Recrystallization using two solvents

This method is the same as the above but where two (or more) solvents are used. This relies on both "compound A" and "impurity B" being soluble in a first solvent. A second solvent is slowly added. Either "compound A" or "impurity B" will be insoluble in this solvent and precipitate, whilst the other of "compound A"/"impurity B" will remain in solution. Thus the proportion of first and second solvents is critical. Typically the second solvent is added slowly until one of the compounds begins to crystallize from solution and then the solution is cooled. Heating is not required for this technique but can be used.
→ Solvent added (clear) to compound (orange) → Solvent heated to give saturated compound solution (orange) → Second solvent (blue) added to compound solution (orange) to give mixed solvent system (green) → Mixed solvent system (green) allowed to cool over time to give crystals (orange) and a saturated mixed solvent system (green-blue).
The reverse of this method can be used where a mixture of solvent dissolves both A and B. One of the solvents is then removed by distillation or by an applied vacuum. This results in a change in the proportions of solvent causing either "compound A" or "impurity B" to precipitate.
→ First solvent added (clear) to compound (orange) → Solvent heated to give saturated compound solution (orange) → Second solvent (blue) added to compound solution (orange) to give first mixed solvent system (green) → Volatile first solvent (clear) is removed (e.g. evaporation) from first mixed solvent system (green) to give a second mixed solvent system (dark-green) → Second mixed solvent system (dark-green) allowed to cool over time to give crystals (orange) and a saturated second mixed solvent system (green-blue).

[@jhyland87]

Great video - I never thought about using two solvents. Thanks for including so much detail. Since this is a minute amount of substance being crystalized, maybe you should show how to use a Craig recrystallization tube. Just a thought.

[@user-ke5pb1yz9o]

What is the sample?

[@tommasopetrella9278]

Good video, thanks.

[@weisu1427]

Is the guy doing the experiment in jail?

[@romainetomatoes2416]

As a chemical technology student myself, I can assure you that those "bars" are called "support stands", and they are very nice to have around when you are doing distillations, titrations, refluxes, and solvent extractions.
In other words, they are there to prevent your apparatus from tipping over, and they just make things easier in general.

[@jhyland87]

Hahaha... Awesome. You win

[@romocity8327]

lol🤣 seriously..bah haa

[@komandanmiliter2231]

Indog 😂