So, i'm just searching around in spaceengine and got the idea of worldbuilding based on one of the planets that exists in the simulation (not quite worldbuilding in a complete sense, but speculating and "building" life on that planet). Now, I've "worldbuilded" many times using spaceengine before, often using hours researching information and finding the scientifically realistic planet for building ecosystems and even civilizations on, but this time is different, I want to build ecosystems based on a planet like Titan, where water-ice is essentially rock and there are life as we don't know it living in the oceans, but so far, I've only found planets with liquid CO2 as oceans, so may I ask, is it scientifically realistic that some lifeforms use liquid CO2 as solvent and what might the chemical composition of that type of lifeform be?
To get liquid CO2 you need above 5.1 atmospheres of pressure, and below -69°F. Note that if the pressure ever falls below this you get flashing to vapor above -109.3°F. So an organism that maintains an internal pressure to keep CO2 liquid might have to worry a lot about cuts.
Once you get liquid CO2 at least some things can dissolve to some extent. This article seems to be some kind of measurement of a process to use liquid CO2 to dissolve the active ingredient out of cannabis.
Presumably there are tweaks that can be made to enhance dissolving things that are needed. And adaptations that would make the things that do dissolve more readily useful.
There might be interesting processes of distillation. Perhaps an organism can dissolve something it wants, then slightly decrease the pressure around the solution and thus draw off the CO2 and leave the material it wants.