What would be the good method and solvent to purify biphenyl?

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SUMMARY

The optimal method to purify biphenyl contaminated with fluorene is through crystallization, leveraging the significant difference in their melting points (biphenyl: 68.93°C, fluorene: 116-117°C). A suitable solvent for this process includes a combination of butanol and ether, as biphenyl is non-polar and remains in the ether phase while fluorene, being more polar, will dissolve in the aqueous phase when treated with NaOH. NaOH effectively deprotonates fluorene, enhancing its solubility in polar solvents. This method ensures the separation of biphenyl from fluorene, allowing for effective purification.

PREREQUISITES
  • Understanding of crystallization techniques
  • Knowledge of solvent polarity and solubility principles
  • Familiarity with acid-base reactions, specifically the deprotonation of fluorene by NaOH
  • Basic knowledge of melting point differences and their implications in purification
NEXT STEPS
  • Research the crystallization process for purifying organic compounds
  • Learn about solvent extraction techniques, particularly using NaOH and ether
  • Study the properties of biphenyl and fluorene, focusing on their polarity and solubility
  • Explore the implications of melting point differences in separation techniques
USEFUL FOR

Chemistry students, organic chemists, and laboratory technicians involved in the purification of organic compounds, particularly those working with biphenyl and fluorene.

Fairway
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Homework Statement



what would be the good method and solvent to purify biphenyl contaminated with fluorene?


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The Attempt at a Solution



The polarity of biphenyl (MP: 68.93°C) and fluorene (MP: 116-117°C ) are same which is non polar but their MP is hugh different. So, I'm not so sure which solvent is good to use. I think cryatallization would be the good method to purify. Could you help on this? Thank you so much.
 
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Fluorene has an acidic proton and the anion is stabilized by aromatic stabilization. NaOH is apparently a strong enough base to deprotonate it.

You could also use an alcohol like butanol or butanol + ether.
 
Thanks for help, It's kind of still confusing becaue the question is asking about to purify the biphenyl from fluorene.
 
Fluorene is somewhat acidic (NaOH can deprotonate it) and is therefore more polar than biphenyl. It would more soluble in a polar solvent like alcohol. What would happen if you were to shake a sample containing fluorene with NaOH and ether? Would you find the fluorene in the organic or the aqueous phase? Would the biphenyl stay in the ether phase or would it cross over into the aqueous phase as well?
 
Thank you so much. It makes sense NaOH and ether will sepearte biphenyl from Fluorene because biphenyl will stay in ether phase. If I understood this earlier, then I would have got the right answer for my lab. Well, Still I'm so happy that I know now. Thank you again!
 

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