Aromaticity and Stereochemistry

Paper Code: 
CHY-202
Credits: 
2
Contact Hours: 
30.00
Max. Marks: 
100.00
Objective: 

To learn about the extra stability of some molecules through aromaticity and Huckel’s rule and also about restricted and free rotation, molecular symmetry, enantiomeric and diastereomeric conditions.

5.00
Unit I: 
Aromaticity
Pre requisite: Nomenclature of benzene derivatives (mono and disubstituted), physical properties.
 
Introduction to aromatic compounds: Benzene, structure and stability, M.O concept, resonance and resonance energy; aromaticity and Huckel’s (4n+2) rule, magnetic criteria.
6.00
Unit II: 
Directing Effects of Substituents
Aromatic electrophilic substitution – general pattern of the mechanism, σ and π complexes, energy profile diagram, activating and deactivating effects of substituents, orientation, o/p ratio, halogenation, nitration, sulphonation and desulphonation, friedel crafts alkylation and acylation; side chain halogenation of alkyl benzenes (toluene, ethyl benzene), Birch reduction.
 
Self Study: Hydrogenation of benzene derivatives, industrial use of aromatic hydrocarbons.
7.00
Unit III: 
Principles of Stereochemistry

Geometrical isomerism: concept of resricted rotation- cis-trans, syn-anti and E,Z system of nomenclature, geometrical isomerism in oximes, amide and alicyclic compounds. Optical isomerism: elements of symmetry,  concept of asymmetry  and  chirality, enantiomers and diastereomers, racemic mixture and meso isomers; molecular chirality- allenes, relative and absolute configuration, nomenclature of optical isomer - D,L nomenclature, sequence  rule and the R,S system of nomenclature, resolution of enantiomers; elementary concepts of asymmetric synthesis (concept  of diastereomeric induction). Elementary concept  of chiral induction through chemical reaction(reaction to bromine to alkane and alkenes)

Self study: Physical properties of enantiomers and diastereomers, optical activity, polarized light, optical activity of enantiomers.

 

6.00
Unit IV: 
Cycloalkanes

Nomenclature, method of preparation, chemical reactions, theory of strainless rings, cyclopropane and its reactivity with halogens.

6.00
Unit V: 
Conformational analysis: Concept of Free Rotation

Newman, Fischer, Sawhorse and Flying-wedge formula; conformation of ethane, n-butane and cyclohexane – axial and equitorial bonds, conformational analysis of monosubstituted and disubstituted cyclohexane (dimethyl cylcohexane), concepts of conformational locking; chair conformation of α and β glucose and their stability.

Essential Readings: 
  1. Organic Chemistry; Fourth Edition; G. Marc Loudon; OxfordUniversity Press, New York , 2002.
  2. Stereochemistry Confirmation and mechanism; Fourth Edition; P.S. Kalsi; New Age International (P) Ltd. Publishers, New Delhi, 1997.
  3.  Organic Chemistry; Sixth Edition; Robert Thornton Morrison & Robert Neilson Boyd; Prentice-Hall of India Pvt. Ltd , New Delhi, 2004.
  4. Stereochemistry of Organic compounds ; First Edition ; Ernest L. Eliel , Samuel H. Wilen; Wiley Interscience ,1994.
Academic Year: 
2019-2020
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