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SASTRA Deemed to be University                                                                    M.Sc. (Chemistry)


               Course Code: CHY409                                                   L   T    P  C
               Semester: I                                                           4   0    0  4

                             ORGANIC REACTION MECHANISMS & STEREOCHEMISTRY

               Course Objectives:
               This course aims to:
                     Understand  the  in-depth  concepts  of  structure,  bonding,  aromaticity  and
                       stereochemistry
                     Learn the importance of reaction intermediates and mechanistic aspects of organic
                       reactions Understand the mechanisms of substitution, addition, elimination reactions
                       and their stereochemical aspects

               UNIT – I                                                                        12 Hours
               STRUCTURE, BONDING AND AROMATICITY
               Structure and Bonding: Atomic and molecular orbitals, hybridization, electronic structure of
               molecules, electronegativity, dipole moment, inductive and field effects, bond distance, angle
               and energies, cross conjugation, resonance, hyperconjugation, steric inhibition of resonance,
               tautomerism, hydrogen bonding, acids and bases, factors affecting the strength of acids and
               bases, HSAB principle.

               Aromaticity:  Huckel’s  theory  of  aromaticity,  aromatic,  anti-aromatic  and  homoaromatic
               systems,  cyclopentadienyl  anion  and  cation,  heterocyclic aromatic  systems,  aromaticity  of
               annulenes and heteroannulenes, fullerenes and fused ring systems.

               UNIT – II                                                                       15 Hours
               REACTIVE INTERMEDIATES AND MECHANISTIC ASPECTS
               Carbocation, carbanion, radicals, carbenes and nitrenes: Generation, geometry, stability and
               reactivity, nucleophilicity, heteroatom nucleophiles, solvent effects, alkene nucleophiles, α-
               effect, ambident nucleophiles: thiocyanate, cyanide, nitrite and nitronium ions, enolate ions,
               allyl  anions,  electrophilicity:  trigonal  electrophiles,  tetrahedral  electrophiles,  hard  and  soft
               electrophiles, ambient electrophiles: aromatic and aliphatic electrophiles.

               Transition state theory, intermediate, transition state, reaction coordinate diagram, linear free
               energy relationships, quantitative correlation of substituent effects on reactivity, Hammett and
               Taft  equations,  microscopic  reversibility,  basic  mechanistic  concepts  like  kinetic  versus
               thermodynamic control, Hammond postulate, Curtin-Hammett principle, isotope effects, cross
               over experiments.

               UNIT – III                                                                      15 Hours
               STEREOCHEMISTRY
               Symmetry elements, optical activity and chirality, absolute and relative configurations, R-S
               system  of  nomenclature,  Fischer,  Newman  and  Sawhorse  projections  and  their
               interconversion, molecules with more than one asymmetric carbon (up to five), homotopic,
               enantiotopic and diastereotopic atoms, groups and faces, pro-chiral centres, Cram’s rule and
               asymmetric  induction,  stereospecific  and  stereoselective  reactions,  optical  isomerism  of
               biphenyls,  allenes  and  spiranes,  compounds  containing  chiral  nitrogen,  sulphur  and




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