to know about physics limits for catalysts in the context of this discussion.

                  It's also become rather apparent that you have invented a position for me and are arguing vociferously against that. I can kind of deduce roughly what you think I think from the direction of your flailing and misplaced barbs, but I would be much obliged if you'd simply tell me what your fanfic of me actually is.

                  • You have a knee-jerk reflex to defend anything that remotely resembles scientific research, regardless of the merits of the particular research in general, and regardless of the quality of execution of a given research project in particular. If you think there's a political valence to the criticisms, and it is the opposite of your tribe's, you crank it up to 11.

                    How'd I do?

                    • How'd I do?

                      About as well as usual: your fanfic about me has no connection to reality. And when I press you to provide any evidence of your claims, you will weirdly enough fail to reply then crop up a few months later with a new fanfic.

                      I now you won't answer: but tell me: if you have to invent so much stuff to support your viewpoint has it not even slightly occurred to you that your viewpoint might be flawed?

                    • Everyone lives in their own little bubble with imagined mortal enemies beyond the walls.

                      My experience, as well as my temperament, informs my subjective opinions, as yours do too.

                      I have no idea who and what you are IRL, but I do notice you like to snipe at caricatures of rightwing demons you seem to think are lurking behind every disagreement of opinion. And assume that the same thing is being done to you.

                      The great paradox of ubiquitous connectivity seems to be that we understand eachother less than when com

  • by ghoul ( 157158 ) on Thursday June 16, 2022 @09:51PM (#62626744)
    So the authors would want to get rid of metallic catalysts and go to what? Non metallic catalysts? We call them enzymes and hormones. So they would like to pump our food and medicines full of artificial enzymes and hormones which cant easily be purified out as they are also carbon compounds. So instead of an easily purified out metal we get frankentomatoes and salads which catalyze your eyes into xanax?

    See I can be alarmist too.
  • ....the ink is probably WAY more toxic than the nib.... and the ink isn't toxic at all..
  • Catalytic converters were a product of mid 1970s fanaticism with air pollution control. Modern engines can accomplish much of the same cleaner burning without one. But laws rarely if ever keep up with technology. In addition to palladium appearing everywhere, one of the effects of the use of a catalytic converter is converting carbon monoxide to carbon dioxide which is a greenhouse gas. So is mandating their use long after better engine technology was ubiquitous contributing to climate change?

    • by ebvwfbw ( 864834 )

      It wasn't fanaticism in the 1970s. I lived it. There used to be so much smog it was hard to breathe or even see more than 1/2 mile, especially in places like Los Angeles. I know what you're thinking, it wasn't low clouds. No kidding. They had to do something. They played with fuel injection. It didn't really help a whole lot. It wasn't until much later with computers that they could control it a lot better. Today they still perform a very valuable service. Los Angeles, NYC, Washington DC, and others would p

  • And market it as Ethyl!
    • by ebvwfbw ( 864834 )

      Lead? Oh good God. Stop with the lead. It's a terrible poison. I bet I have lead in my body from the 1970s. It used to be everywhere. In gasoline, paint, paint on glasses, and so on.

  • https://en.wikipedia.org/wiki/... [wikipedia.org]

    Who doesn't love ultra-high HP/Damage role playing?

    Oh, you can quit Palladium, but once you're in, Palladium will never quit you.

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