Over the course of my worldbuilding, I have looked into many alternative substances from which oceans could be composed that would serve as a viable solvent for biochemistry, and I often run into the issue that most of the commonly suggested solvents contain hydrogen and that most hydrogen-containing liquids other than water react with oxygen, which would prevent an oxygen atmosphere and thereby aerobic metabolism.
The solution to this issue is to use a solvent which does not contain hydrogen in its molecules, since, while these often still react with oxygen, a far higher percentage of them do not.
Solvents which themselves have significant oxidising properties are also not practical.
With this in mind, liquid CO2 seems like the obvious solvent of choice, since it contains no hydrogen, does not react with oxygen, and has only minor oxidising properties itself. I am referring here to true liquid CO2, not to supercritical CO2.
Now, since I do not want the planet to be covered in water ice, it will be necessary for the planet overall to be very low in hydrogen, but this presents another issue: Earth's biochemistry is heavily reliant on hydrogen, so how do we have biochemistry without much of it?
I am looking for the basics of an alternative biochemistry which meets the following criteria:
- Is no more than 5% hydrogen by number of atoms
- Is primarily carbon-based
- Allows aerobic metabolism
- Can operate in a solvent which contains no hydrogen in its molecules, does not react with oxygen, and itself possesses no or only minor oxidising properties; this should preferably be liquid CO2, but any solvent which meets the requirements will do
I understand that I'm asking a lot here, but I do not think this question is beyond the capacity of the people here to answer.
Edit: Just to clarify, I am asking about the molecules in the solvent, not what the solvent should be.