Important General Organic Chemistry Formulas for JEE and NEET

 Page 1


  
?  Points to remember in General Organic Chemistry
1. Inductive effect
The normal C?C bond has no polarity as two atoms of same electronegativity
(EN) value are connected to each other. Hence the bond is nonpolar. Consider
a carbon chain in 1-Chloro butane, here due to more EN of Cl atom C?Cl
bond pair is slightly displaced towards Cl atom hence creating partial negative
(? ?) charge over Cl atom and partial positive (?+) charge over C
1
 atom.
Now since C
1
 is slightly positive, it will also cause shifting of C
1
?C
2
 bond pair
electrons towards itself causing C
2
 to acquire small positive charge. Similarly
C
3
 acquires slightly positive charge creating an induction of charge in carbon
chain. Such an effect is called inductive effect.
Diagram showing I effect
The arrow shows electron withdrawing nature of ? Cl group.
Thus inductive effect may be defined as a permanent displacement of ? bond
pair electrons due to a dipole. (Polar bond)
Some important points  are:
(a) It can also be defined as polarisation of one bond caused by polarisation
of adjacent bond.
(b)  It is also called transmission effect.
(c) It causes permanent polarisation in molecule, hence it is a permanent
effect.
(d) The displacement of electrons takes place due to difference in
electronegativity of the two atoms involved in the covalent bond.
(e) The electrons never leave their original atomic orbital.
(f) Its magnitude decreases with distance and it is almost negligible after 3rd
carbon atom.
(g) The inductive effect is always operative through ? bond, does not involve ?
bond electron.
Types of inductive effects :
(a)? I Effect : The group which withdraws electron cloud is known as ? I
group and its effect is called ? I effect. Various groups are listed in their
decreasing ? I strength as follows.
 > ? > ? > ?NO
2 
> ?SO
2
R > ?CN > ?CHO > ?COOH > ?F >
?Cl > ?Br > ?I > ?OR > ?OH > ?C?CH > ?NH
2
 > ?C
6
H
5
 > ?CH=CH
2
 > ?H.
 (b) + I effect : The group which release electron cloud is known as + I group
and effect is + I effect.
Page 2


  
?  Points to remember in General Organic Chemistry
1. Inductive effect
The normal C?C bond has no polarity as two atoms of same electronegativity
(EN) value are connected to each other. Hence the bond is nonpolar. Consider
a carbon chain in 1-Chloro butane, here due to more EN of Cl atom C?Cl
bond pair is slightly displaced towards Cl atom hence creating partial negative
(? ?) charge over Cl atom and partial positive (?+) charge over C
1
 atom.
Now since C
1
 is slightly positive, it will also cause shifting of C
1
?C
2
 bond pair
electrons towards itself causing C
2
 to acquire small positive charge. Similarly
C
3
 acquires slightly positive charge creating an induction of charge in carbon
chain. Such an effect is called inductive effect.
Diagram showing I effect
The arrow shows electron withdrawing nature of ? Cl group.
Thus inductive effect may be defined as a permanent displacement of ? bond
pair electrons due to a dipole. (Polar bond)
Some important points  are:
(a) It can also be defined as polarisation of one bond caused by polarisation
of adjacent bond.
(b)  It is also called transmission effect.
(c) It causes permanent polarisation in molecule, hence it is a permanent
effect.
(d) The displacement of electrons takes place due to difference in
electronegativity of the two atoms involved in the covalent bond.
(e) The electrons never leave their original atomic orbital.
(f) Its magnitude decreases with distance and it is almost negligible after 3rd
carbon atom.
(g) The inductive effect is always operative through ? bond, does not involve ?
bond electron.
Types of inductive effects :
(a)? I Effect : The group which withdraws electron cloud is known as ? I
group and its effect is called ? I effect. Various groups are listed in their
decreasing ? I strength as follows.
 > ? > ? > ?NO
2 
> ?SO
2
R > ?CN > ?CHO > ?COOH > ?F >
?Cl > ?Br > ?I > ?OR > ?OH > ?C?CH > ?NH
2
 > ?C
6
H
5
 > ?CH=CH
2
 > ?H.
 (b) + I effect : The group which release electron cloud is known as + I group
and effect is + I effect.
  
 >   > ?C(CH
3
)
3
 > ?CH(CH
3
)
2
 > ?CH
2
?CH
3
 > ?CH
3
 > ?D  > ?H
The hydrogen atom is reference for + I and ? I series. The inductive effect of
hydrogen is assumed to be zero.
Ex. Let us consider  effect of COOH & ? COO
?
 in carbon chain
(a) (b)
Due to e¯ donating nature of  carbon chain has become partially
negative but ? COOH is ? I group therefore carbon chain has become partially
positive.
2. Resonance
Resonance is the phenomenon in which two or more structures involving  in
identical position of atom, can be written for a particular  species, all those
possible structures are known as resonating structures or canonical structures.
Resonating structures are only hypothetical but they all contribute to a real
structure which is called resonance hybrid. The resonance hybrid is more
stable than any resonating structure.
?
   ??
Resonance hybrid :
The most stable resonating structure contribute maximum to the resonance
hybrid and less  stable resonating structure contribute minimum to resonance
hybrid.
Conjugation:
A given atom or group is said to be in conjugation with an unsaturated system
if:-
(i) It is directly linked to one of the atoms of the multiple bond through a single
bond.
(ii) It has ð bond, positive charge, negative charge, odd electron or lone pair
electron.
Page 3


  
?  Points to remember in General Organic Chemistry
1. Inductive effect
The normal C?C bond has no polarity as two atoms of same electronegativity
(EN) value are connected to each other. Hence the bond is nonpolar. Consider
a carbon chain in 1-Chloro butane, here due to more EN of Cl atom C?Cl
bond pair is slightly displaced towards Cl atom hence creating partial negative
(? ?) charge over Cl atom and partial positive (?+) charge over C
1
 atom.
Now since C
1
 is slightly positive, it will also cause shifting of C
1
?C
2
 bond pair
electrons towards itself causing C
2
 to acquire small positive charge. Similarly
C
3
 acquires slightly positive charge creating an induction of charge in carbon
chain. Such an effect is called inductive effect.
Diagram showing I effect
The arrow shows electron withdrawing nature of ? Cl group.
Thus inductive effect may be defined as a permanent displacement of ? bond
pair electrons due to a dipole. (Polar bond)
Some important points  are:
(a) It can also be defined as polarisation of one bond caused by polarisation
of adjacent bond.
(b)  It is also called transmission effect.
(c) It causes permanent polarisation in molecule, hence it is a permanent
effect.
(d) The displacement of electrons takes place due to difference in
electronegativity of the two atoms involved in the covalent bond.
(e) The electrons never leave their original atomic orbital.
(f) Its magnitude decreases with distance and it is almost negligible after 3rd
carbon atom.
(g) The inductive effect is always operative through ? bond, does not involve ?
bond electron.
Types of inductive effects :
(a)? I Effect : The group which withdraws electron cloud is known as ? I
group and its effect is called ? I effect. Various groups are listed in their
decreasing ? I strength as follows.
 > ? > ? > ?NO
2 
> ?SO
2
R > ?CN > ?CHO > ?COOH > ?F >
?Cl > ?Br > ?I > ?OR > ?OH > ?C?CH > ?NH
2
 > ?C
6
H
5
 > ?CH=CH
2
 > ?H.
 (b) + I effect : The group which release electron cloud is known as + I group
and effect is + I effect.
  
 >   > ?C(CH
3
)
3
 > ?CH(CH
3
)
2
 > ?CH
2
?CH
3
 > ?CH
3
 > ?D  > ?H
The hydrogen atom is reference for + I and ? I series. The inductive effect of
hydrogen is assumed to be zero.
Ex. Let us consider  effect of COOH & ? COO
?
 in carbon chain
(a) (b)
Due to e¯ donating nature of  carbon chain has become partially
negative but ? COOH is ? I group therefore carbon chain has become partially
positive.
2. Resonance
Resonance is the phenomenon in which two or more structures involving  in
identical position of atom, can be written for a particular  species, all those
possible structures are known as resonating structures or canonical structures.
Resonating structures are only hypothetical but they all contribute to a real
structure which is called resonance hybrid. The resonance hybrid is more
stable than any resonating structure.
?
   ??
Resonance hybrid :
The most stable resonating structure contribute maximum to the resonance
hybrid and less  stable resonating structure contribute minimum to resonance
hybrid.
Conjugation:
A given atom or group is said to be in conjugation with an unsaturated system
if:-
(i) It is directly linked to one of the atoms of the multiple bond through a single
bond.
(ii) It has ð bond, positive charge, negative charge, odd electron or lone pair
electron.
  
Types of  Conjugation :
1. Conjugation between C = C and
C=C ( ?? ? )
2. Conjugation between +ve charge and
C=C (  ?? ? )
3. Conjugation between lone pair and
C=C ( ?? ? )
4. Conjugation between odd electron and
C=C (CH
2
=CH? ?? ? ?CH=CH
2
)
5. Conjugation between negative charge and
C=C ( ?? ? )
3. Mesomeric effect (or Resonance effect)
Mesomeric effect is defined as permanent effect of ? electron shifting from
multiple bond to atom or from multiple bond to single bond or from lone pair to
single bond. This effect mainly operates in conjugated system of double bond.
So that this effect is also known as conjugate effect.
Ex.
Types of Mesomeric effects :
(a) Positive Mesomeric effect (+M effect) :
When the group donates electron to the conjugated system it shows + M
effect.
Relative order of +M groups (usually followed) :
?O > ?NH
2
 > ?NHR > ?NR
2 
> ?OH > ?OR > ?NHCOR > ?OCOR > ?Ph >
?F > ?Cl > ?Br > ?I > ?NO
Ex. (I)
Page 4


  
?  Points to remember in General Organic Chemistry
1. Inductive effect
The normal C?C bond has no polarity as two atoms of same electronegativity
(EN) value are connected to each other. Hence the bond is nonpolar. Consider
a carbon chain in 1-Chloro butane, here due to more EN of Cl atom C?Cl
bond pair is slightly displaced towards Cl atom hence creating partial negative
(? ?) charge over Cl atom and partial positive (?+) charge over C
1
 atom.
Now since C
1
 is slightly positive, it will also cause shifting of C
1
?C
2
 bond pair
electrons towards itself causing C
2
 to acquire small positive charge. Similarly
C
3
 acquires slightly positive charge creating an induction of charge in carbon
chain. Such an effect is called inductive effect.
Diagram showing I effect
The arrow shows electron withdrawing nature of ? Cl group.
Thus inductive effect may be defined as a permanent displacement of ? bond
pair electrons due to a dipole. (Polar bond)
Some important points  are:
(a) It can also be defined as polarisation of one bond caused by polarisation
of adjacent bond.
(b)  It is also called transmission effect.
(c) It causes permanent polarisation in molecule, hence it is a permanent
effect.
(d) The displacement of electrons takes place due to difference in
electronegativity of the two atoms involved in the covalent bond.
(e) The electrons never leave their original atomic orbital.
(f) Its magnitude decreases with distance and it is almost negligible after 3rd
carbon atom.
(g) The inductive effect is always operative through ? bond, does not involve ?
bond electron.
Types of inductive effects :
(a)? I Effect : The group which withdraws electron cloud is known as ? I
group and its effect is called ? I effect. Various groups are listed in their
decreasing ? I strength as follows.
 > ? > ? > ?NO
2 
> ?SO
2
R > ?CN > ?CHO > ?COOH > ?F >
?Cl > ?Br > ?I > ?OR > ?OH > ?C?CH > ?NH
2
 > ?C
6
H
5
 > ?CH=CH
2
 > ?H.
 (b) + I effect : The group which release electron cloud is known as + I group
and effect is + I effect.
  
 >   > ?C(CH
3
)
3
 > ?CH(CH
3
)
2
 > ?CH
2
?CH
3
 > ?CH
3
 > ?D  > ?H
The hydrogen atom is reference for + I and ? I series. The inductive effect of
hydrogen is assumed to be zero.
Ex. Let us consider  effect of COOH & ? COO
?
 in carbon chain
(a) (b)
Due to e¯ donating nature of  carbon chain has become partially
negative but ? COOH is ? I group therefore carbon chain has become partially
positive.
2. Resonance
Resonance is the phenomenon in which two or more structures involving  in
identical position of atom, can be written for a particular  species, all those
possible structures are known as resonating structures or canonical structures.
Resonating structures are only hypothetical but they all contribute to a real
structure which is called resonance hybrid. The resonance hybrid is more
stable than any resonating structure.
?
   ??
Resonance hybrid :
The most stable resonating structure contribute maximum to the resonance
hybrid and less  stable resonating structure contribute minimum to resonance
hybrid.
Conjugation:
A given atom or group is said to be in conjugation with an unsaturated system
if:-
(i) It is directly linked to one of the atoms of the multiple bond through a single
bond.
(ii) It has ð bond, positive charge, negative charge, odd electron or lone pair
electron.
  
Types of  Conjugation :
1. Conjugation between C = C and
C=C ( ?? ? )
2. Conjugation between +ve charge and
C=C (  ?? ? )
3. Conjugation between lone pair and
C=C ( ?? ? )
4. Conjugation between odd electron and
C=C (CH
2
=CH? ?? ? ?CH=CH
2
)
5. Conjugation between negative charge and
C=C ( ?? ? )
3. Mesomeric effect (or Resonance effect)
Mesomeric effect is defined as permanent effect of ? electron shifting from
multiple bond to atom or from multiple bond to single bond or from lone pair to
single bond. This effect mainly operates in conjugated system of double bond.
So that this effect is also known as conjugate effect.
Ex.
Types of Mesomeric effects :
(a) Positive Mesomeric effect (+M effect) :
When the group donates electron to the conjugated system it shows + M
effect.
Relative order of +M groups (usually followed) :
?O > ?NH
2
 > ?NHR > ?NR
2 
> ?OH > ?OR > ?NHCOR > ?OCOR > ?Ph >
?F > ?Cl > ?Br > ?I > ?NO
Ex. (I)
  
(b) Negative Mesomeric effect (?M effect) :
When the group withdraws electron from the conjugated system, it shows
? M effect
Relative order of ?M groups (usually followed) :
?NO >  ?CHO  >     C=O  >  ?C?O?C?R  >  ?C?O?R  >  ?COOH  >  ?CONH   
2  2
>  ?C?O
?
||
O
||
O
||
O
?
?
||
O
Ex. (I)
(II)    H C = CH ? C  N:
2
? +
H C ? CH = C = N:
2 . .
4. Hyperconjugation
It is delocalisation of sigma electron with p-orbital. Also known as ???-
conjugation or no bond resonance. It may takes place in alkene, alkynes,
carbocation, free radical, benzene nucleus.
Necessary Condition : Presence of at least one hydrogen at saturated carbon
which is ? with respect to alkene, alkynes, carbocation, free radical, benzene
nucleus.
(i) Hyperconjugation in alkene
    
(ii) Hyperconjugation in carbocation
   
(iii) Hyperconjugation in radical
Page 5


  
?  Points to remember in General Organic Chemistry
1. Inductive effect
The normal C?C bond has no polarity as two atoms of same electronegativity
(EN) value are connected to each other. Hence the bond is nonpolar. Consider
a carbon chain in 1-Chloro butane, here due to more EN of Cl atom C?Cl
bond pair is slightly displaced towards Cl atom hence creating partial negative
(? ?) charge over Cl atom and partial positive (?+) charge over C
1
 atom.
Now since C
1
 is slightly positive, it will also cause shifting of C
1
?C
2
 bond pair
electrons towards itself causing C
2
 to acquire small positive charge. Similarly
C
3
 acquires slightly positive charge creating an induction of charge in carbon
chain. Such an effect is called inductive effect.
Diagram showing I effect
The arrow shows electron withdrawing nature of ? Cl group.
Thus inductive effect may be defined as a permanent displacement of ? bond
pair electrons due to a dipole. (Polar bond)
Some important points  are:
(a) It can also be defined as polarisation of one bond caused by polarisation
of adjacent bond.
(b)  It is also called transmission effect.
(c) It causes permanent polarisation in molecule, hence it is a permanent
effect.
(d) The displacement of electrons takes place due to difference in
electronegativity of the two atoms involved in the covalent bond.
(e) The electrons never leave their original atomic orbital.
(f) Its magnitude decreases with distance and it is almost negligible after 3rd
carbon atom.
(g) The inductive effect is always operative through ? bond, does not involve ?
bond electron.
Types of inductive effects :
(a)? I Effect : The group which withdraws electron cloud is known as ? I
group and its effect is called ? I effect. Various groups are listed in their
decreasing ? I strength as follows.
 > ? > ? > ?NO
2 
> ?SO
2
R > ?CN > ?CHO > ?COOH > ?F >
?Cl > ?Br > ?I > ?OR > ?OH > ?C?CH > ?NH
2
 > ?C
6
H
5
 > ?CH=CH
2
 > ?H.
 (b) + I effect : The group which release electron cloud is known as + I group
and effect is + I effect.
  
 >   > ?C(CH
3
)
3
 > ?CH(CH
3
)
2
 > ?CH
2
?CH
3
 > ?CH
3
 > ?D  > ?H
The hydrogen atom is reference for + I and ? I series. The inductive effect of
hydrogen is assumed to be zero.
Ex. Let us consider  effect of COOH & ? COO
?
 in carbon chain
(a) (b)
Due to e¯ donating nature of  carbon chain has become partially
negative but ? COOH is ? I group therefore carbon chain has become partially
positive.
2. Resonance
Resonance is the phenomenon in which two or more structures involving  in
identical position of atom, can be written for a particular  species, all those
possible structures are known as resonating structures or canonical structures.
Resonating structures are only hypothetical but they all contribute to a real
structure which is called resonance hybrid. The resonance hybrid is more
stable than any resonating structure.
?
   ??
Resonance hybrid :
The most stable resonating structure contribute maximum to the resonance
hybrid and less  stable resonating structure contribute minimum to resonance
hybrid.
Conjugation:
A given atom or group is said to be in conjugation with an unsaturated system
if:-
(i) It is directly linked to one of the atoms of the multiple bond through a single
bond.
(ii) It has ð bond, positive charge, negative charge, odd electron or lone pair
electron.
  
Types of  Conjugation :
1. Conjugation between C = C and
C=C ( ?? ? )
2. Conjugation between +ve charge and
C=C (  ?? ? )
3. Conjugation between lone pair and
C=C ( ?? ? )
4. Conjugation between odd electron and
C=C (CH
2
=CH? ?? ? ?CH=CH
2
)
5. Conjugation between negative charge and
C=C ( ?? ? )
3. Mesomeric effect (or Resonance effect)
Mesomeric effect is defined as permanent effect of ? electron shifting from
multiple bond to atom or from multiple bond to single bond or from lone pair to
single bond. This effect mainly operates in conjugated system of double bond.
So that this effect is also known as conjugate effect.
Ex.
Types of Mesomeric effects :
(a) Positive Mesomeric effect (+M effect) :
When the group donates electron to the conjugated system it shows + M
effect.
Relative order of +M groups (usually followed) :
?O > ?NH
2
 > ?NHR > ?NR
2 
> ?OH > ?OR > ?NHCOR > ?OCOR > ?Ph >
?F > ?Cl > ?Br > ?I > ?NO
Ex. (I)
  
(b) Negative Mesomeric effect (?M effect) :
When the group withdraws electron from the conjugated system, it shows
? M effect
Relative order of ?M groups (usually followed) :
?NO >  ?CHO  >     C=O  >  ?C?O?C?R  >  ?C?O?R  >  ?COOH  >  ?CONH   
2  2
>  ?C?O
?
||
O
||
O
||
O
?
?
||
O
Ex. (I)
(II)    H C = CH ? C  N:
2
? +
H C ? CH = C = N:
2 . .
4. Hyperconjugation
It is delocalisation of sigma electron with p-orbital. Also known as ???-
conjugation or no bond resonance. It may takes place in alkene, alkynes,
carbocation, free radical, benzene nucleus.
Necessary Condition : Presence of at least one hydrogen at saturated carbon
which is ? with respect to alkene, alkynes, carbocation, free radical, benzene
nucleus.
(i) Hyperconjugation in alkene
    
(ii) Hyperconjugation in carbocation
   
(iii) Hyperconjugation in radical
  
5. Aromatic character [The Huckel 4n + 2 rule]
The following rules are useful in predicting whether a particular compound is
aromatic or non?aromatic. Aromatic compounds are cyclic and planar. Each
atom in an aromatic ring is sp
2
 hybridised. The cyclic ? molecular orbital
(formed by overlap of p-orbitals) must contain (4n + 2) ? electrons, i.e., 2, 6,
10, 14 ........ ? electrons. Where n = an integer 0, 1, 2, 3,..............
Aromatic compounds have characteristic smell, have extra stability and burn
with sooty flame.
Comparision between aromatic, anti aromatic and non-aromatic compounds.
           
Characteristics Aromatic
compounds (A)
Anti Aromatic
compounds (B)
Non-Aromatic
compounds (C)
Example
1. Structure Cyclic, planar all
atoms of ring sp
hybridised
2
Cyclic, planar all
atoms of ring sp
hybridised
2
Cyclic or acyclic
planar,or non planar
sp or sp or sp
2 3
3. MOT
4. Overlapping
5. Resonance
    energy (R.E.)
6. Stability
7. Characteristic
    Reactions
Unpaired e¯s in B.M.O.
Favourable over
lapping of p orbital
Very high
R.E. > 20-25 kcal/mol
Electrophilic
substitution Reaction
Unfavourable over
lapping of p orbital
Zero
Unstable 
not-exist at 
room temperature
Dimerisation 
reaction to attain
stability
B.M.O. / Non-bonding 
M.O.
Simple overlaping
like alkenes
4-8 kcal/mol
like alkenes
Normal stability
like a conjugated
system
Electrophilic  addtion 
reaction like alkenes
Stability of compounds : Aromatic  >  Non-Aromatic > Anti-Aromatic
(A) Carbocation :
Definition :  A carbon intermediate which contain three bond pair & a positive
charge on it is called carbocation.
Hybridisation : Carbocation may be sp
2
 & sp hybridised
Hybridisation Example
sp
2
, , , 
sp H
2
C =  , HC ? 
Carbocations are electron deficient. They have only six electrons in their
valence shell, and because of this, carbocations act as Lewis acids. Most of
the carbocations are short-lived and highly reactive, they occur as intermediates