Surface Chemistry of Titan Options

[Juramike]

Guys, I hate to spoil your enthusiasm, but I doubt any revolution in organic chemistry might be coming from Titan.
I don't know of any chemists hanging around municipal wastewater plants to capitalize on the synthesis of new organic compounds, and there's a lot of "gunk" packed in close contact there

Interesting chemistry, surely. But not revolutionary, imho.

Hmm... The organic chemistry will be the same, but the compounds generated and lying around on/under the surface might be quite interesting and possibly different than those found on Earth.

Titan's atmosphere is going to be making a lot of funky polycyclic and unsaturated compounds. The kinds of things that would hydrolyze and oxidize quickly in Earth's atmosphere (or get eaten by Earth's organisms).

And you just never know where the next therapeutic compound is going to come from.

Here's a case in point: Spinosad, put forward by DowElanco way back in the 90's, was a natual product insecticide isolated from a fungi found under a rum vat in the Caribbean. Wiki here.

(And yes, getting broths from natural and degradative sources was the rage back in the 90's. The deconvolution usually ended up isolating the same things over and over again: usually polyphenolics the bound everything and interfered with fluorescence assay.)

Titan's atmospheric chemsitry and organic geochemistry (did I just invent a new field?) might provide an additional source of interesting compounds.

-Mike

[TheChemist]

Titan's atmospheric chemistry and organic geochemistry (did I just invent a new field?) might provide an additional source of interesting compounds.
-Mike

Ok, interesting compounds I agree, but not revolutionary chemistry ....

And sorry, but there 's already a journal for it

Organic Geochemistry
The International Journal for the Rapid Publication of Current Research in Organic Geochemistry and Biogeochemistry
The Official Journal of the European Association of Organic Geochemists
Description
Organic Geochemistry serves as the only dedicated medium for the publication of peer-reviewed research on all phases of geochemistry in which organic compounds play a major role.......

Scirus gives 12 hits for Titan in it Might be the ideal place to publish your work. I am serious !

[Juramike]

Thanks for the links!

And I had access to the journal as well! [Oh no! Another journal to keep up with!] ...Kind of an interesting journal: the Roman numeraled pages in this journal are for a section that has abstracted references from other journals.



I think that the surface chemistry could actually be pretty straightforward to simulate in a chemical laboratory, once a few parameters have been determined.

The atmospheric chemistry is another story. Messing about with electrical discharges and flammable gasses is not for the lighthearted. It also seems that the exact gas ratios, pressures , ionization or input energies involved, catalytic surfaces floating around in the atmosphere, etc., will make it really tricky to model Titan's upper atmosphere exactly in the laboratory. And Titan doesn't have electrodes dangling in the clouds (so no metal electrode surface effects).

-Mike

[rlorenz]

Ok, interesting compounds I agree, but not revolutionary chemistry ....

You are *probably* right, but I have learned (predicting a lack of dunes on
Titan being a case in point) never to say never.

There is a really, really good discussion of chemical possibilities in the recent
National Academies report Limits to Organic Life in Planetary Systems
http://www.nap.edu/catalog.php?record_id=11919
(free login to download whole report) in fact, it makes an excellent intro
to prebiotic chemistry overall

[ngunn]

Thanks for that excellent link, rlorenz. All 117 pages are now at the top of my holiday reading pile.

[Juramike]

Thank you for the excellent reference!

From p 17: “At lower temperatutes, a single hydrogen bond can hold together a molecular complex for as long a time as a covalent bond holds together a complex at room temperature”.

Whoa! Paradigm shift!

At Titan’s low temperature, many of the lower energy molecule-molecule interactions that are often underappreciated on Earth may become quite significant. (Most chemists are used to thinking about inter and intramolecular hydrogen bonds, probably because of our 298 K water-based bias.)

A couple of examples of the “wussier” interactions include pi-pi interactions, halogen bonds (where halogens act like hydrogen bond donors – yes, it’s weird but it happens), and other pi-dispersive effects. These are actually very important in human biology and are only recently getting noticed.

As an example of "non-H-bond" interactions, here is a diagram showing how a pi-pi "time-out" bond interaction is set up. (Prof. Gregory Petsko is “Da Man” when it comes to the discovery and characterization of the “time-out” bond of pi-pi interactions. He is named in The Limits of Organic Life in Planetary Systems report as one of the members of the Board on Life Sciences on p. vii.)



Here is a table showing bond energies of other intermolecular (and intramolecular) interactions compared to typical H-bond energies that are more familiar. (The arrow direction is non-standard, it shows electronic density flowing from e-rich to e-poor. Most standard arrows show H (electrophilic) transfer direction – obviously this breaks down when dealing with non-H atom effects (like halogen bonds or lone pair dispersive interactions).



So at Titan’s temperatures, aromatic-aromatic interactions, fleeting in free solution on Earth, may “freeze up” systems on Titan. (Also many of the lower energy X-H<--pi or Hal<--O=C interactions as well) This could be key to both low-temperature prebiotic chemistry as well as surfactant and emulsion chemistry that may be happening on the surface or in the lakes.

For any putative (pre)biological systems on colder worlds, these weaker interactions could take the place of the H-bond interactions that occur at warmer temperatures. Imagine the non-H-bonding aromatic-only “base” pairs of a low temperature analog of DNA locking up in a perpendicular arrangement rather than the parallel arrangement of our H-bonding DNA base pairs. Low temperature catalytic interactions could occur the same way, a large molecule could use weaker dispersion interactions to aid the conformational shift to allow lower energy interactions to occur.

So cool interactions could happen with big ugly greasy aromatic macromolecules. Just as long as any catalyzed transformations were also of really low energy.


So what does this mean for Titan exploration?
It means that we might be able to examine low temperature surfactant effects in laboratories on Earth to simulate Titan lake and seas. (Take multicomponent mixtures of hydrocarbon solvents and big aromatics (heterocyclic?), cool it down way low and how it goos up, gels up, or partitions out on shaking. Throw in a few trace dissolved solid materials (benzene, acetonitrile) and see then how it behaves).

It also means that really neat chemistry and effects (pre-biotic) on Titan might involve really big greasy things that are different types of biomolecules than found on Earth. These are things that might not fly at all in a GCMS. For really digging into the chemistry (sorry!) a surface mission might need analytical tools like a LCMS or LC-multidimensional NMR with the LC end dealing with both aqueous phases and normal (organic) phases (so maybe do one analysis set using water, and another using methane as the mobile phase?). With things fairly complicated in size and structrure, MS might just give a subtle clue, but probably won't define structure. That is where detailed NMR work using a variety of experiments will be necessary.

"Natural" products chemistry on Titan will probably deal with big, gnarly, aromatic and heteroaromatic rings stick together that will be very difficult to define structurally. ("Natural" means raining out from atmospheric chemistry, then processed at low temperatures in hydrocarbon solvets, or at warmer temperatures in ammonia-water solution).

-Mike

[marsbug]

Just having fun with an idea that may be utter rubbish: I read many moons ago an article on emergent complexity which suggested that an already very complex system could spontaneosly jump to a new level of complexity by synthesising something not native to itself. The last week I've been flipping through the National Academies report Limits to Organic Life in Planetary Systems ( like to add my thanks to rlorenz for that) and then I re-read this esa article which describes how the pyrolisis products of the aerosols on titan were hydrogen cyanide and ammonia. The thought occcured to me this afternoon that the ammonia, which is suggested as a potential biosolvent and is not naturally present in titans atmosphere, might possibly possibly be the result of emergent behavoir in titans atmospheric chemistry. Thats not to suggest that the aerosols are 'alive' or the chemistry that produced them is, but that the aerosols might be a step along the way slightly further than the organics around them. If you can have a complex titan, could you have an emergent one? Or possibly five hours of taking down numbers of a broken vacuum chamber has just made my brain leak

[belleraphon1]

Thanks rlorenz ....

Wonderful report.... I have been waiting to read this since I first learned about the "Weird Life" conference being held.

Titan is a planet sized cryogenic laboratory of complex organics that have probably been put through many different climate regimes. If Titan has truly lost 5 times as much nitrogen as we currently find, then the surface temperatures were probably higher in the past, and the surface has probaly seen fluctuations in pressure and temperatures over geologic time.

I hate to repeat this, but we really cannot compare Earth temperature laboratory organic chemistry with a planet sized fluctuating cryogenic environment.

We really HAVE to go there to KNOW.

Craig

[belleraphon1]

So what does this mean for Titan exploration?
It means that we might be able to examine low temperature surfactant effects in laboratories on Earth to simulate Titan lake and seas. (Take multicomponent mixtures of hydrocarbon solvents and big aromatics (heterocyclic?), cool it down way low and how it goos up, gels up, or partitions out on shaking. Throw in a few trace dissolved solid materials (benzene, acetonitrile) and see then how it behaves).
-Mike

Hey Mike...

BRAVO.... your comments in the last post . The "Limits of Organic Life in Planetary Systems" report specifically notes that laboratory research on organics at cryotemps is lacking and needed.
p78 "Essentially nothing is known about the solubility of biomolecules in cryogenic solvents. Therefore, research into the possibility of life in cryogenic solvents needs to begin by making fundamental measurements and establishing a database describing the solubility of organic species in such solvents over a range of pressures and temperatures that are relevant to locales in the solar system."

Mike, perhaps you should apply for a NASA grant? (serious here)

And as for revolutionary chemistry (or not), this report also goes out on a limb on pages 74 and 75 states
"Thus the environment of Titan meets the absolute requirements for life. Titan is not at thermodynamic equilibrium. It has abundant carbon-containing molecules and heteroatoms and a fluid environment. Titan’s temperature is low enough to permit a wide range of bonding, covalent and noncovalent. Titan undoubtedly offers other resources believed to be useful for catalysis necessary for life, including metals and surfaces.
This makes inescapable the conclusion that if life is an intrinsic property of chemical reactivity, life should
exist on Titan. Indeed, for life not to exist on Titan, we would have to argue that life is not an intrinsic property of the reactivity of carbon-containing molecules under conditions where they are stable. Rather, we would have to conclude that either life is scarce in these conditions or that there is something special, and better, about the environment that Earth presents (including its water)."

Now I am NOT expecting trees and seaweed... I AM NOT that Craig. But if we do not find some form of living system on Titan, than the Universe becomes a lonlier place and perhaps the chemistry is "just interesting".

Once again ... we won't know till we go and I expect it will take human explorers or their uploads to settle this. And that is a future I will probably not live to see.

Craig

[TheChemist]

What a cool thread we have here !

So cool interactions could happen with big ugly greasy aromatic macromolecules. Just as long as any catalyzed transformations were also of really low energy.
-Mike

That's the key point Mike, those interactions will hold stuff together, but we still need energy to brake bonds, so some kind of catalysis is necessary at low temps.
We have no definite idea about the presence of trace metals on Titan and won't for a very long time unfortunately.

With things fairly complicated in size and structrure, MS might just give a subtle clue, but probably won't define structure. That is where detailed NMR work using a variety of experiments will be necessary.
-Mike

I hear you and I am available

[rlorenz]

As an example of "non-H-bond" interactions, here is a diagram showing how a pi-pi "time-out" bond interaction is set up. (Prof. Gregory Petsko is “Da Man” when it comes to the discovery and characterization of the “time-out” bond of pi-pi interactions.

Another guy you should look out for is Steve Benner, who was an author of this report - big on
chemical evolution.

I actually got to meet him at the invitation-only SciFoo conference last weekend at the Googleplex...
fun to hang out with him, Dave Grinspoon, Freeman Dyson, Oliver Morton, Bob Carlson
(look out for that name in the next few years..) others in attendance included Martin Rees,
Martha Stewart(!), Greg Bear, Neal Stephenson.....

[Juramike]

regarding composition: here's a presentation from Athena Coustenis, which is basically the results from her 2007 paper. See pages 13+14 for mixing ratios (so 1e-6 is 1ppm)

confs.obspm.fr/Blois2006/Presentations/Coustenis_CIRS.pdf

this is stratospheric of course, so not exactly as you would stand on the surface (and most of this stuff condenses out at the tropopause anyway)... GCMS will have some more info on troposphere

Found a handy reference for Titan's atmospheric components in table form here:
http://sci.esa.int/science-e/www/object/in...fobjectid=31187

The numbers in the table seem to agree with the global average from the Coustenis presentation.

(And yes, you'd get a slight headache from CO but not enough HCN to kill you.)

-Mike

[nprev]

Belleraphon, I completely agree that Mike needs to apply for a NASA grant...the man's unpaid purely intellectual contributions are mind-boggling, imagine what he could do with a dedicated staff & a suitably-equipped lab...

<ahem!>...Oh, hey, Mike, we were just talking about you!

BP, damn exciting words in that report, going out on a limb or not. It seems that Titan may well provide a fundamental constraint on the abundance of life in the Universe by virtue of its presence or absence there. Either condition will provide vital data.

[Juramike]

The thought occcured to me this afternoon that the ammonia, which is suggested as a potential biosolvent and is not naturally present in Titans atmosphere, might possibly possibly be the result of emergent behavoir in Titans atmospheric chemistry. Thats not to suggest that the aerosols are 'alive' or the chemistry that produced them is, but that the aerosols might be a step along the way slightly further than the organics around them.

Hmmm...where is all that ammonia? Did it get scrubbed out by HCN to make that super-nifty organic building block (NH4)CN*?

Given Titan’s atmosphere at 3E17kg and HCN present at 1 ppm (1E-6, from the sources above) we get 3E9 kg HCN in the atmosphere.

The mass of cryomagma erupted on the surface is estimated at 5E12 kg/year (estimate from: A.D. Fortes et al Icarus 188 (2007) 139-153 “Ammonium sulfate on Titan: Possible origin and role in cryovolcanism.” Pay-for article: abstract available here.)

Assuming that 0.5 wt% of NH3 is coughed out from cryovolcanic eruptions (Fortes et al used this same percentage to estimate CH4 release from cryovolcanic activity), that gives about 5E9 kg NH3 released/year.

Unfortunately, this is more than enough NH3 (or NH4OH) released in a year to scrub out all the HCN in the atmosphere as (NH4)CN.

And if all the ammonia is locked up as (NH4)2SO4 in solution or frozen up, can this exchange with atmospheric HCN in either solid or liquid phase to then generate (NH4)CN* which can then go away to organic products? And if so, wouldn’t that also scrub out all the atmospheric HCN?

I’m stumped.

-Mike


[*Why is this (NH4)CN stuff so cool?

Even at low temperatures (NH4)CN polymerizes to make complex organic molecules. That much (NH4)CN/year generated would correspond to the eventual production (it did this after 27 years at -78 C in the lab) of 5E6 kg/year of orotic acid after hydrolysis (assuming the 0.1% yield reported in Miyakawa et al. Origins of Life and Evolution of the Biosphere 32 (2002) 209-218. “The Cold Origin of Life: B. Implications based on pyrimidines and purines produced from frozen ammonium cyanide solutions" Pay-for article. Abstract here.)

That's one big pile of potential nucleotide!]

[belleraphon1]

nprev... (I know you are AI... is it gauch to ask if you are an upload?)

it is an exciting time... is it not!!!

COROT and KEPLER will soon give us terrestrial planet stats, while exploration of our own local solar neigbors will gives us clues to what may walk in that wider Universe.

What a time in human history this is!

And Mike... get busy on those grant proposals......

I hesitantly add this link to some pics I took in Watkins Glen, NY....
http://www.flickr.com/photos/7323592@N07/s...360286785/show/

Cannot help but wonder if the stratification in shale will be similar to the srtatification in ices/oranics on Titan in some of those rough channels (my hiking companion was rolling her eyes as I expounded on this thought.... but good friend that she is, she stuck with me).

Craig