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Sourav posted an Question
September 20, 2020 • 04:24 am 30 points
  • IIT JAM
  • Chemistry (CY)

Acidity order.. im confused when to use - i and when to use +r for halogen

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    Reshav

    sir fluoro to ortho effect lgata hi nhi hai it is a small group

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    read module bro.. dia hua hai halogen

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    but kahi pe bhi ho its simple think fluoro is a small group how does it will create inhibition in resonance with benzene ring

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    thats why module is there bro. and chemistry is full of expections 😊

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    please dont go wrong fluorine never create SIR effect yes but in halogen always -I effect is dominating over +M so after then order will 1>2>3>4

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    ortho effect in this case will not be its reason for acidity

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    when OCH3 group create partial sir how does fluorine create ortho effect then

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    go through module and qs bro.. i didn't make the concepts 😅

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    but foreign author books cant be wrong these booklets may have error yes there is SIP when one gp is small and other is bulky but not SIR effect

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    for SIR both needs to be bulky

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    Priyanshu kumar Best Answer

    Sourav here order will 1>2>3>4

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    Ortho benzoic acid is most acidic this you know due to ortho effect

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    Now generally for halogens we see inductive effect and inductive effect decreases with increase in distance so 2>3

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    check this

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    No sourav this is wrong we check +M of fluorine in para position but not here...when we compare with para chloro or bromo benzoic acid then we use

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    Here only inductive effects works so 1>2>3>4

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    so it is wrong?

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    yes

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    let me check pka for confirming

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    ok sir

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    yes sourav para fluorobenzoic acid has pka 4.14

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    and benzoic acid has 4.20

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    sir when to check for +m in halogens?

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    at para position when compare with other halogens at para position

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    but generally check only inductive effect

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    sir here it is written as +R on O fluoro phenol

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    Khud se key notes bnao sourav😊

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    see reason...only take H bonding reason then -I

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    sir theory padhne k bad notes banau k qs karne k bad?

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    exceptions bahut milenge so notes krte jao padhne ke sath sath ek chota copy ya diary me

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