Well, it is possible to imagine a life form that uses liquid ammonia or liquid methane or liquid hydrogen as a solvent. The trouble is that these don’t seem to have the special properties water does.
The most common elements in the universe are hydrogen, helium, oxygen, nitrogen, and carbon. Helium is out, since it doesn’t form compounds. So, H+H makes hydrogen gas, C+H makes methane, N+H makes ammonia, and O+H makes water. These are the most common compounds in the universe.
We can imagine creatures using more exotic compounds, but it is hard to imagine how, say, chlorine might be segregated on a planet enough to form the basis of a biosphere.
And the trouble with silicon is that it really doesn’t form the same sorts of compounds that carbon does. Although silicon can form four bonds like carbon, it doesn’t bond as tightly. We have millions of highly complex carbon compounds on earth, but only a few complex silicon compounds. There might be environments that favor the formation of complex silicon compounds, but we have no idea what those might be. Carbon, on the other hand, sticks itself together all the time. The ability of carbon to form complex compounds is what sets it apart from the rest of the periodic table, silicon included. That’s why we call it “organic chemistry”.