ORGANIC CHEMISTRY NOTES
BATCH: CIS (SIP)
TOPIC : GOC-1 (ELECTRONIC EFFECTS)
Reaction: Breaking of old bonds and formation of new bonds is called as reaction.
Types of Bond dissociation/ fission :
There are two types of bond dissociation for a covalent bond.
Homolyticbond fission Heterolytic bond fission
partition of
is Equal partition of shared pair is unequal electrons
electrons b w constituent shared pair of
of 9
atoms B Ao B
A
an anions cation
B Ao t B
A CENA END
free radical
Ethan EWB neutral
knowns Cii The process is also
il The process is also
as s
Hd known as enlysis
Conditions Ciii Conditions
Ciii when there
is large
temp occurs
a By heating1high difference
in
electronegativity
D in solvent phas
Gz as 290 and favoredformed are stablis
where ions
g By Uv radiation NV by solvation steo H
t
n
CI CI
hV 240 SinnAs Bst
o
sat Ao H
t
o
H
ENA ENB ly 8TH O
c By peroxide 4
AN nst
, I Alkoxide
radical
toweaek.behdofuesion
Hos Y
X g
Hf
solvation is Always exotherim
Note: Electrophiles or electrophilic species : I process
Electrophiles are electron deficient species which can accept a pair of electron.
Electrophiles are generally lewis acid.
Ex. (i) Cationic electrophile ( E ):
Hi Clt Brt It NOI Etf etc
BB Bcb BI Iincomplete
(ii) Neutral electrophile (E): BB octet
2h42 recb FeBB SO vacant d
orbital
Nucleophiles or nucleophilic species:
Nucleophiles are electron rich species having at least one unshared pair of electron.
It can be neutral or negativetely charged. They are always lewis base.
Ex. (i) Anionic nucleophile ( Nu ):
H Cr Br I OH R E SH
ctbcoo.CH etc
(ii) Neutral nucleophiles (Nu):
nio inns riots cnn.o.im etc
Free Radicals : It is an electron deficient species with odd electron around an
Tenpaired
atom. electron
Ex. C H 3 , C2H5 , C2H5O , CH3COO , X etc.
Electronic effects or Electron displacement methods in organic chemistry
The effects which arises due to electronic distribution is called electronic effect.
(+H)
,Inductive effect (I-Effect):
Cic c2 c No polarity in the chain
no difference in ELI
4 3
as
88ft 881 St S
C4 Ct Gas X EN x ENC E n x x s charade
f dipole en E c E
qtcj aE.es CENysENd
p
dipole
Inductive effect can be defined as permanent shifting of sigma electrons in a carbon
chain due to a dipole (polar bond)
Features of Inductive effects -
(i) The displacement of electrons takes place due to difference in electronegativity
of the two atoms involved in the covalent bond.
(ii) It is also called transmission effect.
(iii) It causes permanent polarisation in molecule, hence it is a permanent effect.
(iv) The electrons never leave their original atomic orbital.
(v) It is ditance dependent. Its magnitude decreases with distance and it is almost
2
negligible after 3rd carbon atom.
(vi) The inductive effect is always operative through bond, does not involve
bond electron.
Aa
s r electrons
are affected by
difference
a
in EN
(viii) It is additive in nature.
Types of inductive effects : y
I effect
I effect
88ft Sst St 1I EDA
c C cedi I Sss Ss s
I
EDG Tena C C C OE een.ch
celectron I
electron
EWG
, Note The hydrogen atom is reference for + I and – I series. The inductive effect of
hydrogen is assumed to be zero.
(a)– I Effect : The group which withdraws electron cloud (EWG) is known as – I
group and its effect is called – I effect.
O
NF
3 > >– > – NO2 > –SO2R > –CN > –CHO > –COR >
–COOH > – F > Cl > – Br > – I > –OR > –OH > –C CR > –NH2
> –Ar > –CH=CR2 > –H
EN x Character
is I Ign R gp gNp
EN p3 Csp
iii ftp Isiito n
Csps
moreelectronegative
o
e r in 10,707
O Oz
EN x t S character
s character in
0
sp3 sp2 Sp
o
lS
SprSpr Sp2 sp2
iii CECH N'Hz y OH
y spy cMz
Sp Sp SprSpr vinyl
BATCH: CIS (SIP)
TOPIC : GOC-1 (ELECTRONIC EFFECTS)
Reaction: Breaking of old bonds and formation of new bonds is called as reaction.
Types of Bond dissociation/ fission :
There are two types of bond dissociation for a covalent bond.
Homolyticbond fission Heterolytic bond fission
partition of
is Equal partition of shared pair is unequal electrons
electrons b w constituent shared pair of
of 9
atoms B Ao B
A
an anions cation
B Ao t B
A CENA END
free radical
Ethan EWB neutral
knowns Cii The process is also
il The process is also
as s
Hd known as enlysis
Conditions Ciii Conditions
Ciii when there
is large
temp occurs
a By heating1high difference
in
electronegativity
D in solvent phas
Gz as 290 and favoredformed are stablis
where ions
g By Uv radiation NV by solvation steo H
t
n
CI CI
hV 240 SinnAs Bst
o
sat Ao H
t
o
H
ENA ENB ly 8TH O
c By peroxide 4
AN nst
, I Alkoxide
radical
toweaek.behdofuesion
Hos Y
X g
Hf
solvation is Always exotherim
Note: Electrophiles or electrophilic species : I process
Electrophiles are electron deficient species which can accept a pair of electron.
Electrophiles are generally lewis acid.
Ex. (i) Cationic electrophile ( E ):
Hi Clt Brt It NOI Etf etc
BB Bcb BI Iincomplete
(ii) Neutral electrophile (E): BB octet
2h42 recb FeBB SO vacant d
orbital
Nucleophiles or nucleophilic species:
Nucleophiles are electron rich species having at least one unshared pair of electron.
It can be neutral or negativetely charged. They are always lewis base.
Ex. (i) Anionic nucleophile ( Nu ):
H Cr Br I OH R E SH
ctbcoo.CH etc
(ii) Neutral nucleophiles (Nu):
nio inns riots cnn.o.im etc
Free Radicals : It is an electron deficient species with odd electron around an
Tenpaired
atom. electron
Ex. C H 3 , C2H5 , C2H5O , CH3COO , X etc.
Electronic effects or Electron displacement methods in organic chemistry
The effects which arises due to electronic distribution is called electronic effect.
(+H)
,Inductive effect (I-Effect):
Cic c2 c No polarity in the chain
no difference in ELI
4 3
as
88ft 881 St S
C4 Ct Gas X EN x ENC E n x x s charade
f dipole en E c E
qtcj aE.es CENysENd
p
dipole
Inductive effect can be defined as permanent shifting of sigma electrons in a carbon
chain due to a dipole (polar bond)
Features of Inductive effects -
(i) The displacement of electrons takes place due to difference in electronegativity
of the two atoms involved in the covalent bond.
(ii) It is also called transmission effect.
(iii) It causes permanent polarisation in molecule, hence it is a permanent effect.
(iv) The electrons never leave their original atomic orbital.
(v) It is ditance dependent. Its magnitude decreases with distance and it is almost
2
negligible after 3rd carbon atom.
(vi) The inductive effect is always operative through bond, does not involve
bond electron.
Aa
s r electrons
are affected by
difference
a
in EN
(viii) It is additive in nature.
Types of inductive effects : y
I effect
I effect
88ft Sst St 1I EDA
c C cedi I Sss Ss s
I
EDG Tena C C C OE een.ch
celectron I
electron
EWG
, Note The hydrogen atom is reference for + I and – I series. The inductive effect of
hydrogen is assumed to be zero.
(a)– I Effect : The group which withdraws electron cloud (EWG) is known as – I
group and its effect is called – I effect.
O
NF
3 > >– > – NO2 > –SO2R > –CN > –CHO > –COR >
–COOH > – F > Cl > – Br > – I > –OR > –OH > –C CR > –NH2
> –Ar > –CH=CR2 > –H
EN x Character
is I Ign R gp gNp
EN p3 Csp
iii ftp Isiito n
Csps
moreelectronegative
o
e r in 10,707
O Oz
EN x t S character
s character in
0
sp3 sp2 Sp
o
lS
SprSpr Sp2 sp2
iii CECH N'Hz y OH
y spy cMz
Sp Sp SprSpr vinyl
