Organic 2 Review Problem 33

Organic 2 Review - METHODS AND M ANIPULATION 17 proportions of solute and solvent for recrystallisation the main bulk of the crude material may be

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METHODS AND MANIPULATION 17 proportions of solute and solvent for recrystallisation, the main bulk of the crude material may be recrystallised. If the solvent is water, the material is placed in a beaker or (better) in a conical flask, and a volume of water which is judged to be just insufficient for the purpose is then added, and the mixture gently heated (with the usual addition of fragments of unglazed porcelain) to boiling. More water is then cautiously added until either a clear solution is obtained or until the undissolved material is recognised from the experience gained in (i) as being insoluble impurity. In either case, the boiling solution is then filtered. For this purpose steps must be taken to prevent undue cooling of the solution during filtration, otherwise crystallisation will occur prematurely and choke the filter. This applies more particularly of course if the preliminary test in (i) has shown that crystallisa- tion starts very rapidly on cooling the hot solution. Therefore if
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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