Shweta Thakur posted an Question
January 06, 2021 • 17:15 pm 30 points
  • Chemistry (CY)

Plz explain encircled line...... phe , l>4-nitrophend or 2-nitrophenol > pheno! (b) inductive and hyperconjugation effects ) comparis

W.rt W.rt phenol decreases 4, -Trinitrophenol > 2, 4-Dinitrophe , l>4-Nitrophend or 2-Nitrophenol > Pheno! (b) Inductive and hyperconjugation effects ) comparison of the acidic strength of halophenols. Halogens have both +R and-Leffects, but the - I-effect predominates over the + R-effedt. Therefore, all halophenols (except p-fluorophenol) are more acidic than phenol itself Purther, since -I-effect decreases with distance, therefore, acidic strength of halophenols decreases in the order: o-Halophenol > mn-Halophenol > p-Halophenol (where halogen = CI, Br or I) However, in case of p-fluorophenol (because of almost identical sizes of 2 p-orbitals of C and F),+R- effect and -I-effect of F almost balance each other and hence it is almost as acidic as phenol itself. O-H Amongst o-halophenols, o-fluorophenol is the weakest acid due to strong intramolecular H-bonding. The acidity of other o-halophenols decreases as the -1-effect of the halogen decreases. Thus, the acidity of all the o-halophenols decreases in the order O-Chlorophenol > 0-Bromophenol> o-lodophenol > 0-Pluorophenol o-Fluorophenol (11) Comparison of the acidic strength of cresols. Since alkyl groups are electron-donating duffothi hyperconjugation effect, therefore. all cranal

2 Answer(s) Answer Now
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    Dinesh khalmaniya 1

    in the case of para flupro phenol +M is dominant over -I so it is less Acidic than phenol

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    Priyanshu kumar Best Answer

    4-fluorophenol is the least acidic as the -I and +R effects balance each other out due to almost identical sizes of 2p orbitals of C and F and hence it is almost as acidic as phenol itself.


    This is the case only with para phenol and para fluorophenol has nearly same acidity


    phenol has pka values of 10 and para fluorophenol has pka value of 9.9


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