Class 11 Chemistry Notes GOC – Permanent effect (Inductive Effect) September Sept ember 30, 2012 by Anand Meena — Leave a Comment a Comment
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Inductive effect is an effect in which permanent polarization arises due to partial isplacement of sigma ealong carbon chain or partial displacement of sigma-bonded electron toward more electronegative atom in carbon chain i.e.
X more electronegative 7 (-I effect of X)
Y less electronegative (+I effect of Y) After Carbon number 3, Inductive Effect Disappears.
Between –OH, -OR (-I)
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{C is more electronegative than H. Hence attracts e- from O slightly}
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(Its tendency to attract electron increases)
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It is a permanent effect It is caused due to electronegative difference. It operates via σ bonded electron. It is distance dependent effect. As distance increases, its effect decreases. It can be neglected after third carbon. It is a destabilizing effect. It is divided into 2 parts. (On the basis of electronegativity w.r.t. hydrogen atom) 1. +I effect 2. –I effect If any atom or group having electronegativity greater than that of hydrogen.than it is considered as – I effect and vice-versa.
+I effect
-I effect
Electron releasing group
Electron accepting group
EN less than H
EN greater than H
Those group which are
those group showing –I effect
Showing +I effect, disperses
disperses positive charge on the C-chain
Partial negative charge on the C-chain
Eg. CH3 – CH2 – Cl(- I of Cl) Eg. CH3 – CH2 = CH2 (- I of – CH2 and + I of – CH3) Eg. CH3 – CH2 – C ≡ CH (- I of – C ≡ CH and + I of – CH2 – CH3) Eg. I – Cl +I–I
(- I order) – OH < – OR – C ≡ CH > – CH = CH2
. Why carbon – hydrogen bond is longer than C – T bond . As the mass increases, vibration decreases as a result of which the heavier isotope will be closer to the C-atom for a longer time. There for C – T bond is stronger C – T > C – D > C – H This implies that C – H bond has longest bond length.
To compare the stability of intermediates.
These are real reparable species having measurable stability formed during conversion of reactant to product. (After bond cleavage and before bond formation).
(i) Free radical
(ii) Carbocation
(iii) Carbanion
(iv) Carbene
(v) Nitrene
(vi) Benzyne
They are formed by homolytical and heterolytical cleavage.
