My (very unreliable) school textbook tells me:
Lower alcohols form a solid derivative with certain metal salts.
It is for this reason that ethanol cannot be dried/concentrated using anhydrous calcium chloride.
Nowhere else in the book, is there any reference to this supposed reaction between a lower alcohol (ethanol) and a metal salt (calcium chloride). So I couldn't read more about this from there...
Googling wasn't much help; though I did find this paper that seems to concur with my textbook (albeit, with more detail) ... the paper is dated all the way back to 1923, so I suspect the modern Chemist's view of the matter would be different (the paper makes use of the term "alcoholate", which no longer carries the same meaning).
Does ethanol really react with calcium chloride to form some "solid derivative"?
Do lower alcohols (methanol and ethanol to name a few) really react with "metal salts" (textbook didn't specify, so i would use the following examples: copper sulfate and magnesium chloride)?