I have been keeping my chemical products, sometimes still in solution, in a -20 C freezer that has no lights on the inside. Is this appropriate? What is wrong with this if anything and what should I do instead?
That would, in my opinion, depend on the organic product you are trying to preserve. Some, such as sorbic acid, are highly unstable and sublime quickly, which requires special care when handling and condensing for industrial scale, or small scale usage. Other organics however may readily stay at standard temp. and pressure, or some may not. Again it really depends on the organic you want to manufacture. That's my opinion at least.