Organic Chemistry - Some Basic Principles & Techniques Class 11 Notes Chemistry Chapter 8

 Page 1


? The branch of chemistry which deals with hydrocarbons and their
derivatives is called organic chemistry.
? Carbon forms large number of organic compound because of its properties
of catention and tetravalency.
? Functional Group : An atom or a group of atoms, joined in a specific
manner, which provides certain characteristics chemical properties to the
organic compounds, is called functional group.
? Homologous : A group or series of an organic compound each containing a
characteristics functional group from a homologous series and the members
of the series are called “homologous”. Each successive member differ
by –CH
2 
in molecular formula (14 in molar mass).
? Fission of a Covalent Bond :
(a)  Homolytic cleavage : In this cleavaage, one of the electrons of the
shared pair in a covalent bond goes with each of the bonded atoms.
  (b) Heterolytic cleavage : In heterolytic cleavage the bond breaks in  
such a fashion that the shared pair of electrons remains with one of 
the fragment.
? Electron displacement effects in sigma covalent bonds.
Inductive effect (I) : Polarisation of a bond caused by the polarisation of
adjacent bond is referred to as the inductive effect.
Ions
Page 2


? The branch of chemistry which deals with hydrocarbons and their
derivatives is called organic chemistry.
? Carbon forms large number of organic compound because of its properties
of catention and tetravalency.
? Functional Group : An atom or a group of atoms, joined in a specific
manner, which provides certain characteristics chemical properties to the
organic compounds, is called functional group.
? Homologous : A group or series of an organic compound each containing a
characteristics functional group from a homologous series and the members
of the series are called “homologous”. Each successive member differ
by –CH
2 
in molecular formula (14 in molar mass).
? Fission of a Covalent Bond :
(a)  Homolytic cleavage : In this cleavaage, one of the electrons of the
shared pair in a covalent bond goes with each of the bonded atoms.
  (b) Heterolytic cleavage : In heterolytic cleavage the bond breaks in  
such a fashion that the shared pair of electrons remains with one of 
the fragment.
? Electron displacement effects in sigma covalent bonds.
Inductive effect (I) : Polarisation of a bond caused by the polarisation of
adjacent bond is referred to as the inductive effect.
Ions
136
+ Inductive effect (+ I)
Two types of inductive effect 
– Inductive effect (– I)
? It is a permanent effect and decrease with the increase in distance.
– I effect : —NO
2
 > —F  > —Cl > —Br > —I > —OCH
3
 > – C
6
H
5
+ I effect : —C(CH
3
)
3
 > — CH(CH
3
)
2
 > —C
2
H
5
 > —CH
3
? Electromeric effect : The complete transfer of the shared pair of p
electrons of a multiple bond to one of the atoms in the presence of the 
attacking reagent is called electromeric effect.
? If the transference of e
–
 towards attacking reagent + E effect.
? If the transference of e
–
 takes place away from attacking reagent – E effect.
? Resonance effect (+ R effect) : The polarity produced in the molecule
by the interaction of two p-bond and lone pair of electrons present on an
adjacent atom.
? Hyperconjugation : It is special kind of resonance in which delocalisation
of e
–
 takes place through overlap between s-bond orbital and p-orbital.
It is also called no bond resonance.
+ R Effect :
– R Effect :
Page 3


? The branch of chemistry which deals with hydrocarbons and their
derivatives is called organic chemistry.
? Carbon forms large number of organic compound because of its properties
of catention and tetravalency.
? Functional Group : An atom or a group of atoms, joined in a specific
manner, which provides certain characteristics chemical properties to the
organic compounds, is called functional group.
? Homologous : A group or series of an organic compound each containing a
characteristics functional group from a homologous series and the members
of the series are called “homologous”. Each successive member differ
by –CH
2 
in molecular formula (14 in molar mass).
? Fission of a Covalent Bond :
(a)  Homolytic cleavage : In this cleavaage, one of the electrons of the
shared pair in a covalent bond goes with each of the bonded atoms.
  (b) Heterolytic cleavage : In heterolytic cleavage the bond breaks in  
such a fashion that the shared pair of electrons remains with one of 
the fragment.
? Electron displacement effects in sigma covalent bonds.
Inductive effect (I) : Polarisation of a bond caused by the polarisation of
adjacent bond is referred to as the inductive effect.
Ions
136
+ Inductive effect (+ I)
Two types of inductive effect 
– Inductive effect (– I)
? It is a permanent effect and decrease with the increase in distance.
– I effect : —NO
2
 > —F  > —Cl > —Br > —I > —OCH
3
 > – C
6
H
5
+ I effect : —C(CH
3
)
3
 > — CH(CH
3
)
2
 > —C
2
H
5
 > —CH
3
? Electromeric effect : The complete transfer of the shared pair of p
electrons of a multiple bond to one of the atoms in the presence of the 
attacking reagent is called electromeric effect.
? If the transference of e
–
 towards attacking reagent + E effect.
? If the transference of e
–
 takes place away from attacking reagent – E effect.
? Resonance effect (+ R effect) : The polarity produced in the molecule
by the interaction of two p-bond and lone pair of electrons present on an
adjacent atom.
? Hyperconjugation : It is special kind of resonance in which delocalisation
of e
–
 takes place through overlap between s-bond orbital and p-orbital.
It is also called no bond resonance.
+ R Effect :
– R Effect :
137
? IUPAC Nomenclature of Organic Compounds : Following rules are
used to write the IUPAC name of an organic compound.
Rule 1. : Longest chain rule : The chain containing the principal functional
group, secondary functional group and multiple bonds as many as possible
is the longest possible chain.
In the absence of functional group, secondary group and multiple bonds,
the chain containing the maximum number of C-atoms will be the longest
possible chain e.g.,
Choose the word root from the table given below for the longest possible  
chain.
Word Root for Carbon Chain
Chain length Word root Chain length Word root
 C
1
Meth- C
7
Hept
 C
2
Eth- C
8
Oct
 C
3
Prop- C
9
Non
 C
4
But- C
10
Dec
 C
5
Pent- C
11
Undec
 C
6
Hex- C
12
Dodec
sp
3
–s
sp
2
Page 4


? The branch of chemistry which deals with hydrocarbons and their
derivatives is called organic chemistry.
? Carbon forms large number of organic compound because of its properties
of catention and tetravalency.
? Functional Group : An atom or a group of atoms, joined in a specific
manner, which provides certain characteristics chemical properties to the
organic compounds, is called functional group.
? Homologous : A group or series of an organic compound each containing a
characteristics functional group from a homologous series and the members
of the series are called “homologous”. Each successive member differ
by –CH
2 
in molecular formula (14 in molar mass).
? Fission of a Covalent Bond :
(a)  Homolytic cleavage : In this cleavaage, one of the electrons of the
shared pair in a covalent bond goes with each of the bonded atoms.
  (b) Heterolytic cleavage : In heterolytic cleavage the bond breaks in  
such a fashion that the shared pair of electrons remains with one of 
the fragment.
? Electron displacement effects in sigma covalent bonds.
Inductive effect (I) : Polarisation of a bond caused by the polarisation of
adjacent bond is referred to as the inductive effect.
Ions
136
+ Inductive effect (+ I)
Two types of inductive effect 
– Inductive effect (– I)
? It is a permanent effect and decrease with the increase in distance.
– I effect : —NO
2
 > —F  > —Cl > —Br > —I > —OCH
3
 > – C
6
H
5
+ I effect : —C(CH
3
)
3
 > — CH(CH
3
)
2
 > —C
2
H
5
 > —CH
3
? Electromeric effect : The complete transfer of the shared pair of p
electrons of a multiple bond to one of the atoms in the presence of the 
attacking reagent is called electromeric effect.
? If the transference of e
–
 towards attacking reagent + E effect.
? If the transference of e
–
 takes place away from attacking reagent – E effect.
? Resonance effect (+ R effect) : The polarity produced in the molecule
by the interaction of two p-bond and lone pair of electrons present on an
adjacent atom.
? Hyperconjugation : It is special kind of resonance in which delocalisation
of e
–
 takes place through overlap between s-bond orbital and p-orbital.
It is also called no bond resonance.
+ R Effect :
– R Effect :
137
? IUPAC Nomenclature of Organic Compounds : Following rules are
used to write the IUPAC name of an organic compound.
Rule 1. : Longest chain rule : The chain containing the principal functional
group, secondary functional group and multiple bonds as many as possible
is the longest possible chain.
In the absence of functional group, secondary group and multiple bonds,
the chain containing the maximum number of C-atoms will be the longest
possible chain e.g.,
Choose the word root from the table given below for the longest possible  
chain.
Word Root for Carbon Chain
Chain length Word root Chain length Word root
 C
1
Meth- C
7
Hept
 C
2
Eth- C
8
Oct
 C
3
Prop- C
9
Non
 C
4
But- C
10
Dec
 C
5
Pent- C
11
Undec
 C
6
Hex- C
12
Dodec
sp
3
–s
sp
2
138
Rule 2 : Lowest number rule : Numbering is done in such a way so that :
(1) branching if present gets the lowest number.
(2) the sum of numbers of side chain is lowest.
(3) principal functional group gets the lowest number.
Select the principal functional group from the preference series :
—COOH > —SO
3
H > —COOR > —COX > —CONH
2
 > —CN > —NC 
 > —CHO > C = O > —OH > —SH > —NH
2
 > —OR > = > =
Functional group other than the principal functional group are called 
substituents.
Rule 3
? Naming the prefixes and suffixes : Prefix represents the substituent and
suffix is used for principal functional group.
Primary prefixes are cyclo, bicyclo, di, tri, tetra, tetrakis etc.
Secondary prefixes are tabulated below :
Substituent Prefix Substituent Prefix
—F Fluoro —N=N— diazo
—Cl Chloro —N=O nitroso
—Br Bromo —NO
2
 nitro
Primary suffix are ene, ane or yne used for double, single and triple bonds 
respectively.
Secondary suffixes are tabulated below :
 S.No.  Class Formula Prefix Suffix
1. Acid halides halocarbonyl —oyl halide
2. Alcohols —OH hydroxy —ol
3. Aldehydes —CHO formyl —al
—carbaldehyde
4. Ketones    C = O oxo (keto) —one
5. Amides —CONH
2
 carbamoyl —amide
Page 5


? The branch of chemistry which deals with hydrocarbons and their
derivatives is called organic chemistry.
? Carbon forms large number of organic compound because of its properties
of catention and tetravalency.
? Functional Group : An atom or a group of atoms, joined in a specific
manner, which provides certain characteristics chemical properties to the
organic compounds, is called functional group.
? Homologous : A group or series of an organic compound each containing a
characteristics functional group from a homologous series and the members
of the series are called “homologous”. Each successive member differ
by –CH
2 
in molecular formula (14 in molar mass).
? Fission of a Covalent Bond :
(a)  Homolytic cleavage : In this cleavaage, one of the electrons of the
shared pair in a covalent bond goes with each of the bonded atoms.
  (b) Heterolytic cleavage : In heterolytic cleavage the bond breaks in  
such a fashion that the shared pair of electrons remains with one of 
the fragment.
? Electron displacement effects in sigma covalent bonds.
Inductive effect (I) : Polarisation of a bond caused by the polarisation of
adjacent bond is referred to as the inductive effect.
Ions
136
+ Inductive effect (+ I)
Two types of inductive effect 
– Inductive effect (– I)
? It is a permanent effect and decrease with the increase in distance.
– I effect : —NO
2
 > —F  > —Cl > —Br > —I > —OCH
3
 > – C
6
H
5
+ I effect : —C(CH
3
)
3
 > — CH(CH
3
)
2
 > —C
2
H
5
 > —CH
3
? Electromeric effect : The complete transfer of the shared pair of p
electrons of a multiple bond to one of the atoms in the presence of the 
attacking reagent is called electromeric effect.
? If the transference of e
–
 towards attacking reagent + E effect.
? If the transference of e
–
 takes place away from attacking reagent – E effect.
? Resonance effect (+ R effect) : The polarity produced in the molecule
by the interaction of two p-bond and lone pair of electrons present on an
adjacent atom.
? Hyperconjugation : It is special kind of resonance in which delocalisation
of e
–
 takes place through overlap between s-bond orbital and p-orbital.
It is also called no bond resonance.
+ R Effect :
– R Effect :
137
? IUPAC Nomenclature of Organic Compounds : Following rules are
used to write the IUPAC name of an organic compound.
Rule 1. : Longest chain rule : The chain containing the principal functional
group, secondary functional group and multiple bonds as many as possible
is the longest possible chain.
In the absence of functional group, secondary group and multiple bonds,
the chain containing the maximum number of C-atoms will be the longest
possible chain e.g.,
Choose the word root from the table given below for the longest possible  
chain.
Word Root for Carbon Chain
Chain length Word root Chain length Word root
 C
1
Meth- C
7
Hept
 C
2
Eth- C
8
Oct
 C
3
Prop- C
9
Non
 C
4
But- C
10
Dec
 C
5
Pent- C
11
Undec
 C
6
Hex- C
12
Dodec
sp
3
–s
sp
2
138
Rule 2 : Lowest number rule : Numbering is done in such a way so that :
(1) branching if present gets the lowest number.
(2) the sum of numbers of side chain is lowest.
(3) principal functional group gets the lowest number.
Select the principal functional group from the preference series :
—COOH > —SO
3
H > —COOR > —COX > —CONH
2
 > —CN > —NC 
 > —CHO > C = O > —OH > —SH > —NH
2
 > —OR > = > =
Functional group other than the principal functional group are called 
substituents.
Rule 3
? Naming the prefixes and suffixes : Prefix represents the substituent and
suffix is used for principal functional group.
Primary prefixes are cyclo, bicyclo, di, tri, tetra, tetrakis etc.
Secondary prefixes are tabulated below :
Substituent Prefix Substituent Prefix
—F Fluoro —N=N— diazo
—Cl Chloro —N=O nitroso
—Br Bromo —NO
2
 nitro
Primary suffix are ene, ane or yne used for double, single and triple bonds 
respectively.
Secondary suffixes are tabulated below :
 S.No.  Class Formula Prefix Suffix
1. Acid halides halocarbonyl —oyl halide
2. Alcohols —OH hydroxy —ol
3. Aldehydes —CHO formyl —al
—carbaldehyde
4. Ketones    C = O oxo (keto) —one
5. Amides —CONH
2
 carbamoyl —amide
139
6. Amine —NH
2
 amino —amine 
7. Carboxylic acid —COOH carboxy —carboxylic acid
8. Ester —COOR alkoxy carbonyl —alkyl alkanoate
9. Nitriles —CN cyano —nitrile
10. Sulphonic acid —SO
2
—OH sulpho —sulphonic acid
Here according to the rules, given above, the IUPAC name of a compound 
can be written as ? Prefixes + Word root + Suffixes.
? Secondary prefix + Primary prefix + Word root + primary suffix +
secondary suffix
        4        3            2         1 
  for e.g., CH
3
 CH — CH
2
   CHO  ? Principal functional group
      |   (—al)
     OH   — substituent (hydroxy)
                3 — Hydroxybutanal
?          ?          ?
prefix    word     suffix
root
? If more than two similar functional groups are present, all the groups are
considered as substituent, for e.g.,
  3              2            1
  CH
2
 — CH — CH
2
 |            |           | 
CN      CN       CN
Propane-1, 2, 3-tricarbonitrile
? Naming of Aromatic compounds : IUP AC accepted their common trivial
names e.g.,