Shristy posted an Question
August 06, 2020 • 23:01 pm 30 points
  • IIT JAM
  • Chemistry (CY)

Tcepts in d is in or organic chemis oh oh oh oh o] (9) f ci br

TCepts in d IS in Or Organic Chemis OH OH OH OH O] (9) F CI Br

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    Priyanshu kumar Best Answer

    para fluoro phenol is least acidic

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    In case of p-fluorophenol +R-effect and -Ieffect of Fluorine almost balance each other, hence almost no difference in acidity between p-fluorophenol and phenol.

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    Here fluorine act as +R effect?

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    while other halogens act as -I effect??

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    halogens show both -I effect and +,R effect but in halogens -I effects dominates

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    So all halo phenols are more acidic than phenol

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    but in para fluorophenol these two opposite effects counterbalances

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    see pka values

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    Sir what about if all halogens are at ortho and meta position

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    In meta position only inductive effects acts no mesomeric effect

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    so for meta position -I effect of F>Cl>Br>I

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    got it shristy??

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    N for ortho effect ?? same as para ??

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    here new factor hydrogen bonding works at ortho position

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    In o-fluorophenol fluorine is highly electronegetive, forming H- bond with the H atom of OH group. So the acidic nature of this OH is lowest.

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    And the rest order follow -I effect at ortho position..means ochloro phenol>o bromo phenol>o iodo phenol>o fluoro phenol

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    now got it shristy??

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    ok sir thanku

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    welcome😊👍

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