Si- based life

Lets say we have a silicon-based life. What are the most common
structures and chemical reactions we would encounter with ? and also,
what would be the suitable temperature range for such life to exist ?
(since SiO2 might have to be a gas, or just replaced by another
substance)

On 7 Mar 2004, Amirsaman wrote:
|Lets say we have a silicon-based life. What are the most common
|structures and chemical reactions we would encounter with ? and also,
|what would be the suitable temperature range for such life to exist ?
|(since SiO2 might have to be a gas, or just replaced by another
|substance)

If you throw in an atom of carbon for every dozen atoms of silicon,
you ought to be able to bring down the surrounding environment's
temperature considerably. Otherwise, the average temperature for a
silicon based life form is going to be a lot nearer the melting point
of 'glass.' In any case, we should expect the life form to be capable
of thriving in an environment where the silicon is available to the
life form in a liquid solution of some kind. I don't see why the
silicon *has* to be gaseous. The atoms have to be easily available
for both taking and reducing, and subsequent picking up again.

Higher temperatures make sense, but then so does a higher overall
pressure. You ought to be able to plot out a curve of some kind
on graph paper.

In message , Amirsaman
writes
Lets say we have a silicon-based life. What are the most common
structures and chemical reactions we would encounter with ? and also,
what would be the suitable temperature range for such life to exist ?
(since SiO2 might have to be a gas, or just replaced by another
substance)

Requiring gaseous SiO2 might not be a wise choice - too hot.
But SiO2 might be useful for its skeleton (a la diatoms on Earth).

Given vulcanism to provide some raw ingredients then obtaining energy by
reducing chlorine to HCl, sulphur to H2S and/or oxidising sulphur to SO2

SiCl4 might do as a solvent. Won't get on well with water though.

Silanes will provide some of the building blocks, but I expect you will
still need some carbon atoms in there to get enough interesting
chemistry to make life.

Regards,
--
Martin Brown

you mentioned the Silicanes as possible building blocks. But silicanes
can not get more complicated than Si6H14 and thus, silicanes alone
would not be able to form complex molecules as DNA lets say. So, why
not Si-O chains since they can become very long chains? is it because
there is no variability? or is there some phase problem here?

In article , Martin Brown
wrote:

In message , Amirsaman
writes
Lets say we have a silicon-based life. What are the most common
structures and chemical reactions we would encounter with ?

Life with Silicon would be difficult:

Si does not easily form Pi bonds so we do not have any chemistry
involving additions to molecules at these bonds. ( Lots of redox
reactions do this. )

Si does not form long chains so things like enzymes & proteins
are awkward.

DNA like structures might be possible through SiOx chains
with side groups carrying the genetic information. The details
about reading this info and transcribing it to other Si-based
biomolecules are left as an exercise for the student. ( I certainly
don't know how to do this, and my degree is in Chemistry. )

A great deal of Carbon biochemistry is based on a "lock and
key model" where the shape of the molecule is vital. These
shapes are held by C-C bonds ( both Sigma and Pi ) as well
as electrostatic forces. We do not see these complicated
shapes in Si based molecules.

Finaly, is there enough Chlorine available to form SiCl4 oceans?
The oceans are about 3.5% salt by weight, this means there are
83 water molecules for each NaCl. Since Chlorine has atomic
number 17 ( an odd number ) it is fairly rare.

tom

PS SiCl4 is non-polar, this is also an issue.

--
We have discovered a therapy ( NOT a cure )
for the common cold. Play tuba for an hour.