Question

Part A: Preparation of a Bisulfite - Addition Adduct Ethanol is added to promote the precipitation of the bisulfite - addition adduct. Explain to include partial charges and arrows showing electron movement. Explain the results from the solubility of the bisulfite - addition adduct. Why was the solubility 1. 2. Draw the reaction mechanism for the preparation of the bisulfite - addition adduct. You have 3. test in ether not necessary and it was omitted? Draw the reaction mechanism if applicable 4. Draw the reaction mechanisms for the regeneration of the ketone from 5 % HCl and 5 % NaOH

Answer 1

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
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