Inductive effect pptx

By Dr. Neelam

1. Presented by
Dr. Neelam
Department of chemistry

2. Electron displacement in organic compounds
Theelectrondisplacementinanorganicmoleculemaytakeplaceunder
theinfluenceofanatomorasubstituentgrouporinthepresenceofan
appropriateattackingreagent.
Typesofelectronicdisplacement
(a)Permanentelectronicdisplacement
1.Inductiveeffect
2.Resonanceeffect
3.Mesomericeffect
4.Hyperconjugation
(b)temporaryelectronicdisplacement
1.Electromericeffect(temporaryeffect)

3. (i)Itisapermanenteffect
(ii)Itisdistancedependent
(iii)Itisoperatedthroughσbondnotthroughπ-bond
(iv)Itisnegligibleafterthirdcarbonatom
(v)C–Hbondisthereferenceofinductiveeffecti.e.polarityofC–H
bondisconsideredtobenegligible.
Partial shifting or displacement of σ–electrons towarsmore EN atom of
σ-bond

4. Inductive effects are of two types
(i) +I effect :
The group which releases or donates electron clouds is known as +I group
& effect is called +I effect.
Decreasing order of +I effect :
(ii)–Ieffect:
Theatomorgroupwhichwithdrawselectroncloudsisknownas–I
groupandeffectiscalled–Ieffect.
Decreasingorderof–Ieffect:

6. Applications of Inductive effect
(i)Acidicstrength:Presenceof–Igroupsincreasesacidiccharacter.
Acidicstrengthα–Ieffectgroups
SinceNO
2hasstrong–Ieffect,itsinfluencewillmakecorresponding
acidstronger.
(ii)Basicstrength:Presenceof+Igroupsincreasesbasiccharacter.
Basicstrengthα+Ieffect

7. (iii)Stabilityofcarbocations:
Carbocationsareelectrondeficientspeciesandtheyarestabilisedby+I
effectanddestablisedby–Ieffect.Because+Ieffecttendstodecrease
thepositivechargeand–Ieffecttendstoincreasesthepositivecharge
oncarbocation

8. (iv)Stabilityofcarbanion:
Carbanionsarestabilisedby–Ieffectanddestabilisedby+Ieffect.
(v)Stabilityofcarbonfreeradical:
Carbonfreeradicalsarestabilisedby+Ieffect.
(vi)Dipolemoment:
Greater-Ieffectresultsingreaterdipolemoment.

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