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7.14: Mixed Solvent Crystallization

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    Table 7.14: Procedural summary for mixed solvent crystallization.
    Find a miscible pair of solvents: one in which the desired compound is soluble (called the "soluble solvent") and one in which the compound is insoluble (called the "insoluble solvent").

    Place the impure solid in an Erlenmeyer flask along with a boiling stick (or boiling stones if preferred).

    Add the soluble solvent in portions while heating until the solid just dissolves.

    Allow time in between additions, and allow each addition to come completely to a boil before adding more.

    Add the insoluble solvent in portions with heating until the solution becomes faintly cloudy. Add the "soluble" solvent dropwise with heating until the solution is clarified (transparent).
    Remove the boiling stick (if used) and allow the system to come to room temperature while sitting atop some paper towels and with the flask's mouth covered by a watch glass.

    Scratch with a glass stirring rod to initiate crystallization if necessary.

    Submerge in an ice bath for 10-20 minutes.

    Collect crystals by suction filtration.

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