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The goal of the recrystallization procedure is to obtain purified material with a maximum recovery. For each of the following situations, explain why this goal would be adversely affected.

a) In the solution step, an unnecessarily large volume of solvent is used.
b) The crystals obtained after filtration are not washed with fresh cold solvent before drying.
c) The crystals obtained after filtration are washed with fresh hot solvent before drying.
d) A large quantity of decolorizing agent is used.
e) Crystals are obtained by breaking up the solidified mass of an oil that originally separated from the hot solution.
f) Crystallization is accelerated by placing the flask of hot solution in an ice-water bath.

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a) If too much solvent is used, crystallization will not occur fully as some of the pure compound will tend to remain in solution due to excess solvation rather than precipitating out of solution.

b) If not washed with cold solvent, some ...

Solution Summary

The goals of recrystallization procedures are given. The quantity of decolorizing agents are examined.

See Also This Related BrainMass Solution

Recrystallization Process of 1,1-Diphenylethanol

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I made the Grignard reaction with phenylmagnesiumbromide react with ethyl acetate to give 1,1-diphenylethanol. After drying with sodium sulfate, all in the solution was ether and crude oil solid. After all the ether evaporated or remove by simple distillation, I have is the product. Do I need to all do the simple distillation again to get the product 1,1-diphenylethanol which has the boiling point 165°C and the melting point 77 - 81°C. The product is white crystals from the literature, but it does not mean literature has everything to explain. All I want to know then how can I get the white crystals from the crude brown oil solid? For the recrystallization, I tried acetone as solvent and boil the solution with it. Also, after cooling I add the norit, decolorizing charcoal to decolorize the solution. After that I let the solution cooled, but I do not get the crystals. Please, I need help a lot in getting the product 1,1-diphenylethanol. I need step by step help what I did wrong and what can be done right to get the product.

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