Maybe it’s just been the “apple barrel” cheap brand, but it seems that the lighter green varieties turn into a completely thin green liquid after a few years that smells vaguely like an alcohol/“chemical-ly.”
It’s specifically the greens that do this, so I’m wondering if there’s something in the green pigment that reacts with the binder after time. Most other cheap acrylics tend to dry out - reds more so. Is there some sort of slow chemical reaction happening with the greens instead?
Edit: I found a bottle of Orange just now that went off in the same way. Apple Barrel, matte, “Pumpkin Orange” 2047E.
It’s just a very striking way for paint to degrade. Drying out or just have the binder separate I get, but this one has to be involving some sort of fun chemistry.
Acrylic paint uses water as the solvent, not alcohol, so that’s probably not what you’re smelling. My guess would be the binder breaking down, which is why it turns into a thin fluid while retaining its color. Hard to say for sure without more details like a list of ingredients.