Is this separation scheme/procedure correct for crystallization of A) 50% ethyl
ID: 896150 • Letter: I
Question
Is this separation scheme/procedure correct for crystallization of A) 50% ethyl 4-aminobenzoate, B) 40% benzoin, and C) 10% 1,4 dibromobenzene?
We will only be crystallizing A and B.
Weigh 1. g of (50% ethyl 4-aminobenzoate, 40% benzoin, 10% 1,4 dibromobenzene) and transfer to a clean and dry 50 mL Erlenmeyer flask. Add 10.0 mL of methylene chloride to the Erlenmeyer flask and stir this mixture until all of the solids are dissolved.Transfer solution to a 125 mL separatory funnel and add 5 mL 3M HCl. Bottom organic layer methylene chloride. Top aqueous layer HCl. Extract the aqueous layer with an additional 5mL of 3M HCl. Add NaOH to the aqueous layer. Add methylene chloride. Separate the organic layer from the aqueous. Evaporate under the hood in the hot water bath you are left with the solid ethy-4 aminobenzoin.With the organic layer originally separated evaporate the methylene chloride from the solution. Add 95% ethanol to the solid, heat in hot water bath. Cool the solvent in an ice bath to form crystals. Vacuum the benzoin crystals from the solvent.
Are these steps accurate?
How much NaOH, ethanol should be used?
What am I missing?
OH Add Methylene Chloride Add 4Add NOH Add Methylene Chloa d Methylkne Chloride rgani Layer o Na-Cl OH2 9 95% Ethanol to I0 rystals 0 OH OHExplanation / Answer
Yes , the steps seems to be accurate as,
NaOh is added to neutralize any excess HCl added to extract ethyl 4-aminobenzoate as a chloride salt.So it must be added in equimolar quantity to HCl. An acid-base indicator(phenolphthalein) can be used to check if the solution is neutralized or not.
Ethanol is added to dissolve the solid benzoin,so only a little amount is to be added,on slight warming the solid dissolves ,which is filtered as impurities does not dissolve,When the solution cools crystals separate out.
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