Course

Unit III

Nucleophilic Substitution:SN1, SN2, and Borderline (ion pair), SNi, SET mechanisms, Neighboring group participation, substitution at allylic carbons, substitution at aliphatic trigonal carbon, substitution at vinylic carbon. Effect of substrate structure, nucleophile, leaving group and medium on reactivity. Ambidentnucleophiles and substrates. Aromatic nucleophilic substitution: SNAr, SN1, benzyne and SRN1 mechanisms. Effect of substrate structure, leaving group and attacking nucleophile on reactivity.

Unit IV

Electrophilic substitution: SE2 and SEi, SE1, substitution accompanied by double bond shift. Effect of substrate, leaving group, and solvent on reactivity. Aromatic electrophilic substitution: arenium mechanism, structure reactivity relationship, substituent effect, o/p ratio, ipso substitution, orientation and reactivity, quantitative treatment. Free radical reactions: radical addition. Effect of substrate (aliphatic, aromatic, bridgehead), nature of the radical and solvent on reactivity.

Unit V

Addition reactions: mechanism of electrophilic, nucleophilic and radical addition. Addition to conjugated systems. Orientation and reactivity. Addition of hydrogen halides, oxymercuration, halogenation, sulphenylation, selenylation, addition involving epoxides, addition via organoborane. Addition of water, alcohol, sulphides, to aldehydes, ketones, imines, isothiocyanates, nitro compounds, nitriles. Mannich reaction, elimination reactions: mechanism of elimination reactions E2, E1, E1CB, steric effect. Effect of substrate structure, base, leaving group and medium on reactivity. Mechanism of pyrolytic elimination.

Rearrangement reaction: mechanism of nucleophilic, electrophilic and radical rearrangements. Nature of migration, migratory aptitudes, memory effects. Wagner-Meerwein, Pinacol, Demyanov, dienone-phenol, benzil-benzilic acid, Favorskii, Wolff, Neber, Hofmann, Curtius, Lossen, Schmidt, Beckmann, Baeyer-Villiger, Stevens, benzidine, Hofmann-Loffler and Chapman rearrangements and their mechanisms.

Photochemistry and pericyclic reactions: general principles fate of excited state Jablonski diagram – chemical process photochemistry of alkenes, dienes and polyenes, carbonyl compounds, Norrish type 1 and type 2, Patterno Buchi reaction.Pericyclic reactions: cyclo addition – Diels-Alder reaction, substituent effect on reactivity, regioselectivity and stereochemistry, catalysis of Lewis acids, synthetic applications, enantio-selective Diels-Alder reactions, Intramolecular Diels-Alder reactions. 1,3 dipolar cycloaddition reactivity, regio and stereoselectivity, applications. [2+2] cycloaddition ketenes and alkenes photochemical electrocyclic reactions, orbital symmetry, charged species. Sigmatropic rearrangements [1,3], [1,5], and [1,7] sigmatropic shifts [3,3] sigmatropic rearrangements Cope, Oxy-Cope and Claisen rearrangement. [2,3] rearrangements oxides and ylides Wittig and aza Wittig rearrangements, cheletropic reactions.

TEXT BOOKS1.Michael B Smith, March’s Advanced Organic Chemistry: Reactions, Mechanisms and Structure, 7th edition, Wiley (2015).2.Francis A. Carey and Richard J. Sundberg, Advanced Organic Chemistry – Part A: Structure and Mechanisms, 5th Edition, Springer, 20083.Francis A. Carey and Richard J. Sundberg, Advanced Organic Chemistry – Part B: Reactionsand Synthesis, 5th Edition, Springer, 2008.4.Singh S P and SM Mukherji, Reaction Mechanism in Organic Chemistry, 2014REFERENCES1.Reinhard Bruckner, Advanced Organic Chemistry, Reaction Mechanisms, Elsevier, 20022.R.O.C. Norman and J.M. Coxon, Principles of organic synthesis, CRC press, 20143.Ian Fleming, Frontier Orbitals and Organic Chemical Reactions 1st Edition, Wiley, 1991.