Mechanism of Organic Reactions and Stereochemistry

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, Huckel’s rule with cyclic carbocations/carbanions and heterocyclic compounds, annulenes & kekulene as examples, elementary idea of aromatic, antiaromatic and homoaromatic compounds. Pseudoasymmetry.

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,  One carbon electrophiles reactions: chloromethylation, Gatterman-Koch, Gatterman, Hoesch, Vilsmeier-Haack reaction, Reimer-Tiemann, Kolbe-Schmidt.

General preparation and reactions of alkyl halides, Substitution at sp³ centre - Mechanism: SN¹, SN², SNi mechanisms with stereochemical aspects, effect of solvent, substrate structure, leaving group, nucleophiles including ambident nucleophiles (cyanide & nitrite) substitution involving NGP.

Aryl halides: Preparation, nucleophilic aromatic substitution; Benzyne mechanism, relative reactivity of alkyl, allyl, benzyl, vinyl and aryl halides towards nucleophilic substitution reactions.

Geometrical isomerism: concept of restricted rotation – cis-trans, syn-anti and E,Z system of nomenclature, geometrical isomerism in oximes, amides 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 isomers – 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 of bromine to alkane and alkenes)

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.