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Kind of a follow-up to this earlier question: How could formamide lakes form on an exoplanet?

Suppose the problem of how to get an initial quantity of formamide is solved, and microbial life has arisen. It nevertheless seems highly unlikely that ocean-forming quantities of formamide, or formamide rain, will naturally persist on any realistic planet. (The Limits of Organic Life in Planetary Systems even specifically calls out formamide life as being most likely in desert environments, with formamide occurring in small quantities.)

So, if formamide life is going to spread, it's going to need to manufacture its own biosolvent.

There cannot be lots of water around, because if there were, a) life would've just developed to use water instead of formamide in the first place, and b) formamide will belong-term unstable. So, the water + HCN synthesis path is out, except perhaps as a component of a larger metabolic process that temporarily produces water internally.

Other possible synthesis paths include:

CO + NH3 -> HCONH2

HCOOH (formic acid) + HCN -> HCONH2 + CO

HCOOH (formic acid) + NH3 -> HCONH2 + H2O

4 NH3 + 2 CO2 (not environmentally stable) -> 2 H2NCOONH4 (Ammonium carbamate, used in the production of pyrimidines) -> 2 HCONH2 + N2 + H2 + 2 H2O

There are probably more, and some of these end up potentially interacting with each other. But the biggest issue seems to come down to "how do you get both oxygen and hydrogen without ending up with a ton of water in the environment?"

So, what would a reasonable ecology look like, in terms of biologically-relevant environmental chemicals and producer and consumer metabolisms, that would let formamide-based organisms exist and produce their own endogenous formamide?

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  • $\begingroup$ What sort of worldbuilding are you engaging in? For instance, if this were a tabletop rpg, I'd just tell you to ignore this, and run with it. Such esoteric details are unwarranted. But, if you'd going for a big hardcore science fiction novel, you might decide that this is a dead end unless you really can fully/plausibly explain it. And there are a few in-between answers too... so please, what are you going for here? $\endgroup$
    – John O
    Nov 5 '21 at 20:11
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    $\begingroup$ @JohnO Hard scifi, for integration into a larger narrative universe with a bunch of weird aliens with weird biochemistry. Sort of Hal Clement inspired--Iceworld, Mission of Gravity, Still River, etc. $\endgroup$ Nov 5 '21 at 20:29
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More building of the formamide world!

Here is your prior question. How could formamide lakes form on an exoplanet?

Part of my answer:

Thinking about why life forms would synthesize form amide - it is easy. The energy.

enthalpy of formation of formamide

https://webbook.nist.gov/cgi/cbook.cgi?ID=C75127&Mask=1E9F

When these life forms catch a CO and hook it to ambient NH3 they get a little bit of energy back each time.


Let us build out the world a little more. There is an ammonia atmosphere so NH3 is available any time. CO is the stuff in short supply.

For a microbial ecology we need to regenerate the CO. Let there be autotrophs!

https://en.wikipedia.org/wiki/Formamide

Formamide decomposes into carbon monoxide and ammonia at 180 °C.

HCONH2 → CO + NH3 Traces of hydrogen cyanide (HCN) and water are also observed.

Just as autotrophic plants use radiant energy to split water and store its energy as hydrogen (added to CO2) the autotrophs in the formamide lake capture radiant energy and catalyze decomposition of formamide. The plants release the ammonia and keep the CO which is the valuable stuff. Later the plants can generate energy for themselves by making formamide just as earth plants oxidize the sugar they made.

Formamide plants would have CO within their bodies and fruits just as earth plants have sugars in their bodies.

Now we have a cycle. Autotrophs capturing radiant energy to claim CO from formamide, and heterotrophs that take CO from autotrophs (or loose in the atmosphere, if there is any!) to combine with NH3 and generate formamide and energy.

A remaining question: how would an organism generating CO best store it? What is a starch equivalent? Starch is polymer than can hold a lot of glucose to be cheaply released on need. What is a polymer which can easily release CO at need?


Not a polymer but a good storage place.

carbonyls

enter image description here

Metal carbonyls? This is more like hemoglobin for oxygen than starch for sugar, but the carbon monoxide is readily available. And they are cool looking molecules.

https://en.wikipedia.org/wiki/Iron_pentacarbonyl https://en.wikipedia.org/wiki/Nickel_tetracarbonyl

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  • $\begingroup$ The problem with this cycle is that all of the components for formamide synthesis come from formamide in the first place; thus no new, biogenic formamide is ever produced, and the ecosystem is limited in size by how much primordial formamide there happened to be. It's directly analogous to how regular plants consume water to produce carbohydrates, and animals regenerate water by burning carbohydrates--and what we really want it plants that are able to produce (the equivalent of) additional water as well as additional food molecules to expand the biosphere. $\endgroup$ Nov 6 '21 at 19:39
  • $\begingroup$ The idea of using metal carbonyls as an energy storage medium is kinda neat, though! $\endgroup$ Nov 6 '21 at 19:40
  • $\begingroup$ Check my original scheme. You gave it the green check! It uses ambient ammonia and spontaneously forming CO and critters that scavenge them. I posit high altitude photolysis of water to provide the O which generates CO with methane. The original organisms get their energy scavenging environmental CO just like original earth life scavenged ambient tasty molecules, which got scarce over the eons. $\endgroup$
    – Willk
    Nov 6 '21 at 21:29
  • $\begingroup$ I didn't give it the green check--that was not my question. It's just a relevant one that was suggested as related when I was writing up this question. $\endgroup$ Nov 6 '21 at 22:33
  • $\begingroup$ Maybe the origin of the formamide should remain a mystery (one to be solved later). The planet/cycle could be synthetic, a billion year old experiment by another intelligence. Sort of deus ex, I guess, but if you must have this cycle and there can be no natural origins, then it's fairly plausible. Some K-IIIs just made it for shits and giggles and didn't clean up afterward. Does the cycle have enough longevity for that to be possible, or does it peter out in a million years? $\endgroup$
    – John O
    Nov 7 '21 at 6:06

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