Unit I: Fundamentals of organic reaction mechanism
Types of reagents – Electrophiles and Nucleophiles.Substitution, Addition, Elimination and Rearrangement. Reactive intermediates with examples – Carbocations, Carbanions and Free radicals. Electron displacement effects - Inductive, inductomeric, electromeric, mesomeric, resonance, hyper conjugation and steric effects. Aliphatic nucleophilic substitutions, mechanism of SN1,SN2- effects of structure substrate, solvent, nucleophile and leaving groups - StereochemistryWalden inversion Elimination Reactions:-Hoffmann and Saytzeff rules- cis and trans eliminations – mechanisms of E1 and E2 reactions. Elimination versus substitution. Addition reactions- mechanisms of addition of Bromine and hydrogen halides to double bondsMarkownikoff’s rule and peroxide effect. Polymerisation reactions-Types of polymerisation - free radical, cationic and anionic – polymerisations –including mechanism..
Unit II: Stereochemistry of Organic Compounds
Optical Isomerism: Structural changes responsible for properties: elements of symmetry, molecular chirality, enantiomers, stereogenic centre, optical activity, properties of enantiomers, chiral and achiral molecules with two stereogenic centres, diastereomers, threo and erythro diastereomers, meso compounds, resolution of enantiomers, inversion, retention and racemization and asymmetric synthesis. Relative and absolute configuration, sequence rules, D & L and R & S systems of nomenclature. Geometric isomerism: Determination of configuration of geometric isomers. Cis – trans and E & Z system of nomenclature, geometric isomerism in oximes and alicyclic compounds. Conformational isomerism: Difference between configuration and conformation. Conformational 6 analysis of ethane and n-butane; conformations of cyclohexane, axial and equatorial bonds, conformation of mono alkyl substituted cyclohexane derivatives. Review of Newman projection and Sawhorse formulae, Fischer and flying wedge formulae.
Unit III: Aliphatic Hydrocarbons
Alkanes: Methods of formation (with special reference to Wurtz reaction, Kolbe reaction, CoreyHouse reaction and decarboxylation), physical properties and chemical reactions of alkanes (halogenation, nitration, sulphonation, oxidation and isomerisation reactions) Mechanism of free radical halogenation of alkanes: orientation, reactivity and selectivity. Cycloalkanes: methods of formation (from acetoacetic ester / malonic ester and Dieckmann reaction), chemical reactions (halogenation), Baeyer’s strain theory and its limitations. Ring strain in small rings (cyclopropane and cyclobutane), theory of strainless rings. Alkenes: Accounting for Reactions due to unsaturation in compounds. Regioselectivity in alcohol dehydration.Hofmann elimination, physical properties and relative stabilities of alkenes.Chemical reactions of alkenes – mechanism of hydrogenation, electrophilic and free radical additions, Markownikoff’s rule, hydroboration followed by oxidation, oxymercuration – reduction.Epoxidation, ozonolysis, hydration, hydroxylation and oxidation with KMnO4.Substitution at the allylic and vinylic positions of alkenes. Cycloalkenes: Methods of formation and chemical reactions of cycloalkenes. Alkadienes: Isolated, conjugated and cumulated dienes. Structure of allenes and butadiene, methods of formation, polymerization. Chemical reactions – 1,2 and 1,4 additions. Diels-Alder reaction. Alkynes: Methods of formation (alkylation of acetylene and by elimination reactions). Acidity of alkynes. Chemical reactions of alkynes: Mechanism of electrophilic and nucleophilic addition reactions, hydroboration – oxidation, metalammonia reductions, oxidation.
Unit IV: Aromatic Hydrocarbons
Structure of benzene: molecular formula and Kekule structure. Stability and carbon-carbon bond lengths of benzene, resonance structure, MO picture. Aromaticity : The Huckel rule, aromatic ions. Aromatic electrophilic substitution: General pattern of the mechanism, role of - and - complexes. Mechanism of nitration, halogenation, sulphonation, mercuration and Friedel-Crafts reaction. Energy profile diagrams. Activating and deactivating substituents, orientation and ortho/ para ratio.Side chain reactions of benzene derivatives.Birch reduction.Methods of formation and chemical reactions of alkylbenzenes, alkynylbenzenes and biphenyl.
Unit V: Alkyl and Aryl Halides
Alkyl halides: A study of Alkyl halides highlighting its synthetic applications. Nomenclature and classes of alkyl halides, methods of formation, chemical reactions. Mechanisms of nucleophilic substitution reactions of alkyl halides SN2 and SN1 reactions with energy profile diagrams. Polyhalogen compounds:chloroform, carbon tetrachloride. Aryl halides: Methods of formation of aryl halides, nuclear and side chain reactions. The addition- elimination and the eliminationaddition mechanisms of nucleophilic aromatic substitution reactions.Relative reactivities of alkyl halides vs allyl, vinyl and aryl halides. Synthesis and uses of DDT and BHC.