Shweta Thakur posted an Question
January 06, 2021 • 17:15 pm 30 points
  • IIT JAM
  • 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

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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.

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

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

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