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Photochemistry, Pericyclic Reactions and Disconnection Approach
This course will enable the students to
acquire in-depth knowledge of various photochemical reactions and their basic principles which enables students to learn a variety of photochemical reactions, and their mechanisms and understand the various organic transformations through the disconnection approach.
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Learning and Teaching Strategies |
Assessment Strategies |
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Course Code |
Course Title |
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25CHY321 |
Photochemistry, Pericyclic Reactions and Disconnection Approach (Theory) |
CO95 Distinguish between thermal and photochemical reactions and explain the photochemistry of carbonyl compounds. CO96 Explain the various photochemical reactions of alkenes and aromatic compounds along with singlet oxygen reactions. CO97 Appraise the orbital interactions and orbital symmetry correlations in electrocyclic reactions to solve various problems. C098 Explain and justify pericyclic reactions and their products in cycloaddition and sigmatropic reactions. C099 Justify retrosynthetic methods for the logical dissection of complex organic molecules and devise appropriate routes for their synthesis. Predict logical uses of various reagents in organic synthesis. CO100 Contribute effectively in course-specific interaction. |
Approach in teaching: Interactive lectures, tutorials, group discussions and e-learning.
Learning activities for the students: Peer learning, e- learning, problem solving through tutorials and group discussions.
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Written examinations, Assignments, Quiz
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Laws of photochemistry. Fate of excited molecules: Jablonski diagram, intersystem crossing, energy transfer, photosensitization, quenching, quantum yield, Stern-Volmer equation. Photochemical reactions of ketones – alpha cleavage or Norrish type I cleavage, gamma hydrogen transfer or Norrish type II cleavage; photo reductions; Paterno-Buchi reactions; Photochemistry of α,β-unsaturated ketones, β,γ-unsaturated ketones, cyclohexadienones (cross conjugated and conjugated).
Photochemistry of alkenes: Intramolecular reactions of the olefinic bond, cis-trans isomerisation (stilbene), cyclization reactions, rearrangement of 1,4 and 1,5-dienes, di-π methanerearrangement.
Photochemistry of aromatic compounds: Photochemical rearrangement, photostationary state, 1, 3, 5 – trimethyl benzene to 1, 2, 4-trimethyl benzene.
Miscellaneous Photochemical Reactions- Barton reaction, photo Fries rearrangement of ethers and anilides, singlet oxygen reactions (photo oxygenation).
General characteristics, classification, molecular orbital symmetry.
Electrocyclic reactions: Theories of explanation (FMO, Woodward-Hoffmann and PMO approach), frontier orbitals, electrocyclisation and reterocyclisation of 1,3 butadiene, cyclobutadiene and ,hexatriene derivatives, allylic cations(1,5 diphenylpentadienyl cation) and allylic anions (1,5 diphenylpentadienyl anion), ring opening in bicyclo [4.1.0] heptane derivatives, valence tautomerism.
Cycloaddition reactions: 2+2, 4+2 cycloaddition, 1, 3-dipolar cycloaddition and cheletropic reactions, stereoselectivity (endo, exo), stereospecific and regioselective hydrogen reactions, Lewis-acid catalysis in Diels- Alder reaction.
Sigmatropic rearrangements: Suprafacial and antarafacial shifts of H , sigmatropic shifts involving carbon moieties, 3, 3- and 5, 5-sigmatropic rearrangements, Claisen, Cope and Aza- Cope rearrangements, isomerization of divinyl cyclopropane, Fluxional tautomerism (bullvalene), Ene reaction.
Disconnection approach, Synthons and synthetic equivalents, d, d, dand dsynthons, , functional group inter-conversions, the importance of the order of events in organic synthesis, one group C-X and two group C-X disconnections, chemoselectivity, reversal of polarity, cyclisation reactions, amine synthesis, principle of protection of alcohol, amine, carbonyl and carboxylgroups.
One and Two Group C-C Disconnections
Alcohols and carbonyl compounds, regioselectivity, alkene synthesis, uses of alkynes and aliphatic nitro compounds in organic synthesis, Diels- Alder reaction, 1,3-difunctionalised compounds, α, β-unsaturated carbonyl compounds, control in carbonyl condensations, 1,5- difunctionalised compounds, Michael addition and Robinson annelation.
- Fundamentals of Photochemistry, Third Edition; K.K. Rohatagi and Mukherjee; New Age International Publishers Pvt. Ltd., New Delhi, 2007.
- Reaction Mechanism in Organic Chemistry, Third Edition; S.M. Mukherjee and S.P. Singh; Macmillan, India Ltd., New Delhi, 2003.
- Modern Methods of Organic Synthesis, Fourth Edition; W. Carruthers; Cambridge Univ. Press, UK, 2005.
- CRC Handbook of Organic Photochemistry and Photobiology, Second Edition; W. Horspool and
- F. Lenci; CRC Press LLC, US, 2004.
- Molecular Reactions and Photochemistry, First Edition, C. H. Depuy and L. Orville Chapman; Prentice-Hall of India Pvt. Ltd, New Delhi, 1988.
- Advanced Organic Chemistry Part A & B, Fifth Edition; F. A. Carey and R. J. Sundberg; Springer, US, 2007.
- Designing Organic Synthesis: A Programmed Introduction to the Sython Approach, First Edition; S. Warren; John Wiley and Sons, Great Britain, 2010.
- Organic Synthesis- Concepts, Methods and Starting Materials, J. Fuhrhop and G.Penzillin; Second Edition; Wiley-VCH, New York: 2003.
e-Resources:
- https://epgp.inflibnet.ac.in/Home/ViewSubject?catid=13G8VouhmrFfuhs6rkiyTA== (P-14)
- https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/photchem.htm (Photochemistry)
- https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/pericycl.htm#top1 (Pericyclic reactions)
- https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/synth1.htm#top2 (Disconnection approach)
