Samples of AlCl must therefore be protected from atmospheric moisture to preclude the formation of hydrates .
Similarly , hydrated AlCl is a poor Lewis acid and thus inactive as a catalyst for Friedel - Crafts reactions .
Samples of acid must be protected from atmospheric moisture to preclude the formation of hydrates .
Similarly , hydrated AlCl is a poor Lewis acid and thus inactive as a catalyst for Friedel - Crafts reactions .