Part A: Preparation of a Bisulfite - Addition Adduct Ethanol is added to promote the precipitation...

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Ethanol addition: In general bisulfate addict is very much ionic and thus soluble in water. To get the bisulfate crystals the solution must be super saturated or in other words: The bisulfate adduct must not wholly dissolve into the solvent - that's why ethanol is added during crystallization. This is a two solvent crystallization technique. Addition of ethanol helps forming crystals and at room temperature: ethanol evaporates slowly which further helps for the precipitation of bisulfate adduct \r\n Reaction mechanism: \r\n Solubility Bisulfate adduct is very much soluble in water and other polar solvents. (since bisulfate itself is polar) Solubility of a particular compound generally depends on the nature of the solute and solvent. Ether is essentially a non polar solvent and cannot dissolve a polar substance like bisulfate adduct. That why solubility test if bisulfate in ether is omitted intentionally. Regeneration of ketone from bisulfate adduct: From 5% HCl From 5% NaOH