General Organic Chemistry - IIT JAM PDF Download

 Page 1


 
General Organic Chemistry 
(GOC) 
 
 
          
 
ALL Faculty Members are IITians 
 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
Page 2


 
General Organic Chemistry 
(GOC) 
 
 
          
 
ALL Faculty Members are IITians 
 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
2 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
General Organic Chemistry (GOC) 
Contents 
1. Electron Displacement in Covalent Bonds 
? Inductive Effect 
? Electromeric Effect 
? Hyperconjugation Effect 
? Resonance or Mesomeric Effect 
? Steric Inhibition of Resonance 
 
2. Aromaticity 
? Aromatic, Anti-aromatic, Non-aromatic and Homoaromatic compounds 
? Annulenes 
 
3. Tautomerism 
 
4. Acidity and Basicity 
? Lewis and Bronsted Acid-Base Theory 
? Effect of Structure on Acidity and Basicity 
? Effect of Solvent on Acidity and Basicity 
? Super Acids and Super Bases  
 
5. Exercises 
? Exercise-1 (General Questions) 
? Exercise-2 (Previous Years IIT-JAM Questions) 
? Multiple Select Questions (MCQ) 
? Numerical Ability Test (NAT) Questions 
 
 
Reference Books: Please follow at least one reference book along with this booklet to have 
best understanding of given topics.  
? Organic Chemistry by Paula Yurkanis Bruice (Resonance Theory) 
? Organic Chemistry 11
th
 Edition by T. W. Graham Solomons, Craig B. Fryhle, Scott 
A. Snyder (Basics of All Topics) 
? Advanced Organic Chemistry (Structure and Mechanisms) by Francis A. Carey and 
Richard J. Sundberg (Aromaticity) 
? March’s Advanced Organic Chemistry 6
th
 Edition by Michael B. Smith and Jerry 
March (Acidity and Basicity)  
 
 
Page 3


 
General Organic Chemistry 
(GOC) 
 
 
          
 
ALL Faculty Members are IITians 
 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
2 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
General Organic Chemistry (GOC) 
Contents 
1. Electron Displacement in Covalent Bonds 
? Inductive Effect 
? Electromeric Effect 
? Hyperconjugation Effect 
? Resonance or Mesomeric Effect 
? Steric Inhibition of Resonance 
 
2. Aromaticity 
? Aromatic, Anti-aromatic, Non-aromatic and Homoaromatic compounds 
? Annulenes 
 
3. Tautomerism 
 
4. Acidity and Basicity 
? Lewis and Bronsted Acid-Base Theory 
? Effect of Structure on Acidity and Basicity 
? Effect of Solvent on Acidity and Basicity 
? Super Acids and Super Bases  
 
5. Exercises 
? Exercise-1 (General Questions) 
? Exercise-2 (Previous Years IIT-JAM Questions) 
? Multiple Select Questions (MCQ) 
? Numerical Ability Test (NAT) Questions 
 
 
Reference Books: Please follow at least one reference book along with this booklet to have 
best understanding of given topics.  
? Organic Chemistry by Paula Yurkanis Bruice (Resonance Theory) 
? Organic Chemistry 11
th
 Edition by T. W. Graham Solomons, Craig B. Fryhle, Scott 
A. Snyder (Basics of All Topics) 
? Advanced Organic Chemistry (Structure and Mechanisms) by Francis A. Carey and 
Richard J. Sundberg (Aromaticity) 
? March’s Advanced Organic Chemistry 6
th
 Edition by Michael B. Smith and Jerry 
March (Acidity and Basicity)  
 
 
3 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
Electron Displacement in Covalent Bonds 
The frequently observed electron displacement effects in the covalent molecules are as 
follows: 
Inductive Effect 
The displacement of s-electrons along a saturated carbon chain due to the presence of an 
electron withdrawing or electron donating (repelling) group is called inductive effect or I-
effect. It is a permanent effect. For example, the carbon–carbon bond of ethane is completely 
nonpolar because at each end of the bond there are two identical methyl groups: 
 
Ethane 
The C-C bond is non-polar 
 
This is not the case with the carbon–carbon bond of ethyl fluoride, however: 
 
One end of the bond, the one nearer the fluorine atom, is more negative than the other. This 
polarization of the carbon–carbon bond results from an intrinsic electron-attracting ability of 
the fluorine (because of its electronegativity) that is transmitted through space and through 
the bonds of the molecule. This type of effect is called inductive effect. 
Inductive effect is of two types: 
? –I effect: when the substituent group attached to the chain of carbon atoms is an 
electron withdrawing group, the effect is called –I effect.  
For example, in the following example the fluorine atom is more electronegative than carbon, 
hence, it attracts the s-electrons of C-F bond. As a result the shared s-electrons of C-F bond 
gets displaced towards the fluorine atom. Consequently, the fluorine acquires a partial –ve 
charge (d-) while the carbon atom attached to F acquires a partial +ve charge (d+). The partial 
+ve charge developed on first carbon further attracts the shared s-electrons of C1-C2 bond 
and the second carbon of the chain (i.e. C2) develops a partial +ve charge. The partial +ve 
charge developed on C2 is obviously less than that developed on C1 and is denoted as dd+. 
The third carbon in turn develops a partial positive charge which is still smaller and is 
denoted as ddd+. The process continues and all the carbon atoms of the chain develop partial 
+ve charge in the decreasing magnitude. This –I effect can be shown as follows: 
 
 
  
The inductive effect decreases sharply as one moves away from the electron withdrawing 
group and becomes almost negligible beyond the third carbon atom (C 3) of the chain. 
Some common groups in their decreasing order of –I effect are given below: 
 
-NO2 > CN > -COOH > -F > Cl > Br > -I > -OH > C6H5 
 
? +I effect: When an electron repelling group attached to one end of a carbon chain 
it acquires a partial +ve charge and the first carbon of the chain acquires partial –ve charge 
(d-). This results in the development of comparatively less partial –ve charge (dd-) on C2. The 
Page 4


 
General Organic Chemistry 
(GOC) 
 
 
          
 
ALL Faculty Members are IITians 
 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
2 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
General Organic Chemistry (GOC) 
Contents 
1. Electron Displacement in Covalent Bonds 
? Inductive Effect 
? Electromeric Effect 
? Hyperconjugation Effect 
? Resonance or Mesomeric Effect 
? Steric Inhibition of Resonance 
 
2. Aromaticity 
? Aromatic, Anti-aromatic, Non-aromatic and Homoaromatic compounds 
? Annulenes 
 
3. Tautomerism 
 
4. Acidity and Basicity 
? Lewis and Bronsted Acid-Base Theory 
? Effect of Structure on Acidity and Basicity 
? Effect of Solvent on Acidity and Basicity 
? Super Acids and Super Bases  
 
5. Exercises 
? Exercise-1 (General Questions) 
? Exercise-2 (Previous Years IIT-JAM Questions) 
? Multiple Select Questions (MCQ) 
? Numerical Ability Test (NAT) Questions 
 
 
Reference Books: Please follow at least one reference book along with this booklet to have 
best understanding of given topics.  
? Organic Chemistry by Paula Yurkanis Bruice (Resonance Theory) 
? Organic Chemistry 11
th
 Edition by T. W. Graham Solomons, Craig B. Fryhle, Scott 
A. Snyder (Basics of All Topics) 
? Advanced Organic Chemistry (Structure and Mechanisms) by Francis A. Carey and 
Richard J. Sundberg (Aromaticity) 
? March’s Advanced Organic Chemistry 6
th
 Edition by Michael B. Smith and Jerry 
March (Acidity and Basicity)  
 
 
3 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
Electron Displacement in Covalent Bonds 
The frequently observed electron displacement effects in the covalent molecules are as 
follows: 
Inductive Effect 
The displacement of s-electrons along a saturated carbon chain due to the presence of an 
electron withdrawing or electron donating (repelling) group is called inductive effect or I-
effect. It is a permanent effect. For example, the carbon–carbon bond of ethane is completely 
nonpolar because at each end of the bond there are two identical methyl groups: 
 
Ethane 
The C-C bond is non-polar 
 
This is not the case with the carbon–carbon bond of ethyl fluoride, however: 
 
One end of the bond, the one nearer the fluorine atom, is more negative than the other. This 
polarization of the carbon–carbon bond results from an intrinsic electron-attracting ability of 
the fluorine (because of its electronegativity) that is transmitted through space and through 
the bonds of the molecule. This type of effect is called inductive effect. 
Inductive effect is of two types: 
? –I effect: when the substituent group attached to the chain of carbon atoms is an 
electron withdrawing group, the effect is called –I effect.  
For example, in the following example the fluorine atom is more electronegative than carbon, 
hence, it attracts the s-electrons of C-F bond. As a result the shared s-electrons of C-F bond 
gets displaced towards the fluorine atom. Consequently, the fluorine acquires a partial –ve 
charge (d-) while the carbon atom attached to F acquires a partial +ve charge (d+). The partial 
+ve charge developed on first carbon further attracts the shared s-electrons of C1-C2 bond 
and the second carbon of the chain (i.e. C2) develops a partial +ve charge. The partial +ve 
charge developed on C2 is obviously less than that developed on C1 and is denoted as dd+. 
The third carbon in turn develops a partial positive charge which is still smaller and is 
denoted as ddd+. The process continues and all the carbon atoms of the chain develop partial 
+ve charge in the decreasing magnitude. This –I effect can be shown as follows: 
 
 
  
The inductive effect decreases sharply as one moves away from the electron withdrawing 
group and becomes almost negligible beyond the third carbon atom (C 3) of the chain. 
Some common groups in their decreasing order of –I effect are given below: 
 
-NO2 > CN > -COOH > -F > Cl > Br > -I > -OH > C6H5 
 
? +I effect: When an electron repelling group attached to one end of a carbon chain 
it acquires a partial +ve charge and the first carbon of the chain acquires partial –ve charge 
(d-). This results in the development of comparatively less partial –ve charge (dd-) on C2. The 
4 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
effect continues and all the carbon atoms of the chain develop partial -ve charges in the order 
of decreasing magnitude. This is call +I effect of that electron donating group. This is 
expressed as follows:  
 
+I effect also decreases sharply and become almost negligible beyond the third carbon atom 
(C3) of the chain.  
Some common groups causing +I effect in the order of their decreasing effect are given 
below: 
O
2-
 > C6H5O
-
 > (CH3)3C- > (CH3)2CH- > CH3CH2- > CH3- > D > H 
3°                 2°                 1° 
 Inductive effect plays an important role in the understanding the reactivity of compounds and 
the nature of organic reactions. 
 
Applications of Inductive Effect: 
 
? Acidity of Carboxylic Acids: The pKa values of five different carboxylic acids 
are give below:  
 
 
 
This order is due to that all the halogens are more electronegative than hydrogen. An 
electronegative halogen atom pulls the bonding electrons towards itself.  We know that acidic 
strength of any acid depends on stability of its conjugate base. The more stable is the 
conjugate base of any acid, the more acidic will be the acid. Inductive electron withdrawal 
will stabilize the conjugate base by decreasing the electron density about the oxygen atom. 
Br
C C O
-
H
H
O
Inductive electron withdrawal
 
 
The greater the electron-withdrawing ability (electronegativity) of the halogen substituent, 
the more the acidity is increased because the more its conjugate base is stabilized. Hence the 
fluoro substituted carboxylic acid has highest acidity (lowest pKa) and the acetic acid has 
lowest acidity. 
The effect of a substituent on the acidity of a compound decreases as the distance between the 
substituent and the oxygen atom increases. This is due to the fact that inductive effect 
decreases with distance along carbon chain. For example, 
Page 5


 
General Organic Chemistry 
(GOC) 
 
 
          
 
ALL Faculty Members are IITians 
 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
2 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
General Organic Chemistry (GOC) 
Contents 
1. Electron Displacement in Covalent Bonds 
? Inductive Effect 
? Electromeric Effect 
? Hyperconjugation Effect 
? Resonance or Mesomeric Effect 
? Steric Inhibition of Resonance 
 
2. Aromaticity 
? Aromatic, Anti-aromatic, Non-aromatic and Homoaromatic compounds 
? Annulenes 
 
3. Tautomerism 
 
4. Acidity and Basicity 
? Lewis and Bronsted Acid-Base Theory 
? Effect of Structure on Acidity and Basicity 
? Effect of Solvent on Acidity and Basicity 
? Super Acids and Super Bases  
 
5. Exercises 
? Exercise-1 (General Questions) 
? Exercise-2 (Previous Years IIT-JAM Questions) 
? Multiple Select Questions (MCQ) 
? Numerical Ability Test (NAT) Questions 
 
 
Reference Books: Please follow at least one reference book along with this booklet to have 
best understanding of given topics.  
? Organic Chemistry by Paula Yurkanis Bruice (Resonance Theory) 
? Organic Chemistry 11
th
 Edition by T. W. Graham Solomons, Craig B. Fryhle, Scott 
A. Snyder (Basics of All Topics) 
? Advanced Organic Chemistry (Structure and Mechanisms) by Francis A. Carey and 
Richard J. Sundberg (Aromaticity) 
? March’s Advanced Organic Chemistry 6
th
 Edition by Michael B. Smith and Jerry 
March (Acidity and Basicity)  
 
 
3 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
Electron Displacement in Covalent Bonds 
The frequently observed electron displacement effects in the covalent molecules are as 
follows: 
Inductive Effect 
The displacement of s-electrons along a saturated carbon chain due to the presence of an 
electron withdrawing or electron donating (repelling) group is called inductive effect or I-
effect. It is a permanent effect. For example, the carbon–carbon bond of ethane is completely 
nonpolar because at each end of the bond there are two identical methyl groups: 
 
Ethane 
The C-C bond is non-polar 
 
This is not the case with the carbon–carbon bond of ethyl fluoride, however: 
 
One end of the bond, the one nearer the fluorine atom, is more negative than the other. This 
polarization of the carbon–carbon bond results from an intrinsic electron-attracting ability of 
the fluorine (because of its electronegativity) that is transmitted through space and through 
the bonds of the molecule. This type of effect is called inductive effect. 
Inductive effect is of two types: 
? –I effect: when the substituent group attached to the chain of carbon atoms is an 
electron withdrawing group, the effect is called –I effect.  
For example, in the following example the fluorine atom is more electronegative than carbon, 
hence, it attracts the s-electrons of C-F bond. As a result the shared s-electrons of C-F bond 
gets displaced towards the fluorine atom. Consequently, the fluorine acquires a partial –ve 
charge (d-) while the carbon atom attached to F acquires a partial +ve charge (d+). The partial 
+ve charge developed on first carbon further attracts the shared s-electrons of C1-C2 bond 
and the second carbon of the chain (i.e. C2) develops a partial +ve charge. The partial +ve 
charge developed on C2 is obviously less than that developed on C1 and is denoted as dd+. 
The third carbon in turn develops a partial positive charge which is still smaller and is 
denoted as ddd+. The process continues and all the carbon atoms of the chain develop partial 
+ve charge in the decreasing magnitude. This –I effect can be shown as follows: 
 
 
  
The inductive effect decreases sharply as one moves away from the electron withdrawing 
group and becomes almost negligible beyond the third carbon atom (C 3) of the chain. 
Some common groups in their decreasing order of –I effect are given below: 
 
-NO2 > CN > -COOH > -F > Cl > Br > -I > -OH > C6H5 
 
? +I effect: When an electron repelling group attached to one end of a carbon chain 
it acquires a partial +ve charge and the first carbon of the chain acquires partial –ve charge 
(d-). This results in the development of comparatively less partial –ve charge (dd-) on C2. The 
4 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
effect continues and all the carbon atoms of the chain develop partial -ve charges in the order 
of decreasing magnitude. This is call +I effect of that electron donating group. This is 
expressed as follows:  
 
+I effect also decreases sharply and become almost negligible beyond the third carbon atom 
(C3) of the chain.  
Some common groups causing +I effect in the order of their decreasing effect are given 
below: 
O
2-
 > C6H5O
-
 > (CH3)3C- > (CH3)2CH- > CH3CH2- > CH3- > D > H 
3°                 2°                 1° 
 Inductive effect plays an important role in the understanding the reactivity of compounds and 
the nature of organic reactions. 
 
Applications of Inductive Effect: 
 
? Acidity of Carboxylic Acids: The pKa values of five different carboxylic acids 
are give below:  
 
 
 
This order is due to that all the halogens are more electronegative than hydrogen. An 
electronegative halogen atom pulls the bonding electrons towards itself.  We know that acidic 
strength of any acid depends on stability of its conjugate base. The more stable is the 
conjugate base of any acid, the more acidic will be the acid. Inductive electron withdrawal 
will stabilize the conjugate base by decreasing the electron density about the oxygen atom. 
Br
C C O
-
H
H
O
Inductive electron withdrawal
 
 
The greater the electron-withdrawing ability (electronegativity) of the halogen substituent, 
the more the acidity is increased because the more its conjugate base is stabilized. Hence the 
fluoro substituted carboxylic acid has highest acidity (lowest pKa) and the acetic acid has 
lowest acidity. 
The effect of a substituent on the acidity of a compound decreases as the distance between the 
substituent and the oxygen atom increases. This is due to the fact that inductive effect 
decreases with distance along carbon chain. For example, 
5 
 
Ashoka Scientific Forum 
2637, Hudson Lane, Behind Khalsa College, Near G.T.B. Nagar Metro Station Gate No. 3 & 4, New Delhi – 110009 
Mob.011-47455430, 08860929430, e-mail: info@asfinstitute.com, www.asfinstitute.com  
 
 
 
Acidity also increases with the increase in the no. of halogen atoms. For example, 
trichloroactetic acid is more acidic than chloroacetic acid which is further more acidic than 
acetic acid. 
 
 
 
? Acidity of Alcohols and Phenols: Phenol is more acidic than an alcohol. This is 
due to the stabilization of phenol’s conjugate base by electron withdrawal and by increased 
resonance energy (we will discuss this when we read resonance effect). 
 
 
 
The OH group of phenol is attached to an sp
2
 carbon that is more electronegative than the sp
3
 
carbon to which the OH group of cyclohexanol is attached. Greater inductive electron 
withdrawal by the carbon stabilizes the conjugate base by decreasing the electron density of 
its negatively charged oxygen. Hence, phenol is more acidic that aliphatic alcohols. 
The presence of halogens increases acidity because they stabilize the negative charge on the 
alkoxide oxygen (conjugate base of alcohols) by electrostatic attraction. The inductive effect 
in alcohols increases with the number of electronegative groups but decreases with distance 
from the oxygen. Hence 1-Chloroethanol is far more acidic than ethanol. 
 
? Basicity of Amines: Increasing strength in the nitrogenous bases is related to the ease 
with which they are prepared to take up protons and, therefore, the availability of unshared 
electron pair on nitrogen. Hence, the substituents which increase (electron donating) the 
electron density on nitrogen increases the basic strength of amines and substituents which are 
electron withdrawing decrease the basicity of amines. For example, the basic strength of alkyl 
amines in the gaseous phase is as follows: 
 
(CH3)3N > (CH3)2NH > CH3NH2 > NH3 (in gas phase) 
 
Introduction of alkyl groups in ammonia increases the basic strength in gaseous medium 
because alkyl groups increase the electron density on nitrogen through their inductive 
electron donating property. 
But, this is not the case in solution phase (water). In water the acidity of alkyl amines 
follows the order: 
(CH3)2NH > (CH3)3N > CH3NH2 > NH3 (in solution)