Recrystallization_Presentation microteaching 13.10.ppt

What is Recrystallization?
Method to purify solid compounds
Principle
Advantages and disadvantages

2. Recrystallization
A Techni que for Puri fication of Soli ds
• . Kumbhare Manoj R.
Dr. Kumbhare Ma
•
Professor
• S.M.B.T. Coll ege of Pharmacy
• Dhamangaon Nashik (M.S.).
• Professor
• S.M.B.T. Coll ege of Pharmacy
• Dhamangaon Nashik (M.S.).
Dr. Kumbhare Manoj R.
Professor
S.M.B.T. College of Pharmacy
Dhamangaon Nashik (M.S.).

3. At the end of session student will
able to explain
•What is Recrystallization?
• Method to purify solid compounds
•Principle
•Advantages and disadvantages
3

4. Principle
• Solubility increases with temperature
• Compound dissolves in hot solvent and
crystallizes out when cooled
• Impurities stay dissolved
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5. Steps in Recrystallization
•1. Choose solvent
•2. Dissolve impure solid in hot solvent
•3. Filter hot solution
•4. Cool to form crystals
•5. Filter crystals
•6. Dry purified crystals
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6. Choosing the Right Solvent
•Compound dissolves in hot, not cold solvent
• Solvent should not react with compound
• Common: Water, ethanol, acetone
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7. Hot Filtration
•Removes insoluble impurities
• Done while solution is hot
• Prevents premature crystallization
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8. Cooling and Crystallization
• Cool solution slowly for large, pure crystals
• Rapid cooling → small crystals with more
impurities
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9. Filtration and Drying
• Separate crystals using vacuum filtration
•Wash with small amount of cold solvent
•Dry on filter paper or in oven
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10. Example
• Impure benzoic
acid purified using
hot water
• After cooling →
pure white crystals
• Purity tested by
melting point
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Advantages:
• Simple and effective
• Produces highly pure crystals
Limitations:
• Not suitable for all compounds
• Some product loss in solvent

11. Summary and conclusion
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Recrystallization is purifying a solid by dissolving it hot, then
cooling it to form pure crystals. 
Advantages:
• Simple and effective
• Produces highly pure crystals
Limitations:
• Not suitable for all compounds
• Some product loss in solvent

12. •All students understood … Yes or No
•Questions
•1. What is recrystallization ?.....L-1. 02 M
•2. Explain techniques of recrystallization. L-2…03 M
•References
https://faculty.ksu.edu.sa/sites/default/files/vogelpractical_organic_chemistry_5th_edition.pdf
Any Question ?
Thank You
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