Recrystallization is a method used to purify chemicals by dissolving a mixture of a compound and its impurities, in an appropriate solvent, prior to heating the solution.
[1] Following the dissolution of crude product, the mixture will passively cool, yielding a crystallized compound and its impurities as separate entities.
[2] The solvent utilized in single-solvent recrystallization must dissolve the crude reaction mixture only when it is heated to reflux.
[3] The heated solution is then passively cooled, yielding a crystallized product absent of impurities.
[7] The technique makes use of the single solvent system, outlined above, by dissolving a crude reaction mixture, in a minimum amount of hot solvent, before gravity filtering the saturated solution to remove insoluble matter.
A solvent is added (white) to a compound (orange) → Solvent is heated to give a saturated compound solution (orange) → Saturated compound solution (orange) is allowed to cool over time, yielding crystals (orange) as separate from an impure solution (pale-orange).
A solvent is added (white) to a compound (light orange) → Compound is heated to dissolution, providing a saturated solution (light orange) → Second solvent (orange) added to the saturated solution (light orange) to give a mixed solvent system (orange) → Mixed solvent system (orange) allowed to cool over time, yielding crystals (light orange) as separate from a saturated mixed solvent system (orange).
A solvent is added (white) to a mixture of a compound (orange) and insoluble substance (purple) → Solvent is heated to give a saturated compound solution (orange) and an insoluble substance (purple) → Saturated compound solution (orange) is filtered to remove the insoluble substance (purple) → Saturated compound solution (orange) is allowed to cool over time yielding crystals (orange) as separate from an impure solution (pale-orange).
→ Solvent added (clear) to compound (orange) to give compound solution (orange) → Vessel sealed but a small hole allows solvent vapour (clear) to slowly evaporate from compound solution (orange) over time to give crystals (orange) and a saturated solution (pale-orange).
→ Solvent added (clear) to compound (orange) to give compound solution (orange) → The second solvent added (blue) to the compound solution (orange) to give mixed solvent system (green) → Vessel sealed but a small hole allows solvent vapour (clear) to slowly evaporate over time to give crystals (orange) and a saturated mixed solvent solution (blue-green).
→ Solvent added (clear) to compound (orange) in the first vessel to give compound solution (orange) → The first vessel is placed in a second vessel contain second solvent (blue). The second vessel is sealed, and the first vessel is also sealed, although a small hole in the first vessel is present. This hole allows volatile solvent vapour (blue) to slowly evaporate from the second vessel and condensate (that is infuse) into the first vessel, to give a mixed solvent system (green) → Over time this gives crystals (orange) and a saturated mixed solvent system (green-blue).
→ Solvent added (clear) to compound (orange) to give compound solution (orange) → The second solvent added (blue) carefully so that the two solvents do not mix. → The two solvents mix (diffuse) slowly over time to give crystals (orange) at the solvent interface (green)
→ Solvent added (clear) to compound (orange) to give a compound solution (orange) → The second solvent added (blue) to the second tube chamber → The two solvents mix slowly over time, the mixing is slowed by a fine sinter separating the two solvent chambers, to give crystals (orange) at the solvent interface (green) over time
