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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 outcome (at course level) |
Learning and Teaching Strategies |
Assessment Strategies |
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Course Code |
Course Title |
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24CHY321 |
Photochemistry, Pericyclic Reactions and Disconnection Approach (Theory) |
CO98: Distinguish between thermal and photochemical reactions and explain the photochemistry of carbonyl compounds. CO99: Explain the various photochemical reactions of alkenes and aromatic compounds along with singlet oxygen reactions. CO100: Appraise the orbital interactions and orbital symmetry correlations in electrocyclic reactions to solve various problems. CO101: Explain and justify pericyclic reactions and their products in cycloaddition and sigmatropic reactions. CO102: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. CO103: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 methane rearrangement.
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, d1, d2, d3 and d4 synthons, , 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 carboxyl groups.
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)
